Climate Policy

Linking Science and Policy to Support the Implementation of the Minamata Convention on Mercury

The Minamata Convention on Mercury, with its objective to protect human health and the environment from the dangers of mercury (Hg), entered into force in 2017. The Convention outlines a life-cycle approach to the production, use, emissions, releases, handling, and disposal of Hg. As it moves into the implementation phase, scientific work and information are critically needed to support decision-making and management. This paper synthesizes existing knowledge and examines three areas in which researchers across the natural sciences, engineering, and social sciences can mobilize and disseminate knowledge in support of Hg abatement and the realization of the Convention’s objective: (1) uses, emissions, and releases; (2) support, awareness raising, and education; and (3) impacts and effectiveness. The paper ends with a discussion of the future of Hg science and policy.

Responses of deposition and bioaccumulation in the Great Lakes region to policy and other large-scale drivers of mercury emissions

Mercury (Hg) emissions pose a global problem that requires global cooperation for a solution. However, neither emissions nor regulations are uniform world-wide, and hence the impacts of regulations are also likely to vary regionally. We report here an approach to model the effectiveness of regulations at different scales (local, regional, global) in reducing Hg deposition and fish Hg concentrations in the Laurentian Great Lakes (GL) region. The potential effects of global change on deposition are also modeled. We focus on one of the most vulnerable communities within the region, an Indigenous tribe in Michigan's Upper Peninsula (UP) with a high fish consumption rate. For the GL region, elements of global change (climate, biomass burning, land use) are projected to have modest impacts (<5% change from the year 2000) on Hg deposition. For this region, our estimate of the effects of elimination of anthropogenic emissions is a 70% decrease in deposition, while our minimal regulation scenario increases emissions by 35%. Existing policies have the potential to reduce deposition by 20% with most of the reduction attributable to U.S. policies. Local policies within the Great Lakes region show little effect, and global policy as embedded in the Minamata Convention is projected to decrease deposition by approximately 2.8%. Even within the GL region, effects of policy are not uniform; areas close to emission sources (Illinois, Indiana, Ohio, Pennsylvania) experience larger decreases in deposition than other areas including Michigan's UP. The UP landscape is highly sensitive to Hg deposition, with nearly 80% of lakes estimated to be impaired. Sensitivity to mercury is caused primarily by the region's abundant wetlands. None of the modeled policy scenarios are projected to reduce fish Hg concentrations to the target that would be safe for the local tribe. Regions like Michigan's UP that are highly sensitive to mercury deposition and that will see little reduction in deposition due to regulations require more aggressive policies to reduce emissions to achieve recovery. We highlight scientific uncertainties that continue to limit our ability to accurately predict fish Hg changes over time.

Mid-Western U.S. Heavy Summer-Precipitation in Regional and Global Climate Models: The Impact on Model Skill and Consensus Through an Analogue Lens

Extreme precipitation events pose a significant threat to public safety, natural and managed resources, and the functioning of society. Changes in such high-impact, low-probability events have profound implications for decision-making, preparation and costs of mitigation and adaptation efforts. Understanding how extreme precipitation events will change in the future and enabling consistent and robust projections is therefore important for the public and policymakers as we prepare for consequences of climate change.

Projection of extreme precipitation events, however, particularly at the local scale, presents a critical challenge: the climate model-based simulations of precipitation that we currently rely on for such projections—general circulation models (GCMs)—are not very realistic, mainly due to the models’ coarse spatial resolution. This coarse resolution precludes adequate representation of highly influential, small-scale features such as moisture convection and topography. Regional circulation models (RCMs) provide much higher resolution and better representation of such features, and are thus often perceived as an optimum approach to producing more accurate heavy precipitation statistics than GCMs. However, they are much more computationally intensive, time-consuming and expensive to run.

In a previous paper, the researchers developed an algorithm that detects the occurrence of heavy precipitation events based on climate models’ well-resolved, large-scale atmospheric circulation conditions associated with those events—rather than relying on these models’ simulated precipitation. The algorithm’s results corresponded with observations with much greater precision than the model-simulated precipitation.

In this paper, the researchers show that the performance of the new algorithm in detecting heavy precipitation event is not dependent on the model resolution and even better than that of precipitation simulated from RCMs. The algorithm thus presents a robust and economic way to assess extreme precipitation frequency across a broad range of GCMs and multiple climate change scenarios with minimal computational requirements.   

David L. Chandler | MIT News Office 
April 6, 2018

Putting a price on carbon, in the form of a fee or tax on the use of fossil fuels, coupled with returning the generated revenue to the public in one form or another, can be an effective way to curb emissions of greenhouse gases. That’s one of the conclusions of an extensive analysis of several versions of such proposals, carried out by researchers at MIT and the National Renewable Energy Laboratory (NREL).

Carbon taxes could make significant dent in climate change, study finds
Meeting the Goals of the Paris Agreement: Temperature Implications of the Shell Sky Scenario

The Paris Agreement makes long-term energy and climate projections particularly important because it calls for a goal that likely requires an energy system that is based on a radically different fuel mix than currently in use. This presents a challenge for energy companies as they try to anticipate the types of energy and fuels that will be required to stay competitive while meeting environmental requirements. A new scenario (called Sky) developed by Shell International examines the challenge of moving to an energy system with net-zero CO2 emissions and gradually eliminate emissions from deforestation by midway through the second half of the century (specifically by the year of 2070). Using the MIT Integrated Global System Modeling (IGSM) framework, we simulate a 400-member ensemble, reflecting uncertainty in Earth system response of global temperature change associated with the Sky scenario by 2100. We find that for the median climate parameters the global surface temperature increase by 2100 is 1.75°C above the pre-industrial levels with an 85% probability of remaining below 2°C. The geographic distribution of the temperature change shows a stronger warming in Polar regions. If, in addition, there is a significant effort directed toward global reforestation then, with median climate parameters, temperature increase by 2100, is near 1.5°C above pre-industrial levels.

Bioenergy with carbon capture and storage: key issues and major challenges

Projections of the pathways that reduce carbon emission to the levels consistent with limiting global average temperature increases to 1.5°C or 2°C above pre-industrial levels often require negative emission technologies like bioelectricity with carbon capture and storage (BECCS). We review the global energy production potential and the ranges of costs for the BECCS technology.  We then represent a version of the technology in the MIT Economic Projection and Policy Analysis (EPPA) model to see how it competes with other low carbon options under stabilization scenarios. We find that, with a global price on carbon designed to achieve climate stabilization goals, the technology could make a substantial contribution to energy supply and emissions reduction in the second half of the 21st century. The main uncertainties weighing on bioelectricity with carbon capture and storage are biomass availability at large scale, the pace of improvements in carbon capture technologies, the availability and cost of CO2 storage, and social acceptance.  Commercial viability would appear to depend strongly on a policy environment, such as carbon pricing, that would advantage it, given the technology costs we assume. Compared to previous studies, we provide a consistent approach to evaluate all of the components of the technology, from growing biomass to CO2 storage assessment. Our results show that global economic costs and needed carbon prices to hit the stabilization target are substantially lower with the technology available at reasonable costs.

Next Steps in Tax Reform

The GOP tax reform, now adopted as the 2017 Tax Cuts and Jobs Act, aimed to cut business taxes to stimulate investment, lower some personal taxes, eliminate deductions and tax credits to help pay for the tax reductions, and reduce the shifting of profits abroad by U.S. companies. Some of these objectives have been achieved, but at the cost of a potentially substantial increase in the fiscal deficit, among other problems. As a result, corrections will be needed in future years.

Many of the Act’s undesirable features reflect its drafters’ inability to come up with sufficient revenue to compensate for the tax reductions. This paper explores a carbon dioxide (CO2) tax as perhaps the only measure that’s consistent with the declared tax-reform principles of the GOP leadership, likely to draw Democratic support, and large enough to compensate for the Act’s revenue-losing provisions. After summarizing the process that led to the Act and its major shortcomings, the researchers—applying the MIT U.S. Regional Energy Policy (USREP) model—show how, when the Act is opened up for repairs, a CO2 tax could help correct its flaws while serving environmental goals.

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