Forests are disappearing globally, a fact that unfortunately shouldn't surprise you. But it's also not a particularly helpful statistic. If you want to combat the decline, you have to know why forests are disappearing in the first place, when means figuring out where they've disappeared—as well as where they've come back.
Adding regional clarity to global forest data is the goal of an ambitious research project by a team of 15 researchers from the University of Maryland, Google, and the US Geological Survey. Following an analysis of a whopping 654,178 Landsat images, they calculated the change of global forest cover and plotted it all on a map, which you can tool around with above.
The results were published today in Science, and show global change on an impressively precise scale. For example, dramatic losses in Sumatra highlight just how impacted that country's forest systems have been in the last decade as development increases. On the other hand, a muddled matrix of forest loss and gain in central Canada, which is the result of a mature logging industry.
Overall, the researchers found that from 2000-2012, 2.3 million square kilometers of global forest cover was lost, and 0.8 million square kilometers was gained. But as you can see, regional insights like those mentioned above are the true value, as it's simply too hard to try to define cause and effect when looking at a global or climatic scale. The resulting lack of clarity makes informed management decisions harder to make.
“Losses or gains in forest cover shape many important aspects of an ecosystem including, climate regulation, carbon storage, biodiversity and water supplies, but until now there has not been a way to get detailed, accurate, satellite-based and readily available data on forest cover change from local to global scales,” University of Maryland professor Matthew Hansen, the lead author on the paper, said in a release.
Of four forest zones—tropical, subtropical, temperate, and boreal—the researchers only found one type of climate that exhibited a global trend: tropical forests, with losses increasing by a total of 2101 square kilometers a year. That's despite Brazil's commendable efforts to slow deforestation in the Amazon, a change "offset by increasing forest loss in Indonesia, Malaysia, Paraguay, Bolivia, Zambia, Angola, and elsewhere," the authors write.
For the other three forest types, forestry is a major factor, especially in subtropical forests like those in the American South, where "forests are often as a crop and the presence of long-lived natural forests is relatively rare." In well-regulated forestry industries, this loss is mitigated by replanting requirements, and the high turnover endemic to subtropical forests made that region also have the lowest ratio of loss-to-gain. In other words, while a whole lot of forests were cut down, a whole lot were also replanted, something that doesn't happen when deforestation is driven by land conversion, such as in the Amazon.
A similar situation was recorded in temperate forests, many of which feature mature hardwood industries. Temperate forests and boreal forests are also largely affected by fires, whose impacts are harder to predict than that of logging. Still, for temperate forests, 1.6 square kilometers of cover were lost for every one gained, which suggests that current harvests aren't sustainable—or that we're not replanting enough trees.
Even then, that's an overly broad conclusion, as some regions are more sustainably harvested than others. And that's the exact point of the map: Because the range of economic, regulatory, and environmental factors that contribute to forest loss is too broad to make global conclusions, making data more precise on smaller scales is key to effective management.
Of course, being able to refine data to such small scales—the researchers say their map has a resolution of 30 meters, which is stunning—requires massive data sources, and the ability to process it in an effective fashion. Remember, more than 600,000 satellite images spanning 12 years went into the making of this map. Naturally, having the capabilities of the USGS's open data efforts with the Landsat program is a huge boost, as well as the talent and power of Google. The researchers hope that their work can set a model for data-driven forest management in the future.
"Given such progressive data policies and image processing capabilities, it is now possible to use advanced computing systems, such as the Google cloud, to efficiently process and characterize global-scale time-series data sets in quantifying land change," the wrote. "There are several satellite systems in place or planned for collecting data with similar capabilities to Landsat. Similar free and open data policies would enable greater use of these data for public good and foster greater transparency of the development, implementation, and reactions to policy initiatives that affect the world’s forests."
The authors note that Brazil has already incorporated data-driven analysis into its forestry strategy, which has resulted in large decreases in deforestation rates. (The Brazilian Amazon is still disappearing.) It's a model for other countries looking to take smarter approaches to their forest management, especially in the Amazon. Of course, even smart regulation can be circumvented by corruption, which has afflicted many of the world's developing nations. At least now there's a solid model for tracking where it happens, something that hasn't existed before. The next step is putting such powerful tools to use.