We Only Have 3 Years Left to Prevent a Climate Disaster, Scientists Warn

A group of the world’s leading thinkers on climate change have issued an urgent call for the world to reach peak greenhouse gas emissions by 2020, as global leaders prepare for a gathering in Germany next month.

The group, led by former United Nations climate chief and Paris Agreement architect Christiana Figueres, warns in a piece published in the journal Nature that the planet could face unsafe — and irreversible – levels of temperature increases if greenhouse gas emissions do not begin to fall by 2020. The piece calls on energy policymakers to implement policies to move the world to 30% renewable energy by 2020 and stop approving new coal-fired power plants, among other initiatives.

“There will always be those who hide their heads in the sand and ignore the global risks of climate change,” the group writes. “But there are many more of us committed to overcoming this inertia.”

The commentary in Nature follows an April report published by the group, which calls itself Mission 2020, showing that the goal of keeping temperatures from rising more than 2°C (3.6°F) by 2100 outlined in the Paris Agreement on climate change would become unattainable if emissions continue to rise or even flatline after 2020.

Chances of meeting that goal were dealt a blow when President Trump said in June that the U.S. would withdraw from the global climate pact, but other world leaders recommitted to it in the days following the announcement. The Mission 2020 group also calls for world leaders to use the upcoming G20 summit in Hamburg to discuss measures to address global warming and the continued implementation of the Paris Agreement. And German Chancellor Angela Merkel has already suggested that the topic will be a top priority during the meeting, setting the stage for a potential confrontation with Trump.

“The European Union unconditionally stands by its agreement in Paris and will implement it speedily and with determination,” Merkel said on Thursday, according to a BBC report. “More than that: since the decision of the United States to leave the Paris climate agreement, we are more determined than ever to make it a success.”

The group of climate change thinkers also emphasized in their commentary that much of the action on climate change will occur beyond national governments and praised cities and municipal governments for committing to take their own action to address the issue. “I don’t see anyone in a waiting pattern,” Figueres told TIME in an interview earlier this year. “No matter which way you look you can see that there are many different stakeholders acting because they know this is the path toward the future.”