Implications for Global Climate
Compared to other ecosystems, the boreal forest
responds relatively quickly to changes in climate. Moreover, analysis of meteorological trends from
1961-90 shows that temperature increases are occurring most rapidly over the interiors of continents at
high latitudes (43°N to 65°N)–precisely the location of the boreal forest. In the last 40 years, average
temperatures have increased over these regions by as much as 1.25°C per decade (Sellers et al. 1997). If
the world’s missing carbon is in fact being stored within the boreal forest, and if the present warming
trend is turning the boreal forest into a source of carbon, then there could be a significant increase
in the rate of carbon build-up in the atmosphere. Scientists fear that by the year 2100 the amount of
carbon dioxide in the atmosphere might actually double pre-industrial levels (Wofsy 1999)–to more than
560 parts per million (the 1990 level was 353 parts per million).
In theirScience article, Wofsy and his colleagues note that the global mean temperature is
predicted to increase by about 2°C by the year 2100. They state that warming of this magnitude would
likely completely thaw the deep layers of frozen boreal soil at the old black spruce site and, as they
dry, significantly increase the decomposition of the carbon there. If this trend occurs on a large scale
across the boreal ecosystem, the decomposing boreal soils could significantly accelerate the rate of
rise of carbon dioxide levels in the atmosphere.
Today, Wofsy, Hall, and their BOREAS colleagues can only speculate what will happen to the boreal
ecosystem over the next century. But their hope is that as they continue to collect more data and refine
their models, they can one day solve the mystery of the missing carbon and accurately predict what
future levels of carbon dioxide will be. "How can we manage the forests for economic return and still
keep carbon out of the atmosphere?" Wofsy asks rhetorically. "If we are to have any hope of managing the
world’s ecosystems more efficiently, we need to understand the system better."
- Sellers, P.J., F.G. Hall, R.D. Kelly, A. Black, D. Baldocchi, J. Berry, M. Ryan, K.J. Ranson, P.M.
Crill, D.P. Lettenmaier, H. Margolis, J. Cihlar, J. Newcomer, D. Fitzjarrald, P.G. Jarvis, S.T.
Gower, D. Halliwell, D. Williams, B. Goodison, D.E. Wickland, and F.E. Guertin, 1997: BOREAS in
1997: Experiment Overview, Scientific Results and Future Directions,Journal of Geophysical
Research, 102, pp. 28731-28770.
- Hall, Forrest G. Personal Interview, 1999.
- Goulden, M.L., S.C. Wofsy, J.W. Harden, S.E. Trumbore, P.M. Crill, S.T. Gower, T. Fries, B.C. Daube,
S.-M. Fan, D.J. Sutton, A. Bazzaz, and J.W. Munger, 1998: Sensitivity of Boreal Forest Carbon
Balance to Soil Thaw,Science,279, pp. 214-217.
- Wofsy, Steven C. Personal Interview, 1999.
Findings from One BOREAS Study Site
Work on the
ground is a necessary component of the scientific process, even at NASA. These researchers are
collecting samples of vegetation for the BOREAS archive. (Photograph courtesy BOREAS project)