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Cold and Warm, Again and Again

By: Dr. Ricky Rood, 7:23 PM GMT on July 21, 2009

Cold and Warm, Again and again

I have been in Colorado since the beginning of May. The weather has been wet and mostly cool. This weekend there was an extreme heat alert in Los Angeles, which was attributed stubborn high pressure over the Southwest. And tonight in Boulder, Colorado, once again thunderstorms form to the east of the Rockies and move from the northwest towards the southeast. (One, perhaps, has to be a meteorologist to perceive the connectedness in those sentences.)

So this wet weather got me to thinking. Last winter it was cold in the eastern half of the U.S. and there was a lot of chatter about the cold winter demonstrating that global warming was a hoax. As I recall, but I can’t find the quote right now, I read one place that God had taken back the Earth from the scientists. Here are my blogs from last winter. ( Cold in a Warm World , Cold in the East , Last Year and This Year ). So two things struck me, why have I not seen a lot of chatter about the current weather here in Colorado and the lack of global warming, and what is it like in the rest of the world?

I think the answer to the first question is easy. In the United States much of the argument about global warming is driven by what goes on in Washington, New York, and Chicago. It’s been known, at least since the Dust Bowl days, that the weather in Washington has a large impact on weather and climate funding and policy. The answer to the second question is pretty easy to answer, and it is worth a look.

Here is temperature information from the National Climatic Data Center (NCDC) .

Figure 1: Difference of observed temperature in June 2009 from the 30 year average calculated from 1961 to 1990 observations.

What strikes me about this imagine is the lack of blue on the graph. The nice comfortable area where I currently reside, Colorado, is there. And there are small cooler than average regions in Europe, Asia, and South America. Africa is just hot. Virtually all of the oceanic area is warmer than normal. In fact, according to the NCDC discussion the sea surface temperatures were the warmest on record for June. Taking land and ocean together, June 2009 was the second warmest on record. The warm sea surface temperatures are part of an El Nino event which is evolving. (June El Nino discussion, Current El Nino discussion ) The El Nino is currently predicted to be a moderate event, but at this point, the temperatures are flirting with new records of global warmth.

So my cool little part of the United States is not so representative of the world. When I look at a map of global temperature anomalies, the difference from the average, I expect to see warmer and cooler regions. That is because many climate phenomena are associated with waves and the position of waves. Waves have a warm part and a cool part, and if the wave is positioned itself a few hundred kilometers east or west, north or south, warmer and cooler temperatures are observed. I also look at the land sea contrast. For example, if the flow is such that maritime air enters the continent in a different region than average, then in summer, that is likely to appear as a cool anomaly on the continent. This is true even if the same air comprised a warm anomaly out over the ocean. In the observations, on the continents warm and cool patterns appear together in a wave-like pattern. There is nothing that defies intuition.

Just for kicks, I decided to look at the observations for June 2008, a year ago.

Figure 2: Difference of observed temperature in June 2008 from the 30 year average calculated from 1961 to 1990 observations.

There are two things that strike me in this figure from a year ago. The first is the similarity of the cool anomalies on the continent. Second is the structure over the ocean. The cool patch over the Pacific is connected to a spreading cool region in western North American. The pattern is suggestive of what might be expected from a series of storms flowing onto the Canadian and Alaskan coasts. The difference over the oceans (and Africa?) for the two years is consistent with the evolution of El Nino. The June 2008 temperatures were also much warmer than normal.

It is simple to look at these maps and see that that planet is warmer than the 30 year average defined by 1961-1990. My casual observations of maps suggest, to me, some level of understanding of the warm and cool features. These are related to El Nino, the position of waves in the atmosphere, and oceanic-continental temperature contrasts. The attribution of causation to these elements of the climate system requires more analysis, but there is nothing in the observations that suggest that global warming is not real. It just reminds me that because it is only 63 degrees (F) at noon in Boulder, CO, does not mean the rest of the world is the same.


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.