Drought sensitivity of Amazonian carbon balance revealed by atmospheric measurements.
Feedbacks between land carbon pools and climate provide one of the largest sources of uncertainty in our predictions of global climate. Estimates of the sensitivity of the terrestrial carbon budget to climate anomalies in the tropics and the identification of the mechanisms responsible for feedback effects remain uncertain. The Amazon basin stores a vast amount of carbon, and has experienced increasingly higher temperatures and more frequent floods and droughts over the past two decades. Here we report seasonal and annual carbon balances across the Amazon basin, based on carbon dioxide and carbon monoxide measurements for the anomalously dry and wet years 2010 and 2011, respectively. We find that the Amazon basin lost 0.48 ± 0.18 petagrams of carbon per year (Pg C yr(-1)) during the dry year but was carbon neutral (0.06 ± 0.1 Pg C yr(-1)) during the wet year. Taking into account carbon losses from fire by using carbon monoxide measurements, we derived the basin net biome exchange (that is, the carbon flux between the non-burned forest and the atmosphere) revealing that during the dry year, vegetation was carbon neutral. During the wet year, vegetation was a net carbon sink of 0.25 ± 0.14 Pg C yr(-1), which is roughly consistent with the mean long-term intact-forest biomass sink of 0.39 ± 0.10 Pg C yr(-1) previously estimated from forest censuses. Observations from Amazonian forest plots suggest the suppression of photosynthesis during drought as the primary cause for the 2010 sink neutralization. Overall, our results suggest that moisture has an important role in determining the Amazonian carbon balance. If the recent trend of increasing precipitation extremes persists, the Amazon may become an increasing carbon source as a result of both emissions from fires and the suppression of net biome exchange by drought.
1] Instituto de Pesquisas Energéticas e Nucleares (IPEN)-Comissao Nacional de Energia Nuclear (CNEN)-Atmospheric Chemistry Laboratory, 2242 Avenida Professor Lineu Prestes, Cidade Universitaria, Sao Paulo CEP 05508-000, Brazil [2].
L V
LV
Gatti
1] School of Geography, University of Leeds, Woodhouse Lane, Leeds LS9 2JT, UK [2].
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M
Gloor
1] Global Monitoring Division, Earth System Research Laboratory, National Oceanic and Atmospheric Administration, 325 Broadway, Boulder, Colorado 80305, USA [2] Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado, Boulder, Colorado 80309, USA [3].
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JB
Miller
Environmental Change Institute, School of Geography and the Environment, University of Oxford, South Parks Road, Oxford OX1 3QY, UK.
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Doughty
Environmental Change Institute, School of Geography and the Environment, University of Oxford, South Parks Road, Oxford OX1 3QY, UK.
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Malhi
Instituto de Pesquisas Energéticas e Nucleares (IPEN)-Comissao Nacional de Energia Nuclear (CNEN)-Atmospheric Chemistry Laboratory, 2242 Avenida Professor Lineu Prestes, Cidade Universitaria, Sao Paulo CEP 05508-000, Brazil.
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Domingues
Instituto de Pesquisas Energéticas e Nucleares (IPEN)-Comissao Nacional de Energia Nuclear (CNEN)-Atmospheric Chemistry Laboratory, 2242 Avenida Professor Lineu Prestes, Cidade Universitaria, Sao Paulo CEP 05508-000, Brazil.
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Basso
Instituto de Pesquisas Energéticas e Nucleares (IPEN)-Comissao Nacional de Energia Nuclear (CNEN)-Atmospheric Chemistry Laboratory, 2242 Avenida Professor Lineu Prestes, Cidade Universitaria, Sao Paulo CEP 05508-000, Brazil.
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A
Martinewski
Instituto de Pesquisas Energéticas e Nucleares (IPEN)-Comissao Nacional de Energia Nuclear (CNEN)-Atmospheric Chemistry Laboratory, 2242 Avenida Professor Lineu Prestes, Cidade Universitaria, Sao Paulo CEP 05508-000, Brazil.
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Correia
Instituto de Pesquisas Energéticas e Nucleares (IPEN)-Comissao Nacional de Energia Nuclear (CNEN)-Atmospheric Chemistry Laboratory, 2242 Avenida Professor Lineu Prestes, Cidade Universitaria, Sao Paulo CEP 05508-000, Brazil.
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Borges
Center for Weather Forecasts and Climate Studies, Instituto Nacional de Pesquisas Espaciais (INPE), Rodovia Dutra, km 39, Cachoeira Paulista CEP 12630-000, Brazil.
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Freitas
Center for Weather Forecasts and Climate Studies, Instituto Nacional de Pesquisas Espaciais (INPE), Rodovia Dutra, km 39, Cachoeira Paulista CEP 12630-000, Brazil.
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Braz
1] Environmental Change Institute, School of Geography and the Environment, University of Oxford, South Parks Road, Oxford OX1 3QY, UK [2] Remote Sensing Division, INPE (National Institute for Space Research), 1758 Avenida dos Astronautas, São José dos Campos CEP 12227-010, Brazil.
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Anderson
Departamento de Ciencias Atmosfericas/Instituto de Astronomia e Geofisica (IAG)/Universidade de Sao Paulo, 1226 Rua do Matao, Cidade Universitaria, Sao Paulo CEP 05508-090, Brazil.
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H
Rocha
Crew Building, The King's Buildings, West Mains Road, Edinburgh EH9 3JN, UK.
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J
Grace
School of Geography, University of Leeds, Woodhouse Lane, Leeds LS9 2JT, UK.
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Phillips
1] School of Tropical and Marine Biology and Centre for Terrestrial Environmental and Sustainability Sciences, James Cook University, Cairns 4870, Queensland, Australia [2] Imperial College London, Silwood Park Campus, Buckhurst Road, Ascot SL5 7PY, Berkshire, UK.
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Lloyd
D001272:Atmosphere / Q000737:chemistry*; D018533:Biomass; D058448:Biota; D001938:Brazil; D057486:Carbon Cycle; D002245:Carbon Dioxide / Q000032:analysis; D002248:Carbon Monoxide / Q000032:analysis; D055864:Droughts / Q000706:statistics & numerical data*; D005390:Fires / Q000706:statistics & numerical data; D005618:Fresh Water / Q000032:analysis; D010788:Photosynthesis; D011891:Rain; D012621:Seasons; D014197:Trees / Q000378:metabolism; D014329:Tropical Climate
D002245:Carbon Dioxide; D002248:Carbon Monoxide