To limit warming to 2°C above pre-Industrial temperatures in 2100, there has to be decisive government action and soon – before 2035, to be exact. What's more, unless exceptionally radical action takes place, it is already too late to limit warming to 1.5°C. This is the latest warning from climate scientists in the UK and Netherlands, published in the European Geosciences Union journal Earth System Dynamics.
The purpose of the "deadline" is to "stimulate the sense of urgency to act for politicians and policymakers,” study author Henk Dijkstra, a professor at Utrecht University, said in a statement.
Scientists from Utrecht University in the Netherlands and Oxford University in the UK used data accumulated from climate models to calculate this so-called "point of no return". That is the last year it is possible to avert the most dangerous versions of climate change provided strong action is taken to curb greenhouse gas emissions – pass this point and catastrophic climate change is pretty much inevitable, they say.
"The 'point of no return' concept has the advantage of containing time information, which we consider very useful to inform the debate on the urgency of taking climate action," lead author Matthias Aengenheyster, a doctoral researcher at Oxford University, added.
Of course, a lot depends on what action is taken. The more drastic the action, the more warming prevented – and the later we can leave it. The year 2035 was decided upon because it allows for a (relatively) moderate rate of conversion to renewables while keeping the likelihood of warming below 2°C in 2100 at 67 percent. That means, based on their climate models, there is still a 33 percent chance warming will exceed 2°C by the end of the century if governments take decisive action by 2035.
Decisive action in this instance means increasing the share of renewable energy by 2 percent each year. If we upped this to 5 percent, we could buy ourselves an extra 10 years, the study authors say. Incorporate carbon capture (or "negative emissions" technology) and we can add on an extra six to 10 years (at most). To remain below the more ambitious 1.5°C limit, however, we would have to increase the share of renewable energy to 5 percent by 2027.
At this point, it is worth noting that since the nineties, we have only been able to increase the share of renewables by a measly 3.6 percent (from virtually nothing).
What's more, these figures don't necessarily take into consideration that energy usage may increase over time. (As an example, energy use for cooling appliances are expected to soar as we see more and more summers like this.) Or that there are so many uncertainties our current climate models cannot necessarily predict.
But it's a start.
"In our study we show that there are strict deadlines for taking climate action," said Dijkstra. "We conclude that very little time is left before the Paris targets [to limit global warming to 1.5°C or 2°C] become infeasible even given drastic emission reduction strategies."