Earth lost a staggering amount of forest cover in 2017

Last year saw the second-largest tropical tree cover loss on record since 1999, in large part because of human-caused fires in the Amazon, a new analysis from the World Resources Institute and University of Maryland found.

What it means: Trees absorb huge amounts of carbon dioxide annually, preventing even more global warming. Losing tree cover means there's the potential for accelerating warming, as well as a range of other effects, including damage to biodiversity.

What they found: Using satellite data, the team found the tropics lost 15.8 million hectares, or 39 million acres, of tree cover in 2017. It's the equivalent of losing 40 footballs fields of trees a day for an entire year, researchers found.

Keep in mind: Tree cover loss is not the same as deforestation. Instead, it means the removal of tree canopy due to human and natural causes, and includes trees in plantations as well as natural forests.

Yes, but: The biggest contributor to forest cover loss is the clearing of forests for agriculture and other human uses.

• Brazil was by far the greatest contributor to tree cover loss in tropical countries. There were 4.52 million hectares lost.
• According to WRI and the University of Maryland report, the Amazon had more fires in 2017 than any other year since such monitoring began in 1999.
• Tree cover loss in the Democratic Republic of Congo reached a record high in 2017, up by 6% over 2016.

Why it's happening: The report blames lack of enforcement, political uncertainty, and the rollback of strict environmental protections as reasons for the spike in fires. In addition to these factors, the Amazon has been increasingly prone to drought conditions, and climate projections show this will worsen with time as climate change continues.

• Peace can be bad for trees. Interestingly, Colombia saw a spike in tree cover loss, likely because a peace deal struck between the government and the Revolutionary Armed Forces of Colombia, or FARC, freed up large areas of forest that had been under FARC control. That led people to move into these areas and resulted in a 46% increase in tree cover loss in that country.

The good news: In Indonesia, where peat fires in 2015 caused greenhouse gas emissions to spike to industrialized country levels, the country saw a significant decline in tree cover loss last year.

• There was also a drop in forest loss in peat areas, likely due to government policies that prohibit draining the peat, which contains greenhouse gases that are released if the land is drained or burned.
• The relatively wet El Niño weather pattern also helped prevent fires, analysts found.

Also, while losses are high in the tropics, tree cover is actually gaining ground in some industrialized countries, though the losses are far outpacing the gains.

The bottom line: The global loss of tropical forests makes addressing climate change more difficult. Yes, companies have made pledges to source palm oil and other forest products only from sustainable sources, and countries have regulations to try to halt deforestation, but these aren't fully solving the problem.