Date: Wednesday, June 07, 2023
Time: 03:30 pm

Department Seminar: James Randerson

Wednesday, June 07, 2023 | 03:30 pm
James Randerson
Event Details

Title: The weak terrestrial carbon sink hypothesis

Abstract: Over the past thirty years, consensus estimates of the contemporary global carbon budget compiled by the Intergovernmental Panel on Climate Change (IPCC) and Global Carbon Project (GCP) report a strong net land carbon sink that is comparable in magnitude to carbon uptake by the world’s oceans. One line of evidence for this comes from the north-south gradient of atmospheric CO2, with uptake by northern temperate terrestrial ecosystems required to weaken the interhemispheric difference simulated by atmospheric models forced by fossil fuel emissions and ocean exchange. A second line of evidence comes from global atmospheric O2 measurements that show multi-decadal rates of O2 decline are slower than expected from fossil fuel burning alone. Additional indirect and direct evidence for a land sink comes from increases in the CO2 annual cycle, global satellite greening trends, eddy covariance tower measurements, and forest inventory observations. Here we describe an analysis of satellite-derived aboveground biomass time series that indicates the land sink that is more than a factor of 3 lower than the GCP budget estimate for the 2001-2019 period. We then describe a hypothesis for reconciling the weak land sink with other terms in the global budget.

The Department of Earth System Science acknowledges our presence on the ancestral and unceded territory of the Acjachemen and Tongva peoples, who still hold strong cultural, spiritual and physical ties to this region.