| Summary: | Understanding the relative contributions of individual countries to global climate change for different time periods is essential for mitigation strategies that seek to hold nations accountable for their historical emissions. Previous assessments of this kind have compared countries by their greenhouse gas emissions, but have yet to consider the full spectrum of the short-lived gases and aerosols. In this study, we use the radiative forcing of anthropogenic emissions of long-lived greenhouse gases, ozone precursors, aerosols, and from albedo changes from land cover change together with a simple climate model to evaluate country contributions to climate change. We assess the historical contribution of each country to global surface temperature change from anthropogenic forcing ( Δ T _s ), future Δ T _s through year 2100 given two different emissions scenarios, and the Δ T _s that each country has committed to from past activities between 1850 and 2010 (committed Δ T _s ). By including forcings in addition to the long-lived greenhouse gases the contribution of developed countries, particularly the United States, to Δ T _s from 1850 to 2010 (58%) is increased compared to an assessment of CO _2 -equivalent emissions for the same time period (52%). Contributions to committed Δ T _s evaluated at year 2100, dominated by long-lived greenhouse gas forcing, are more evenly split between developed and developing countries (55% and 45%, respectively). The portion of anthropogenic Δ T _s attributable to developing countries is increasing, led by emissions from China and India, and we estimate that this will surpass the contribution from developed countries around year 2030.
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