Inside the Climate Tutorial

Thanks to an article at Wired, we get a first glimpse into what transpired at the March 21 courtroom tutorial called by Federal District court  Judge Alsup.  From a science perspective, it looks at the moment like a missed opportunity.  The oil company lawyers sat in silence, allowing Chevron’s lead attorney to speak for them, and he mainly quoted from IPCC documents.  The calculation seems to be taking a position that we didn’t know more and not any sooner than the IPCC came to conclusions in their series of assessment reports.  The plaintiffs let alarmist scientists present on their behalf, and can now claim their opinions were not refuted.

The Wired article is In the Courtroom, Climate Science Needs Substance–and Style Excerpts below with my bolds.

Outside the usual procedural kabuki of the courtroom, the truth is no one really knew what to expect from this court-ordered “tutorial.” For a culture based in large measure on precedent, putting counsel and experts in a room to hash out climate change for a trial—putting everyone on the record, in federal court, on what is and is not true about climate science—was literally unprecedented.

What Alsup got might not have been a full on PowerPoint-powered preview of the trial. But it did reveal a lot about the styles and conflicts inherent in the people who produce the carbon and the people who study it.

The other petrochemists put forth Theodore Boutrous, an AC-130 gunship of a lawyer who among other things got the US Supreme Court to overturn the California law against same-sex marriage. Here, retained specifically by Chevron, Boutrous argued what seemed to be climate change’s chapter-and-verse. He extolled the virtues of the several IPCC reports, 2013 most recently, and quoted them liberally. Boutrous talked about how the reports’ conclusions have gotten more and more surefooted about “anthropogenic” causes of climate change—it’s people!—and outcomes like sea level rise. “From Chevron’s perspective, there’s no debate about climate science,” Boutrous said. “Chevron accepts what this scientific body—scientists and others—what the IPCC has reached consensus on.”

Still, over the course of the morning, Boutrous nevertheless tried to neg the IPCC in two specific ways. One was a classic: He challenged the models that climate scientists use to attempt to predict the future. These computer models, Boutrous said, are “increasingly complex. That can make the modeling more powerful.” But with great power comes great potential wrongness. “Because it’s an attempt to represent things in the real world, the complexity can bring more risk.” He assured the court that Chevron agreed with the IPCC approach—posting up a slide pulled from an IPCC report that showed the multicolored paths of literally hundreds of models, using different emissions scenarios and essentially describing the best case and worst case (and a bunch of in-between cases). It looked like a blast of fireworks emerging from observed average temperature, headed chaotically up and to the right.

So here comes the crux of the thing—a question not of whether climate change is real, but whether you can ascribe blame for it. Leaning heavily on more IPCC quotes, Boutrous showed slides and statistics saying that climate change is a global problem that doesn’t differentially affect the West Coast of North America and isn’t caused by any one emitter. Or even any one source of emissions. Anthropogenic emissions are driven by things like population size, economic activities, lifestyle, energy use, land use patterns, and technology and climate policy, according to the IPCC. “The IPCC does not say it’s the extraction and production of oil,” Boutrous said. “It’s economic activity that creates the demand for energy and that leads to emissions.”

If that seems a little bit like the “guns don’t kill people; people kill people” of petrochemical capitalism, well, Judge Alsup did start the morning by saying today was a day for science, not politics.

So what knives did the representatives of the state of California bring to this oil-fight? Here’s where style is interesting. California didn’t front lawyers. For the science tutorial, the municipalities fronted scientists—people who’d been first authors on chapters in the IPCC reports from which Boutrous quoted, and one who’d written a more recent US report and a study of sea level rise in California. They knew their stuff and could answer all of Judge Alsup’s questions … but their presentations were more like science conference fodder than well-designed rhetoric.

For example, Myles Allen, leader of the Climate Research Program at the University of Oxford, gave a detailed, densely-illustrated talk on the history and science of climate change…but he also ended up in an extended back and forth with Alsup about whether Svante Arrhenius’ 1896 paper hypothesizing that carbon dioxide in Earth’s atmosphere warmed the planet explicitly used the world “logarithmic.” Donald Wuebbles, an atmospheric scientist at the University of Illinois and co-author of the Nobel Prize-winning 2007 IPCC report, mounted a grim litany of all the effects scientists can see, today, of climate, but Alsup caught him up asking for specific things he disagreed with Boutrous on—a tough game since Boutrous was just quoting the IPCC.

Then Alsup and Wuebbles took a detour into naming other renewable power sources besides solar and wind. “Nuclear would not put out any CO2, right? We might get some radiation as we drive by, but maybe in retrospect we should have taken a hard look at nuclear?” Alsup interrupted. “No doubt solar is good where you can use it, but do you really think it could be a substitute for supplying the amount of power America used in the last 30 years?”

“I think solar could be a significant factor of our energy future,” Wuebbles said. “I don’t think there’s any one silver bullet.”

In part, one might be tempted to put some blame on Alsup here. You might remember him from such trials as Uber v. Waymo, where he asked for a similar tutorial on self-driving car technology. Or from Oracle v. Google, a trial for which Alsup taught himself a little of the programming language Java so he’d understand the case better. Or from his intercession against the Trump administration’s attempt to cancel the Deferred Action for Childhood Arrivals program, protecting the immigration status of so-called Dreamers. “He’s kind of quirky and not reluctant to do things kind of outside the box,” said Deborah Sivas, Director of the Environmental and Natural Resource Law & Policy Program at Stanford Law School. “And I think he sees this as a precedent-setting case, as do the lawyers.”

It’s possible, then, to infer that Alsup was doing more than just getting up to speed on climate change on Wednesday. The physics and chemistry are quite literally textbook, and throughout the presentations he often seemed to know more than he was letting on. He challenged chart after chart incisively, and often cut in on history. When Allen brought up Roger Revelle’s work showing that oceans couldn’t absorb carbon—at least, not fast enough to stave off climate change, Alsup interrupted.

“Is it true that Revelle initially thought the ocean would absorb all the excess, and that he came to this buffer theory a little later?” Alsup asked.

“You may know more of this history than I do,” Allen said.

But on the other hand, some of what the litigators seemed to not know sent the scientists in the back in literal spasms. When Boutrous couldn’t answer Alsup’s questions about the specific causes of early 20th-century warming (presumably before the big industrial buildup of the 1950s), Allen and Wuebbles, sitting just outside the gallery, clenched fists and looked like they were having to keep from shouting out the answer. Later, Alsup acknowledged that he’d watched An Inconvenient Truth to prepare, and Boutrous said he had, too.

All of which makes it hard to tell whether bringing scientists to this table was the right move. And maybe that has been the problem all along. The interface where utterly flexible law and policy moves against the more rigid statistical uncertainties of scientific observation has always been contested space. The practitioners of both arts seem foreign to each other; the cultural mores differ.

Maybe that’s what this “tutorial” was meant for. As Sivas says, the facts aren’t really in doubt here. Or rather, most of them aren’t, and maybe Alsup will use today as a kind of discovery process, a way to crystalize the difference between uncertainty in science and uncertainty under the law. “That’s what judges do. They decide the credibility of one expert over another,” Sivas says. “That doesn’t mean it’s scientific truth. It means it’s true as a legal claim.”

The skeptical scientific brief was filed by esteemed scientists Happer, Koonin and Lindzen, but its effect is not yet evident.  More details are at Cal Climate Tutorial: The Meat


Cal Climate Tutorial: The Meat

Prevous posts provided the context regarding the Climate Tutorial requested by Judge Alsup in the lawsuit case filed by California cities against big oil companies: Cal Court to Hear Climate Tutorial

An overview of a submission by Professors Happer, Koonin and Lindzen was in Climate Tutorial for Judge Alsup

This post goes into the meat and potatoes of that submission with excerpts from Section II: Answers to specific questions (my bolds)

Question 1: What caused the various ice ages (including the “little ice age” and prolonged cool periods) and what caused the ice to melt? When they melted, by how much did sea level rise?

The discussion of the major ice ages of the past 700 thousand years is distinct from the discussion of the “little ice age.” The former refers to the growth of massive ice sheets (a mile or two thick) where periods of immense ice growth occurred, lasting approximately eighty thousand years, followed by warm interglacials lasting on the order of twenty thousand years. By contrast, the “little ice age” was a relatively brief period (about four hundred years) of relatively cool temperatures accompanied by the growth of alpine glaciers over much of the earth.

Tutorial 1

The last glacial episode ended somewhat irregularly. Ice coverage reached its maximum extent about eighteen thousand years ago. Melting occurred between about twenty thousand years ago and thirteen thousand years ago, and then there was a strong cooling (Younger Dryas) which ended about 11,700 years ago. Between twenty thousand years ago and six thousand years ago, there was a dramatic increase in sea level of about 120 meters followed by more gradual increase over the following several thousand years. Since the end of the “little ice age,” there has been steady increase in sea-level of about 6 inches per century.


As to the cause of the “little ice age,” this is still a matter of uncertainty. There was a long hiatus in solar activity that may have played a role, but on these relatively short time scales one can’t exclude natural internal variability. It must be emphasized that the surface of the earth is never in equilibrium with net incident solar radiation because the oceans are always carrying heat to and from the surface, and the motion systems responsible have time scales ranging from years (for example ENSO) to millennia.

The claim that orbital variability requires a boost from CO2 to drive ice ages comes from the implausible notion that what matters is the orbital variations in the global average insolation (which are, in fact, quite small) rather than the large forcing represented by the Milankovitch parameter. This situation is very different than in the recent and more modest shorter-term warming, where natural variability makes the role of CO2 much more difficult to determine.

Question 2: What is the molecular difference by which CO2 absorbs infrared radiation but oxygen and nitrogen do not?

Molecules like CO2, H2O, CO or NO are called a greenhouse-gas molecules, because they can efficiently absorb or emit infrared radiation, but they are nearly transparent to sunlight. Molecules like O2 and N2 are also nearly transparent to sunlight, but since they do not absorb or emit thermal infrared radiation very well, they are not greenhouse gases. The most important greenhouse gas, by far, is water vapor. Water molecules, H2O, are permanently bent and have large electric dipole moments.

Question 3: What is mechanism by which infrared radiation trapped by CO2 in the atmosphere is turned into heat and finds its way back to sea level?

Unscattered infrared radiation is very good at transmitting energy because it moves at the speed of light. But the energy per unit volume stored by the thermal radiation in the Earth’s atmosphere is completely negligible compared to the internal energy of the air molecules.

Although CO2 molecules radiate very slowly, there are so many CO2 molecules that they produce lots of radiation, and some of this radiation reaches sea level. The figure following shows downwelling radiation measured at the island of Nauru in the Tropical Western Pacific Ocean, and at colder Point Barrow, Alaska, on the shore of the Arctic Ocean.

So the answer to the last part of the question, “What is the mechanism by which … heat … finds its way back to sea level?” is that the heat is radiated to the ground by molecules at various altitudes, where there is usually a range of different temperatures. The emission altitude is the height from which radiation could reach the surface without much absorption, say 50% absorption. For strongly absorbed frequencies, the radiation reaching the ground comes from low-altitude molecules, only a few meters above ground level for the 667 cm-1 frequency at the center of the CO2 band. More weakly absorbed frequencies are radiated from higher altitudes where the temperature is usually colder than that of the surface. But occasionally, as the data from Point Barrow show, higher-altitude air can be warmer than the surface.

Closely related to Question 3 is how heat from the absorption of sunlight by the surface gets back to space to avoid a steadily increasing surface temperature. As one might surmise from the figure, at Narau there is so much absorption from CO2 and by water vapor, H2O, that most daytime heat transfer near the surface is by convection, not by radiation. Especially important is moist convection, where the water vapor in rising moist air releases its latent heat to form clouds. The clouds have a major effect on radiative heat transfer. Cooled, drier, subsiding air completes the convection circuit. Minor changes of convection and cloudiness can have a bigger effect on the surface temperature than large changes in CO2 concentrations.

Question 4: Does CO2 in the atmosphere reflect any sunlight back into space, such that the reflected sunlight never penetrates the atmosphere in the first place?

The short answer to this question is “No”, but it raises some interesting issues that we discuss below.

Molecules can either scatter or absorb radiation. CO2 molecules are good absorbers of thermal infrared radiation, but they scatter almost none. Infrared radiant energy absorbed by a CO2 molecule is converted to internal vibrational and rotational energy. This internal energy is quickly lost in collisions with the N2 and O2 molecules that make up most of the atmosphere. The collision rates, billions per second, are much too fast to allow the CO2 molecules to reradiate the absorbed energy, which takes about a second. CO2 molecules in the atmosphere do emit thermal infrared radiation continuously, but the energy is almost always provided by collisions with N2 and O2 molecules, not by previously absorbed radiation. The molecules “glow in the dark” with thermal infrared radiation.

H2O CO2 absorption spectrums

The figure shows that water vapor is by far the most important absorber. It can absorb both thermal infrared radiation from the Earth and shorter-wave radiation from the Sun. Water vapor and its condensates, clouds of liquid or solid water (ice), dominate radiative heat transfer in the Earth’s atmosphere; CO2 is of secondary importance.

If Question 4 were “Do clouds in the atmosphere reflect any sunlight back into space, such that the reflected sunlight never penetrates the atmosphere in the first place?” the answer would be “Yes”. It is common knowledge that low clouds on a sunny day shade and cool the surface of the Earth by scattering the sunlight back to space before it can be absorbed and converted to heat at the surface.

The figure shows that very little thermal radiation from the surface can reach the top of the atmosphere without absorption, even if there are no clouds. But some of the surface radiation is replaced by molecular radiation emitted by greenhouse molecules or cloud tops at sufficiently high altitudes that the there are no longer enough higher-altitude greenhouse molecules or clouds to appreciably attenuate the radiation before it escapes to space. Since the replacement radiation comes from colder, higher altitudes, it is less intense and does not reject as much heat to space as the warmer surface could have without greenhousegas absorption.

As implied by the figure, sunlight contains some thermal infrared energy that can be absorbed by CO2. But only about 5% of sunlight has wavelengths longer than 3 micrometers where the strongest absorption bands of CO2 are located. The Sun is so hot, that most of its radiation is at visible and near-visible wavelengths, where CO2 has no absorption bands.

Question 5: Apart from CO2, what happens to the collective heat from tail pipe exhausts, engine radiators, and all other heat from combustion of fossil fuels? How, if at all, does this collective heat contribute to warming of the atmosphere?

After that energy is used for heat, mobility, and electricity, the Second Law of Thermodynamics guarantees that virtually all of it ends up as heat in the climate system, ultimately to be radiated into space along with the earth’s natural IR emissions. [A very small fraction winds up as visible light that escapes directly to space through the transparent atmosphere, but even that ultimately winds up as heat somewhere “out there.”]

How much does this anthropogenic heat affect the climate? There are local effects where energy use is concentrated, for example in cities and near power plants. But globally, the effects are very small. To see that, convert the global annual energy consumption of 13.3 Gtoe (Gigatons of oil equivalent) to 5.6 × 1020 joules. Dividing that by the 3.2 × 107 seconds in a year gives a global power consumption of 1.75 × 1013 Watts. Spreading that over the earth’s surface area of 5.1 × 1014 m2 results in an anthropogenic heat flux of 0.03 W/m2 . This is some four orders of magnitude smaller than the natural heat fluxes of the climate system, and some two orders of magnitude smaller than the anthropogenic radiative forcing.

Question 6: In grade school many of us were taught that humans exhale CO2 but plants absorb CO2 and return oxygen to the air (keeping the carbon fiber). Is this still valid? If so why hasn’t plant life turned the higher levels of CO2 back into oxygen? Given the increase in population on earth (four billion), is human respiration a contributing factor to the buildup of CO2?

If all of the CO2 produced by current combustion of fossil fuels remained in the atmosphere, the level would increase by about 4 ppm per year, substantially more than the observed rate of around 2.5 ppm per year, as seen in the figure above. Some of the anthropogenic CO2 emissions are being sequestered on land or in the oceans.


There is evidence that primary photosynthetic productivity has increased somewhat over the past half century, perhaps due to more CO2 in the atmosphere. For example, the summerwinter swings like those in the figure above are increasing in amplitude. Other evidence for modestly increasing primary productivity includes the pronounced “greening” of the Earth that has been observe by satellites. An example is the map above, which shows a general increase in vegetation cover over the past three decades.

The primary productivity estimate mentioned above would also correspond to an increase of the oxygen fraction of the air by 50 ppm, but since the oxygen fraction of the air is very high (209,500 ppm), the relative increase would be small and hard to detect. Also much of the oxygen is used up by respiration.

The average human exhales about 1 kg of CO2 per day, so the 7 billion humans that populate the Earth today exhale about 2.5 x 109 tons of CO2 per year, a little less than 1% of that is needed to support the primary productivity of photosynthesis and only about 6% of the CO2 “pollution” resulting from the burning of fossil fuels. However, unlike fossil fuel emissions, these human (or more generally, biological) emissions do not accumulate in the atmosphere, since the carbon in food ultimately comes from the atmosphere in the first place.

Question 7: What are the main sources of CO2 that account for the incremental buildup of CO2 in the atmosphere?

The CO2 in the atmosphere is but one reservoir within the global carbon cycle, whose stocks and flows are illustrated by Figure 6.1 from IPCC AR5 WG1:

There is a nearly-balanced annual exchange of some 200 PgC between the atmosphere and the earth’s surface (~80 Pg land and ~120 Pg ocean); the atmospheric stock of 829 Pg therefore “turns over” in about four years.

Human activities currently add 8.9 PgC each year to these closely coupled reservoirs (7.8 from fossil fuels and cement production, 1.1 from land use changes such as deforestation). About half of that is absorbed into the surface, while the balance (airborne fraction) accumulates in the atmosphere because of its multicentury lifetime there. Other reservoirs such as the intermediate and deep ocean are less closely coupled to the surface-atmosphere system.

Much of the natural emission of CO2 stems from the decay of organic matter on land, a process that depends strongly on temperature and moisture. And much CO2 is absorbed and released from the oceans, which are estimated to contain about 50 times as much CO2 as the atmosphere. In the oceans CO2 is stored mostly as bicarbonate (HCO3 – ) and carbonate (CO3 – – ) ions. Without the dissolved CO2, the mildly alkaline ocean with a pH of about 8 would be very alkaline with a pH of about 11.3 (like deadly household ammonia) because of the strong natural alkalinity.

Only once in the geological past, the Permian period about 300 million years ago, have atmospheric CO2 levels been as low as now. Life flourished abundantly during the geological past when CO2 levels were five or ten times higher than those today.

Question 8: What are the main sources of heat that account for the incremental rise in temperature on earth?

The only important primary heat source for the Earth’s surface is the Sun. But the heat can be stored in the oceans for long periods of time, even centuries. Variable ocean currents can release more or less of this stored heat episodically, leading to episodic rises (and falls) of the Earth’s surface temperature.

Incremental changes of the surface temperature anomaly can be traced back to two causes: (1) changes in the surface heating rate; (2) changes in the resistance of heat flow to space. Quasi periodic El Nino episodes are examples of the former. During an El Nino year, easterly trade winds weaken and very warm deep water, normally blown toward the coasts of Indonesia and Australia, floats to the surface and spreads eastward to replace previously cool surface waters off of South America. The average temperature anomaly can increase by 1 C or more because of the increased release of heat from the ocean. The heat source for the El Nino is solar energy that has accumulated beneath the ocean surface for several years before being released.

On average, the absorption rate of solar radiation by the Earth’s surface and atmosphere is equal to emission rate of thermal infrared radiation to space. Much of the radiation to space does not come from the surface but from greenhouse gases and clouds in the lower atmosphere, where the temperature is usually colder than the surface temperature, as shown in the figure on the previous page. The thermal radiation originates from an “escape altitude” where there is so little absorption from the overlying atmosphere that most (say half) of the radiation can escape to space with no further absorption or scattering. Adding greenhouse gases can warm the Earth’s surface by increasing the escape altitude. To maintain the same cooling rate to space, the temperature of the entire troposphere, and the surface, would have to increase to make the effective temperature at the new escape altitude the same as at the original escape altitude. For greenhouse warming to occur, a temperature profile that cools with increasing altitude is required.

Over most of the CO2 absorption band (between about 580 cm-1 and 750 cm-1 ) the escape altitude is the nearly isothermal lower stratosphere shown in the first figure. The narrow spike of radiation at about 667 cm-1 in the center of the CO2 band escapes from an altitude of around 40 km (upper stratosphere), where it is considerably warmer than the lower stratosphere due heating by solar ultraviolet light which is absorbed by ozone, O3. Only at the edges of the CO2 band (near 580 cm-1 and 750 cm-1 ) is the escape altitude in the troposphere where it could have some effect on the surface temperature. Water vapor, H2O, has emission altitudes in the troposphere over most of its absorption bands. This is mainly because water vapor, unlike CO2, is not well mixed but mostly confined to the troposphere.


To summarize this overview, the historical and geological record suggests recent changes in the climate over the past century are within the bounds of natural variability. Human influences on the climate (largely the accumulation of CO2 from fossil fuel combustion) are a physically small (1%) effect on a complex, chaotic, multicomponent and multiscale system. Unfortunately, the data and our understanding are insufficient to usefully quantify the climate’s response to human influences. However, even as human influences have quadrupled since 1950, severe weather phenomena and sea level rise show no significant trends attributable to them. Projections of future climate and weather events rely on models demonstrably unfit for the purpose. As a result, rising levels of CO2 do not obviously pose an immediate, let alone imminent, threat to the earth’s climate.

Full text of submission is here

Climate Tutorial for Judge Alsup

H/T tomomason for noticing this document submitted to Judge Alsup’s requested tutorial

The Honorable William H. Alsup

The covering letter and the submission itself are here.  Below are excerpts of introductory and overview comments.

The Court has invited a tutorial on global warming and climate change, which is set to occur March 21, 2018. The Court also identified specific questions to be addressed at the tutorial. Pursuant to Civil L.R. 7-11, Professors William Happer, Steven E. Koonin, and Richard S. Lindzen respectfully ask the Court to accept their presentation (attached to this motion as Exhibit A) in response to the Court’s questions. The professors would be honored to participate directly in the tutorial if the Court desires.

The Court’s specified questions include topics that have been the subject of the professors’ study and analysis for decades. These men have been thought and policy leaders in the scientific community and in the administrations of two different U.S. Presidents. They have extensive research experience with the specific issues the Court identified. As such, they offer a valuable perspective on these issues. The attached presentation contains three sections: (1) an overview; (2) responses to the Court’s questions; and (3) biographies of the professors.

Overview from the Submission

Our overview of climate science is framed through four statements:

1. The climate is always changing; changes like those of the past half-century are common in the geologic record, driven by powerful natural phenomena

2. Human influences on the climate are a small (1%) perturbation to natural energy flows

3. It is not possible to tell how much of the modest recent warming can be ascribed to human influences

4. There have been no detrimental changes observed in the most salient climate variables and today’s projections of future changes are highly uncertain

We offer supporting evidence for each of these statements drawn almost exclusively from the Climate Science Special Report (CSSR) issued by the US government in November, 2017 or from the Fifth Assessment Report (AR5) issued in 2013-14 by the UN’s Intergovernmental Panel on Climate Change or from the refereed primary literature.

To summarize this overview, the historical and geological record suggests recent changes in the climate over the past century are within the bounds of natural variability. Human influences on the climate (largely the accumulation of CO2 from fossil fuel combustion) are a physically small (1%) effect on a complex, chaotic, multicomponent and multiscale system. Unfortunately, the data and our understanding are insufficient to usefully quantify the climate’s response to human influences. However, even as human influences have quadrupled since 1950, severe weather phenomena and sea level rise show no significant trends attributable to them. Projections of future climate and weather events rely on models demonstrably unfit for the purpose. As a result, rising levels of CO2 do not obviously pose an immediate, let alone imminent, threat to the earth’s climate.

The submission includes detailed responses to each of the judge’s questions and are well worth reading.

Spring Outlook AER

Dr. Judah Cohen has posted his outlook on the spring in Arctic and NH at his AER blog.  Exerpts below with my bolds.


  • The Arctic Oscillation (AO) is currently slightly negative and is predicted to trend positive but never to stray too far from neutral . The bulk of the atmospheric response to the polar vortex (PV) disruption, which occurred in February seems to have already occurred though some lingering influences continue.
  • The current negative AO is reflective of positive pressure/geopotential height anomalies across the North Atlantic side of the Arctic and negative pressure/geopotential height anomalies across the mid-latitudes of the North Atlantic.
  • The North Atlantic Oscillation (NAO) is currently also negative with positive pressure/geopotential height anomalies across Greenland and negative pressure/geopotential height anomalies across the mid-latitudes of the North Atlantic. The forecasts are for the NAO to also trend positive and then straddle neutral the next two weeks.
  • The PV is predicted to linger across Western Siberia over the next two weeks. This will contribute to persistent troughing/negative geopotential height anomalies across northern Eurasia including Europe. This will allow cold temperatures now stretching from Northern Asia to Europe and the United Kingdom (UK) to mostly remain in place with some fluctuation in intensity over the next two weeks.
  • Currently ridging/positive geopotential height anomalies south of the Aleutians is contributing to troughing/negative geopotential height anomalies in the Gulf of Alaska and the West Coast of North America with additional ridging/positive geopotential height anomalies in central North America and more troughing/negative geopotential height anomalies downstream across the Eastern United States (US). This pattern in general favors normal to above normal temperatures for western North America and normal to below normal temperatures in the Eastern US.
  • However the pattern across North America is predicted to be slowly progressive with time and become much less amplified. This will lead to a general weakening of temperature anomalies for much of the continent, though warm temperature anomalies in the Western US are predicted to remain consistent in magnitude.
  • I continue to believe that the ongoing stratospheric PV displacement in Western Siberia favors overall cold temperatures for Siberia that extend into Europe as well as a cold bias in temperatures in the Northeastern US. These cold temperature anomalies are likely to persist as long as the stratospheric PV lingers across Siberia.

Arctic Methane

AWI sea-ice physicists have erected an ice camp to investigate melt ponds on Arctic sea ice. Credit: Photo : Alfred-Wegener-Institut / Mar Fernandez

Two recent papers enrich our understanding of interactions between oceans, ice and dissolved methane. The latest one is described in a Science Daily article Wandering greenhouse gas Climate models need to take into account the interaction between methane, the Arctic Ocean and ice by E. Damm et al. of Alfred Wegener Institute March 16, 2018. Excerpts with my bolds.

On the seafloor of the shallow coastal regions north of Siberia, microorganisms produce methane when they break down plant remains. If this greenhouse gas finds its way into the water, it can also become trapped in the sea ice that forms in these coastal waters. As a result, the gas can be transported thousands of kilometres across the Arctic Ocean and released in a completely different region months later.

AWI geochemist Dr Ellen Damm tested the waters of the High North for the greenhouse gas methane. In an expedition to the same region four years later, she had the chance to compare the measurements taken at different times, and found significantly less methane in the water samples.

Ellen Damm, together with Dr Dorothea Bauch from the GEOMAR Helmholtz Centre for Ocean Research in Kiel and other colleagues, analysed the samples to determine the regional levels of methane, and the sources. By measuring the oxygen isotopes in the sea ice, the scientists were able to deduce where and when the ice was formed. To do so, they had also taken sea-ice samples. Their findings: the ice transports the methane across the Arctic Ocean. And it appears to do so differently every year.

“As more seawater freezes it can expel the brine contained within, entraining large quantities of the methane locked in the ice,” explains AWI researcher Ellen Damm. As a result, a water-layer is formed beneath the ice that contains large amounts of both salt and methane. Yet the ice on the surface and the dense saltwater below, together with the greenhouse gas it contains, are all pushed on by the wind and currents. According to Thomas Krumpen, “It takes about two and a half years for the ice formed along the coast of the Laptev Sea to be carried across the Arctic Ocean and past the North Pole into the Fram Strait between the east cost of Greenland and Svalbard.” Needless to say, the methane trapped in the ice and the underlying saltwater is along for the ride.

The rising temperatures produced by climate change are increasingly melting this ice. Both the area of water covered by sea ice and the thickness of the ice have been decreasing in recent years, and thinner ice is blown farther and faster by the wind. “In the past few years, we’ve observed that ice is carried across the Arctic Ocean faster and faster,” confirms Thomas Krumpen. And this process naturally means major changes in the Arctic’s methane turnover. Accordingly, quantifying the sources, sinks and transport routes of methane in the Arctic continues to represent a considerable challenge for the scientific community.

Sea ice drift trajectories leading to the 60°E section and δ18O isotopic composition (filled symbols) and salinity (open symbols) in sea ice at this section. Backward drift trajectories from the 60°E section show the sea ice formation areas, i.e. off shore within the Laptev Sea and in the coastal polynya areas. Trajectories were calculated based on a combination of sea ice motion and concentration products from passive microwave satellite data. The colour of the end node indicates the source area of sampled sea ice. Trajectories with red end nodes were formed in polynyas, namely the New Siberian (NS) Polynya, Taymyr (T) Polynya, Northeastern Taymyr (NET) Polynya and East Severnaya Zemlya (ESZ) Polynya. Grey end nodes refer to trajectories that were formed during freeze-up further offshore. The colour coding of the start node characterizes the month of formation (primarily October) of the individual trajectories. The δ18O ice isotopic composition reflects the δ18O composition of the water column from which each segment of the ice core was formed. Light values below about −4‰ indicate formation in coastal polynyas while values above −2‰ indicate freeze-up formation offshore. Salinity of the ice cores is in all cases below 4. The map is generated with IDL (Interactive Data Langue), software for analysis and visualization of data provided by Harris Geospatial Solutions (

The paper itself is The Transpolar Drift conveys methane from the Siberian Shelf to the central Arctic Ocean

Abstract: Methane sources and sinks in the Arctic are poorly quantified. In particular, methane emissions from the Arctic Ocean and the potential sink capacity are still under debate. In this context sea ice impact on and the intense cycling of methane between sea ice and Polar surface water (PSW) becomes pivotal. We report on methane super- and under-saturation in PSW in the Eurasian Basin (EB), strongly linked to sea ice-ocean interactions.

In the southern EB under-saturation in PSW is caused by both inflow of warm Atlantic water and short-time contact with sea ice. By comparison in the northern EB long-time sea ice-PSW contact triggered by freezing and melting events induces a methane excess. We reveal the Transpolar Drift Stream as crucial for methane transport and show that inter-annual shifts in sea ice drift patterns generate inter-annually patchy methane excess in PSW.

Using backward trajectories combined with δ18O signatures of sea ice cores we determine the sea ice source regions to be in the Laptev Sea Polynyas and the off shelf regime in 2011 and 2015, respectively. We denote the Transpolar Drift regime as decisive for the fate of methane released on the Siberian shelves.

From the study conclusions: Our study is focused on sea ice-ocean interaction, while the role of sea ice–air fluxes and oxidation as pathways of methane in the Arctic need further investigation.

Our study confirms that methane release from sea ice is coupled to the ice freeze and melt cycle. Hence the intensity of freeze events in winter and the amount of summer sea ice retreat primarily triggers how much methane is released during transport within the TDS in the central Arctic.

To which extent the interior Arctic Ocean might act as a final or just a temporal sink, i.e. with final efflux to the atmosphere, is another open question. Furthermore, sea ice retreat, thinning, and decreasing multiyear and increasing first-year sea ice will have, yet, unconsidered consequences for the sea ice-air exchange and the source-sink balance of the greenhouse gas methane in the Arctic. In addition to the potential source capacity for efflux from the northern Eurasian Basin, the potential sink capacity of the southern EB for atmospheric methane might be enhanced if the volume of inflowing AW increases and the region becomes seasonally ice free in the future.

How the Ocean Processes Methane

Another study looks at ancient stored methane in the Arctic in relation to ongoing natural fluxes that were the focus of the above research. The paper is described in a Science Daily article Release of ancient methane due to changing climate kept in check by ocean waters by Katy J. Sparrow, John D. Kessler et al. 2018

Trapped in ocean sediments near continents lie ancient reservoirs of methane called methane hydrates. These ice-like water and methane structures encapsulate so much methane that many researchers view them as both a potential energy resource and an agent for environmental change. In response to warming ocean waters, hydrates can degrade, releasing the methane gas. Scientists have warned that release of even part of the giant reservoir could significantly exacerbate ongoing climate change.

However, methane only acts as a greenhouse gas if and when it reaches the atmosphere — a scenario that would occur only if the liberated methane travelled from the point of release at the seafloor to the surface waters and the atmosphere.

A team of scientists conducted fieldwork just offshore of the North Slope of Alaska, near Prudhoe Bay. Sparrow calls the spot “ground zero” for oceanic methane emissions resulting from ocean warming. In some parts of the Arctic Ocean, the shallow regions near continents may be one of the settings where methane hydrates are breaking down now due to warming processes over the past 15,000 years. In addition to methane hydrates, carbon-rich permafrost that is tens of thousands of years old — and found throughout the Arctic on land and in seafloor sediments — can produce methane once this material thaws in response to warming. With the combination of the aggressive warming occurring in the Arctic and the shallow water depths, any released methane has a short journey from emission at the seafloor to release into the atmosphere.

We do observe ancient methane being emitted from the seafloor to the overlying seawater, confirming past suspicions,” Kessler says. “But, we found that this ancient methane signal largely disappears and is replaced by a different methane source the closer you get to the surface waters.” The methane at the surface is instead from recently produced organic matter or from the atmosphere.

“We found that very little ancient methane reaches surface waters even in the relatively shallow depths of 100 feet. Exponentially less methane would be able to reach the atmosphere in waters that are thousands of feet deep at the very edge of the shallow seas near continents, which is the area of the ocean where the bulk of methane hydrates are,” Sparrow says. “Our data suggest that even if increasing amounts of methane are released from degrading hydrates as climate change proceeds, catastrophic emission to the atmosphere is not an inherent outcome.

Full text of study is Limited contribution of ancient methane to surface waters of the U.S. Beaufort Sea shelf


It seems our knowledge of Arctic methane is incomplete but growing. It is good news to understand how ancient methane released from sediment is neutralized by ocean processes before it can be released. And it is also good that methane captured by shelf sea ice is transported to the North Pole.


The news releases repeat the erroneous claim that methane (CH4) is 25 times more powerful GHG than CO2.  That exaggerated number comes from comparing the two gases on a mass basis. Because CH4 has a lesser atomic weight, a kilogram will have more molecules than the same mass of CO2.  But radiative activity depends on the volume, not the mass.

More background on CH4 as a GHG:  Much Ado About Methane

Arctic Freezing Week


After stalling first week of March, Arctic ice is coming on strong now.  The image above shows the last week, setting new maximums for 2018 for NH overall, as well in Barents Sea.  The graph below shows that as of yesterday, Barents is well above the 11 year average, and even ahead of 2014 the highest year in the decade.

Barents day074

Meanwhile ice extent is increasing on the Pacific side as well.  Bering rapidly grew 200k km2 in a week, setting a new 2018 maximum, while Okhotsk added 110k km2 for a new max ice extent there.


The graph below shows how strongly the Arctic is now freezing over.


Note the average max on day 62 and 2018 max yesterday on day 74, now matching 2007 and 120k km2 above last year.  SII (NOAA) continues to show ~200k km2 less extent.

Drift ice in Okhotsk Sea at sunrise.

The graph below shows 2018 NH ice extents since day 1, with and without the Pacific basins Bering and Okhotsk, compared to 11 year averages (2007 to 2017 inclusive).
The deficit is almost entirely due to Bering, with the shortfall closing in the last week.

Newsflash: NH Snow Exceptionally Huge This Year

Over land the northern hemisphere Globsnow snow-water-equivalent SWE product and over sea the OSI-SAF sea-ice concentration product. Credit: Image courtesy of Finnish Meteorological Institute

This just in from  Science Daily thanks to the Finnish Meteorological Institute: Exceptionally large amount of winter snow in Northern Hemisphere this year  March 14, 2018.

Excerpts below include both factual and speculative content (with my bolds.)

The new Arctic Now product shows with one picture the extent of the area in the Northern Hemisphere currently covered by ice and snow. This kind of information, which shows the accurate state of the Arctic, becomes increasingly important due to climate change.

In the Northern Hemisphere the maximum seasonal snow cover occurs in March. “This year has been a year with an exceptionally large amount of snow, when examining the entire Northern Hemisphere. The variation from one year to another has been somewhat great, and especially in the most recent years the differences between winters have been very great,” says Kari Luojus, Senior Research Scientist at the Finnish Meteorological Institute.

The information has been gleaned from the Arctic Now service of the Finnish Meteorological Institute, which is unique even on a global scale. The greatest difference compared with other comparable services is that traditionally they only tell about the extent of the ice or snow situation.

“Here at the Finnish Meteorological Institute we have managed to combine data to form a single image. In this way we can get a better situational picture of the cryosphere — that is, the cold areas of the Northern Hemisphere,” Research Professor Jouni Pulliainen observes. In addition to the coverage, the picture includes the water value of the snow, which determines the water contained in the snow. This is important information for drafting hydrological forecasts on the flood situation and in monitoring the state of climate and environment in general.

Information on the amount of snow is also sent to the Global Cryosphere Watch service of the World Meteorological Organisation (WMP) where the information is combined with trends and statistics of past years. Lengthy series of observation times show that the total amount of snow in the Northern Hemisphere has declined in the spring period and that the melting of the snow has started earlier in the same period. Examination over a longer period (1980-2017) shows that the total amount of snow in all winter periods has decreased on average.

Also, the ice cover on the Arctic Ocean has grown thinner and the amount and expanse of perennial ice has decreased. Before 2000 the smallest expanse of sea ice varied between 6.2 and 7.9 million square kilometres. In the past ten years the expanse of ice has varied from 5.4 to 3.6 million square kilometres. Extreme weather phenomena — winters in which snowfall is sometimes quite heavy, and others with little snow, will increase in the future.  (Speculation for sure.)

Here is the MASIE chart from yesterday, confirming extensive snow this year:

Bering Ice Deficit Gone in Five Days

An update to yesterdays post  Premature Arctic Ice Fears which discussed lop-sided media coverage of  a temporary ice shortfall in Bering Sea.  Now today, the image above shows that in just five days, that deficit has been obliterated.  Since day 66, Bering added 170k km2 to go over 400k km2, close to the previous Bering high in 2018 on day 34.  That was the last Arctic region where some alarm could be raised.  Overall, 2018 is now higher than 2017 at this date, having reached a new maximum of 14.6M km2.

Premature Arctic Ice Fears


Click on image to enlarge.

The alarms are sounding about lack of ice extent in Bering Sea, studiously ignoring what else is happening in the Arctic.  For instance the above image shows the last 10 days on the European side, with Barents Sea on the right growing steadily to a new maximum. On the left, Gulf of St. Lawrence ice is retreating as usual while Baffin Bay holds steady.

The Barents recovery is interesting and bears watching.  See how 2018 compares with other years in the Graph below.

Barents day070

Note the recent 2018 dramatic rise above average.  Meanwhile on the Pacific side the seesaw between Bering and Okhotsk continues:

In the last ten days, Bering has gone up, then down, and back up to arrive at the same extent.  In the same period Okhotsk added 70k km2.

Ice extents for February and March appear in the graph below; 11 year average is 2007 to 2017 inclusive.

Note that ice growth slows down in February and March since the Arctic core is frozen and extent can only be added at the margins.  MASIE shows 2018 is now matching 2017, while SII is running about 200k km2 lower.  The 11 year average maxed on day 62 at 15.1M km2 while this year  max was on day 69, ~560k km2 lower . It remains to be seen what max will end up in 2018

It is natural for alarmists to focus on Bering Sea, since that is the only place where a sizable deficit appears (for the moment).  The graph below show NH ice extent from day 1, with and without B and O (Bering and Okhotsk, the Pacific basins that will melt out by September anyway.)


Here’s your Valentine’s Day Greeting:

And here’s your PC candy for Valentine’s Day.






Rise and Fall of the Modern Warming Spike


The first graph appeared in the IPCC 1990 First Assessment Report (FAR) credited to H.H.Lamb, first director of CRU-UEA. The second graph was featured in 2001 IPCC Third Assessment Report (TAR) the famous hockey stick credited to M. Mann.

A previous post Rise and Fall of CAGW described the process that began with Hansen’s flashy Senate testimony in 1988, later supported by Santer’s flashy paper in 1996. This post traces a second iteration that ensued following Michael Mann’s production of the infamous Climate Hockey Stick graph in 1998. The image at the top comes from the 2001 IPCC TAR (Third Assessment Report) signifying the immediate embrace of this alarmist tool by consensus climatists.  The message of the graph was to assert a spike in modern warming unprecedented in the last 1000 years.  This claim of a “Modern Warming Spike” required a flat temperature profile throughout the Middle Ages (since 1000 AD).

The background to the process steps (image below) from Ross Pomeroy’s paper is provided followed by text and references for the rise and fall of the theory intended to erase Medieval Warming comparable to the present day. Sources of material are listed at the end and  included here with my bolds.

How Theories Advance and Collapse

Seeing how disarray defines psychology, it makes perfect sense that the field’s leading theories are vulnerable to collapse. Having watched this process play out a number of times, a clear pattern has emerged. Let’s call it the “Six Stages of a Failed Psychological or Sociological Theory.”

Stage 1: The Flashy Finding. An intriguing report is published with subject matter that lends itself to water cooler conversation, say, for example, that sticking a pen in your mouth to force a smile makes things seem funnier. Media outlets provide gushing coverage.

Stage 1 Modern Warming Spike Theory


Figure 2.20: Millennial Northern Hemisphere (NH) temperature reconstruction (blue) and instrumental data (red) from AD 1000 to 1999, adapted from Mann et al. (1999). Smoother version of NH series (black), linear trend from AD 1000 to 1850 (purple-dashed) and two standard error limits (grey shaded) are shown. Source: IPCC Third Assessment Report

Since the IPCC believes that the warming from 1975 to 1998 was mainly man-made, but not the warming in earlier centuries, it would like to be able to demonstrate that recent warming is ‘unprecedented’. But it isn’t. Temperatures in many parts of the world appear to be lower than they were in the Medieval Warm Period (MWP, c. 900-1400), and also in the earlier Roman Warm Period (c. 200 BC – 600 AD). During the MWP the Vikings tilled now-frozen farms in Greenland and were buried there in ground that is now permafrost ( Hundreds of peer-reviewed articles show that the MWP was a global phenomenon (Idso & Singer, 2009, 69-94;;, and was not confined to parts of the northern hemisphere, as the IPCC likes to assert.

Those wanting to “get rid of” the MWP run into the problem that it shows up strongly in the data. Shortly after Deming’s article appeared, a group led by Shaopeng Huang of the University of Michigan completed a major analysis of over 6,000 borehole records from every continent around the world. Their study went back 20,000 years. The portion covering the last millennium is shown in Figure 4.


The similarity to the IPCC’s 1995 graph is obvious. The world experienced a “warm” interval in the medieval era that dwarfs 20th century changes. The present-day climate appears to be simply a recovery from the cold years of the “Little Ice Age.”

Huang and coauthors published their findings in Geophysical Research Letters 6 in 1997. The next year, Nature published the first Mann hockey stick paper, commonly called “MBH98.”7 Mann et al. followed up in 1999 with a paper in GRL (“MBH99”) extending their results from AD1400 back to AD1000.8 In early 2000 the IPCC released the first draft of the TAR. The hockey stick was the only paleoclimate reconstruction shown in the Summary, and was the only one in the whole report to be singled out for repeated presentation. The borehole data received a brief mention in Chapter 2 but the Huang et al. graph was not shown. A small graph of borehole data taken from another study and based on a smaller sample was shown, but it only showed a post-1500 segment, which, conveniently, trended upwards.


Figure 2.19: Reconstructed global ground temperature estimate from borehole data over the past five centuries, relative to present day. Shaded areas represent ± two standard errors about the mean history (Pollack et al., 1998). Superimposed is a smoothed (five-year running average) of the global surface air temperature instrumental record since 1860 (Jones and Briffa, 1992). Source: IPCC Third Assessment Report WG 1

Stage 2: The Fawning Replications. Other psychologists, usually in the early stages of their careers, leap to replicate the finding. Most of their studies corroborate the effect. Those that don’t are not published, perhaps because the researchers don’t want to step on any toes, or because journal editors would prefer not to publish negative findings.

Stage 2 Modern Warming Spike Theory

As the hockey stick began to appear in the scientific literature, it emerged that 1998 was the warmest year in Phil Jones’s 150-year record of thermometer data. The length of the hockey stick blade just grew. Those in charge of publicizing the work of climate scientists and making the case for man-made climate change were understandably excited. Controversial science swiftly morphed into a propaganda tool.

The World Meteorological Organization put the hockey stick on the cover of its 1999 report on climate change. Then IPCC chiefs decided to give it pride of place in their 2001 IPCC report. Moreover, based on the hockey stick, they stated that “it is likely that the 1990s was the warmest decade and 1998 the warmest year during the past thousand years”. That attracted attention — and trouble. The doubts expressed in that paper title about “uncertainties and limitations” were melting away.


1999 WMO statement on the Climate.

An article in the Guardian (here) describes the struggle leading to victory for the Hockey Stick.

Emails exchanged in September 1999 reveal intense disagreement about whether Mann’s hockey stick should go into the IPCC summary for policymakers – the only bit of the report that usually gets read outside the scientific community – or whether other reconstructions using tree ring data alone should get priority. One of the main tree-ring constructions was by Briffa. The emails also expose major tensions between a desire for scrupulous honesty about uncertainties, and the desire for a simple story to tell the policymakers. The IPCC’s core job is to present a “consensus” on the science, but in this critical case there was no easy consensus.

The tensions were summed up in an email sent on 22 September 1999 by Met Office scientist Chris Folland, in which he alerted key researchers that a diagram of temperature change over the past thousand years “is a clear favourite for the policy makers’ summary”

But there were two competing graphs – Mann’s hockey stick and another, by Jones, Briffa and others. Mann’s graph was clearly the more compelling image of man-made climate change. The other “dilutes the message rather significantly,” said Folland. “We want the truth. Mike [Mann] thinks it lies nearer his result.” Folland noted that “this is probably the most important issue to resolve in chapter 2 at present.”

Mann, Jones and Briffa eventually settled their differences. And the hockey stick was given pride of place in the IPCC report. Folland says: “My recollection is that the final version [of the IPCC summary], which contains the hockey stick, satisfied Keith and everyone else in the end — after the usual vigorous scientific debate.” And after the three came under attack from climate sceptics, all reference to these past spats disappeared from the emails as they faced a common foe.

Stage 3: A Consensus Forms. The finding is now taken for granted, regularly appearing in pop psychology stories and books penned by writers like Malcolm Gladwell or Jonah Lehrer. Millions of people read about it and “armchair” explain it to their friends and family.

Stage 3 Modern Warming Spike Theory

In its 2001 Third Assessment Report, the IPCC used the iconic ‘hockey stick’ graph to try and show that modern warming was indeed ‘unprecedented’. The graph was produced by Michael Mann (now at Penn State University in the US), Ray Bradley and Malcolm Hughes (MBH), and published in Nature and Geophysical Research Letters in 1998 and 1999. At that time, the standard view was that the Medieval Warm Period and subsequent Little Ice Age (c. 1400-1850) were global events. But some climatologists saw the MWP as an embarrassment and spoke of the need to ‘get rid of it’. MBH’s temperature reconstruction did exactly that: it showed 900 years of gradually declining temperatures followed by a dramatic increase in the 20th century. The hockey stick played a central role in mobilizing political and public opinion in favour of drastic action to curb greenhouse gas emissions.

Al Gore with a version of the Hockey Stick graph in the 2006 movie An Inconvenient Truth

“As soon as the IPCC Report came out, the hockey stick version of climate history became canonical. Suddenly it was the “consensus” view, and for the next few years it seemed that anyone publicly questioning the result was in for a ferocious reception.” Ross McKitrick.What is the ‘Hockey Stick’ Debate About?  

Stage 4: The Rebuttal. After a few decades, a new generation of researchers look to make a splash by questioning prevailing wisdom. One team produces a more methodologically-sound study that debunks the initial finding. Media outlets blare the “counterintuitive” discovery.

Stage 4 Modern Warming Spike Theory

The hockey stick was based on historical temperature proxies (mainly tree rings), with the 20th-century instrumental temperature record tacked on the end. Incredibly, although the MBH articles were peer reviewed, nobody tried to replicate and verify the work, even though it overturned well-established views on climate history. It was only several years later that Steve McIntyre, a Canadian mathematician and retired mining consultant, began to investigate the matter. Mann did his best to obstruct him; he refused to release his computer code, saying that ‘giving them the algorithm would be giving in to the intimidation tactics that these people are engaged in’.

McIntyre, with the help of economist Ross McKitrick, went on to write several articles in 2003 and 2005, exposing the flaws in the hockey-stick reconstruction. They showed that the shape of the graph was determined mainly by suspect bristlecone/foxtail tree-ring data, and that Mann’s computer algorithm was so biased that it could produce hockey sticks even out of random noise; in short, Mann’s statistical methods ‘mined’ for hockey-stick signals in the proxy data, which were then assigned exaggerated weight in the reconstruction – thereby giving a whole new meaning to the term ‘Man(n)-made warming’!

In 2006 McIntyre & McKitrick’s criticisms were upheld by two expert committees in the US – the National Academy of Sciences (NAS) panel and a congressional panel headed by statistician Edward Wegman. Wegman pointed out that the palaeoclimate field is dominated by ‘a tightly knit group of individuals who passionately believe in their thesis’, and that ‘the work has been sufficiently politicized that they can hardly reassess their own public positions without losing credibility’.

McKitrick wrote in 2005:

Since our work has begun to appear we have enjoyed the satisfaction of knowing we are winning over the expert community, one at a time. Physicist Richard Muller of Berkeley studied our work last year and wrote an article about it:

“[The findings] hit me like a bombshell, and I suspect it is having the same effect on many others. Suddenly the hockey stick, the poster-child of the global warming community, turns out to be an artifact of poor mathematics.”

In an article in the Dutch science magazine Natuurwetenschap & Techniek, Dr. Rob van Dorland of the Dutch National Meteorological Agency commented “It is strange that the climate reconstruction of Mann passed both peer review rounds of the IPCC without anyone ever really having checked it. I think this issue will be on the agenda of the next IPCC meeting in Peking this May.”

In February 2005 the German television channel Das Erste interviewed climatologist Ulrich Cubasch, who revealed that he too had been unable to replicate the hockey stick (emphasis added):

He [Climatologist Ulrich Cubasch] discussed with his coworkers – and many of his professional colleagues – the objections, and sought to work them through… Bit by bit, it became clear also to his colleagues: the two Canadians were right. …Between 1400 and 1600, the temperature shift was considerably higher than, for example, in the previous century. With that, the core conclusion, and that also of the IPCC 2001 Report, was completely undermined.

Recently Steve MacIntyre and I received an email from Dr. Hendrik Tennekes, retired director of the Royal Meteorological Institute of the Netherlands. He wrote to convey comments he wished to be communicated publicly: “The IPCC review process is fatally flawed. The behavior of Michael Mann is a disgrace to the profession.”

The original MBH graph compared to a corrected version produced by MacIntyre and McKitrick after undoing Mann’s errors.

Stage 5: Proper Replications Pour In. Research groups attempt to replicate the initial research with the skepticism and precise methodology that should’ve been used in the first place. As such, the vast majority fail to find any effect.

Stage 5 Modern Warming Spike Theory

The IPCC dealt with the devastating rebuttal by hiding the hockey stick within a spaghetti graph of various paleo proxies to diffuse the issue, while still claiming unprecedented modern warming.

In the IPCC’s 2007 Fourth Assessment Report, the hockey stick was included in a ‘spaghetti diagram’ alongside six other temperature reconstructions, which showed greater variability in the past but still no pronounced MWP. These ‘independent’ studies are the work of Mann’s colleagues and make use of the same flawed proxies as well as dubious statistical techniques (Montford, 2010, 266-308). The data were carefully cherry-picked to exclude tree-ring series that showed a prominent MWP ( Palaeoclimatologist Rosanne D’Arrigo actually told the NAS panel that cherry-picking was necessary if you wanted to make cherry pie (i.e. hockey sticks). And Jan Esper has stated: ‘The ability to pick and choose which samples to use is an advantage unique to dendroclimatology’ – a statement that would make any reputable scientist shudder (Montford, 236, 288-9).

Sixteen of the articles cited in AR4 failed to meet the IPCC’s own publication deadlines for cited references; all of them were written by IPCC contributing authors in support of the AGW cause. The most notable case is a paper by Eugene Wahl and Caspar Ammann. The authors of chapter 6 desperately needed this paper to counter McIntyre & McKitrick’s criticisms of the hockey stick, as the authors claimed to have validated Mann’s results. The leaked emails show that members of the Team pressurized Climatic Change editor Stephen Schneider to ensure that the paper was processed quickly enough to meet IPCC deadlines, though this was not entirely successful. Wahl and Ammann referred to arguments in another unpublished paper they had written, which was not even submitted until well after the first paper had gone forward for IPCC review. Jones advised the authors to be dishonest: ‘try and change the Received date! Don’t give those skeptics something to amuse themselves with’ (1189722851). Both papers finally appeared in September 2007. The authors conceded that the hockey stick failed a key test for statistical significance, but claimed it passed another test and promised to provide details in their Supplementary Information. When this was finally made available a year later, it became clear that torturous statistical manipulations were required to enable the test to be passed (Montford, 2010, 201-19, 338-42, 424-6; The shenanigans involved in the Wahl & Ammann saga are quite breathtaking.

But the credibility of the hockey stick claims was attacked repeatedly:

Stage 6: The Theory Lives On as a Zombie. Despite being debunked, the theory lingers on in published scientific studies, popular books, outdated webpages, and common “wisdom.” Adherents in academia cling on in a state of denial – their egos depend upon it.

Stage 6 Modern Warming Spike Theory

There are still hardcore alarmist blogs that defend the hockey stick graph, but IPCC itself has dropped it without explicitly disowning it.

About 1000 years ago, large parts of the world experienced a prominent warm phase which in many cases reached a similar temperature level as today or even exceeded present-day warmth. While this Medieval Warm Period (MWP) has been documented in numerous case studies from around the globe, climate models still fail to reproduce this historical warm phase. The problem is openly conceded in the most recent IPCC report from 2013 (AR5, Working Group 1) where in chapter 5.3.5. the IPCC scientists admit (pdf here):

“Continental-scale surface temperature reconstructions show, with high confidence, multi-decadal periods during the Medieval Climate Anomaly (950 to 1250) that were in some regions as warm as in the mid-20th century and in others as warm as in the late 20th century.”  pg.386

“The timing of warm and cold periods is mostly consistent across reconstructions (in some cases this is because they use similar proxy compilations) but the magnitude of the changes is clearly sensitive to the statistical method and to the target domain (land or land and sea; the full hemisphere or only the extra-tropics; Figure 5.7a). Even accounting for these uncertainties, almost all reconstructions agree that each 30-year (50-year) period from 1200 to 1899 was very likely colder in the NH than the 1983–2012 (1963–2012) instrumental temperature NH reconstructions covering part or all of the first millennium suggest that some earlier 50-year periods might have been as warm as the 1963–2012 mean instrumental temperature, but the higher temperature of the last 30 years appear to be at least likely the warmest 30-year period in all reconstructions (Table 5.4). However, the confidence in this finding is lower prior to 1200, because the evidence is less reliable and there are fewer independent lines of evidence. There are fewer proxy records, thus yielding less independence among the reconstructions while making them more susceptible to errors in individual proxy records. The published uncertainty ranges do not include all sources of error (Section, and some proxy records and uncertainty estimates do not fully represent variations on time scales as short as the 30 years considered in Table 5.4. Considering these caveats, there is medium confidence that the last 30 years were likely the warmest 30-year period of the last 1400 years.” Pg.410

Meanwhile a multitude of studies confirm that medieval warming was widespread and not limited to regions in the Northern Hemisphere, as Mann and others have claimed. For example the  MWP Mapping Project  led by Dr. Sebastian Luening, Prof. Dr. Fritz Vahrenholt (authors of ‘The neglected sun‘).

red: MWP warming
blue: MWP cooling (very rare)
yellow: MWP more arid
green: MWP more humid
grey: no trend or data ambiguous

Most of western North America and Africa were experiencing drought conditions during the MWP (except some areas in Southwest Africa). In contrast, Australia and the Carribean was more humid. Globally, 99% of all paleoclimatic temperature studies compiled in the map so far show a prominent warming during the MWP. This includes Antarctica and the Arctic.


“Regarding the Hockey Stick of IPCC 2001 evidence now indicates, in my view, that an IPCC Lead Author working with a small cohort of scientists, misrepresented the temperature record of the past 1000 years by (a) promoting his own result as the best estimate, (b) neglecting studies that contradicted his, and (c) amputating another’s result so as to eliminate conflicting data and limit any serious attempt to expose the real uncertainties of these data.” – John Christy, Examining the Process concerning Climate Change Assessments,  Testimony 31 March 2011



Presentation to the National Academy of Sciences Expert Panel, “Surface Temperature Reconstructions for the Past 1,000-2,000 Years   Stephen Mcintyre and Ross McKitrick  2006

Climategate and the Inquiries,Ken Gregory

Climategate and the Corruption of Climate Science David Pratt

IPCC TAR and the hockey stick Judith Curry 2014

Global Warming Bombshell Richard Mueller 2004

When the IPCC ‘disappeared’ the Medieval Warm Period Frank Lansner 2010


Todays temperatures are cooler than the Medieval Warming Period, which was preceded by an even warmer Roman Warm Period, which followed an even warmer Minoan Warm Period.  We are in an Interglacial age about 11,500 years old, and the overall trend is cooling.

Figure 37. Holocene global temperature change reconstruction. a. Red curve, global average temperature reconstruction from Marcott et al., 2013, figure 1. The averaging method does not correct for proxy drop out which produces an artificially enhanced terminal spike, while the Monte Carlo smoothing eliminates most variability information. b. Black curve, global average temperature reconstruction from Marcott et al., 2013, using proxy published dates, and differencing average. Temperature anomaly was rescaled to match biological, glaciological, and marine sedimentary evidence, indicating the Holocene Climate Optimum was about 1.2°C warmer than LIA. c. Purple curve, Earth’s axis obliquity is shown to display a similar trend to Holocene temperatures. Source: Marcott et al., 2013.
Source:Judith Curry Nature Unbound III: Holocene climate variability (Part A)