To: J Mitchell <jfbmitchell@meto.govt.uk> From: pjm8x@amazon.evsc.virginia.edu (Patrick J. Michaels) Dear John. I know the transient experiment is 'different". But in your sulfate-free transient, already published, interpolation between your year 21-30 and 41-50 illustrations (radiatively, I have us at year 38) gives a high northern latitude warming of close to 3° for now. The sulfate model clearly also has high latitude warming by that iteration number, and what I want to know is how much and where. Hence my request for the gridpoint data from the transient. The lack of observed high latitide warming (effectively ignored in the IPCC 1995 draft chapter 6) indicates to me that the net warming predicted to date (which begins about 20 years ago) is in some not inconsiderable fraction from a place that in fact didn't warm but is treated by the model as sulfate free. This is very important for IPCC readers to know. Can you help me with this? Roy Jenne says he would be very pleased if you would promptly send him a high latitude sample of the 1.5m temperature transient, output from the sulfate/greenhouse model, say, gridpoints north of 60 degrees from model analog years 1900-2050. Roy would be very careful about sending it out. Best, Pat Michaels I agree not to cite, quote, or copy any portion of your upcoming Nature paper on the sulfate transient greenhouse model, except in my review of the draft 1995 IPCC report. Thank you for your attention to this! I know you are very busy. As you are aware, Roy Jenne does not have the gridded output from the model that generated the Nature report, which is what I have requested from you for my Review of the IPCC draft. But I do understand your position on this. Sincerely, Pard 1. Mahal Patrick J. Michaels Associate Professor Statement of Patrick J. Michaels to the Subcommittee on Energy and Power, U.S. House of Representatives, February 21, 1989: ABSTRACT Anthropogenerated global climatic change is potentially the most serious environmental disturbance ever created by technological man. However, the problem is much more complicated than is generally perceived. Because of the combined effect of the anthropogenerated thermally active trace gases, we have effectively gone over half way to a doubling of atmospheric carbon dioxide content from the preindustrial background. If the earth's surface temperatures were in equilibrium, mean global temperatures would have risen almost two degrees Celsius. Some of that warming has not been realized because of oceanic thermal lag. However, even liberal estimates of that lag suggest we should have warned at least one degree. Surprisingly, .the Southern Hemisphere--the "water" hemisphere--shows more of "greenhouse"-like signature than the Northern Hemisphere, where there has been no significant trend in mean temperature over the last 55 years. on Estimates of global warming over the last century have been thought to range between 0.4 and 0.7 ̊C, depending upon analysis. A study over the U.S. on the relative effect of urbanization those records suggests a possible bias in the warmest estimates of nearly 0.4°C, which, if extended globally, leaves a net warming of 0.3 °C, or more than three times less than suggested by the average of sophisticated climate models, even assuming considerable oceanic thermal lag. Further, a detailed analysis of U.S. temperatures shows that nighttime temperatures are warning relative to daytime readings since the important additions of trace gases. In fact, daytime temperatures have declined over the same period. If the primary warming continued to take place at night, the world of changed trace gases is much more benign than the current expectations. I conclude that basing sweeping environmental policy upon clouded vision is especially risky, even if the otherwise rational. such policy is I would like to thank the Subcommittee for inviting my commentary on the important topic of anthropogenerated climatic change. As a matter of introduction, I note recent news and editorial stories stating that evidence is sufficiently compelling for the U.S. to now factor anthropogenerated global warming into the domestic and foreign policy matrix. The tenor of these pieces-and I have seen several--is that while there some areas of disagreement or inconsistencies in our current understanding, is high time for sweeping proaction. it My purpose here is not to throw roadblocks in the way of sensible environmental policy. No one on this panel would contest the fact that anthropogenerated global climatic change is potentially the most serious environmental disturbance ever created by technological man. My purpose is rather to underscore that policy should be commensurate with the state of scientific knowledge. as It is doubtless that carbon dioxide, an effective absorber of infrared radiation, is increasing exponentially in the atmosphere a result of man's activities. First measurements from Hawaii found concentrations of 315 parts million (ppm) in the late 1950's, while today's concentrations are nearly 350ppm. In the early 1980's, the "preindustrial" background concentration estimated at 295ppm, giving an increase of 19% since the beginning of widespread thermometric records. was If the earth had come to immediate thermal equilibrium, that change could have produced a global warming of 0.7 C. Because measured warming was thought to be between 0.4 and 0.7° C, depending upon which record is used, the observed changes initially seemed consonant with anthropogenerated CO2 increases. Several findings since then indicate the problem is much more complicated. These include the exponential increases in other thermally-active trace gases, new findings on the geographic distribution of warming and its division between night and day, and recent work on the effect of urban bias on regional temperatures. Commentary of these will comprise the balance of my testimony. 1. Changes in trace-gas concentrations. Antarctic ice core measurements now place the background CO2 concentration between 260 and 280 ppm. If we use the midpoint, the expected equilibrium warming could be 1.1 ̊C. Other thermally active trace gases have also been increasing exponentially, in particular, methane, nitrogen oxides, and the chloroflourocarbons. Tom Wigley, of the University of East Anglia, calculates that the combined effect of these should be equivalent to an additional effective increase of 57ppm. Thus, if all of the other radiatively active gases were expressed as if 407ppm, or 151% of a background of 270ppm. Under equilibrium conditions, the earth should have warmed 1.8 C from these trace gas disturbances. If the lower limit background of 260ppm is used, the expected mean global warming is very close to two degrees Celsius. As noted above, measured warming has been between 0.4 and 0.7° C. As noted below, that warming itself is subject to some question. 2. The Spatial and Temporal Distribution of Observed warming There is an unknown lag effect that occurs because of the oceans. Wigley has calculated, however, that even the most liberal estimates of this lag imply an expected warming of 1.0 C (or 1.2° with the lower background CO2 of 260ppm). At best, the earth appears to have warmed up only half as much as our average forecasts indicate it should have. A mathematical argument in Dr. Schneider's Journal Climatic Change suggested the oceans mitigate expected surface warming by a factor of three. might The oceanic lag argument is complicated by the differing behavior of the Earth's hemispheres. Southern Hemisphere temperatures, according to Jones and others at East Anglia, display a thermal signal that is much like we would expect in a Greenhouse Worldlittle change through the 1940's, followed by an exponential increase, albeit one of approximately half the magnitude expected even with liberal thermal lag arguments. no Northern hemisphere temperatures show at least one-half of their increase before the major trace gas emissions. In fact, there is statistically significant trend for the last 55 years. Hugh Elsaesser, of the Lawrence Laboratory, demonstrated that most of our hemisphere's warming can be ascribed to a period during Woodrow Wilson's presidency. Most scientists directly involved with this research problem cite the hemispheric disparity as either counter to or beyond the current pale of our understanding. 3. The Diurnal Problem Work by Tom Karl and others from NOAA provide an additional layer of complexity on the climate change problem. Careful analyses of the unurbanized Historical Climate Network data indicate that daily temperature ranges over the United States are declining since the significant addition of trace gases. In particular, it appears that night minimum temperatures rising relative to daytime maxima. The implication is that greenhouse effect could be expressing itself primarly as a rise in the nighttime temperatures, while daytime temperatures are the |