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Climate change

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


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Journal ArticleDOI
TL;DR: It is shown that land-use change plays an additional important role in controlling regional runoff values, particularly in the tropics, and its contribution is substantially larger than that of climate change.
Abstract: The significant worldwide increase in observed river runoff has been tentatively attributed to the stomatal “antitranspirant” response of plants to rising atmospheric CO2 [Gedney N, Cox PM, Betts RA, Boucher O, Huntingford C, Stott PA (2006) Nature 439: 835–838]. However, CO2 also is a plant fertilizer. When allowing for the increase in foliage area that results from increasing atmospheric CO2 levels in a global vegetation model, we find a decrease in global runoff from 1901 to 1999. This finding highlights the importance of vegetation structure feedback on the water balance of the land surface. Therefore, the elevated atmospheric CO2 concentration does not explain the estimated increase in global runoff over the last century. In contrast, we find that changes in mean climate, as well as its variability, do contribute to the global runoff increase. Using historic land-use data, we show that land-use change plays an additional important role in controlling regional runoff values, particularly in the tropics. Land-use change has been strongest in tropical regions, and its contribution is substantially larger than that of climate change. On average, land-use change has increased global runoff by 0.08 mm/year2 and accounts for ≈50% of the reconstructed global runoff trend over the last century. Therefore, we emphasize the importance of land-cover change in forecasting future freshwater availability and climate.

550 citations

Journal ArticleDOI
28 Aug 1997-Nature
TL;DR: In this paper, a simple coupled atmosphere-ocean climate model is used to show that the Atlantic thermohaline circulation is not only sensitive to the final atmospheric CO2 concentration attained, but also depends on the rate of change in the atmosphere.
Abstract: Present estimates of the future oceanic uptake of anthropogenic CO2 and calculations of CO2-emission scenarios1 are based on the assumption that the natural carbon cycle is in steady state. But it iswell known from palaeoclimate records2,3,4,5 and modelling studies6,7,8,9 that the climate system has more than one equilibrium state, and that perturbations can trigger transitions between them. Anticipated future changes in today's climate system due to human activities have the potential to weaken the thermohaline circulation of the North Atlantic Ocean10,11,12, which would greatly modify estimates of future oceanic CO2 uptake13. Here we use a simple coupled atmosphere–ocean climate model to show that the Atlantic thermohaline circulation is not only sensitive to the final atmospheric CO2 concentration attained, but also depends on the rate of change of the CO2 concentration in the atmosphere. A modelled increase to 750 parts per million by volume (p.p.m.v.) CO2 within 100 years (corresponding approximately to a continuation of today's growth rate) leads to a permanent shut-down of the thermohaline circulation. If the final atmospheric concentration of 750 p.p.m.v. CO2 is attained more slowly, the thermohaline circulation simply slows down. The reason for this rate-sensitive response of the climate system lies with the transfer of buoyancy in the form of heat and fresh water from the uppermost layers of the ocean into the deep waters below. This sensitivity of the simulated thermohaline circulation to the rate ofchange of atmospheric CO2 concentration has potentially important implications for the choice of future CO2-emission scenarios1.

550 citations

Journal ArticleDOI
TL;DR: In this article, the authors provide an assessment of key impacts of climate change at warming levels of 1.5°C and 2°C, including extreme weather events, water availability, agricultural yields, sea-level rise and risk of coral reef loss.
Abstract: . Robust appraisals of climate impacts at different levels of global-mean temperature increase are vital to guide assessments of dangerous anthropogenic interference with the climate system. The 2015 Paris Agreement includes a two-headed temperature goal: "holding the increase in the global average temperature to well below 2 °C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5 °C". Despite the prominence of these two temperature limits, a comprehensive overview of the differences in climate impacts at these levels is still missing. Here we provide an assessment of key impacts of climate change at warming levels of 1.5 °C and 2 °C, including extreme weather events, water availability, agricultural yields, sea-level rise and risk of coral reef loss. Our results reveal substantial differences in impacts between a 1.5 °C and 2 °C warming that are highly relevant for the assessment of dangerous anthropogenic interference with the climate system. For heat-related extremes, the additional 0.5 °C increase in global-mean temperature marks the difference between events at the upper limit of present-day natural variability and a new climate regime, particularly in tropical regions. Similarly, this warming difference is likely to be decisive for the future of tropical coral reefs. In a scenario with an end-of-century warming of 2 °C, virtually all tropical coral reefs are projected to be at risk of severe degradation due to temperature-induced bleaching from 2050 onwards. This fraction is reduced to about 90 % in 2050 and projected to decline to 70 % by 2100 for a 1.5 °C scenario. Analyses of precipitation-related impacts reveal distinct regional differences and hot-spots of change emerge. Regional reduction in median water availability for the Mediterranean is found to nearly double from 9 % to 17 % between 1.5 °C and 2 °C, and the projected lengthening of regional dry spells increases from 7 to 11 %. Projections for agricultural yields differ between crop types as well as world regions. While some (in particular high-latitude) regions may benefit, tropical regions like West Africa, South-East Asia, as well as Central and northern South America are projected to face substantial local yield reductions, particularly for wheat and maize. Best estimate sea-level rise projections based on two illustrative scenarios indicate a 50 cm rise by 2100 relative to year 2000-levels for a 2 °C scenario, and about 10 cm lower levels for a 1.5 °C scenario. In a 1.5 °C scenario, the rate of sea-level rise in 2100 would be reduced by about 30 % compared to a 2 °C scenario. Our findings highlight the importance of regional differentiation to assess both future climate risks and different vulnerabilities to incremental increases in global-mean temperature. The article provides a consistent and comprehensive assessment of existing projections and a good basis for future work on refining our understanding of the difference between impacts at 1.5 °C and 2 °C warming.

549 citations

Journal ArticleDOI
03 Jun 1999-Nature
TL;DR: The authors used several different climate-model versions to demonstrate that the observed sea-level-pressure trends, including their magnitude, can be simulated by realistic increases in greenhouse-gas concentrations, while changes in ozone concentrations are not necessary to simulate the observed climate trends.
Abstract: The temperature of air at the Earth's surface has risen during the past century1, but the fraction of the warming that can be attributed to anthropogenic greenhouse gases remains controversial. The strongest warming trends have been over Northern Hemisphere land masses during winter, and are closely related to changes in atmospheric circulation. These circulation changes are manifested by a gradual reduction in high-latitude sea-level pressure, and an increase in mid-latitude sea-level pressure associated with one phase of the Arctic Oscillation (a hemisphere-scale version of the North Atlantic Oscillation)2. Here we use several different climate-model versions to demonstrate that the observed sea-level-pressure trends, including their magnitude, can be simulated by realistic increases in greenhouse-gas concentrations. Thus, although the warming appears through a naturally occurring mode of atmospheric variability, it may be anthropogenically induced and may continue to rise. The Arctic Oscillation trend is captured only in climate models that include a realistic representation of the stratosphere, while changes in ozone concentrations are not necessary to simulate the observed climate trends. The proper representation of stratospheric dynamics appears to be important to the attribution of climate change, at least on a broad regional scale.

549 citations

Journal ArticleDOI
23 Sep 2004-Ibis
TL;DR: Although there is a substantial body of evidence for changes in the phenology of birds, particularly of the timing of migration and of nesting, the consequences of these responses for a species’ population dynamics is still an area requiring in-depth research.
Abstract: Weather is of major importance for the population dynamics of birds, but the implications of climate change have only recently begun to be addressed. There is already compelling evidence that birds have been affected by recent climate changes. This review suggests that although there is a substantial body of evidence for changes in the phenology of birds, particularly of the timing of migration and of nesting, the consequences of these responses for a species’ population dynamics is still an area requiring in-depth research. The potential for phenological miscuing (responding inappropriately to climate change, including a lack of response) and for phenological disjunction (in which a bird species becomes out of synchrony with its environment) are beginning to be demonstrated, and are also important areas for further research. The study of climatically induced distributional change is currently at a predictive modelling stage, and will need to develop methods for testing these predictions. Overall, there is a range of intrinsic and extrinsic factors that could potentially inhibit adaptation to climate change and these are a high priority for research.

548 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20253
20247
202312,805
202223,277
20217,120
20206,646