Regional Analysis

Land-use change in the continental United States: Are there tipping points?

Abstract: Land use in the U.S. is driven by multiple forces operating at the global level such as income and population growth, yield and productivity improvement, trade policy, climate change, and changing diets. Future land use has implications for biodiversity, run-off, carbon storage, ecosystem values, agriculture and the broader economy. We investigate those forces in the U.S. and their implications from a multi-sector, multi-system dynamics (MSD) perspective focused on understanding dynamics and resilience in complex interdependent systems.

Historical trends show slightly increased grassland and natural forest areas and decreases in cropland. We project these trends will be intensified under higher pressures for agricultural land or reduced under lower pressures, with no evidence of tipping points toward larger agricultural land abandonment or deforestation. However, U.S. sectoral output and trade, fertilizer use, N2O and CH4 emissions from agriculture activities, and CO2 emissions from land-use change are substantially impacted under several land-use forcing scenarios.

The role of shale gas in shaping the U.S. long-run CO2 emissions

Abstract: The shale gas boom in the U.S. has lowered the U.S. CO2 emissions in recent years mainly through substitution of gas for coal in power generation. Will the shale gas boom reduce the emissions in the long-run as well?

To study this, we consider a counterfactual without the shale gas boom based on a general equilibrium modeling for the 2011 U.S. economy. To enhance the power sector modeling, the supply responses of coal-fired and gas-fired generations are calibrated to existing research. We find that if gas prices remain at 2007 levels in 2011, only a model setting that allows very little reduction in electricity demand, reflecting a short-run demand response, generates an increase in economy-wide emissions. For all other cases, the higher gas price under the counterfactual will have a dampening effect on economic activities and consequently lowers economy-wide emissions, even though the power sector emissions may increase due to the gas-to-coal switch.

In other words, without any policy intervention, although the shale gas boom could reduce emissions in the short run, it may lead to higher emissions in the long run if the low gas prices persist. Our finding suggests that extrapolating the current decline in emissions due to the shale gas boom to the distant future could be misleading. Instead, if curbing emissions is the goal, rather than depending upon the cheap gas, policies and measures for cutting emissions remain imperative.

Today Russia’s economy depends heavily upon its abundant fossil fuel resources. Russia is one of the world’s largest exporters of fossil fuels, and a number of its key exporting industries—including metals, chemicals and fertilizers—draw on fossil resources. The nation also consumes fossil fuels at a relatively high rate; it’s the world’s fourth largest emitter of carbon dioxide.

Decarbonize and diversify
Impacts of climate change policies worldwide on the Russian economy

Abstract: Because the Russian economy relies heavily on exports of fossil fuels, the primary source of human-induced greenhouse gas (GHG) emissions, it may be adversely impacted by Paris Agreement-based climate policies that target reductions in GHG emissions. Applying the MIT Economic Projection and Policy Analysis (EPPA) model to assess the impacts on the Russian economy of the efforts of the main importers of Russian fossil fuels to follow the global goals of the Paris Agreement, we project that climate-related actions outside of Russia will lower the country’s GDP growth rate by about one-half of a percentage point. The Paris Agreement is also expected to raise Russia’s risks of facing market barriers for its exports of energy-intensive goods, and of falling behind in the development of low-carbon energy technologies that most of the world is increasingly adopting.  

Key policy insights:

  • Regardless of its domestic emissions reduction efforts, Russia will not be able to sustain its current trajectory of fossil fuel export-based development due to climate policies worldwide.
  • To address the challenge of climate-related energy transition, Russia needs a new comprehensive development strategy that accounts for the post-Paris Agreement global energy landscape.
  • The key elements of such a strategy include diversification of the economy, moving to low-carbon energy sources, and investing in human capital development.
  • Our diversification scenarios show that redistribution of income from the energy sector to the development of human capital would benefit the economy.
  • The largest impact of investment re-orientation from the fossil fuel sector would be on manufacturing, services, agriculture and food production.
Seasonal source variability of carbonaceous aerosols at the Rwanda Climate Observatory

Abstract: Sub-Saharan Africa (SSA) is a global hot spot for aerosol emissions, which affect the regional climate and air quality. In this paper, we use ground-based observations to address the large uncertainties in the source-resolved emission estimation of carbonaceous aerosols. Ambient fine fraction aerosol was collected on filters at the high-altitude (2590 m a.s.l.) Rwanda Climate Observatory (RCO), a SSA background site, during the dry and wet seasons in 2014 and 2015. The concentrations of both the carbonaceous and inorganic ion components show a strong seasonal cycle, with highly elevated concentrations during the dry season. Source marker ratios, including carbon isotopes, show that the wet and dry seasons have distinct aerosol compositions. The dry season is characterized by elevated amounts of biomass burning products, which approach ∼95 % for carbonaceous aerosols. An isotopic mass-balance estimate shows that the amount of the carbonaceous aerosol stemming from savanna fires may increase from 0.2 µg m−3 in the wet season up to 10 µg m−3 during the dry season. Based on these results, we quantitatively show that savanna fire is the key modulator of the seasonal aerosol composition variability at the RCO.

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