Deforestation by cutting down trees, thinning of our forests, and by intentional and unintentional forest fires have been ongoing over last few centuries as human development and our human population has exploded. We chop down trees for its timber, to build fencing, furniture, and homes. Forests are cleared to make room to grow crops, create pastures, build cities, and increase development. Climate change also contributes to deforestation by increasing the prevalence of forest fires which further erode our natural wood resources. In this post, I focus on forests in the Amazon and in California, both of which have suffered for years the negative consequences of human actions.
The Amazon Rainforest
The Amazon rainforest has been cleared by humans for agriculture purposes such as to grow crops like palm and soybeans, as well as to raise livestock. This not only releases carbon dioxide into the atmosphere, but it also alters the composition of the rainforest making it much more susceptible to fire. Figure 1 below demonstrates the deforestation occurring in the Amazon basin from 2001 to 2010. From the varied timeline of deforestation we see that deforestation is not a new problem. Figure 1 highlights which areas have experienced deforestation in more recent times. The colored dot indicates the year of deforestation in a particular area (Song et al. 2015).
Figure 1: A study of the year of deforestation in the Amazon basin. (a) the Amazon basin. (b) Xingu river basin, Brazil. (c) Colombia. (d) Rondonia, Brazil.
Real-time detection systems such as DETER-B or MODIS-based DETER are quite helpful to detect when and where deforestation is occurring, which in turn helps people evaluate the best course for mitigation and adaptation. Diniz et al. argue that DETER-B is more advanced than MODIS because of its enhanced detection abilities.
The situation in Brazil’s Amazon forest has deteriorated under the Brazilian government’s policies which encourage increasing agricultural activity and decreasing limitations on deforestation. Brazil’s current president, Jair Bolsonaro, is widely viewed as a strong ally of the Ruralists, a group supporting Brazil’s agriculture industry, and he has even gone on record to state that deforestation data released by Brazil's National Institute for Space Research are false (Escobar 2019).
Fires in the Amazon rainforest have increased by 80% over the past year (National Geographic). As of September 2019, there have been in excess of 90,000 fires in the Brazilian Amazon forest. It is believed that the fires are purposely caused by illegal human activity to prepare the land for planting profitable crops, such as soybeans, or to make more room for pastures. This concept and additional details are explained in the video below by the news company Vox.
Discussion of the illegal clearing of forests through intentional fires in the Amazon
California
Recent forest fires around other parts of the world contribute to climate change. California is a case in point. Seventy-five percent of California's largest fires have occurred only since 2000. The unprecedented frequency of California’s wildfires can be attributed in part to climate change. Temperatures over the past century have increased by roughly 1.67 degrees celsius. Droughts and drier areas caused by climate change lead to increased dryness of vegetation and make forests more vulnerable to spontaneous fires.
Human activity has adversely impacted our forests as well when a fire is extinguished at the first sign of smoke and by not letting them burn out naturally. Even though this sounds counterintuitive, forests burn to curb overgrowth naturally. If forests were allowed to burn every once in a while, the fuel for fires, such as smaller shrubs and trees, would burn away so that they could not ignite taller trees (Young et al. 2017). Yet from 1998 to 2008, only 0.4 percent of all United States forest fires were left to burn out naturally (NPR).
Action must be taken quickly. Based on an aerial survey by the USDA, since 2010 there has been a loss of over 100 million trees. In 2016 alone, roughly 60 million trees were lost. California’s Governor Newsom continues to declare states of emergencies around California as citizens suffer from the consequences of forest fires (Stephens et al. 2018). The most recent one was in late October, 2019 as a result of the Kincade and Tick fires and its negative impacts on Sonoma and Los Angeles County (California Office of Governor). Although I discuss the loss of forests from fires in California, the figure below demonstrates that there are many other drivers of forest cover loss and that losses occur from wildfires from all around the world.
Figure 2: Main drivers of forest cover loss from 2001 to 2015 (Curtis et al. 2018)
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