Why forests matter

To deal with climate change, we need to start investing in forest plantations and stop clearing natural forests
April 28, 2007

The world's forests make a significant contribution to keeping carbon dioxide (CO2) levels down to acceptable limits. They contain more carbon, in the form of their living biomass, soils and associated wetlands, than all the world's fossil fuel reserves put together. Indeed, it is difficult to see how the problem of climate change can be solved without addressing our management of the world's forests, but they are virtually ignored at the policy level.

We usually assume that the countries that consume the greatest amount of fossil fuels make the greatest contribution to global warming. But what really matters is a country's net carbon emissions—its total emissions, regardless of origin, minus the carbon that is fixed back down to earth again, mainly by plants.

Seven to 12 per cent of the emissions attributed to the EU's consumption of fossil fuels are permanently sequestered away again by its forests. Conversely, although Indonesia is responsible for only about 87m tonnes of carbon emissions annually—1 per cent of global emissions—those due to forest clearance and fires are believed to be in excess of 2bn tonnes a year, occasionally even more. This is probably greater than the net emissions of the US.

The world's overall forest area has been fairly stable for the last 50 years, but there has been substantial variation between regions. France has increased its forested area from 14 per cent in the 1830s to nearly 30 per cent today, with much of Europe and the US showing a similar trend—the forests in these regions are net carbon sinks. In contrast, across vast swathes of the tropics, forests are in rapid decline, with losses of 1 to 3 per cent a year, with Indonesia leading the way. The resultant carbon emissions from these heavily damaged forests and other forms of environmental disturbance exceed those being fixed back down by the recovering forests elsewhere, and are responsible for a third of the rise in atmospheric levels of CO2.

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The problem is not the use of wood, but the places we choose to get it from. One way of reducing the pressure on natural forests is to plant fast-growing trees on land set aside for the purpose, rather as we do for agricultural crops. Such forest plantations have increased to more than 200m hectares in recent years, but most are used to produce "value-added" materials such as paper, rather than to supply construction and firewood that developing countries need.

Many forestry companies are shifting their operations to the subtropical belt, where trees can grow very fast indeed. Southern Brazil, Uruguay, Chile, South Africa and New Zealand are experiencing especially high levels of commercial investment in plantation forestry, and India and China are financing their own schemes. Poplar, eucalyptus and pine species are favoured, but if these successes can be replicated with the species used for construction and fuel wood—activities that are responsible for 85 per cent of the world's demand for timber—then even the existing plantations could easily supply all the world's wood needs indefinitely.

But the slow growth rate of trees suitable for construction or burning is a serious deterrent to anyone wishing to produce them from scratch. Governments and corporations need to get the R&D process rolling. The development of high-intensity forest plantations and the biotechnological research that goes with it should not be seen as incompatible with environmental protection, but rather as a crucial part of it.

The recently published Stern report suggested that paying the six developing countries with the worst rates of deforestation to protect their forests would cost up to US$11bn a year, but even this will not stop the destruction if the people living there have no alternative but to cut down trees for their cooking and heating needs. Viewed in this way, not only is the development of forest biotechnology essential to environmental protection, but it also represents good value for money, as compared to many of the alternatives under consideration.

A global plan to halt and even reverse the large-scale disturbance of natural forests and other wild areas is clearly needed. If this can be achieved, then much of the rise in atmospheric CO2 levels will be fixed back down of its own accord, as the volume of living biomass recovers and leaf litter contributes to deeper soils. The larger the area of natural forest and other wild places set aside for this, the greater the benefit will be.

If we fail to do this sufficiently quickly, we risk the danger that natural feedback effects will begin to magnify human-induced climatic change. For instance, forests and their soils are tremendous reservoirs of carbon, and climate change is rapidly exposing many of them to unsuitable growing conditions. The very stresses of climate change itself may cause forests to become large emitters of CO2 and other greenhouse gases, instead of acting as sinks as they do now. Of greatest concern are the boreal forests and associated wetlands in Canada, Alaska, Scandinavia and Russia, where the largest temperature swings are expected. They could contribute to the "tipping point," whereby a self-sustaining cycle of global warming will be initiated, with unpredictable consequences.

Policymakers can do much to deal with these problems, but the carbon clock is already ticking.