Warming over-estimated by 30-50%

Warming during past century overestimated by 30-50%

We might anticipate temperatures to accelerate downwards shortly


5 Mar 09 - A recent paper by meteorologist Joseph D’Aleo, Executive Director of Icecap, shows that warming during the past century may have been overestimated by 30-50%.

The problem is that several global data bases (GISS, GHCN, CRU) include station dropout, missing data, siting issues, and insufficient or even no adjustment for urbanization. This makes them unusable or even unreliable for trend analysis.

Using USHCN data from the United States - which at least is stable and has much less missing data - D’Aleo shows that temperature trends are cyclical in nature and correlate far better with solar and multidecadal ocean cycles.

D’Aleo’s shows that short term fluctuations are driven by factors such as ENSO and volcanic eruptions, while longer term cycles are mainly driven by cycles in the sun and oceans (although changes in the last half century have been increasingly blamed on humans).

A more active sun is a brighter slightly hotter sun, and when the sun is hotter the earth is a little hotter. This small effect is magnified by other more indirect solar influences. When the sun is more active although its brightness (mainly visible light) only increases by 0.1%, the ultraviolet radiation increases by 6-8% and the even shorter wavelengths by a factor of two or more. These UV rays create and destroy ozone in the high atmosphere, both of which are exothermic effects and produce heat.

Work by Labitzke and Shindell at NASA GISS have shown this to be important. Shindell showed how this factor may have been responsible for the little ice age.

When the sun is more active there are more flares and eruptive activity which cause rapid increases in the solar winds, which in turn causes ionization storms in the earth’s atmosphere with resultant heating.

Also importantly, an active sun causes the earth’s magnetic shield to diffuse more cosmic rays from reaching into our atmosphere. Since these rays have a low water cloud formation enhancing effect (recently confirmed in the laboratory), an active sun usually means less low clouds and thus warmer temperatures. In all these cases, a more active sun brings warming.

Ocean Multidecadal Cycles

The Pacific and Atlantic undergo multidecadal cycles the order of 50 to 70 years. In the Pacific this cycle is called the Pacific Decadal Oscillation. A warm Pacific (positive PDO Index) from 1922 to 1947 and again 1977 to 1997 was accompanied by more El Ninos, while a cool Pacific was accompanied by more La Ninas (in both cases a frequency difference of close to a factor of 2).

Scafetta and West (2007) have suggested that the total solar effect may be responsible for at least 50% of the warming since 1900.

Since El Ninos have been shown to lead to global warming and La Ninas global cooling, this should have an affect on annual mean temperature trends in North America.

Clearly, US annual temperatures over the last century have correlated far better with cycles in the oceans and sun than carbon dioxide. The correlation with carbon dioxide seems to have vanished or even reversed in the last decade.

Given the recent cooling of the Pacific and Atlantic and rapid decline in solar activity, we might anticipate given these correlations, temperatures to accelerate downwards shortly.

Did you catch that? We might anticipate temperatures to accelerate
downwards shortly.

See Joe D'Aleo's icecap website here
http://icecap.us/index.php.

See entire paper, along with lots of graphs:
http://www.ilovemycarbondioxide.com/pdf/US..._since_1895.pdf
Thanks to Hans Schreuder for this link