Climate change

About: Climate change is a research topic. Over the lifetime, 99222 publications have been published within this topic receiving 3572006 citations.

Selecting global climate models for regional climate change studies

Abstract: Regional or local climate change modeling studies currently require starting with a global climate model, then downscaling to the region of interest. How should global models be chosen for such studies, and what effect do such choices have? This question is addressed in the context of a regional climate detection and attribution (D&A) study of January-February-March (JFM) temperature over the western U.S. Models are often selected for a regional D&A analysis based on the quality of the simulated regional climate. Accordingly, 42 performance metrics based on seasonal temperature and precipitation, the El Nino/Southern Oscillation (ENSO), and the Pacific Decadal Oscillation are constructed and applied to 21 global models. However, no strong relationship is found between the score of the models on the metrics and results of the D&A analysis. Instead, the importance of having ensembles of runs with enough realizations to reduce the effects of natural internal climate variability is emphasized. Also, the superiority of the multimodel ensemble average (MM) to any 1 individual model, already found in global studies examining the mean climate, is true in this regional study that includes measures of variability as well. Evidence is shown that this superiority is largely caused by the cancellation of offsetting errors in the individual global models. Results with both the MM and models picked randomly confirm the original D&A results of anthropogenically forced JFM temperature changes in the western U.S. Future projections of temperature do not depend on model performance until the 2080s, after which the better performing models show warmer temperatures.

Climate Change 1995: Economic and Social Dimensions of Climate Change

Abstract: Summary for policymakers 1. Introduction: scope of the assessment 2. Decision-making frameworks for addressing climate change 3. Equity and social considerations 4. Intertemporal equity, discounting and economic efficiency 5. Applicability of techniques of cost-benefit analysis to climate change 6. The social costs of climate change: greenhouse damage and the benefits of control 7. A generic assessment of response options 8. Estimating the costs of mitigating greenhouse gases 9. A review of mitigation cost studies 10. Integrated assessment of climate change: an overview and comparison of approaches and results 11. An economic assessment of policy instruments for combating climate change.

Influence of carbon‐nitrogen cycle coupling on land model response to CO2 fertilization and climate variability

Abstract: [1] Nutrient cycling affects carbon uptake by the terrestrial biosphere and imposes controls on carbon cycle response to variation in temperature and precipitation, but nutrient cycling is ignored in most global coupled models of the carbon cycle and climate system. We demonstrate here that the inclusion of nutrient cycle dynamics, specifically the close coupling between carbon and nitrogen cycles, in a terrestrial biogeochemistry component of a global coupled climate system model leads to fundamentally altered behavior for several of the most critical feedback mechanisms operating between the land biosphere and the global climate system. Carbon-nitrogen cycle coupling reduces the simulated global terrestrial carbon uptake response to increasing atmospheric CO2 concentration by 74%, relative to a carbon-only counterpart model. Global integrated responses of net land carbon exchange to variation in temperature and precipitation are significantly damped by carbon-nitrogen cycle coupling. The carbon cycle responses to temperature and precipitation variation are reduced in magnitude as atmospheric CO2 concentration rises for the coupled carbon-nitrogen model, but increase in magnitude for the carbon-only counterpart. Our results suggest that previous carbon-only treatments of climate-carbon cycle coupling likely overestimate the terrestrial biosphere's capacity to ameliorate atmospheric CO2 increases through direct fertilization. The next generation of coupled climate-biogeochemistry model projections for future atmospheric CO2 concentration and climate change should include explicit, prognostic treatment of terrestrial carbon-nitrogen cycle coupling.

Assessment of Climate Change for the Baltic Sea Basin

Abstract: BACC (BALTEX Assessment of Climate Change for the Baltic Sea Basin) integrates available knowledge of historical, current and expected future climate change. The unique feature of BACC is the combination of evidence on climate change and related impacts on marine, freshwater and terrestrial ecosystems in the Baltic Sea Basin, which encompasses the entire water catchment region surrounding the Baltic Sea.

Response of northern forests to CO2-induced climate change

Abstract: Climate changes resulting from increases in atmospheric CO2 are expected to alter forest productivity and species distributions. But forest response to climate change depends in part on changes in soil water and nitrogen availability which limit tree growth. Here we report an investigation into the possible responses of northeastern North American forests to a warmer and generally drier climate by driving a linked forest productivity/soil process model with climate model predictions corresponding to a doubling of CO2. The greatest changes occurred at the current boreal/cool temperate forest border. Simulated productivity and biomass increased on soils that retained adequate water for tree growth and decreased on soils with inadequate water. Simulated changes in vegetation composition altered soil nitrogen availability, which in turn amplified the vegetation changes. The simulated responses of the forests were results of a positive feedback between carbon and nitrogen cycles, bounded by negative constraints of soil moisture availability and temperature.