A new study shows that strong and rapid action to cut emissions of carbon dioxide and other greenhouse gases will help to slow down the rate of global warming over the next twenty years. This highlights that immediate action on climate change can bring benefits within lifetimes, and not just far into the future.
Scientists already agree that rapid and deep emissions reductions made now will limit the rise in global temperatures during the second half of the century. However, pinpointing shorter-term benefits over the next few decades has been more challenging, particularly as natural cycles in global atmosphere and ocean systems can cause slow ups and downs in temperature that temporarily mask human influence on the climate.
But, by using a novel approach that combines large amounts of data from different sources, a new study from the University of Leeds has untangled human-induced warming from natural variability on much shorter timescales than previously thought possible.
The study, published in Nature Climate Change, used thousands of simulations from different climate models alongside multiple estimates of observed natural climate variability to investigate how various levels of emissions cuts could affect the speed of global warming over the next two decades.
The findings show that reducing emissions in line with the Paris Agreement, and in particular with its aim to pursue efforts to stabilise global warming at 1.5°C above pre-industrial levels, has a substantial effect on warming rates over the next 20 years, even after natural variability is taken into account.
In fact, the risk of experiencing warming rates that are stronger than anything previously seen would be 13 times lower with rapid and deep emissions cuts, compared to an “average” future that continues to rely heavily on fossil fuels: a fossil-fuel heavy future could see temperatures rise by up to 1-1.5°C in the next 20 years – meaning the Paris Agreement temperature limits will be breached well before 2050.
Likely ranges of the rate of global warming over the next twenty years for different emissions scenarios. These are calculated by combining thousands of simulations from a simple climate model (FaIR) with information on how the climate varies naturally (bright colours), and also using simulations from state-of-the-art (CMIP6) climate models (pastel colours) which were constrained according to how well they represent warming seen in the recent past.
Dr McKenna said: “Our results show that it’s not only future generations that will feel the benefits of rapid and deep cuts in emissions. Taking action now means we can prevent global warming from accelerating in the next few decades, as well as get closer to the goal of limiting warming in the longer term.
“It will also help us to avoid the impacts that more rapid and extreme temperature changes could bring.
“With global temperatures currently rising at around 0.2˚C per decade, without urgent action on climate change we are clearly in danger of breaching the Paris Agreement. These findings are further motivation for both governments and non-state actors to set stringent greenhouse gas mitigation targets, combining a green recovery from the economic impacts of coronavirus with reaching net-zero emissions as soon as possible.”
The paper Stringent mitigation substantially reduces risk of unprecedented near-term warming rates is published in Nature Climate Change, DOI: 10.1038/s41558-020-00957-9