climate change
A woman walks past a map showing the elevation of the sea in the last 22 years during the World Climate Change Conference 2015 at Le Bourget, near Paris, France.Reuters

The world has just three more years to turn the overall greenhouse gas emissions to a downward path, a group of prominent scientists and policymakers said on Wednesday. The scientists, along with policymakers, claim that it would become impossible to contain climate change within safe limits after 2020.

The group based their estimates on simple mathematics. The group was led by Christina Figueres, who oversaw United Nations (UN) negotiations which resulted in the Paris climate agreement.

According to the group's estimates, the world will exhaust its emission budget in the next 15 years, with about 41 billion tonnes of carbon dioxide emitted every year from energy consumption and other sources.

The group added that since the emissions cannot go down to zero after 15 years, the world leaders must implement a downward path for greenhouse gas emissions immediately. If the emissions were suddenly reduced to zero, that would mean that the world economy would come to an absolute halt.

The Human Dynamics of Climate Change map, that predicts climate changes, trade, crop production, etc till the year 2100.
The 'Human Dynamics of Climate Change' map, that predicts climate changes, trade, crop production, etc till the year 2100.Met Office Hadley Centre

"When it comes to climate, timing is everything," Figueres and her co-authors, including scientists Hans Joachim Schellnhuber and Stefan Rahmstorf of the Potsdam Institute for Climate Impact Research, wrote in a commentary. 

The commentary, which was published in the online journal Nature, has six authors and is endorsed by dozens of co-signers from the climate science and policy world.

"The whole purpose of this comment ... is to wake up the intentionality and the ingenuity that we must bring to this effort, because of the urgency," Figueres said during a press call.

The paper written by Figueres was aimed at influencing the upcoming iG20 summit in Germany. It also mentions United States President Donald Trump's decision to withdraw the US from the global climate accord -- the Paris Climate deal.