Regrowing forests can sequester CO2 and offset the loss carbon to land-use change
Through practices such as forest clearance and cropland cultivation,
humans have altered 42-68% of the Earth’s surface and added over a
hundred billion tones of carbon dioxide (CO2) to the atmosphere. Elena
Shevliakova and collegues of Cooperative Institute for Climate Studies
(CICS) at Princeton University and at NOAA used a new land model LM3V to
provide the global estimate of how much of the CO2 emitted
from land has been offset by forest regrowth. They used four different
scenarios, and found that even extensive human interference caused the
net loss of only 1.1-1.3 billion tones of carbon per year in the 1990s –
about half of previous estimates. One factor that may explain this is
the 0.35-0.6 billion tones of carbon per year absorbed by plants growing
back after disturbance, mostly in tropical forests.
The new land model LM3V is developed in collaboration with the
scientists from Geophysical Fluid Dynamics Laboratory (GFDL) and is a
component of the GFDL Earth System Models (ESMs). ESMs will be used in
the next, 5th assessment of Intergovernmental Panel on Climate Change
(IPCC) to explore interactions between carbon cycle, climate change, and
land cover changes. LM3V is specifically designed to address the
consequences of human activities including cropland and pasture
dynamics, shifting cultivation, logging, fire, and resulting patterns of
The smaller magnitude of the land-use source relative to previous
estimates implies a smaller magnitude of the “missing sink”, that
scientists have been seeking to help them balance the global carbon
budget. LM3V provides GFDL ESMS with modeling capabilities to explore
the consequences of land-use/land-management changes and its
implications for climate in the past and under future scenarios.
Shevliakova, Elena, S W Pacala, S Malyshev, P C D Milly, and Lori T Sentman, et al., June 2009: Carbon cycling under 300 years of land use change: Importance of the secondary vegetation sink. Global Biogeochemical Cycles, 23, GB2022, doi:10.1029/2007GB003176.
Click here to access the manuscript that is in press.