Climate change

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

Projected increase in continental runoff due to plant responses to increasing carbon dioxide

Abstract: An assessment of the contribution of plant physiological effects to future changes in continental water runoff suggests that flooding risk under future global warming scenarios may be greater than was assumed. The stomatal pores that allow CO2 to enter plants and water to escape open less widely when CO2 concentrations are high, reducing water loss from the plant and thus leaving more water at the land surface. This effect may have contributed to the increase in continental runoff observed during the twentieth century, but most predictions of future changes in runoff don't account for it. The concept of 'CO2 equivalent', widely used to compare the effects of greenhouse gases on climate, does not account for this effect, so it may need to be revisited in light of these findings. An ensemble of experiments is used with a global climate model to assess the contribution of plant 'physiological forcing' to future changes in continental runoff. It is found that the effect increases simulated global mean runoff by 6 per cent when the concentration of carbon dioxide is doubled relative to pre-industrial levels; an increase that is comparable to that simulated in response to climate change caused by radiative forcing. This finding suggests that the risk of flooding may be greater than previously assumed under future global warming scenarios. In addition to influencing climatic conditions directly through radiative forcing, increasing carbon dioxide concentration influences the climate system through its effects on plant physiology1. Plant stomata generally open less widely under increased carbon dioxide concentration2, which reduces transpiration1,3,4,5,6 and thus leaves more water at the land surface7. This driver of change in the climate system, which we term ‘physiological forcing’, has been detected in observational records of increasing average continental runoff over the twentieth century8. Here we use an ensemble of experiments with a global climate model that includes a vegetation component to assess the contribution of physiological forcing to future changes in continental runoff, in the context of uncertainties in future precipitation. We find that the physiological effect of doubled carbon dioxide concentrations on plant transpiration increases simulated global mean runoff by 6 per cent relative to pre-industrial levels; an increase that is comparable to that simulated in response to radiatively forced climate change (11 ± 6 per cent). Assessments of the effect of increasing carbon dioxide concentrations on the hydrological cycle that only consider radiative forcing9,10,11 will therefore tend to underestimate future increases in runoff and overestimate decreases. This suggests that freshwater resources may be less limited than previously assumed under scenarios of future global warming, although there is still an increased risk of drought. Moreover, our results highlight that the practice of assessing the climate-forcing potential of all greenhouse gases in terms of their radiative forcing potential relative to carbon dioxide does not accurately reflect the relative effects of different greenhouse gases on freshwater resources.

Increased crop damage in the US from excess precipitation under climate change

Abstract: Recent flooding and heavy precipitation events in the US and worldwide have caused great damage to crop production. Ifthe frequency of these weather extremes were to increase in the near future, as recent trends for the US indicate and as projected by global climate models (e.g., US National Assessment, Overview Report, 2001, The Potential Consequences ofClimate Variability and Change, National Assesment Synthesis Team, US Global Change Research Program, Washington, DC; Houghton et al., 2001, IPCC Climate Change 2001: The Scientific Basis, Third Assessment Report ofthe Intergovernmental Panel on Climate Change, Cambridge University Press, Cambridge, 335pp.), the cost ofcrop losses in the coming decades could rise dramatically. Yet current assessments of the impacts of climate change on agriculture have not quantified the negative effects on crop production from increased heavy precipitation and flooding (Impacts ofclimate change and variability on agriculture, in: US National Assessment Foundation Document, 2001. National Assessment Synthesis Team, US Global Change Research Program, Washington DC.). In this work, we modify a dynamic crop model in order to simulate one important effect of heavy precipitation on crop growth, plant damage from excess soil moisture. We compute that US corn production losses due to this factor, already significant under current climate, may double during the next thirty years, causing additional damages totaling an estimated $3 billion per year. These costs may either be borne directly by those impacted or transferred to private or governmental insurance and disaster relief programs. r 2002 Elsevier Science Ltd. All rights reserved.

The Future of Species Under Climate Change: Resilience or Decline?

Abstract: As climates change across already stressed ecosystems, there is no doubt that species will be affected, but to what extent and which will be most vulnerable remain uncertain. The fossil record suggests that most species persisted through past climate change, whereas forecasts of future impacts predict large-scale range reduction and extinction. Many species have altered range limits and phenotypes through 20th-century climate change, but responses are highly variable. The proximate causes of species decline relative to resilience remain largely obscure; however, recent examples of climate-associated species decline can help guide current management in parallel with ongoing research.

European climate in the late twenty-first century: regional simulations with two driving global models and two forcing scenarios

Abstract: A basic analysis is presented for a series of regional climate change simulations that were conducted by the Swedish Rossby Centre and contribute to the PRUDENCE (Prediction of Regional scenarios and Uncertainties for Defining EuropeaN Climate change risks and Effects) project For each of the two driving global models HadAM3H and ECHAM4/OPYC3, a 30-year control run and two 30-year scenario runs (based on the SRES A2 and B2 emission scenarios) were made with the regional model In this way, four realizations of climate change from 1961–1990 to 2071–2100 were obtained The simulated changes are larger for the A2 than the B2 scenario (although with few qualitative differences) and in most cases in the ECHAM4/OPYC3-driven (RE) than in the HadAM3H-driven (RH) regional simulations In all the scenario runs, the warming in northern Europe is largest in winter or late autumn In central and southern Europe, the warming peaks in summer when it locally reaches 10 °C in the RE-A2 simulation and 6–7 °C in the RH-A2 and RE-B2 simulations The four simulations agree on a general increase in precipitation in northern Europe especially in winter and on a general decrease in precipitation in southern and central Europe in summer, but the magnitude and the geographical patterns of the change differ markedly between RH and RE This reflects very different changes in the atmospheric circulation during the winter half-year, which also lead to quite different simulated changes in windiness All four simulations show a large increase in the lowest minimum temperatures in northern, central and eastern Europe, most likely due to reduced snow cover Extreme daily precipitation increases even in most of those areas where the mean annual precipitation decreases