Papers by Marco Steinacher
Climate of the Past, 2013
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Journal of Climate, 2013
ABSTRACT This paper summarizes the results of an intercomparison project with Earth System Models... more ABSTRACT This paper summarizes the results of an intercomparison project with Earth System Models of Intermediate Complexity (EMICs) undertaken in support of the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5). The focus is on long-term climate projections designed to: (i) quantify the climate change commitment of different radiative forcing trajectories, and (ii) explore the extent to which climate change is reversible on human timescales. All commitment simulations follow the four Representative Concentration Pathways (RCPs) and their extensions to 2300. Most EMICs simulate substantial surface air temperature and thermosteric sea level rise commitment following stabilization of the atmospheric composition at year-2300 levels. The meridional overturning circulation (MOC) is weakened temporarily and recovers to near pre-industrial values in most models for RCPs 2.6–6.0. The MOC weakening is more persistent for RCP 8.5. Elimination of anthropogenic CO2 emissions after 2300 results in slowly decreasing atmospheric CO2 concentrations. At year 3000 atmospheric CO2 is still at more than half its year-2300 level in all EMICs for RCPs 4.5–8.5. Surface air temperature remains constant or decreases slightly and thermosteric sea level rise continues for centuries after elimination of CO2 emissions in all EMICs. Restoration of atmospheric CO2 from RCP to pre-industrial levels over 100–1000 years requires large artificial removal of CO2 from the atmosphere and does not result in the simultaneous return to pre-industrial climate conditions, as surface air temperature and sea level response exhibit a substantial time lag relative to atmospheric CO2.
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Climate affects the biogeochemical cycles on land and in the ocean, and, in turn, the concentrati... more Climate affects the biogeochemical cycles on land and in the ocean, and, in turn, the concentrations of the greenhouse gases carbon dioxide (CO2) and methane (CH4). Polar ice core records show that the concentration of both gases increased significantly over the last 21,000 years. However, the timing and amplitude of concentration variations are different for the two gases. While CO2
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Temperature and precipitation show large and abrupt variations in the past as recorded in climate... more Temperature and precipitation show large and abrupt variations in the past as recorded in climate archives. In addition, these records demonstrate that the concentrations of atmospheric methane, which is the third most important anthropogenic greenhouse gas, follows closely temperature on glacial/interglacial time scales as well as rapid climate changes in the northern hemisphere. Examples of abrupt changes are the Dansgaard-Oeschger
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Nature Climate Change
Atmospheric concentrations of the three important greenhouse gases (GHGs) CO2, CH4 and N2O are me... more Atmospheric concentrations of the three important greenhouse gases (GHGs) CO2, CH4 and N2O are mediated by processes in the terrestrial biosphere that are sensitive to climate and CO2. This leads to feedbacks between climate and land and has contributed to the sharp rise in atmospheric GHG concentrations since pre-industrial times. Here, we apply a process-based model to reproduce the historical atmospheric N2O and CH4 budgets within their uncertainties and apply future scenarios for climate, land-use change and reactive nitrogen (Nr) inputs to investigate future GHG emissions and their feedbacks with climate in a consistent and comprehensive framework(1). Results suggest that in a business-as-usual scenario, terrestrial N2O and CH4 emissions increase by 80 and 45%, respectively, and the land becomes a net source of C by AD 2100. N2O and CH4 feedbacks imply an additional warming of 0.4-0.5 degrees C by AD 2300; on top of 0.8-1.0 degrees C caused by terrestrial carbon cycle and Albed...
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Nature, 2013
Climate targets are designed to inform policies that would limit the magnitude and impacts of cli... more Climate targets are designed to inform policies that would limit the magnitude and impacts of climate change caused by anthropogenic emissions of greenhouse gases and other substances. The target that is currently recognized by most world governments places a limit of two degrees Celsius on the global mean warming since preindustrial times. This would require large sustained reductions in carbon dioxide emissions during the twenty-first century and beyond. Such a global temperature target, however, is not sufficient to control many other quantities, such as transient sea level rise, ocean acidification and net primary production on land. Here, using an Earth system model of intermediate complexity (EMIC) in an observation-informed Bayesian approach, we show that allowable carbon emissions are substantially reduced when multiple climate targets are set. We take into account uncertainties in physical and carbon cycle model parameters, radiative efficiencies, climate sensitivity and carbon cycle feedbacks along with a large set of observational constraints. Within this framework, we explore a broad range of economically feasible greenhouse gas scenarios from the integrated assessment community to determine the likelihood of meeting a combination of specific global and regional targets under various assumptions. For any given likelihood of meeting a set of such targets, the allowable cumulative emissions are greatly reduced from those inferred from the temperature target alone. Therefore, temperature targets alone are unable to comprehensively limit the risks from anthropogenic emissions.
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Global Biogeochemical Cycles, 2009
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Geophysical Research Letters, 2012
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Ecological Monographs, 2013
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Biogeosciences, 2009
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Biogeosciences, 2013
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Biogeosciences, 2012
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Biogeosciences, 2010
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Atmospheric Chemistry and Physics, 2013
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Papers by Marco Steinacher