John Metcalfe was CityLab’s Bay Area bureau chief, covering climate change and the science of cities.
New high-resolution maps show that we've gobbled up green space more than twice the size of Texas.
It can be difficult to picture the rapid and widespread destruction of the world's forests, though many of us live in cities plucked clean of woodland. But scientists have done just that with these depressingly detailed global-deforestation maps, which contain high-resolution images showing how humanity is sawing down trees like a voracious colony of giant leaf-cutter ants.
"Global Forest Change" is a Google Earth-powered map based on more than half a million Landsat images taken from 1999 to 2012, and assembled by researchers at the University of Maryland, Google, the U.S. Geological Survey and elsewhere. Using bright red coloring to represent tree loss, it shows that the pace of deforestation has kept far ahead of regrowth. Since 2000, the planet has lost 2.3 million square kilometers. It's grown only 800,000 square kilometers back, making a net deficit of 1.5 million square kilometers (roughly 580,000 square miles), according to a study published yesterday in Science.
Not all of this destruction is caused by humans. Natural phenomena, such as wildfires, huge storms, plant pests and diseases, also exterminate trees with regularity. But this new model gives clear proof that activities like logging are having a big impact on how quickly forests are disappearing. The scientists know that partly by studying how tree cover has actually rebounded in Brazil since the country started really protecting its rainforest. Whereas Brazil had an annual forest loss of about 15,444 square miles in the early 2000s, by 2010 and 2011 the rate of eradication was down by half.
But that story of hope and regrowth is "more than offset" by massive disturbances elsewhere. So where are the most imperiled forests? Here is the researcher's take:
[S]ubtropical forests were found to have the highest rates of change, largely due to intensive forestry land uses. The disturbance rate of North American subtropical forests, located in the Southeast United States, was found to be four times that of South American rainforests during the study period; more than 31 percent of U.S. southeastern forest cover was either lost or regrown. At national scales, Paraguay, Malaysia and Cambodia were found to have the highest rates of forest loss. Paraguay was found to have the highest ratio of forest loss to gain, indicating an intensive deforestation dynamic.
The satellite imagery also depicts strong vegetation ruination in Bolivia, Angola, and Zambia. In terms of what the future bodes, Indonesia is a particularly bad place to be if you breathe CO2. The country has doubled its yearly deforestation rate to 7,722 square miles since the beginning of the 21st century, according to the researchers.
Have a look at the historical disturbances in woodland in some of these regions; for a more complete explanation of what the scientists measured, be sure to check out the full map. The key:
Western Indonesia is riddled with destroyed forests:
The American Southeast shows signs of vast change:
Regrowth in Brazil is paired with great patches of deforestation in Paraguay and Argentina:
To give you an idea of how eagle-eyed this model is, take a look at a couple of urban areas, like the San Francisco Bay region where trees die and grow in the Presidio:
And here's Houston:
Maps courtesy of the University of Maryland et al.