Tropical Forests Emit More Carbon Than They Absorb

A new study has shown that tropical forests are not absorbing as much carbon as we think they are.  Published in the journal “Science” on September 28, 2017, researchers found that 68.9% of our overall losses from the net release of carbon is attributed to deforestation and degradation, which is a substantially greater number than our overall gains by forest growth[1].

Scientists tested this theory out by taking a new approach to the situation.  Usually, the carbon balance between tropical forests is measured by estimates from satellites that analyze the change between two different time periods as well as biomass density of the forests.  Although this is useful, it typically does not take into account forest degradation, which can affect the biomass loss accounted for in satellite images.  Scientists mapped out current aboveground carbon rates in order to estimate the data over a 12-year period, which accounts for the amount of carbon in degraded and untouched forests.

On every continent, net carbon losses exceed net carbon gains, which ultimately cancels out the effectiveness of the trees in tropical forests.  It isn’t that reforestation is contributing to more carbon in the environment, but it is that the positive effects are masked by the mass rate of excessive logging and deforestation.  The net loss of tropical forests can be broken down into these major percentages – 59.8% in tropical regions of America, 23.8% in Africa, and 16.3% in Asia.

The carbon released annually amounts to 425.2 ± 92.0 Tg C yr–1 or 425 million metric tons, which is greater than the emissions released from vehicles in the United States every year[2]. Emissions from tropical forests need to be reduced so that we can restore forests and their role to store carbon, as well as keep the global temperature from rising too high.

Most of the hands-on research was carried out in South America, specifically Brazil, where scientists are more detailed in their research about emissions in regional rainforests.  The net loss in aboveground carbon decreased during 2004-2012 when the policies on illegal deforestation were stricter.  After a reform to their protection law in 2013, carbon net loss in Brazil has steadily increased due to degradation[3].  If policy-makers were to create more strict deforestation laws, it would help the net losses of carbon decrease, making for a better environment.

The scientists conducting the study hope that the results are eye-opening to land managers and policy makers, propelling them to take pointed action against the increasing carbon emissions in our environment.  Tropical forests have the power to decrease, as well as stabilize the large amounts of carbon in the atmosphere, and by minimizing emissions through ending deforestation and degradation, we can begin reversing some of the damage done and move towards a green future.


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