PLEA Network

11 November 2024, Carbon Brief: Guest post: What 1.5C overshoot would mean for climate impacts and adaptation. With average global temperatures set to see another record high this year, the chances of holding warming to no more than 1.5C continue to dwindle. Keeping warming below 1.5C by the end of the century – in line with the long-term goal of the Paris Agreement – now likely involves “overshooting” 1.5C and then bringing temperatures back down later by removing carbon dioxide (CO2) from the atmosphere. (What this means for “net-negative” emissions is covered in a previous guest post.) This raises a number of unknowns in terms of what overshoot means for the impacts of climate change on the planet, people and ecosystems. For example, even if global temperatures can be brought back down again by the end of the century, will the impacts of climate change also reduce? Will coral reefs be able to recover or will glaciers reform? What will it mean for the world’s coastlines, food production and endangered species? For the past three years, we have been working on a Horizon Europe-funded project called PROVIDE to dive deeper into what overshoot really looks like for countries, regions and cities. This data is available on the Climate Risk Dashboard – a tool to help people see how climate change will affect them and how it depends on the actions taken today. Until carbon emissions are reduced to net-zero, the world will not stop warming. Delay will result in ever more intense climate impacts – and increase the risk of crossing irreversible thresholds. Urban heat stress under overshoot One of the clearest and most acute impacts of climate change is on extreme heatwaves. Our findings suggest that, were global average temperatures to decline, extreme heat events in most locations will also decrease, on average. But achieving a new balance in local climates would be a slow process, influenced by ongoing climate system adjustments for decades – if not centuries – to come. Reversing climate change would most probably take several decades, even if overshoot is limited to a few tenths of a degree. This implies that the climate risks that generations alive today will be exposed to are largely determined by collective actions today. Read more here