Same Old Arctic `Warming'

Same Old Arctic `Warming'

by Willis Eschenbach

A recent study, entitled RECENT WARMING OF ARCTIC MAY AFFECT WORLDWIDE CLIMATE
< http://www.gsfc.nasa.gov/topstory/2003/1023esuice.html > has used satellite data for the first time to reveal the changes at the top of the world. However, rather than just reporting the changes, the authors have built a small amount of information into a large scare. They imply that this warning is unprecedented in history, and that it supports the theory that the "greenhouse effect" is dangerously warming the planet.

First, let's look at the data. Here is the graphic from the site showing warming as revealed by 20 years of satellite temperature records, from 1981 to 2001:

This looks bad, very bad. Almost all of the area has warmed, except Greenland and the north of Russia. Surely this shows global warming run amok.

However, things come back into perspective when we look at the scale.

The darkest blue only represents -0.4°C cooling, and the darkest red only represents +0.4°C warming. There is no red at all in the graphic; the darkest brown shown reveals the maximum warming is about +0.2°C. Most of the area only shows about +0.1°C warming. Nowhere has the Arctic warmed by even a quarter of a degree.

Since the average Arctic temperature includes the blue (cooling) areas, the average temperature rise for the entire Arctic area shown must be less than +0.1°C in 20 years, or less than half a degree per century. This is much less than the accepted estimate of the historical warming of the earth for the last several hundred years, which has been about 1° per century.

It is also less warming than the satellites report for the Northern Hemisphere troposphere for the same period. For the period of the NASA/GISS study (1981-2001), the satellite data shows that the Northern Hemisphere troposphere warmed by +0.2 degrees (which is also about 1° per century, no different from pre-industrial times). Since the Arctic has warmed by only +0.1°C during the same time, the Arctic is clearly warming about half as fast as the Northern Hemisphere.

Now, computer models have fared very poorly in predicting both the weather and the climate. They not only give incorrect answers, they routinely disagree with each other. However, all the computer models agree on one thing -- if CO2 causes global warming, the first areas to warm will be the Poles. This is because of the physics of the greenhouse effect, where the cooler the air, the more infrared is captured by the greenhouse gases.

However, here we see that, rather than warming faster than the rest of the world, the Arctic is lagging behind. This is the signature of natural warming (likely driven by the changing temperature of the sun), not of CO2 forced warming.

One final note -- the study's authors make the following claim:

"According to Comiso's study, when compared to longer term ground-based surface temperature data, the rate of warming in the Arctic over the last 20 years is eight times the rate of warming over the last 100 years."

There are several problems with this claim. The first is that it is mathematically impossible. Since the warming during the last 20 years averaged about 0.1°C (an average rate of about 0.005°C per year), they are claiming that the Arctic warmed for the last 100 years at an eighth of that rate, or about +0.0006° per year. However, at that rate it would only warm +0.06°C in a century, which is less than the study says it has warmed in the last twenty years.

But perhaps they mis-spoke, perhaps they meant that it was 8 times the warming rate of the 100 years previous to the study, from 1882 to 1982. The problem with this interpretation is that there is no data to support it -- as the authors point out, this is the first study to be done using satellite data. Prior to this, data has been collected at a relatively small number of Arctic stations. The data to support the miniscule claimed increase of +0.06° per century is simply not available.

And finally, even the best of Arctic temperature records could not claim significance for a change this small, less than a tenth of a degree per century, because the instruments are not sufficiently accurate to give results significant to this tiny amount.

Arctic Warming Summary:

Is the Arctic warming? Yes, for the past 20 years it has warmed at a rate of about half a degree per century, or five thousandths (0.005) of a degree per year.

Does this tend to prove that human activity is causing "global warming"? No, it tends to prove the opposite, that the observed warming is not due to the increase in greenhouse gases. The Arctic is warming less than the rest of the Northern Hemisphere, not more as it would if greenhouse gases were the cause of the warming.

Is this warming of +0.5°C per century unusual in history? No, the observed warming is half of the generally accepted estimate of pre-industrial warming (about 1° per century).

Is this warming of +0.5°C per century unusual in the Arctic? Because we have so little data from the far North, we don't really know. However, +0.5°C per century is well within the range of the observations that we have for the Arctic, which generally either show no warming at all, or a warming of less than 1°C per century.

Looking at the Arctic graphic GISS showed (bove), I saw that the northern end of the Norwegian/Swedish peninsula was one of the areas that had warmed the most. I was curious to see what the ground temperature stations had to say about this recent warming, so I got the data from NASA/GISS, the same people who had done the recent study. Here are the records of five ground stations, showing the 15 year Gaussian averages of the temperature differences compared to 1981:

Some points of interest about this data:

The warmest period in this part of the Arctic, as in the USA and in most of the world, was the 1930s. Not the 1990s, not the 1980s, -- the 1930s.

The greatest warming occurred from 1900 to 1930, well before the massive post-war rise in CO2 that occurred from 1945 onward.

From the 1930s to the 1980s, temperatures were falling and CO2 levels were rising.

Since the climate is currently cooler than it was in the 1930's, their predictions of climate disaster have no scientific basis.

All of this demonstrates that, because of decade and century long temperature swings, it is very foolish to draw any conclusions from a mere 20 years of data, whether it is from satellites or from ground stations.

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