title: Tropical nighttime warming as a dominant driver of variability in the terrestrial carbon sink.
abstract: The terrestrial biosphere is currently a strong carbon (C) sink but may switch to a source in the 21st century as climate-driven losses exceed CO2-driven C gains, thereby accelerating global warming. Although it has long been recognized that tropical climate plays a critical role in regulating interannual climate variability, the causal link between changes in temperature and precipitation and terrestrial processes remains uncertain. Here, we combine atmospheric mass balance, remote sensing-modeled datasets of vegetation C uptake, and climate datasets to characterize the temporal variability of the terrestrial C sink and determine the dominant climate drivers of this variability. We show that the interannual variability of global land C sink has grown by 50-100% over the past 50 y. We further find that interannual land C sink variability is most strongly linked to tropical nighttime warming, likely through respiration. This apparent sensitivity of respiration to nighttime temperatures, which are projected to increase faster than global average temperatures, suggests that C stored in tropical forests may be vulnerable to future warming.
authors.affiliation: Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544; Department of Biology, University of Utah, Salt Lake City, UT 84112; anderegg@princeton.edu pacala@princeton.edu.
authors.forename: William R L
authors.initials: WR
authors.lastname: Anderegg
authors.affiliation: Department of Ecosystem and Conservation Sciences, University of Montana, Missoula, MT 59812;
authors.forename: Ashley P
authors.initials: AP
authors.lastname: Ballantyne
authors.affiliation: Department of Ecosystem and Conservation Sciences, University of Montana, Missoula, MT 59812;
authors.forename: W Kolby
authors.initials: WK
authors.lastname: Smith
authors.affiliation: Program in Atmospheric and Oceanic Sciences, Princeton University, Princeton, NJ 08544;
authors.forename: Joseph
authors.initials: J
authors.lastname: Majkut
authors.affiliation: Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544;
authors.forename: Sam
authors.initials: S
authors.lastname: Rabin
authors.affiliation: Ocean and Earth Science, University of Southampton, Southampton SO17 1BJ, United Kingdom;
authors.forename: Claudie
authors.initials: C
authors.lastname: Beaulieu
authors.affiliation: Northern Research Station, US Department of Agriculture Forest Service, Newtown Square, PA 19073;
authors.forename: Richard
authors.initials: R
authors.lastname: Birdsey
authors.affiliation: National Oceanic and Atmospheric Administration Geophysical Fluid Dynamics Laboratory, Princeton, NJ 08540;
authors.forename: John P
authors.initials: JP
authors.lastname: Dunne
authors.affiliation: Woods Hole Research Center, Falmouth, MA 02540;
authors.forename: Richard A
authors.initials: RA
authors.lastname: Houghton
authors.affiliation: Department of Earth and Environment, Boston University, Boston, MA 02215;
authors.forename: Ranga B
authors.initials: RB
authors.lastname: Myneni
authors.affiliation: Northern Research Station, US Department of Agriculture Forest Service, Newtown Square, PA 19073;
authors.forename: Yude
authors.initials: Y
authors.lastname: Pan
authors.affiliation: Program in Atmospheric and Oceanic Sciences, Princeton University, Princeton, NJ 08544;
authors.forename: Jorge L
authors.initials: JL
authors.lastname: Sarmiento
authors.affiliation: Department of Ecosystem and Conservation Sciences, University of Montana, Missoula, MT 59812;
authors.forename: Nathan
authors.initials: N
authors.lastname: Serota
authors.affiliation: National Oceanic and Atmospheric Administration Geophysical Fluid Dynamics Laboratory, Princeton, NJ 08540;
authors.forename: Elena
authors.initials: E
authors.lastname: Shevliakova
authors.affiliation: National Oceanic and Atmospheric Administration, Earth System Research Laboratory, Boulder, CO 80305.
authors.forename: Pieter
authors.initials: P
authors.lastname: Tans
authors.affiliation: Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544; anderegg@princeton.edu pacala@princeton.edu.
authors.forename: Stephen W
authors.initials: SW
authors.lastname: Pacala
mesh_terms: D057965:Carbon Sequestration; D017753:Ecosystem; D057232:Global Warming; D014329:Tropical Climate
keywords: asymmetrical warming; carbon budget; climate change; climate feedback; inversion model