(CNN) - International targets to cut emissions and limit climate change will be missed due to rises in deforestation and delays in changing how humans use land, a new study warns.
Nearly 100 countries pledged to make their use of land less damaging to the climate, mainly by limiting deforestation rates and boosting forest restocking, when they signed the Paris Agreement in 2015.
But those commitments were unrealistic and need to be stepped up dramatically, according to researchers at the Karlsruhe Institute of Technology and the University of Edinburgh, who pointed to inaction by richer countries and a rise in deforestation in several countries since the treaty was signed.
The agreement committed almost 200 countries to keep global warming well below 2 degrees Celsius above pre-industrial levels -- and below 1.5 degrees if possible.
"In most cases, little progress has been made, [and] often, the situation has actually worsened in the last three years," said Calum Brown, lead author of the study, published Monday in the journal Nature Climate Change.
"Many of the plans for mitigation in the land system were unrealistic in the first place and now threaten to make the Paris target itself unachievable," added Brown, a researcher at the Karlsruhe Institute of Technology.
Brazil increased deforestation by 29% between 2015 and 2016 despite reductions in the decade before the Paris Agreement was signed, the study says, essentially making the country's emission promises impossible to meet.
Palm oil cultivation in Indonesia and Peru has also scuppered deforestation efforts and led to increased emissions rates, it says.
"The commitments were never sufficient, which is bad enough, but also the commitments that have been made are not realistic given the political support they have in general," said co-author Peter Alexander, a lecturer in global food security at the University of Edinburgh.
"Ongoing destruction of tropical forests in Brazil, the Democratic Republic of the Congo and Indonesia is particularly concerning, because these forests store huge quantities of carbon, as well as containing high levels of biodiversity," added co-author Mark Rounsevell, a professor of land use change at the Karlsruhe Institute of Technology.
"Attempts to protect these forests have had limited success, and laws against felling have recently been rolled back," he said.
The study is one of many in recent months to warn that countries are falling woefully short of achieving the targets of the Paris treaty.
The agreement, once seen as a landmark eleventh-hour attempt at stemming the catastrophic impact of climate change, has also been denounced by a number of leaders elected since it was signed, including US President Donald Trump and Brazilian President Jair Bolsonaro.
"Richer countries have not been leading the way, either in reducing their own emissions or in reducing the pressure on developing nations," Alexander said.
"We need to find rapid but realistic ways of changing human land use if we are to meet our climate change targets."
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