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[1] We develop and use a new version of the Terrestrial Ecosystem Model (TEM) to study how rates of methane (CH 4) emissions and consumption in high-latitude soils of the Northern Hemisphere have changed over the past century in response to observed changes in the region's climate. We estimate that the net emissions of CH 4 (emissions minus consumption)(More)
The MIT Joint Program on the Science and Policy of Global Change is an organization for research, independent policy analysis, and public education in global environmental change. It seeks to provide leadership in understanding scientific, economic, and ecological aspects of this difficult issue, and combining them into policy assessments that serve the(More)
Exposure of plants to ozone inhibits photosynthesis and therefore reduces vegetation production and carbon sequestration. The reduced carbon storage would then require further reductions in fossil fuel emissions to meet a given CO 2 concentration target, thereby increasing the cost of meeting the target. Simulations with the Terrestrial Ecosystem Model(More)
A global biofuels program will lead to intense pressures on land supply and can increase greenhouse gas emissions from land-use changes. Using linked economic and terrestrial biogeochemistry models, we examined direct and indirect effects of possible land-use changes from an expanded global cellulosic bioenergy program on greenhouse gas emissions over the(More)
We used a biogeochemistry model, the Terrestrial Ecosystem Model (TEM), to study the net methane (CH4) fluxes between Alaskan ecosystems and the atmosphere. We estimated that the current net emissions of CH4 (emissions minus consumption) from Alaskan soils are approximately 3 Tg CH4/yr. Wet tundra ecosystems are responsible for 75% of the region's net(More)
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 (CO 2), and changes in tropospheric ozone on crop, pasture, and forest(More)
[1] Terrestrial ecosystems of the northern high latitudes (above 50°N) exchange large amounts of CO 2 and CH 4 with the atmosphere each year. Here we use a process-based model to estimate the budget of CO 2 and CH 4 of the region for current climate conditions and for future scenarios by considering effects of permafrost dynamics, CO 2 fertilization of(More)
In this review article, we explore how surface-level ozone affects trees and crops with special emphasis on consequences for productivity and carbon sequestration. Vegetation exposure to ozone reduces photosynthesis, growth, and other plant functions. Ozone formation in the atmosphere is a product of NO x , which are also a source of nitrogen deposition.(More)
The role of sinks in climate policy has been controversial and confused. The major supporters for including sinks in an international climate policy under the Kyoto Protocol were the Umbrella Group of countries, led by the USA and including Australia, Canada, Japan and Russia. This group also pushed strongly for international emissions trading, imagining(More)
The Arctic has experienced much greater warming than the global average in recent decades due to polar amplification. Warming has induced ecological changes that have impacted climate carbon-cycle feed-backs, making it important to understand the climate and vegetation controls on carbon (C) dynamics. Here we used the Holocene Thermal Maximum (HTM, 11e9 ka(More)