June 13, 2015
As hoped for by Paris COP promoters, and by Californians looking for El Nino precipitation, the Blob in the North Pacific has intensified and may at least partly fulfill both expectations.
HADSST3 results for May are now in, and the sea surface temperature warming anomaly is up:
Global +0.12C over last May,
NH +0.16C over last May.
That will show up also in air temperature estimates, since 71% of the earth’s surface is covered by oceans. For example, UAH TLT anomalies show Global oceans +0.06C over last May, but Global land -0.1C, so Global UAH is only up +0.02C over May 2014. (Note: UAH uses satellites to measure air temperatures many meters above land or ocean, while surface datasets like HADCRUT, BEST, GISTEMP use the measured SSTs in their global mean temperature estimates).
The Blob difference shows up in UAH in the NH results: NH anomaly is +0.07 over last year, with the same increase showing over land and ocean. Interestingly, UAH shows the North Pole cooler than a year ago, the TLT over the Arctic being -0.06 less than a year ago. The South Pole land air temps are a whopping -0.2C colder than last May.
As far as Arctic Ice is concerned, the Blob probably caused the Bering Sea to melt out more than one month earlier than last year. About 10% of the water entering the Arctic Ocean comes from Bering, so there should be some impact on ice melting the immediate BCE region (Beaufort, Chukchi, East Siberian Seas). So far, in that region, 2015 is tracking last year’s melt at a slightly lower extent -4%, not yet a significant effect from the Blob.
More on Arctic Ice melt season here:
Background on the Blob
Many have noticed the warm water anomaly in the Northern Pacific, which shows up as a weak El Nino, but somewhat unexpected and out of the ordinary pattern. The warm Pacific SST last year almost pushed 2014 to a new record average surface temperature, and fossil fuel activists are pinning their Paris hopes on this year.
So it is timely for the Meteorologist who named this event to provide a clear explanation of the natural causes of the Blob phenomenon.
From Nicholas Bond (excerpted from post linked below):
The development of the blob of unusually warm water can be attributed largely to an unusual weather pattern that set up shop over a large region extending from the North Pacific Ocean across North America from October 2013 into February 2014.
This pattern featured a strong and long-lasting weather pattern with higher-than-normal pressure – called a ridge – over the ocean centered offshore of the Pacific Northwest. This ridge of high pressure reduced the number and intensity of storms making landfall, leading to reduced precipitation west of the Continental Divide compared to seasonal norms.
In a study published earlier this month, my colleagues and I fingered the stubborn high-pressure ridge mentioned above, and in particular the weak winds associated with it. The result was a lower-than-normal rate in how quickly heat is transferred from the ocean to the atmosphere, and slower movement of cooler water into the formation region of the blob.
In other words, the unusual atmospheric conditions produced less cooling than typical for the season from fall 2013 through much of the following winter, yielding the sea surface temperature anomaly pattern. So we can essentially blame the ridge for the blob, but what caused the ridge in the first place?
The ocean circulation – that is, the currents – and the weather during the past year, which was unusual in its own right, combined to cause the blob to evolve into a wide strip of relatively warm water along the entire West Coast of North America (see image, below).
This happens to be a pattern that has occurred before in association with decades-long shifts in ocean temperature known as the Pacific Decadal Oscillation (PDO). Previous expressions of the PDO have had major and wide-ranging impacts on the marine ecosystem including salmon and other species of fish; recent developments are receiving a great deal of attention from fishery-oceanographers along the West Coast.