Climate Policy

Quantifying and monetizing potential climate change policy impacts on terrestrial ecosystem carbon storage and wildfires in the United States

This paper develops and applies methods to quantify and monetize projected impacts on terrestrial ecosystem carbon storage and areas burned by wildfires in the contiguous United States under scenarios with and without global greenhouse gas mitigation. The MC1 dynamic global vegetation model is used to develop physical impact projections using three climate models that project a range of future conditions. We also investigate the sensitivity of future climates to different initial conditions of the climate model. Our analysis reveals that mitigation, where global radiative forcing is stabilized at 3.7 W/m2 in 2100, would consistently reduce areas burned from 2001 to 2100 by tens of millions of hectares. Monetized, these impacts are equivalent to potentially avoiding billions of dollars (discounted) in wildfire response costs. Impacts to terrestrial ecosystem carbon storage are less uniform, but changes are on the order of billions of tons over this time period. The equivalent social value of these changes in carbon storage ranges from hundreds of billions to trillions of dollars (discounted). The magnitude of these results highlights their importance when evaluating climate policy options. However, our results also show national outcomes are driven by a few regions and results are not uniform across regions, time periods, or models. Differences in the results based on the modeling approach and across initializing conditions also raise important questions about how variability in projected climates is accounted for, especially when considering impacts where extreme or threshold conditions are important.

© 2015 the authors

Scenarios of Global Change: Integrated Assessment of Climate Impacts

Using the MIT Integrated Global System Modeling (IGSM) framework, we assess the climate impacts of emission scenarios exhibiting global mean surface temperatures ranging between 2.4°C and 4.3°C above pre-industrial by 2100. We compare the outcomes from these forward-looking scenarios against the common goal described by the target-driven scenario of 2°C. Without further policy measures, the agreement at COP-21 in Paris is projected to result in a 3.5°C increase in global temperature in 2100 relative to pre-industrial levels. Scenarios developed by Shell International (called Mountains and Oceans) exhibit a substantial movement towards temperature stabilization, as they result in increases of only 2.4–2.7°C by 2100. Valuable components of these scenarios include a substantial shift to renewable energy and deployment of carbon capture and storage (CCS). These scenarios are successful in mitigating a large portion of water stress impacts and air pollution damages. They also significantly mitigate increases in ocean acidity. These projections show the significant value of policies that do not quite reach 2°C stabilization, but fall substantially close to that target by the end of the century. The challenge of meeting the Paris Agreement’s aspiration to limit warming to 1.5°C is monumental, yet may be desirable if societies see the 2°C impacts, described here, as running too much risk.

To assess the likely impact of climate change on U.S. agriculture, researchers typically run a combination of climate and crop models that project how yields of maize, wheat and other key crops will change over time. But the suite of models commonly used in these simulations, which account for a wide range of uncertainty, produces outcomes that can range from substantial crop losses to bountiful harvests. These mixed results often leave farmers and other agricultural stakeholders perplexed as to how best to adapt to climate change.

Gauging the Impact of Climate Change on U.S. Agriculture

On July 6, MIT Joint Program Deputy Director Sergey Paltsev was a keynote speaker at the International Conference on Economic Modeling, EcoMod 2016, in Lisbon, Portugal. EcoMod is the world’s leading research, advisory and educational nonprofit network focused on promoting advanced modeling and statistical techniques in economic policy and decision-making. The annual conference draws hundreds of economic policy modelers from around the world.

Energy Scenarios: The Value and Limits of Scenario Analysis

Recognizing the substantial costs involved in addressing climate change through both mitigation and adaptation measures, the Paris Agreement stipulates that developed countries provide at least $100 billion a year in climate financing to developing countries, and support their transition to lower-carbon economies through international cooperation. One avenue for such cooperation is to link carbon markets—emissions trading systems that put a cap on carbon—in developed and developing regions.

Meeting Climate Goals through International Carbon Markets

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