Adaptation planning must include 1.5°C overshoot scenarios

The world is getting alarmingly close to global warming of 1.5°C and overshooting this limit is becoming inevitable. Ample scientific evidence shows the warmer it gets, the worse impacts and damages will be. There are limits to adaptation, so it is clear we will not be able to “adapt our way out” of this looming crisis.

Continued and rapidly strengthened mitigation that limits the magnitude and duration of a 1.5°C overshoot is critical to slow warming down within two decades and then bend the curve downward. Even with sufficient mitigation action to limit 1.5°C overshoot, there is a very high need for adaptation measures, given emerging and expected impacts even at 1.5°C.

Even at current levels of warming, Europe has been battered in recent years by extreme heat, wildfires, flooding, and droughts taking lives and livelihoods.In the face of these worsening events, and to prepare for end-of-century warming, a new report from the European Scientific Advisory Board on Climate Change (ESABCC) advising the European Union EU, calls on the EU to urgently strengthen its policy framework for effective and coherent adaptation, including adopting a common reference scenario for adaptation planning across Member States.

In itself, that is a valid call.

But the ESABCC report recommends the EU consider only one temperature scenario: 2.8–3.3°C of global warming by 2100, covering the range of temperature projections from current policies. While it does recommend considering hotter possible futures, there was no mention of the necessity or value of considering how adaptation should look in scenarios of overshoot where temperatures rise above 1.5°C and then fall back to safe levels. Nor is there an account of how residual damages would be much more manageable at 1.5°C.

This sends a misguided message that 2.8–3.3°C of warming is baked in. The focus on a high level of warming created a false impression – that media immediately amplified – both that this scenario inevitable, and that Europe could adapt to this level of warning.

But reaching 3.3°C or even 2.8°C by 2100 is not set in stone. We can and must reach zero global CO2 emissions by mid-century and net negative emissions thereafter (and equally rapid action on non-CO2 emissions like methane). We have almost 75 years to bend the curve and get back on a path to safe levels of warming well below 1.5°C by the end of the century. Our Highest Possible Ambition scenario shows how.