The Influence on Climate Change of Differing Scenarios for Future Development Analyzed Using the MIT Integrated Global System Model

Abstract and PDF report are also available on the MIT Joint Program on the Science and Policy of Global Change website (http://globalchange.mit.edu/).A wide variety of scenarios for future development have played significant roles in climate policy discussions. This paper presents projections of greenhouse gas (GHG) concentrations, sea level rise due to thermal expansion and glacial melt, oceanic acidity, and global mean temperature increases computed with the MIT Integrated Global Systems Model (IGSM) using scenarios for 21st century emissions developed by three different groups: intergovernmental (represented by the Intergovernmental Panel on Climate Change), government (represented by the U.S. government Climate Change Science Program) and industry (represented by Royal Dutch Shell plc). In all these scenarios the climate system undergoes substantial changes. By 2100, the CO2 concentration ranges from 470 to 1020 ppm compared to a 2000 level of 365 ppm, the CO2-equivalent concentration of all greenhouse gases ranges from 550 to 1780 ppm in comparison to a 2000 level of 415 ppm, sea level rises by 24 to 56 cm relative to 2000 due to thermal expansion and glacial melt, oceanic acidity changes from a current pH of around 8 to a range from 7.63 to 7.91. The global mean temperature increases by 1.8 to 7.0 degrees C relative to 2000.The IGSM model used here is supported by the U.S. Department of Energy, U.S. Environmental Protection Agency, U.S. National Science Foundation, U.S. National Aeronautics and Space Administration, U.S. National Oceanographic and Atmospheric Administration and the Industry and Foundation Sponsors of the MIT Joint Program on the Science and Policy of Global Change

Analysis of Climate Policy Targets under Uncertainty

Abstract and PDF report are also available on the MIT Joint Program on the Science and Policy of Global Change website (http://globalchange.mit.edu/).Although policymaking in response to the climate change is essentially a challenge of risk management, most studies of the relation of emissions targets to desired climate outcomes are either deterministic or subject to a limited representation of the underlying uncertainties. Monte Carlo simulation, applied to the MIT Integrated Global System Model (an integrated economic and earth system model of intermediate complexity), is used to analyze the uncertain outcomes that flow from a set of century-scale emissions targets developed originally for a study by the U.S. Climate Change Science Program. Results are shown for atmospheric concentrations, radiative forcing, sea ice cover and temperature change, along with estimates of the odds of achieving particular target levels, and for the global costs of the associated mitigation policy. Comparison with other studies of climate targets are presented as evidence of the value, in understanding the climate challenge, of more complete analysis of uncertainties in human emissions and climate system response.This study received support from the MIT Joint Program on the Science and Policy of Global Change, which is funded by a consortium of government, industry and foundation sponsors

Hyperdeterminants as integrable discrete systems

We give the basic definitions and some theoretical results about hyperdeterminants, introduced by A. Cayley in 1845. We prove integrability (understood as 4d-consistency) of a nonlinear difference equation defined by the 2x2x2-hyperdeterminant. This result gives rise to the following hypothesis: the difference equations defined by hyperdeterminants of any size are integrable. We show that this hypothesis already fails in the case of the 2x2x2x2-hyperdeterminant.Comment: Standard LaTeX, 11 pages. v2: corrected a small misprint in the abstrac

Valuing Climate Impacts in Integrated Assessment Models: The MIT IGSM

http://globalchange.mit.edu/research/publications/reports/allWe discuss a strategy for investigating the impacts of climate change on Earth’s physical, biological and human resources and links to their socio-economic consequences. The features of the integrated global system framework that allows a comprehensive evaluation of climate change impacts are described with particular examples of effects on agriculture and human health. We argue that progress requires a careful understanding of the chain of physical changes—global and regional temperature, precipitation, ocean acidification and polar ice melting. We relate those changes to other physical and biological variables that help people understand risks to factors relevant to their daily lives—crop yield, food prices, premature death, flooding or drought events, land use change. Finally, we investigate how societies may adapt, or not, to these changes and how the combination of measures to adapt or to live with losses will affect the economy. Valuation and assessment of market impacts can play an important role, but we must recognize the limits of efforts to value impacts where deep uncertainty does not allow a description of the causal chain of effects that can be described, much less assigned a likelihood. A mixed approach of valuing impacts, evaluating physical and biological effects, and working to better describe uncertainties in the earth system can contribute to the social dialogue needed to achieve consensus—where it is needed—on the level and type of mitigation and adaptation actions that are required.The MIT Integrated Global System Model (IGSM) and its economic component used in the analysis, the MIT Emissions Prediction and Policy Analysis (EPPA) model, is supported by a consortium of government, industry, and foundation sponsors of the MIT Joint Program on the Science and Policy of Global Change. (For a complete list of sponsors, see: http://globalchange.mit.edu)

Global economic effects of changes in crops, pasture, and forests due to changing climate, carbon dioxide, and ozone

Author Posting. © The Author(s), 2007. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Energy Policy 35 (2007): 5370-5383, doi:10.1016/j.enpol.2006.01.040.Multiple environmental changes will have consequences for global vegetation. To the extent that crop yields and pasture and forest productivity are affected there can be important economic consequences. We examine the combined effects of changes in climate, increases in carbon dioxide, and changes in tropospheric ozone on crop, pasture, and forest lands and the consequences for the global and regional economies. We examine scenarios where there is limited or little effort to control these substances, and policy scenarios that limit emissions of CO2 and ozone precursors. We find the effects of climate and CO2 to be generally positive, and the effects of ozone to be very detrimental. Unless ozone is strongly controlled damage could offset CO2 and climate benefits. We find that resource allocation among sectors in the economy, and trade among countries, can strongly affect the estimate of economic effect in a country.This research was supported by the US Department of Energy, US Environmental Protection Agency, US National Science Foundation, US National Aeronautics and Space Administration, US National Oceanographic and Atmospheric Administration; and the Industry and Foundation Sponsors of the MIT Joint Program on the Science and Policy of Global Chang

Validity of ejection fraction as a measure of myocardial functional state: impact of asynchrony

Aims The goal of this study was to test whether peculiarities of left ventricular (LV) regional function place limits on the validity of ejection fraction (EF) as a measure of the myocardial functional state. Methods and results Transthoracic and transoesophageal data from patients with a variety of cardiac conditions were used for analysis of LV regional function. The focus was on the effects of mechanical asynchrony. Ejection fraction was calculated on the basis of LV end-diastolic volume and end-systolic volume obtained by two different ways: (i) end-systolic volume as a whole; and (ii) the sum of all regional end-systolic volumes (which may occur at different times). The relative difference, D-EF, between EFs obtained by (i) and (ii) was taken as the ‘merit ’ of EF. A value of zero is the highest merit. Irrespective of the examination method, we found that D-EF was always higher than zero, and that its value depended on the extent of mechanical asynchrony. Conclusions Ejection fraction is not the arithmetic average of regional EFs. An increase of asynchrony increases D-EF, i.e. it reduces the merit of EF as a measure of cardiac function

Probabilistic Forecast for 21st Century Climate Based on Uncertainties in Emissions (without Policy) and Climate Parameters

Abstract and PDF report are also available on the MIT Joint Program on the Science and Policy of Global Change website (http://globalchange.mit.edu/).The MIT Integrated Global System Model is used to make probabilistic projections of climate change from 1861 to 2100. Since the model's first projections were published in 2003 substantial improvements have been made to the model and improved estimates of the probability distributions of uncertain input parameters have become available. The new projections are considerably warmer than the 2003 projections, e.g., the median surface warming in 2091 to 2100 is 5.1°C compared to 2.4°C in the earlier study. Many changes contribute to the stronger warming; among the more important ones are taking into account the cooling in the second half of the 20th century due to volcanic eruptions for input parameter estimation and a more sophisticated method for projecting GDP growth which eliminated many low emission scenarios. However, if recently published data, suggesting stronger 20th century ocean warming, are used to determine the input climate parameters, the median projected warning at the end of the 21st century is only 4.1°C. Nevertheless all our simulations have a very small probability of warming less than 2.4°C, the lower bound of the IPCC AR4 projected likely range for the A1FI scenario, which has forcing very similar to our median projection. The probability distribution for the surface warming produced by our analysis is more symmetric than the distribution assumed by the IPCC due to a different feedback between the climate and the carbon cycle, resulting from a different treatment of the carbon-nitrogen interaction in the terrestrial ecosystem.his work was supported in part by the Office of Science (BER), U.S. Department of Energy Grant No. DE-FG02-93ER61677, NSF, and by the MIT Joint Program on the Science and Policy of Global Change

Conical geometry and quantum entropy of a charged Kerr black hole

We apply the method of conical singularities to calculate the tree-level entropy and its one-loop quantum corrections for a charged Kerr black hole. The Euclidean geometry for the Kerr-Newman metric is considered. We show that for an arbitrary periodization in Euclidean space there exists a conical singularity at the horizon. Its $\delta$-function like curvatures are calculated and are shown to behave similar to the static case. The heat kernel expansion for a scalar field on this conical space background is derived and the (divergent) quantum correction to the entropy is obtained. It is argued that these divergences can be removed by renormalization of couplings in the tree-level gravitational action in a manner similar to that for a static black hole.Comment: 22 pages, latex, no figures; minor corrections mad

Corrigendum

Author Posting. © American Meteorological Society, 2010. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Climate 23 (2010): 2230–2231, doi:10.1175/2009JCLI3566.1.Corrigendum: Sokolov, A., and Coauthors, 2009: Probabilistic forecast for twenty-first-century climate based on uncertainties in emissions (without policy) and climate parameters. J. Climate, 22, 5175–5204