Sustainable development depends upon understanding interactions among multiple complex subsystems, but scientific research tends to focus on one (or part of one) subsystem at a time. This review describes recent progress toward more integrated, interdisciplinary science that is problem-driven, solution-oriented, and intentionally policy-relevant, and then discusses future directions for this science.
More than 30 Mt CO2-equivalent CH4 and N2O emissions are embodied in meat traded internationally in 2010, and the total is increasing at roughly 4% per year. This reflects a trend of increasing livestock production in countries with lower input costs, less efficient practices, and more permissive environmental regulations, which act to decrease global food costs and incentivize both global demand and international trade.
A suite of global models show that, without new climate policies, abundant natural gas will not act to reduce GHG emissions or mitigate climate change. Consistent with our earlier findings for the US, abundant (and therefore cheap) gas may delay deployment of low-carbon energy sources and increase overall energy use.
Leaking methane isn't the only reason natural gas may not reduce GHG emissions: gas also competes against low-carbon renewable energy sources. Across a range of gas supplies, our modeling shows that abundant gas replaces both coal and renewables and in the end has little effect on future US GHG emissions even if there is no leakage. Policy may reduce emissions; cheap gas on its own won't.
As of 2012, power plants existing worldwide represent roughly 300 billion tons of future CO2 emissions, assuming individual plants operate for a lifetime of 40 years. Moreover, committed emissions from the power sector have been growing globally at a rate of about 4% per year. This paper presents a formal method of commitment accounting that can inform public policy by quantifying future emissions implied by current investments.