Forests that are properly cared for can take the world a long way towards cutting carbon emissions, US-based researchers say – far enough to go at least a quarter of the way to reaching the UN’s target.

They report that stopping deforestation and allowing young secondary forests to grow back could establish a “forest sink” – an area that absorbs carbon dioxide rather than releasing it into the atmosphere – which by 2100 could grow by over 100 billion metric tons of carbon, about ten times the current annual rate of global fossil fuel emissions.

The researchers say capturing more carbon in land and forests is no substitute for eliminating the world’s dependence on fossil fuels, which it is consuming so prodigally that the consequent rise in greenhouse gas levels is driving global warming.

But better management to reduce emissions and enhance carbon absorption capacity, they say, could let forests and agricultural land help the world to move at least a quarter of the way towards meeting the more ambitious of the two goals adopted in the 2015 Paris Agreement – limiting temperature rise to 1.5°C.

Asian initiatives

The report, by Woods Hole Research Center, is accompanied by another from Forest Climate Analytics which includes case studies from three Asian countries.

Through large-scale tree planting efforts, the three – China, India and South Korea – have together removed more than 12 billion metric tons of CO2 from the atmosphere over the past two decades.

The Woods Hole report says there is 40% more carbon stored in forested lands than in known fossil fuel deposits worldwide – almost five times more carbon than can be added to the atmosphere without exceeding the less challenging Paris goal of 2°C, the authors say.

“Releasing this carbon into the atmosphere through continuing deforestation not only commits us to the worst impacts of climate change, but also results in the loss of a globally important carbon sink,” said Martin Herold, professor of geoinformation science and remote sensing at Wageningen University in the Netherlands

“People often misunderstand the longevity of forests – sure, individual trees die, but forests naturally grow back. As long as the land use does not change, forests are a permanent fixture of the earth’s carbon sequestering architecture. Protecting the carbon stored in forests is no different than taking action to ensure fossil deposits stay underground.”

The countries which have ratified the Paris Agreement are due to meet in the German city of Bonn from 6 to 17 November, with possible ways of strengthening it high on their agenda, and are likely to debate the role of forests at length. The UN’s Food and Agriculture Organisation reported in 2015 that, while forested areas had decreased since 1990, the rate of net forest loss had been cut by 50%.

“We cannot meet the Paris Agreement’s goal of limiting warming to 1.5°C without utilizing the potential of forests and agricultural soils to store more carbon,”said Philip Duffy, president and executive director of Woods Hole Research Center.

The Woods Hole researchers say aggressive action to reduce emissions from the land sector can buy more time for a rapid transition to a decarbonised economy. Ending tropical forest loss, improving tropical forest management, and restoring 500 million hectares of tropical forests could reduce emissions enough to provide 10-15 years of extra time to reduce the use of fossil fuels, they write.

Low investment

Governments have already received many warnings that forests are vital to climate change mitigation. Other forms of land use are equally important. The latest findings certainly offer hope of a possible way to reduce carbon emissions, but another recent study concluded that tropical forests release more carbon than they absorb (scientists from Woods Hole were among the authors).

The researchers say there are striking benefits when governments invest heavily in forests. Rough estimates of cost per ton of CO2 sequestration range from a low of about US$2 in India to US$26 per ton in China.

But there is a major gap in funding for forests, they say. Investments in stopping deforestation make up less than 1.5% – US$2.3 bn – of the US$167 bn committed by multilateral institutions and developed country donors since 2010 to climate change mitigation.

The researchers say the average annual deforestation rates in forests over which indigenous peoples have secure tenure are significantly lower than in those without it.

A 2016 report from the Rights and Resources Initiative (RRI), Woods Hole Research Center and the World Resources Institute reported that indigenous peoples and local communities hold at least 54,546 million metric tons of carbon in the tropical forests they live in globally – just under a quarter of the total carbon found above ground in the global tropics.