There is a lot of attention on the effects of fossil fuels on climate change. But the effects of deforestation and the use of forest lands for agriculture are often overlooked. A recent study by Cornell University addresses the effects of deforestation on climate change. We interviewed the Natalie Mahowald, the lead author for the study.

To put things into perspective, can you give an estimate of the effect of deforestation on the climate?

Right now it is contributing about 40% of the warming we are experiencing. By 2100 it could force a warming of 1 degree.

Which areas have the most deforestation at the moment?

Tropical areas are at most risk for deforestation right now.

What are the main mechanisms between deforestation and climate change?

Deforestation directly releasing carbon dioxide during the deforestation. In addition much of the deforested lands are converted to agriculture or pasture usage, both of which cause emissions of green house gases like methane and nitrous oxide. These contribute to the warming from deforestation.

There is a lot of attention on CO2 as a greenhouse gas, but does deforestation also causes higher emissions of other greenhouse gasses?

Deforestation leads to agriculture and pasture usage in many cases, and both cause emissions of green house gases…

In the study you stress the importance of looking at these effects on a longer time-scale, or multi-centennial legacy of current land-use decisions. Can you explain why this is important?

Solving climate change is a really really difficult problem which will require at a minimum a conversion of our energy sector to sustainable energy extremely fast: potentially faster than can be technically done, but perhaps also faster than is politically feasible. Deforestation, as we show here, and the conversion to agriculture and pasture usage also contributes to climate change. In addition, to avoid the worst of climate change, we also need to remove carbon dioxide from the atmosphere, which we don’t have good technologies for, unless they use a lot of land, which has many environmental impacts, as well as causing climate change themselves. Thus it is likely that we will be dealing with the impact of climate change for a long time: thus understanding the long term implications of land use, which not only causes emissions of CO2 during conversion, as well as the emission during agriculture and pasture usage, but also causes the removal of a long term natural sink of carbon in the forests.

What are the possible measures available to revert the process of deforestation?

Deforestation is a difficult process to control, but understanding that stopping deforestation not only protects biodiversity but climate could bring more resources to bear on the problem. Deforestation can be driven by large businesses but often is driven by individual poor citizens looking for a way to feed themselves. So providing incentives for locals to protect the forests, as well give them a livelihood has been successful approach for protecting forests.

Is it also possible to change our agriculture in a way so that the soil functions more as a carbon sink and emits fewer greenhouse gasses?

Yes, there are ways to make agriculture more sustainable, and these efforts need to be enhanced and incorporated. Most of these approaches also enhance soil fertility so this is a win-win situation.

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