One of the challenges of driving action on climate change is the gap between taking action and seeing any benefits. We'll have to act now to limit greenhouse gas emissions if we want to limit total global warming to less than 2°C and minimize negative effects. Yet most indications are that the benefits of these efforts may not be noticeable for decades, and they will only increase gradually with time.

For some, this notion may reduce the sense of urgency for developing effective, comprehensive climate-mitigation plans. This complacency is present in parts of the world where climate change is already wreaking havoc through alterations in extreme weather events.

Given the rising number of extreme weather events, a team of scientists recently explored the time frame required to see a positive influence of cutting down our carbon emissions. In an investigation recently published in Nature Climate Change, scientists looked into how quickly benefits of climate mitigation strategies—meaning dropping CO 2 emissions—reduce the risk of heat waves.

The researchers answered these questions using climate-model simulations. These models can be run with different levels of emissions, some assuming a very aggressive mitigation scenario with lowered emissions, others assuming emissions that are unchecked, producing significant increases in emissions over time. By comparing model runs with different levels of emissions, the researchers were able to develop an understanding of the time required for effects of mitigation plans to be noticeable.

In particular, the team focused on extreme events that occurred on average once every 10 years when emissions continue to rise unchecked. They then introduced different levels of emissions mitigation until the probability of such an event is half as likely, occurring only once every 20 years. Using this method, the scientists determined that for many regions, it takes less than 20 years of emissions reductions to drop the probability of extreme hot weather by more than 50 percent after mitigation has begun.

Given the focus on limiting global warming to 2°C, the team looked specifically at emissions cuts that would keep us within that limit. In terms of heat waves, the effects of such aggressive mitigation strategies would be felt during the 2040s, significantly earlier than is generally believed.

These findings reveal that some of the effects of climate changes can be significantly reduced with aggressive mitigation plans and that the effects would be felt on a much shorter time frame than was previously thought. For most people, however, the 2040s remain far into the future, so it's not clear that this would be enough to drive public action.

Nature Climate Change, 2017. DOI: 10.1038/NCLIMATE3259 (About DOIs).