Detection and Attribution of Rapid Large-scale Shifts in the Terrestrial Carbon Cycle

Wolfgang Buermann, UCLA Institute of the Environment, buermann@ucla.edu (Presenter)
Jorge Sarmiento, Princeton University, jls@princeton.edu
George James Collatz, NASA GSFC, jim.collatz@nasa.gov
David Medvigy, Princeton University, dmedvigy@princeton.edu
Claudie Beaulieu, Princeton University, beaulieu@princeton.edu

A series of recent studies have suggested that the Earth underwent significant synchronous climatic shifts around 1988/89 towards enhanced warming in the northern latitudes and increased solar radiation associated with reduced cloudiness in the tropics. Results from our new synthesis analysis based on the growth rate of atmospheric CO2, fossil fuel emission estimates, and modeled ocean CO2 uptake reveal that there may have been also a major shift towards greater land carbon uptake around this time frame. Findings from the Transcom3 atmospheric inversion experiments also reveal the rapid shift in the land carbon balance. The shift cannot be explained by emissions related to changes in land use, which show a transient increase.

Findings from our analysis on the northern seasonal cycle of atmospheric CO2 (Pt. Barrow), satellite greenness (NDVI), and climate data suggest the possibility of an abrupt large-scale shift towards enhanced carbon uptake in North America that took place also in the last 1980s. They show that a relatively abrupt shift towards warmer springtime conditions in the late 1980s led to increased plant growth and an earlier onset of carbon uptake, but that thereafter springtime temperatures only weakly increased with no further shifts in vegetation activity and in the onset of carbon. While for the 1980s increased growing season productivity (as indicated by positive trends in the Pt. Barrow CO2 amplitudes and summer NDVI) could be observed, a parallel trend towards drier summer conditions since the early 1990s appears to have led to a plateauing in productivity.

We are currently developing a general framework for the detection and attribution of rapid regime or large-scale shifts in the terrestrial carbon cycle. The framework consists of statistical methods to detect changes in the fundamental behavior of the carbon cycle as well as terrestrial ecosystem simulations (CASA and ED2) to independently identify regions/ecosystems in which carbon uptake is consistent with the timing, magnitude and spatial distributions of carbon sinks derived from atmospheric and oceanic studies. The detection and attribution of rapid large-scale shifts in the global carbon cycle is of primary concern for society since they lead to feedbacks that either amplify or diminish physical climate change.

Presentation Type:  Poster

Session:  Global Change Impact & Vulnerability   (Tue 11:30 AM)

Associated Project(s): 

• Buermann, Wolfgang: Detection and Attribution of Rapid Large-scale Shifts in the Terrestrial Carbon Cycle ...details

Poster Location ID: 120