Includes bibliographical references (p. 14-15). / Abstract in HTML and technical report in HTML and PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change website (http://mit.edu/globalchange/www/).

This paper analyzes the determinants of deforestation in the Brazilian Amazon. From a model of optimal land use, it derives and then estimates a deforestation equation on country-level data for the period 1978 to 1988. The data include a deforestation measure from satellite images, which is a great advance in that it allows improved within-country analysis. Evidence exists that: increased road density in a country leads to more deforestation in that country and in neighboring countries; government-subsidized development projects increase deforestation; greater distance from markets south of the Amazon leads to less deforestation; and better soil quality leads to more deforestation. The results for government provision of credit are mixed across specifications. The population density, although the primary explanatory variable in most previous empirical work, does not have a significant effect when all the variables motivated within the model are included. However, a quadratic specification yields a more robust population result: the first few people entering an empty country have significantly more impact than the same number of people added to a densely populated country. This result suggests the importance of the spatial distribution of population. / Abstract in HTML and technical report in HTML and PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change website (http://mit.edu/globalchange/www/). / Includes bibliographical references.

A multi-sector multi-region general equilibrium model of economic growth and emissions is used to explore the conditions that will determine the market penetration of CO2 capture and disposal technology. / Includes bibliographical references (p. 16). / Abstract in HTML and technical report in HTML and PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change website (http://mit.edu/globalchange/www/). / Support through a government-industry partnership including the U.S. Dept. of Energy. 901214-HAR, DE-F02-94ER61937, DE-F02-94ER61713 Support from U.S. Environmental Protection Agency. CR-820662-02 Support from a group of corporate sponsors from the United States, Europe and Japan, and the Electric Power Research Institute. W02141-23

The MIT Emissions Prediction and Policy Analysis (EPPA) model is applied to an exploration of the national emissions obligations that would be required to stabilize atmospheric CO2 concentrations at levels now under active discussion. The results indicate that the needed voluntary participation will be difficult to achieve, not least because nations at very different income levels would have to undertake similarly costly emissions restrictions. The need for more attention to the linkage between short-term policy proposals and long-term stabilization goals is highlighted. / Includes bibliographical references (p. 16). / Abstract in HTML and technical report in HTML and PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change website (http://mit.edu/globalchange/www/).

This paper discusses the design of efficient environmental policies in general and reviews omissions and shortcomings of the presentation of the economic dimensions of climate change in the Intergovernmental Panel on Climate Change (IPCC) Working Group III's Report: "Climate Change 1995 Economic and Social Dimensions of Climate Change: Contribution of Working Group III to the Second Assessment Report of the Intergovernmental Panel on Climate Change" (Cambridge Univ. Press, Cambridge, UK, 1996). / Includes bibliographical references (p. 15-16). / Abstract in HTML and technical report in HTML and PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change website (http://mit.edu/globalchange/www/).

The Terrestrial Ecosystem Model (TEM, version 4.0) was used to estimate net primary production (NPP) in China for contemporary climate and NPP responses to elevated CO₂ and climate changes projected by three atmospheric general circulation models (GCMs): Goddard Institute for Space Studies (GISS), Geophysical Fluid Dynamic Laboratory (GFDL) and Oregon State University (OSU). For contemporary climate at 312.5 ppmv CO₂, TEM estimates that China has an annual NPP of 3,653 TgC/yr (10^12 gC/yr). Temperate broadleaf evergreen forest is the most productive biome and accounts for the largest portion of annual NPP in China. The spatial pattern of NPP is closely correlated to the spatial distributions of precipitation and temperature.Annual NPP of China is sensitive to changes in CO₂ and climate. At the continental scale, annual NPP of China increases by 6.0% (219 TgC/yr) for elevated CO₂ only (519 ppmv CO₂). For climate change with no change in CO₂, the response of annual NPP ranges from a decrease of 1.5% (54.8 TgC/yr) for the GISS climate to an increase of 8.4% (306.9 TgC/yr) for the GFDL-q climate. For climate change at 519 ppmv CO₂, annual NPP of China increases substantially, ranging from 18.7% (683 TgC/yr) for the GISS climate to 23.3% (851 TgC/yr) for the GFDL-q climate. Spatially, the responses of annual NPP to changes in climate and CO₂ vary considerably within a GCM climate. Differences among the three GCM climates used in the study cause large differences in the geographical distribution of NPP responses to projected climate changes. The interaction between elevated CO₂ and climate change plays an important role in the overall response of NPP to climate change at 519 ppmv CO₂. / Includes bibliographical references (p. 14-17). / Abstract in HTML and technical report in HTML and PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change website (http://mit.edu/globalchange/www/). / Supported by the National Aeronautics and Space Administration's Earth Observing System. NAGW-2669. Supported by the Dept. of Energy's National Institute for Global Environmental Change. 901214-HAR Supported by the Joint Program on Science and Policy of Global Change at MIT. CE-S-462041

The climatological impact of increases in greenhouse gas concentrations in the atmosphere, despite being a subject of intensive study in recent years, is still very uncertain. One major uncertainty affecting possible climate change that has not received enough attention is the uncertainty in heat uptake by the deep ocean. We analyze the influence of this process and its uncertainty on climate predictions by means of numerical simulations with a 2-dimensional climate model. In the case of high climate sensitivity, as a result of uncertainty in deep ocean heat uptake, there is more than a factor of two uncertainty in the predicted increase of surface temperature. The corresponding uncertainty in the sea level rise due to thermal expansion is much larger than the uncertainty in the predicted temperature change and is significant even in the case of low climate sensitivity. / Includes bibliographical references (p. 3). / Abstract in HTML and technical report in HTML and PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change website (http://mit.edu/globalchange/www/).

Policies under consideration within the Climate Convention would impose CO₂ controls on only a subset of nations. A model of economic growth and emissions, coupled to an analysis of the climate system, is used to explore the consequences of a sample proposal of this type. The results show how economic burdens are likely to be distributed among nations, how carbon "leakage" may counteract the reductions attained, and how policy costs may be influenced by emissions trading. We explore the sensitivity of results to uncertainty in key underlying assumptions, including the influence on economic impacts and on the policy contribution to long-term climate goals. / Includes bibliographical references (p. 16). / Abstract in HTML and technical report in HTML and PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change website (http://mit.edu/globalchange/www/).

In a partial factorial model experiment, we used the Terrestrial Ecosystem Model (TEM, version 4.0) to assess the relative roles of changes in CO2, temperature, precipitation and cloudiness in equilibrium responses of primary production and carbon storage. In the experiment, we used two levels of atmospheric CO2 concentration (315 and 522 ppmv CO2), contemporary climate and changes in temperature, precipitation and cloudiness as estimated by a 3-dimensional atmospheric general circulation model (Geophysical Fluid Dynamic Laboratory-GFDL) and a 2-dimensional climate model (Land-Ocean climate model at Massachusetts Institute of Technology) for doubled CO2. The results show that elevated CO2 and projected increases in temperature account for most of the overall equilibrium responses of NPP and carbon storage to changes in climate and CO2, while the projected changes in precipitation and cloudiness contribute least. This is partly attributable to the magnitudes of changes in CO2 and climate variables as projected by the climate models. The results also show that the interactions among changes in CO2 and climate variables play a significant role in the equilibrium responses of NPP and carbon storage to changes in CO2 and climate. Of all the interaction terms, the interaction between a change in CO2 and a change in temperature is the most significant. / Includes bibliographical references (p. 21-25). / Abstract in HTML and technical report in HTML and PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change website (http://mit.edu/globalchange/www/).

Emissions of carbon dioxide from combustion of fossil fuels, which may contribute to long-term climate change, are projected through 2050 using reduced form models estimated with national-level panel data for the period 1950-1990. We employ a flexible form for income effects, along with fixed time and country effects, and we handle forecast uncertainty explicitly. We find an "inverse-U" relation with a within-sample peak between carbon dioxide emissions (and energy use) per capita and per captia income. Using the income and population growth assumptions of the Intergovernmental Panel on Climate Change (IPCC), we obtain projections significantly and substantially above those of the IPCC. / Includes bibliographical references (p. 25-27). / Abstract in HTML and technical report in HTML and PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change website (http://mit.edu/globalchange/www/). / Supported by the U.S. Department of Energy, the MIT Center for Energy and Environmental Policy Research, the MIT Joint Program on the Science and Policy of Global Change, and the National Science Foundation.