Deforestation is doing much more than raising global carbon levels

Wind patterns and heat distribution are among the factors now believed to be impacted by the rapid depletion of forests around the world. 

Scientists have long understood the relationship between trees and the amount of carbon in the atmosphere. The greater the flora, the lower the CO2 count as woodlands take in the gas and expel oxygen, which humans and other animals breathe. 

However, a new study published in the journal Frontiers in Forests and Global Change suggests the impact of deforestation goes well beyond the amount of carbon in the air. The Unseen Effects of Deforestation: Biophysical Effects on Climate, produced by the Alliance of Biodiversity International and the International Center for Tropical Agriculture, identifies a number of additional impacts from regional-scale felling of trees, emphasising that many climate models take these into account but few policymakers pay attention.

One major issue researchers point to is the way heat distribution changes with less tree cover – specifically, the smaller and lower the forest canopy the less widely heat is dispersed. This is significant, as air temperatures are usually taken at ground level, which is also where the many animals, including humans, live. 

Water cycles are another key factor. Trees act as a pump transferring moisture from the floor into the atmosphere. As a result, the number of trees, and their density, directly contributes to the amount of down-wind rainfall. Meanwhile, biogenic volatile organic compounds (BVOCs) – which influence cloud formation – are also a product of forests. Thicker areas of trees produce these in higher numbers, making clouds brighter so they reflect more of the sun’s energy back into space. 

In related news, new data has been released suggesting the Amazon rainforest could be losing its resilience to extreme weather events. 

Image credit: Neil Palmer / CIAT