Thank you for soliciting my testimony on the nature of Carbon Dioxide as a "pollutant" with regard to global climate change. I regard a "pollutant" as something that produces a demonstrable net negative impact on climate and ecosystems.
"Negative" and "positive" impacts on climate are value judgements made byhuman beings. Within that limitation, I submit the following:
This testimony demonstrates that the observed climate changes that haveaccompanied the enhancement of the natural greenhouse effect have beenconsiderably smaller than they were originally forecast to be, and thatthey are likely to remain similarly small. Further, they are inordinatelyconfined into the winter, rather than the summer, and, within the winters,they are inordinately confined to the coldest, deadliest airmasses. Thereis no overall statistically significant warming in the average temperatureof the United States, which is a record of 105 years in length. While theUnited Nations has stated that during the greenhouse enhancement, "thebalance of evidence suggests a discernible human influence on globalclimate," I cannot view what has happened as a net negative; some mighteasily argue that it is a net benefit. Under neither interpretation doesthis qualify carbon dioxide as a climatic "pollutant."
In January, 1989, over ten years ago, I first testified on climate changein this House. I argued that the computerized climate models from that erawere dramatically overpredicting future warming, and that the observedhistory of climate projected a much more moderate warming, of 1.0°C to1.5°C, over the next century. I further argued that it would eventually berecognized that this moderate climate change would be inordinatelyexpressed in the winter vs. the summer, in the night vs. the day, and thatoverall it was plausible to argue that these changes conferred a netbenefit upon our world.
If I had the perfect vision of knowing what would have happened to theclimate in the next ten years, how the scientific literature evolved-in itsattempts to explain the lack of warming, and in its refusal to recognizepersistent, damaging and pervasive errors in the forecast that continue tothis 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 thelowest statistical range forecast by climate models. Recent observedchanges 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 NorthernHemisphere is confined to the very coldest airmasses. The warming outsideof these airmasses is a minuscule 0.2°C per century (Michaels et al., 1999).
The variation, or unpredictability, of regional temperatures has declinedsignificantly 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 decreasedwhile flooding has not increased. (Lins and Slack, 1999).
Maximum winds in hurricanes that affect the United States havesignificantly declined (Houghton et al., 1995), and there is no evidencefor a global increase in damaging storms (Landsea et al. ,1996).
The Kyoto Protocol to the United Nations Framework Convention on ClimateChange will have no discernable impact on global climate within anyreasonable policy timeframe (Wigley, 1998).
In toto, these findings lead inescapably to the conclusion Carbon Dioxideis not a "pollutant," and plausibly argue that it is a net benefit…
Once greenhouse warming starts, it proceeds as straight line, not as anexponential increase.
What differs between the models is not their functional form-straightlines-but the slope (or rate of increase) in those lines. In fact, themean and standard error of the warming are 0.25°C ± 0.07°C/decade, wherethe confidence range is at 67%.
Which of these models is likely to be correct? Under the assumption oflinearity, nature helps to provide an answer, as global near-surfacetemperature 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 isslightly below the low confidence limit given by the ensemble of modelsshown 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 winterand 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 approximatelyhalf of these values. Crop yields quintupled. Life span doubled, in partbecause of better nutrition. Winters warmed. Growing seasons lengthened.The planet became greener. Increasing carbon dioxide had something to dowith each and every one of these. There is simply no logical reason toassume that doing the same, this time in 50, instead of 100 years, willhave any different effect in kind. That kind of improvement in the qualityof human life could hardly be caused by a "pollutant."