The 2010 Amazon Drought
04 Feb 2011-Science (American Association for the Advancement of Science)-Vol. 331, Iss: 6017, pp 554-554
TL;DR: A decade of satellite-derived rainfall data is analyzed to compare both the 2010 and 2005 drought in Amazonia and predict the impact of the 2010 drought as 2.2 × 1015 grams of carbon, largely longer-term committed emissions from drought-induced tree deaths.
Abstract: In 2010, dry-season rainfall was low across Amazonia, with apparent similarities to the major 2005 drought. We analyzed a decade of satellite-derived rainfall data to compare both events. Standardized anomalies of dry-season rainfall showed that 57% of Amazonia had low rainfall in 2010 as compared with 37% in 2005 (≤-1 standard deviation from long-term mean). By using relationships between drying and forest biomass responses measured for 2005, we predict the impact of the 2010 drought as 2.2 × 10(15) grams of carbon [95% confidence intervals (CIs) are 1.2 and 3.4], largely longer-term committed emissions from drought-induced tree deaths, compared with 1.6 × 10(15) grams of carbon (CIs 0.8 and 2.6) for the 2005 event.
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Stockholm Resilience Centre1, Australian National University2, University of Copenhagen3, McGill University4, Stellenbosch University5, University of Wisconsin-Madison6, Wageningen University and Research Centre7, Stockholm University8, Royal Swedish Academy of Sciences9, Potsdam Institute for Climate Impact Research10, Commonwealth Scientific and Industrial Research Organisation11, International Livestock Research Institute12, University College London13, Stockholm Environment Institute14, The Energy and Resources Institute15, University of California, San Diego16, Royal Institute of Technology17
TL;DR: An updated and extended analysis of the planetary boundary (PB) framework and identifies levels of anthropogenic perturbations below which the risk of destabilization of the Earth system (ES) is likely to remain low—a “safe operating space” for global societal development.
Abstract: The planetary boundaries framework defines a safe operating space for humanity based on the intrinsic biophysical processes that regulate the stability of the Earth system. Here, we revise and update the planetary boundary framework, with a focus on the underpinning biophysical science, based on targeted input from expert research communities and on more general scientific advances over the past 5 years. Several of the boundaries now have a two-tier approach, reflecting the importance of cross-scale interactions and the regional-level heterogeneity of the processes that underpin the boundaries. Two core boundaries—climate change and biosphere integrity—have been identified, each of which has the potential on its own to drive the Earth system into a new state should they be substantially and persistently transgressed.
7,169 citations
Stockholm Resilience Centre1, Stockholm University2, University of Copenhagen3, University of Exeter4, Royal Swedish Academy of Sciences5, University of Arizona6, Scott Polar Research Institute7, Stanford University8, Université catholique de Louvain9, Potsdam Institute for Climate Impact Research10, Australian National University11, Wageningen University and Research Centre12, University of Potsdam13
TL;DR: The risk that self-reinforcing feedbacks could push the Earth System toward a planetary threshold that, if crossed, could prevent stabilization of the climate at intermediate temperature rises and cause continued warming on a “Hothouse Earth” pathway even as human emissions are reduced is explored.
Abstract: We explore the risk that self-reinforcing feedbacks could push the Earth System toward a planetary threshold that, if crossed, could prevent stabilization of the climate at intermediate temperature rises and cause continued warming on a "Hothouse Earth" pathway even as human emissions are reduced. Crossing the threshold would lead to a much higher global average temperature than any interglacial in the past 1.2 million years and to sea levels significantly higher than at any time in the Holocene. We examine the evidence that such a threshold might exist and where it might be. If the threshold is crossed, the resulting trajectory would likely cause serious disruptions to ecosystems, society, and economies. Collective human action is required to steer the Earth System away from a potential threshold and stabilize it in a habitable interglacial-like state. Such action entails stewardship of the entire Earth System-biosphere, climate, and societies-and could include decarbonization of the global economy, enhancement of biosphere carbon sinks, behavioral changes, technological innovations, new governance arrangements, and transformed social values.
1,685 citations
Centre national de la recherche scientifique1, Commonwealth Scientific and Industrial Research Organisation2, National Oceanic and Atmospheric Administration3, United States Department of Energy4, University of California, Irvine5, Central Maine Community College6, Seconda Università degli Studi di Napoli7, Max Planck Society8, Swiss Federal Institute for Forest, Snow and Landscape Research9, Utrecht University10, Carma11, National Center for Atmospheric Research12, University of East Anglia13, Massachusetts Institute of Technology14, VU University Amsterdam15, Goddard Space Flight Center16, University of Bern17, Nagoya University18, Imperial College London19, Royal Netherlands Meteorological Institute20, University of California, San Diego21, National Institute of Water and Atmospheric Research22
TL;DR: In this paper, the authors construct decadal budgets for methane sources and sinks between 1980 and 2010, using a combination of atmospheric measurements and results from chemical transport models, ecosystem models, climate chemistry models and inventories of anthropogenic emissions.
Abstract: Methane is an important greenhouse gas, responsible for about 20% of the warming induced by long-lived greenhouse gases since pre-industrial times. By reacting with hydroxyl radicals, methane reduces the oxidizing capacity of the atmosphere and generates ozone in the troposphere. Although most sources and sinks of methane have been identified, their relative contributions to atmospheric methane levels are highly uncertain. As such, the factors responsible for the observed stabilization of atmospheric methane levels in the early 2000s, and the renewed rise after 2006, remain unclear. Here, we construct decadal budgets for methane sources and sinks between 1980 and 2010, using a combination of atmospheric measurements and results from chemical transport models, ecosystem models, climate chemistry models and inventories of anthropogenic emissions. The resultant budgets suggest that data-driven approaches and ecosystem models overestimate total natural emissions. We build three contrasting emission scenarios-which differ in fossil fuel and microbial emissions-to explain the decadal variability in atmospheric methane levels detected, here and in previous studies, since 1985. Although uncertainties in emission trends do not allow definitive conclusions to be drawn, we show that the observed stabilization of methane levels between 1999 and 2006 can potentially be explained by decreasing-to-stable fossil fuel emissions, combined with stable-to-increasing microbial emissions. We show that a rise in natural wetland emissions and fossil fuel emissions probably accounts for the renewed increase in global methane levels after 2006, although the relative contribution of these two sources remains uncertain. © 2013 Macmillan Publishers Limited.
1,668 citations
TL;DR: In this article, the authors derived a forest drought-stress index (FDSI) for the southwestern United States using a comprehensive tree-ring data set representing AD 1000-2007, which is approximately equally influenced by the warm-season vapour-pressure deficit (largely controlled by temperature) and cold-season precipitation, together explaining 82% of the FDSI variability.
Abstract: As the climate changes, drought may reduce tree productivity and survival across many forest ecosystems; however, the relative influence of specific climate parameters on forest decline is poorly understood. We derive a forest drought-stress index (FDSI) for the southwestern United States using a comprehensive tree-ring data set representing AD 1000–2007. The FDSI is approximately equally influenced by the warm-season vapour-pressure deficit (largely controlled by temperature) and cold-season precipitation, together explaining 82% of the FDSI variability. Correspondence between the FDSI and measures of forest productivity, mortality, bark-beetle outbreak and wildfire validate the FDSI as a holistic forest-vigour indicator. If the vapour-pressure deficit continues increasing as projected by climate models, the mean forest drought-stress by the 2050s will exceed that of the most severe droughts in the past 1,000 years. Collectively, the results foreshadow twenty-first-century changes in forest structures and compositions, with transition of forests in the southwestern United States, and perhaps water-limited forests globally, towards distributions unfamiliar to modern civilization. As the global climate changes, drought is expected to reduce productivity and tree survival across many forests; however, the relative influence of climate variables on forest decline remains poorly understood. A drought-stress index based on tree-ring data—newly developed for the southwestern United States—is found to be equally influenced by evaporation (primarily temperature driven) and precipitation and may serve as a holistic forest-vigour indicator in water-limited forests.
1,562 citations
Max Planck Society1, University of Innsbruck2, Centre national de la recherche scientifique3, ETH Zurich4, Stockholm University5, Oeschger Centre for Climate Change Research6, Tuscia University7, Potsdam Institute for Climate Impact Research8, University of Aberdeen9, International Institute for Applied Systems Analysis10, University of Antwerp11, University of Potsdam12
TL;DR: The mechanisms and impacts of climate extremes on the terrestrial carbon cycle are explored, and a pathway to improve the understanding of present and future impacts ofClimate extremes onThe terrestrial carbon budget is proposed.
Abstract: The terrestrial biosphere is a key component of the global carbon cycle and its carbon balance is strongly influenced by climate. Continuing environmental changes are thought to increase global terrestrial carbon uptake. But evidence is mounting that climate extremes such as droughts or storms can lead to a decrease in regional ecosystem carbon stocks and therefore have the potential to negate an expected increase in terrestrial carbon uptake. Here we explore the mechanisms and impacts of climate extremes on the terrestrial carbon cycle, and propose a pathway to improve our understanding of present and future impacts of climate extremes on the terrestrial carbon budget.
1,290 citations
References
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TL;DR: The forest biome of Amazonia is one of Earth's greatest biological treasures and a major component of the Earth system, and this century, it faces the dual threats of deforestation and stress from climate change.
Abstract: The forest biome of Amazonia is one of Earth's greatest biological treasures and a major component of the Earth system. This century, it faces the dual threats of deforestation and stress from climate change. Here, we summarize some of the latest findings and thinking on these threats, explore the consequences for the forest ecosystem and its human residents, and outline options for the future of Amazonia. We also discuss the implications of new proposals to finance preservation of Amazonian forests.
1,552 citations
TL;DR: Records from multiple long-term monitoring plots across Amazonia are used to assess forest responses to the intense 2005 drought, a possible analog of future events that may accelerate climate change through carbon losses and changed surface energy balances.
Abstract: Amazon forests are a key but poorly understood component of the global carbon cycle. If, as anticipated, they dry this century, they might accelerate climate change through carbon losses and changed surface energy balances. We used records from multiple long-term monitoring plots across Amazonia to assess forest responses to the intense 2005 drought, a possible analog of future events. Affected forest lost biomass, reversing a large long-term carbon sink, with the greatest impacts observed where the dry season was unusually intense. Relative to pre-2005 conditions, forest subjected to a 100-millimeter increase in water deficit lost 5.3 megagrams of aboveground biomass of carbon per hectare. The drought had a total biomass carbon impact of 1.2 to 1.6 petagrams (1.2 × 1015 to 1.6 × 1015 grams). Amazon forests therefore appear vulnerable to increasing moisture stress, with the potential for large carbon losses to exert feedback on climate change.
1,545 citations
TL;DR: In 2005, large sections of southwestern Amazonia experienced one of the most intense droughts of the last hundred years, which severely affected human population along the main channel of the Amazon River and its western and southwestern tributaries, the Solimoes and the Madeira Rivers, respectively as mentioned in this paper.
Abstract: In 2005, large sections of southwestern Amazonia experienced one of the most intense droughts of the last hundred years. The drought severely affected human population along the main channel of the Amazon River and its western and southwestern tributaries, the Solimoes (also known as the Amazon River in the other Amazon countries) and the Madeira Rivers, respectively. The river levels fell to historic low levels and navigation along these rivers had to be suspended. The drought did not affect central or eastern Amazonia, a pattern different from the El Nino–related droughts in 1926, 1983, and 1998. The choice of rainfall data used influenced the detection of the drought. While most datasets (station or gridded data) showed negative departures from mean rainfall, one dataset exhibited above-normal rainfall in western Amazonia. The causes of the drought were not related to El Nino but to (i) the anomalously warm tropical North Atlantic, (ii) the reduced intensity in northeast trade wind moisture tr...
662 citations
TL;DR: In this paper, the authors analyzed the spatial extent of these droughts and fire response to the 2005 Amazonian drought with TRMM and NOAA-12 data, respectively, and found that the area of leakage forest fires was more than five times greater than the area directly deforested.
Abstract: [1] There has been an increasing awareness of the possibility of climate change causing increased drought frequency in Amazonia, with ensuing impacts on ecosystems and human populations. This debate has been brought into focus by the 1997/1998 and 2005 Amazonian droughts. We analysed the spatial extent of these droughts and fire response to the 2005 drought with TRMM and NOAA-12 data, respectively. Both droughts had distinct fingerprints. The 2005 drought was characterized by its intensification throughout the dry season in south-western Amazonia. During 2005 the annual cumulative number of hot pixels in Amazonia increased 33% in relation to the 1999–2005 mean. In the Brazilian state of Acre, at the epicentre of the 2005 drought, the area of leakage forest fires was more than five times greater than the area directly deforested. Fire leakage into flammable forests may be the major agent of biome transformation in the event of increasing drought frequency.
446 citations
TL;DR: It is suggested that the current carbon sink in intact forests is unlikely to continue, and that the tropical forest biome may even become a large net source of carbon, via one or more of four plausible routes: changing photosynthesis and respiration rates, biodiversity changes in intact forest, widespread forest collapse via drought, and widespread Forest collapse via fire.
Abstract: Tropical forests are global epicentres of biodiversity and important modulators of the rate of climate change. Recent research on deforestation rates and ecological changes within intact forests, both areas of recent research and debate, are reviewed, and the implications for biodiversity (species loss) and climate change (via the global carbon cycle) addressed. Recent impacts have most likely been: (i) a large source of carbon to the atmosphere, and major loss of species, from deforestation and (ii) a large carbon sink within remaining intact forest, accompanied by accelerating forest dynamism and widespread biodiversity changes. Finally, I look to the future, suggesting that the current carbon sink in intact forests is unlikely to continue, and that the tropical forest biome may even become a large net source of carbon, via one or more of four plausible routes: changing photosynthesis and respiration rates, biodiversity changes in intact forest, widespread forest collapse via drought, and widespread forest collapse via fire. Each of these scenarios risks potentially dangerous positive feedbacks with the climate system that could dramatically accelerate and intensify climate change. Given that continued land-use change alone is already thought to be causing the sixth mass extinction event in Earth's history, should such feedbacks occur, the resulting biodiversity and societal consequences would be even more severe.
340 citations