Climate change is melting the ice caps, causing sea level rise, heatwaves, and more frequent natural disasters. But if governments worldwide do not take drastic action in the next 15 or so years to reduce greenhouse gas emissions, we could reach a “point of no return,” according to a study published today in the journal Earth System Dynamics.
The study, led by researchers from the Utrecht Centre for Complex Systems Studies and at Oxford University, modeled the probability of reaching climate targets depending on how quickly and how effectively various countries switched to renewable energy. The researchers found that unless drastic action is taken starting now, we have already missed our deadline to limit global warming to 1.5 degrees Celsius, and that we are rapidly approaching what the scientists dubbed the “point of no return”: when keeping warming below 2 degrees Celsius before the end of the century — as laid out in the Paris Climate Agreement — will be unlikely.
“We show that there are strict deadlines for taking climate action,” Henk Dijkstra, a professor at Utrecht University in the Netherlands and one of the study’s authors said in a statement. Dijkstra said there was “very little time” left before the Paris targets became infeasible, even with drastic emissions reductions. “We hope that ‘having a deadline’ may stimulate the sense of urgency to act for politicians and policy makers,” he added.
Two degrees Celcius is generally agreed to be the safe threshold for global temperature rise. If the earth warms more than this, the earth could unleash its own cascading impacts like the release of carbon dioxide trapped beneath Arctic ice (which has already begun), while other systems, like coral reefs, might simply be pushed beyond the point of recovery. With every degree, say scientists, the risks of food insecurity, species extinction and environments becoming inhospitable to human habitation increases.
In the December 2015 Paris Agreement, global leaders agreed to meet various goals in attempt to curb emissions, and keep global temperatures from rising more than 2 degrees Celsius by 2100. But the researchers said that it was “questionable” if even even those commitments were sufficient. (At the moment, no major industrialized country is even on track to meet those original pledges.) “If the Paris Agreement targets are to be met, there may be very few years left for policy makers to start cutting emissions,” the researchers write in the paper.
“To reach any time of climate target, we need to bring emissions to zero at some point,” Matthias Aengenheyster, a doctoral researcher at Oxford University and the study's lead author, told The Outline. “I think essentially what we’re trying to do is give some sort of overview about the options and say, ‘Ok, this is what would be the impact of having this adjustment; if we expand renewable energy this fast, these are the consequences,’” he added.
To work out the latest possible date that countries could begin ambitiously reducing their fossil fuel emissions and still meet the 2 degree goal, the researchers compared two scenarios in which the global share of renewable energy rose by 2 percent and 5 percent respectively. In the 2 percent scenario, countries would have to begin drastically reducing emissions before 2035. In the second scenario — where countries switch to renewable energy at a faster rate — the globe would have an extra 10 years before it reached the “point of no return.”
While the share of renewable energy has risen from almost nothing to 3.6 percent in the past two decades, we still have a long way to go before emissions reductions are significantly reduced, said Rick van der Ploeg, a professor of economics at Oxford University who also took part in the study. "Considering the slow speed of large-scale political and economic transformations,” van der Ploeg said, “decisive action is still warranted.” He and his colleagues also considered a “negative emissions” scenario, in which carbon dioxide was removed from the atmosphere. But even in this case, the “point of no return” could only be delayed by up to 10 years.
Aengenheyster, the lead author, said it helped to think about the various actions governments could take like “screws” which could be tightened or loosened in various combinations to help meet the goals set under the Paris Agreement. “We really try to look at the impact of these different screws we can modify,” Aengenheyster told The Outline, adding that the numbers in the study were not simply results, but depended on “actual choices” made by human beings.