natural variation

Mild Winter Makes March Madness

The month of March was unusually warm in the U.S. Some media have said this is more evidence of, or “consistent with” global warming. See this over-the-top storyin the Arizona Daily Star. But the mild winter has nothing to do with anthropogenic global warming.

Even the National Climate Data Center (NCDC) of NOAA does not attribute the warm winter to global warming:

Record and near-record breaking temperatures dominated the eastern two-thirds of the nation and contributed to the warmest March on record for the contiguous United States, a record that dates back to 1895. The average temperature of 51.1 degrees F was 8.6 degrees F above the 20th century average for March and 0.5 degrees F warmer than the previous warmest March in 1910. Of the more than 1,400 months that have passed since the U.S. record began, only one month, January 2006, has seen a larger departure from its average temperature than March 2012.

A persistent weather pattern during the month led to 25 states east of the Rockies having their warmest March on record. An additional 15 states had monthly temperatures ranking among their ten warmest. That same pattern brought cooler-than-average conditions to the West Coast states of Washington, Oregon, and California.

Here is the March temperature record according to NCDC.

March-2012-temps

Notice that March, 1910, was almost as warm. Dr. Martin Hoerling, of NOAA, writes:

“Various hypotheses on this heatwave’s plausible causes were tested, some verified, some refuted. Though preliminary and not final in its conclusions, it is demonstrated that much of the heatwave magnitude can be explained from a perspective of elementary physical understanding of the consequences of unusually strong and persistent poleward heat transport by low level southerly winds that extended from the Gulf of Mexico to the Canadian Prairie.”

Dr. Roy Spencer, Principal Research Scientist at the University of Alabama in Huntsville, agrees that the southerly wind component was the chief cause:

[O]ne of the basic concepts you learn in meteorology is “mass continuity”. If there is persistent and widespread southerly flow over the U.S., there must be (by mass continuity) the same amount of northerly flow elsewhere at the same latitude.

That means that our unusual warmth is matched by unusual coolness someplace else.

If you claim, “Well, maybe global warming caused the extra southerly flow!”, you then are also claiming (through mass continuity) that global warming ALSO caused extra northerly flow (with below normal temperatures) somewhere else.

And no matter what anyone has told you, global warming cannot cause colder than normal weather. It’s not in the physics. The fact that warming has been greatest in the Arctic means that the equator-to-pole temperature contrast has been reduced, which would mean less storminess and less North-South exchange of air masses — not more.

See also:

20th Century temperatures explained as natural recovery from Little Ice Age

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20th Century temperatures explained as natural recovery from Little Ice Age

AkasufaA well-referenced paper by Syun-Ichi Akasofu, International Arctic Research Center, University of Alaska Fairbanks, contends that 20th Century warming can be explained as a linear recovery from the “Little Ice Age (LIA)” as modified by solar-induced multi-decadal oscillations.  The author notes that the recovery since the end of the LIA in about 1850 has proceeded at the rate of 0.5°C/century and is expected to continue at least until the year 2100.  The author predicts that global temperature increase to 2100 will be “0.5°C ± 0.2° C, rather than 4° C ± 2.0° C predicted by the IPCC.”

This paper contains many interesting graphics and provides a good short summary of natural variation and the evidence for such variation.  The author does not find any evidence of influence by carbon dioxide emissions.  In fact, the author debunks some of the supposed evidence used to support the greenhouse effect.

The abstract reads:

A number of published papers and openly available data on sea level changes, glacier retreat, freezing/break-up dates of rivers, sea ice retreat, tree-ring observations, ice cores and changes of the cosmic-ray intensity, from the year 1000 to the present, are studied to examine how the Earth has recovered from the Little Ice Age (LIA). We learn that the recovery from the LIA has proceeded continuously, roughly in a linear manner, from 1800-1850 to the present. The rate of the recovery in terms of temperature is about 0.5°C/100 years and thus it has important implications for understanding the present global warming. It is suggested on the basis of a much longer period covering that the Earth is still in the process of recovery from the LIA; there is no sign to indicate the end of the recovery before 1900. Cosmic-ray intensity data show that solar activity was related to both the LIA and its recovery. The multi-decadal oscillation of a period of 50 to 60 years was superposed on the linear change; it peaked in 1940 and 2000, causing the halting of warming temporarily after 2000. These changes are  natural  changes, and in order to determine the contribution of the manmade greenhouse effect, there is an urgent need to identify them correctly and accurately and remove them from the present global warming/cooling trend.

Reference:

Akasofu, S.-I. 2010. On the recovery from the Little Ice Age. Natural Science 2: 1211-1224.

[Link to full paper, click on Full Text]