Forests are our best natural defense against climate change.
Every year the burning of trees releases approximately 20% of all global carbon emissions.
You’ve probably heard the Amazon Rainforest referred to as the “lungs of the earth,” since its trees take in so much carbon dioxide, CO2, and “breathe” out oxygen. However, all living things, including trees, must respire and “breathe” out CO2 as well. It’s better to think of the rainforests as a force that counteracts global warming. Plants, such as the many millions of trees that make up the rainforest, take in CO2 in order to make food via photosynthesis. This food is usually stored in the form of glucose, which is a carbon-rich sugar. Thus, the rainforest is a major contributor to carbon storage, and any carbon stored within the trees isn’t contributing to the greenhouse effect and warming the planet as a greenhouse gas.
However, degradation and deforestation releases the carbon stored within the trees back into the atmosphere at an alarming rate. About 30% of our carbon emissions come from burning the rainforests alone. According to a study published in Global Change Biology in 2014, forests that experienced disturbances such as logging and fires stored 40% less carbon than undisturbed forests.
What is degradation? The authors of the paper define anthropogenic forest degradation as “the reduction in the overall capacity of a forest to supply goods and services including carbon storage, climate regulation, and biodiversity conservation. It can result from various types of human disturbances, such as selective logging, understory fires, and overhunting.”1 Let’s look at one part of that definition: climate regulation. We know that when the trees store carbon, they’re keeping it out of the atmosphere, and when they are chopped down and decompose or are burned, that carbon is released back into the atmosphere. This carbon then functions as a greenhouse gas. Climate scientists Deborah Lawrence and Karen Vandecar recently released a paper that detailed the effects of deforestation on climate change. As deforestation increases, global warming is exacerbated, and global temperature increases and precipitation patterns are altered. What’s more, Amazonia is the region most affected by such effects of deforestation, and would experience a temperature increase of up to 3.8°C and a precipitation decrease of around 15% of annual rainfall if total deforestation were to occur.
The effects of climate change would wreak havoc on the ecosystems of the Amazon. Andean cloud forests, for example, are home to thousands of species that live nowhere else. Their habitat range is temperature-dependent, so as global temperatures increase, their habitable range moves upslope. However, in a 2013 paper on the implications for biodiversity loss with climate change, David Lutz pointed out that many of the species living in the cloud forests can’t keep pace with the change in habitat – their current pace of upslope migration “is around 2% of what it needs to be to stay in equilibrium with climate change by 2100.” This means that unless humans give the migrating species a boost in their journey up the mountain by physically altering the environment to allow the seedlings to take hold (and give up our rate of fossil fuel consumption), many of these endemic species will go extinct – a huge loss for biodiversity.
The Amazon forest is a major player in determining global climate. It pulls the most important greenhouse gas from the air and puts it in storage. It transpires water, creating clouds that carry moisture around the world. It provides ecological services and is home to much of the world’s biodiversity. However, as the forest is degraded and destroyed, the power of the Amazon to mitigate global climate change is weakened, and it is adversely affected by the implications of climate change.
1. Berenguer, E., Ferreira, J., Gardner, T. A., Aragão, L. E. O. C., De Camargo, P. B., Cerri, C. E., Durigan, M., Oliveira, R. C. D., Vieira, I. C. G. and Barlow, J. (2014), A large-scale field assessment of carbon stocks in human-modified tropical forests. Global Change Biology, 20: 3713–3726. doi: 10.1111/gcb.12627