difference between the 1930 to 1950 average and the 1860 to 1920 average, the difference is only about 0.2 degrees Centigrade. The skeptics also argue that there was little change in greenhouse gas concentrations pre-1940 hence the observed changes in temperature cannot be attributed to the greenhouse effect. However, a careful examination of the changing in radiative forcing shows that about 35% of the radiative forcing occurred before 1940, hence contributing to an enhanced greenhouse effect prior to 1940. FCCC Article 2 ... Q18. Article 2 of the Framework Convention on Climate Change states: "The ultimate objective of this Convention . . . is to achieve ... stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system.” Q18.1. How is this level to be determined? A18.1. The Parties to the Framework Convention on Climate Change, informed by the latest scientific, technical and economic information, should determine both the appropriate stabilization level and the most appropriate pathway to stabilization. In addition, national policymakers should determine the appropriate choice of technologies, policies and practices that most suit their national circumstances. The IPCC has already published two comprehensive assessments and a number of technical papers and special reports that can assist policymakers in this critical task. The IPCC Third Assessment Report will, like the first two assessment reports, be comprehensive, policy relevant, but not policy prescriptive. As discussed in the answer to question 2.1, the Third Assessment Report will include a Synthesis Report specifically designed to provide scientific, technical and economic information relevant to key policy-relevant questions. For example, the Synthesis Report could address the following questions related to assessing the most appropriate stabilization level; What are the climatic, impact and economic consequences of different stabilization projected changes in climate and sea level at the regional and global level; the economic costs and benefits and social issues (including equity) associated with the projected impacts and adaptation options; the technologies, policies and measures that can be used for mitigation; the economic costs and benefits and distributional/equity issues associated with mitigation. Q18.2. What is the scientific justification for setting greenhouse-gas stabilization at this level? - A18.2. As I stated in the answer to question 18.1 the level should be set by policymakers, informed by scientific, technical and economic information. Setting the level will depend on a number of factors, including: (i) how risk adverse policymakers want to be will they hide behind scientific uncertainty hoping that we are overestimating the impact of human activities on the climate system, or will they realize that we could be underestimating the impacts of human activities; (ii) to what degree they are willing to take a global view, rather than a national view, given there are "regional winners and losers"; (iii) to what degree they consider future generations that will bear the full impact on climate change; (iv) to what degree to they want to protect ecological systems such as forests and coral reefs. Q18.3. How is the phrase "dangerous anthropogenic interference with the climate system" defined? A18.3. Article 2 of the Convention states: "the stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system. Such a level should be achieved within a timeframe sufficient to allow ecosystems to adapt naturally to climate change, to ensure that food production is not threatened and to enable economic development to proceed in a sustainable manner". Q18.4. Will any of the emission reduction proposals currently under consideration achieve this goal of stabilization? A18.4. No. Stabilization of carbon dioxide, the major anthropogenic greenhouse gas, will require global emissions reductions. Stabilization will eventually require global emissions to be reduced to between 2 and 3 billion tons of Carbon per year, in contrast to today's global emissions of about 6 billion tons of Carbon per year. HEARING OF THE SUBCOMMITTEE ON ENERGY AND ENVIRONMENT COMMITTEE ON SCIENCE U.S. HOUSE OF REPRESENTATIVES on Countdown to Kyoto-Part 3: The Administration's Global Climate Change Proposal Thursday, November 6, 1997 Post-Hearing Questions and Answers Dr. Patrick Michaels Professor of Environmental Sciences University of Virginia and Senior Fellow in Environmental Studies Cato Institute What Will an Agreement Accomplish for the Environment? Q1. A1. Your analysis indicates very little benefit from the President's plan, even assuming the models are correct-a big if. How much would CO2 emissions have to be cut to have a substantial impact on projected warming if current models are correct? This depends upon which climate model is used, and is indicative of the lack of reliability inherent in these models. The new model from the Geophysical Fluid Dynamics Laboratory (not yet published in the refereed literature) projects a warming of around 4.0° C over the course of the next century. While I do not believe this forecast is warranted by the observed data on global warming, it gives some guidance on how much emissions would have to be reduced to prevent "significant" warming, which I take to be around 2.0° over the next 100 years. Roughly speaking, the GFDL model would require that the atmospheric concentration of equivalent CO2 be stabilized somewhere around the current effective value of 440 parts per million (ppm). This would require reducing emissions to the point that there is no longer any year-to-year increase in the overall concentration. I would estimate that is equivalent to an emission level observed somewhere back in the 1920s, or roughly an 80% reduction from On the other hand, one could assume that the new model from the National Center for Atmospheric Research (NCAR), as described in the May 16, 1997 issue of Science is correct. It does a better job than most of tracking past temperatures, it does not contain as many “fudge factors" (those are the words of Science and not mine), and it only projects a warming of about 1.4° C over the next 100 years if we continue our exponential growth of 0.7%/year in emissions. In other words, doing nothing is perfectly acceptable within the 2.0° C envelope. All of this leads to a much more central policy question: If one believes in the more extreme models, current emission reduction proposals will be totally insufficient, only causing economic dislocation and not preventing much warming. On the other hand, if one believes that the cooler models are correct, why bother doing anything? In other words, what has been proposed will satisfy neither assumption. Apocalyptic Politics Q2. A2. In the July 1997 edition of New Scientist, you are quoted as saying, “You can't make a case for a global apocalypse out of a 1.5°C warming. It destroys the issue. If politics weren't driving this we could all meet on common ground." For the record, what did you mean by that statement? The most likely warming scenario for the next century, based upon observed data and models that fit the observed data well is for a warming of 1.0-1.5° C, primarily in the coldest airmasses in winter. This is well within the "consensus" of 1.0-3.0° of the United Nations Intergovernmental Panel on Climate Change. I believe that most scientists who have looked carefully at the observed data would agree with the lower end of that range, and that it is not the apocalyptic problem that is often portrayed. Unfortunately, the political process does not promote agreement, for several reasons. Probably the most prominent is scientific funding. Clearly a statement that warming will be in the low end of the range reduces the glamour of the issue and would result in a decrease in the current federal support level of $2.1bn/year for global change research. So scientists feel a pressure NOT to publicly acknowledge that the low end of the estimates is more likely. Administration Warming Claims-Do They Stand Up? Q3. A3. The Vice President recently pointed to human-induced global warming for the melting of Grinnell Glacier in Glacier National Park. Can the state of Grinnell Glacier be linked to global warming? According to the National Park Service's own literature, Grinnell Glacier began melting in the mid-19th century as the earth began to escape from the "little ice age”, a cold period that reached its nadir around 1750. Perhaps more interesting, though, is the fact that summer daytime temperatures in the Glacier Park climate district have not increased in the last 100 years (Figure 1). Glaciers, of course, melt most during summer days. Therefore the melting of Grinnell is not related to 20th century climate change, which is the only century in which humans have appreciably changed the greenhouse effect. Any attempt to imply that humans are causing the melting in this particular area, as the Vice President implied last September, is misleading and not based upon the known temperature history of the Glacier Park region. FIGURE 1. Summer daytime temperatures from the Climatological Division containing Glacier National Park. Source: National Climatic Data Center, U.S. Department of Commerce, Asheville, North Carolina. |