Global Warming Projections vs. the Data: Are the Data Reliable?

According to projections by computer models of climate change, a temperature rise of about 0.4 degrees C should have occurred in the last twenty years because of the large increases in CO2 and other minor greenhouse gases. But temperature measurements from satellites for the period 1978-1997 show no temperature rise at all.

Some people argue that the satellite measurements are unreliable, but in fact they are the most precise measurements of global temperature available. The satellite temperature survey includes 99% of the earth?s surface. Surface temperature measurements, however, are uneven over the three-quarters of the earth’s surface covered by oceans, and provide essentially no coverage of the polar regions.

But where ground-based measurements are accurate, for example in Europe and North America, the correlation coefficient between satellite and surface measurements is 0.95 – close to perfect agreement. (Perfect agreement would be a coefficient of 1.00.) This is also the case when one compares satellite data to the temperature measurements gathered from the network of weather balloons. Neither the satellites nor the balloons show any significant warming trend over the last twenty years.

Objections also have been raised to the satellite data on the grounds that they are a measure of temperatures in the atmosphere rather than the actual temperatures on the surface of the earth. However, the models predict at least as great a warming in the lower atmosphere as at the surface. Moreover, the precise temperature record provided by satellites is not affected by systematic errors like the urban heat-island effect, i.e., the artificial warming associated with heavily populated areas. Therefore, the lack of a warming trend in the satellite data indicates unambiguously that the actual warming is much less than the models predict.

In fact, no reliable global temperature measurements show the rise predicted by the computer models. These results support the conclusion that the computer models are exaggerating the warming by a large factor. If global warming forecasts for the next century are corrected for this exaggeration, the warming due to human activities is so small as to be lost in natural climate fluctuations.

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