“Negative” and “positive” impacts on climate are value judgements made by human beings. Within that limitation, I submit the following:
This testimony demonstrates that the observed climate changes that have accompanied the enhancement of the natural greenhouse effect have been considerably smaller than they were originally forecast to be, and that they are likely to remain similarly small. Further, they are inordinately confined into the winter, rather than the summer, and, within the winters, they are inordinately confined to the coldest, deadliest airmasses. There is no overall statistically significant warming in the average temperature of the United States, which is a record of 105 years in length. While the United Nations has stated that during the greenhouse enhancement, “the balance of evidence suggests a discernible human influence on global climate,” I cannot view what has happened as a net negative; some might easily argue that it is a net benefit. Under neither interpretation does this qualify carbon dioxide as a climatic “pollutant.”
In January, 1989, over ten years ago, I first testified on climate change in this House. I argued that the computerized climate models from that era were dramatically overpredicting future warming, and that the observed history of climate projected a much more moderate warming, of 1.0°C to 1.5°C, over the next century. I further argued that it would eventually be recognized that this moderate climate change would be inordinately expressed in the winter vs. the summer, in the night vs. the day, and that overall it was plausible to argue that these changes conferred a net benefit upon our world.
If I had the perfect vision of knowing what would have happened to the climate in the next ten years, how the scientific literature evolved-in its attempts to explain the lack of warming, and in its refusal to recognize persistent, damaging and pervasive errors in the forecast that continue to this date-I would have changed not one word.
This testimony explains why.
In the last ten years, we have learned that:
Observed surface warming is most consistent with a forecast below the lowest statistical range forecast by climate models. Recent observed changes are several times beneath what was forecast a mere ten years ago, assuming historical changes in carbon dioxide (see Hansen, et al., 1998).
The postwar ratio of winter-to-summer warming is greater than two-to-one (Balling et al., 1998)
Over three-quarters of the cold half-year warming in the Northern Hemisphere is confined to the very coldest airmasses. The warming outside of these airmasses is a minuscule 0.2°C per century (Michaels et al., 1999).
The variation, or unpredictability, of regional temperatures has declined significantly on a global basis while there is no change for precipitation (Michaels et al., 1998)
In the United States, streamflow records show that drought has decreased while flooding has not increased. (Lins and Slack, 1999).
Maximum winds in hurricanes that affect the United States have significantly declined (Houghton et al., 1995), and there is no evidence for a global increase in damaging storms (Landsea et al. ,1996).
The Kyoto Protocol to the United Nations Framework Convention on Climate Change will have no discernable impact on global climate within any reasonable policy timeframe (Wigley, 1998).
In toto, these findings lead inescapably to the conclusion Carbon Dioxide is not a “pollutant,” and plausibly argue that it is a net benefit…
Once greenhouse warming starts, it proceeds as straight line, not as an exponential increase.
What differs between the models is not their functional form-straight lines-but the slope (or rate of increase) in those lines. In fact, the mean and standard error of the warming are 0.25°C ± 0.07°C/decade, where the confidence range is at 67%.
Which of these models is likely to be correct? Under the assumption of linearity, nature helps to provide an answer, as global near-surface temperature has risen as a straight line, too, in the last three decades. The slope since 1968, when warming began, is 0.15°C/decade. This is slightly below the low confidence limit given by the ensemble of models shown here…
Models are also linear with respect to their cold and warm season warmings. Given the differential that we have seen since 1968, the expected winter and summer half-year warmings work out to 1.45 and 1.15° C, respectively, in the next century.
During this century, we experienced a temperature rise of approximately half of these values. Crop yields quintupled. Life span doubled, in part because of better nutrition. Winters warmed. Growing seasons lengthened. The planet became greener. Increasing carbon dioxide had something to do with each and every one of these. There is simply no logical reason to assume that doing the same, this time in 50, instead of 100 years, will have any different effect in kind. That kind of improvement in the quality of human life could hardly be caused by a “pollutant.”