Reverse climate change: Plant and preserve global forestland

By Brian Stone

If there is a silver lining to the failure of the Copenhagen climate accords to produce a legally binding treaty on global warming, it is this: instituting a robust and lasting agreement a year from now is a more desirable outcome than instituting a weak agreement today.

But what variables might change in the near term that could give rise to more favorable conditions for a binding and effective agreement on climate change?

One important shift under way is the growing recognition that greenhouse gas reductions are not the only option we have to slow and ultimately reverse global warming. Restoring and expanding global forests can also cool the planet.

While such a declaration may constitute heresy in a political and scientific arena in which climate change and the greenhouse effect have come to be understood as one and the same, global warming is not driven by greenhouse gases alone.

It is also driven by the quantity of heat that is emitted from the Earth’s surface and ultimately absorbed by greenhouse gases in the atmosphere.

The phenomenon of global warming can be likened to a pot of boiling water: placing a lid over the pot traps outgoing heat energy and raises the temperature inside, but turning up the burner under the pot also raises temperature, quite independent of the placement of the lid.

The extensive loss of forest and other vegetative cover across the Earth’s surface is significantly increasing the quantity of heat emitted to the atmosphere, contributing in turn to a rise in temperature.

How significant is the role of global land surface change compared to the role of greenhouse gases in bringing about global warming?

A review of the now extensive scientific literature on land use and climate change appearing in the journal Science concludes that land use change and greenhouse gas emissions may be contributing to climate change in equal parts.

At the scale of the planet as a whole, the influence of deforestation on climate can be hard to discern, as deforestation in one region of the planet can be offset by reforestation in another.

But when measured at the regional to sub-continental scale, the impacts of land use on climate have been shown to be roughly equivalent to the effects of greenhouse gases on temperature.

At the scale of cities, where most of the global population now lives and where approximately 80 percent of greenhouse gases are emitted, land use has a much more pronounced effect on climate than greenhouse gases, contributing to rates of warming that are often double that of the planet as a whole.

In urbanized areas such as Atlanta, land use strategies emphasizing tree planting and the use of reflective building materials are far more likely to lower temperatures over the coming decades than greenhouse gas reductions alone.

Recognition of the direct and significant influence global forests have on temperature, distinct from the more modest benefits forests provide in the form of carbon sequestration, is a potential game changer in the realm of international climate policy.

At present, a principal obstacle to reaching an agreement concerns the limited ability of developing nations to ratchet down carbon emissions from the fossil intensive industries needed to propel their economies.

Yet, many of these same developing nations are home to the globally significant forest ecosystems most in need of protection and regeneration.

Formal recognition of the climate-regulating benefits of forests in international cap and trade programs would create a new mechanism for nations to trade forest regeneration credits in concert with carbon reduction credits.

Developing economies would benefit from a new revenue stream that could be used to modernize industry and reduce emissions; developed economies would benefit from increased flexibility in meeting treaty obligations. And the planet would benefit from having both the land surface and atmospheric drivers of global warming mitigated.

The good news is that global scientists are increasingly aware of the significance of land use to climate change.

A report of contributing scientists to the Intergovernmental Panel on Climate Change (IPCC) published in advance of the Copenhagen conference acknowledges for the first time the direct, non-emissions related influence of global deforestation on climate and calls for future IPCC assessments to account for such changes in climate models.

This is a first step toward a more comprehensive approach to climate change. The next step is for climate treaty negotiators to work in the post-Copenhagen period to develop a new international framework for managing climate change, one that capitalizes on the benefits of global forest regeneration for climate change mitigation in concert with emissions reductions.

Such an approach not only makes use of the full array of management tools available to us but also lays the groundwork for a grand bargain between developed and developing economies and, in so doing, provides a promising way forward from Copenhagen.

Brian Stone is a professor of Environmental Planning at the Georgia Institute of Technology. His latest research on land use and climate change appears this month in the Journal of Environmental Science and Technology.