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Title: Warm spring reduced carbon cycle impact of the 2012 US summer drought

The global terrestrial carbon sink offsets one-third of the world's fossil fuel emissions, but the strength of this sink is highly sensitive to large-scale extreme events. In 2012, the contiguous United States experienced exceptionally warm temperatures and the most severe drought since the Dust Bowl era of the 1930s, resulting in substantial economic damage. It is crucial to understand the dynamics of such events because warmer temperatures and a higher prevalence of drought are projected in a changing climate. Here in this paper, we combine an extensive network of direct ecosystem flux measurements with satellite remote sensing and atmospheric inverse modeling to quantify the impact of the warmer spring and summer drought on biosphereatmosphere carbon and water exchange in 2012. We consistently find that earlier vegetation activity increased spring carbon uptake and compensated for the reduced uptake during the summer drought, which mitigated the impact on net annual carbon uptake. The early phenological development in the Eastern Temperate Forests played a major role for the continental-scale carbon balance in 2012. The warm spring also depleted soil water resources earlier, and thus exacerbated water limitations during summer. Our results show that the detrimental effects of severe summer drought on ecosystem carbonmore » storage can be mitigated by warming-induced increases in spring carbon uptake. However, the results also suggest that the positive carbon cycle effect of warm spring enhances water limitations and can increase summer heating through biosphere-atmosphere feedbacks.« less
Authors:
ORCiD logo [1] ;  [2] ;  [3] ; ORCiD logo [4] ; ORCiD logo [5] ;  [6] ;  [7] ;  [8] ;  [9] ;  [10] ;  [11] ; ORCiD logo [12]
  1. Univ. of California, Berkeley, CA (United States). Dept. of Environmental Science, Policy, and Management; Federal Inst. of Technology, Zurich (Switzerland). Dept. of Environmental Systems Science
  2. Macquarie Univ., NSW (Australia). Dept. of Biological Sciences
  3. California Inst. of Technology (CalTech), Pasadena, CA (United States). Jet Propulsion Lab.
  4. Univ. of California, Berkeley, CA (United States). Dept. of Environmental Science, Policy, and Management
  5. Univ. of Wisconsin, Madison, WI (United States). Dept. of Atmospheric and Oceanic Sciences
  6. Harvard Univ., Cambridge, MA (United States). Dept. of Organismic and Evolutionary Biology
  7. US Dept. of Agriculture (USDA), Tucson, AZ (United States). Agricultural Research Service, Southwest Watershed Research Center
  8. Oregon State Univ., Corvallis, OR (United States). Dept. of Forest Ecosystems and Society
  9. Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Biology
  10. Univ. of Kansas, Lawrence, KS (United States). Dept. of Geography
  11. Wageningen Univ., Wageningen (The Netherlands). Dept. of Meteorology and Air Quality; Univ. of Groningen, Groningen (The Netherlands)
  12. Wageningen Univ., Wageningen (The Netherlands). Dept. of Meteorology and Air Quality
Publication Date:
OSTI Identifier:
1249736
Grant/Contract Number:
AC02-05CH11231; 300083; EF-1065029
Type:
Published Article
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America
Additional Journal Information:
Journal Volume: 113; Journal Issue: 21; Journal ID: ISSN 0027-8424
Publisher:
National Academy of Sciences, Washington, DC (United States)
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC); National Aeronautics and Space Administration (NASA); National Science Foundation (NSF); European Commission (EC)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; seasonal climate anomalies; carbon uptake; ecosystem fluxes; biosphere–atmosphere feedbacks; eddy covariance