Fred Singer Writes the Washington Post

To: Editor, Washington Post:

It seems that every January we are treated to a press conference claiming that the past year has been the hottest in the century. Last January we were told that 1996 was the warmest year, a year earlier we were told that 1995 was the warmest year. I suppose this is designed to make people believe that there is a warming trend in progress, such as might be expected as a consequence of manmade greenhouse warming. The problem is that the global data from weather satellites have been showing a cooling trend for the last 19 years. What's wrong?

In the first place, the press briefing by NOAA really does not convince one that 1997 was the warmest year. If one reads the fine print, one learns that the land data have shown a cooling, and that the ocean data have shown a warming, which was largely due to El Nino. When combined by some kind of global index, which is not further explained, one finds the claim that 1997 was warmer than 1996 or 1995. Much depends on who analyzes the data. The NOAA analysis sets the second warmest year in 1990, which implies that the years between 1990 and 1997 must have been cooler. Why don't we have a press release about that? The British Meteorological Office puts the second warmest year as 1995, while the respected NASA Goddard Institute for Space Studies in New York claims that 1997 equalled the record of 1995. What this proves is that the differences are minute.

In any case, even if there were a warming trend, it is considerably smaller than what climate models calculate based on the increase in greenhouse gases. This becomes quite clear when one tries to explain why the climate cooled between 1940 and 1975. Evidently, the natural fluctuations, whatever their cause, outweigh the human influence.

There is, however, a real discrepancy between the satellite data and the surface data quoted in the NOAA press briefing. And there are good reasons why one should prefer the satellite data to the surface data:

1. First of all, the satellite data are truly global, while the surface measurements leave vast areas of the Earth without data. This is particularly true in the Southern Hemisphere, and for the oceans, which cover 70% of the Earth's surface.

2. While the satellite data use a single instrument of very high precision, the surface data have to be assembled from a multitude of instruments on different continents with uncertain calibrations. This is particularly true for ocean data, which have to be glued together from ship readings of sea surface temperature, from buoys, and from island stations that measure the temperature of the lower atmospere and not the sea surface. Even the latter data set is not homogeneous. Some measurements come from the intake water from ships, others from the measurement of water temperature hauled up in buckets, while others still use infrared sensing from satellites, which only refers to the uppermost "skin" of the ocean.

3. The land stations are subject to the well-know "urban heat island" effect and other local disturbing influences. It has been shown again and again that surface warming trends observed at many weather stations are due to the expansion of population, nearby industrial activity, or just the removal of trees, the paving of the ground, etc.

4. Finally, when comparing observations with climate models, satellite data are more relevant than surface data, since the satellite senses the temperature of the lower atmosphere, which is exactly what the climate models calculate.

S. Fred Singer, Ph.D.

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