Heat hazard! 57 more superhot days a year by 2100 — and that’s not the worst case!

The world is heading towards nearly two additional months of superhot days a year by 2100, with small, poorer nations disproportionately affected compared to the largest carbon emitters, a new study reveals.

However, it could have been worse! Believe it or not, this is a significantly mitigated outcome, thanks to the landmark Paris climate agreement, initiated a decade ago.

Without the Paris Accord, we would be looking at an additional 114 superhot days per year — double the anticipated 57 days under our current national commitments.

However, Potsdam Climate Institute director Johan Rockstrom warned, “People shouldn't be relieved that we are no longer on the 4-degree warming pre-Paris trajectory because the current track would still imply a disastrous future for billions of humans on Earth.”

An international consortium of climate scientists from World Weather Attribution and US-based Climate Central employed advanced computer simulations to evaluate the Paris Agreement’s impact on extreme heat events globally. Their report (pending peer review) examined heat rates in over 200 countries for 2015, present-day statistics vs projections for two future warming scenarios: one where global warming is limited to 2.6°C and the other reflecting the pre-agreement trajectory towards 4°C.

Climate Central’s vice president for science Kristina Dahl stressed, “There will be pain and suffering because of climate change. But if you look at this difference between 4 degrees Celsius of warming and 2.6 degrees Celsius of warming, that reflects the last 10 years and the ambitions that people have put forth. And to me, that's encouraging.”

The study defines ‘superhot days’ as those exceeding the temperature of 90 per cent of comparable days from 1991 to 2020. Since 2015, the average number of such days increased by 11 globally up to 2020. And this is the level of heat, Dahl points out, that “sends people to the emergency room. Heat kills people.”

Co-author Friederike Otto from Imperial College London noted that the impact of this extra warmth could affect tens of thousands or millions, extracting a deadly toll in heatwaves.

The report calculates that the 2023 southern Europe heatwave became 70 per more likely and 0.6°C warmer than a decade earlier because of this climate change — with future similar events projected to be substantially hotter if emissions are not curtailed further.

Where the heat’s hottest

The findings also underscore stark inequities in climate impact: small oceanic nations such as the Solomon Islands, Samoa, Panama and Indonesia will endure the highest increases in superhot days, despite contributing minimally to global emissions. Panama alone may experience 149 additional days annually.

On the other hand, major polluters like the US, China and India, responsible for 42 per cent of atmospheric carbon dioxide, face far fewer increases in extreme heat days.

University of Victoria climate scientist Andrew Weaver remarked, “This report beautifully and tangibly quantifies what we've been saying for decades. The impacts of global warming are going to disproportionately affect developing nations that historically haven't emitted significant quantities of greenhouse gases. Global warming is driving yet another wedge between have and have-not nations; this will ultimately sow seeds of further geopolitical instability.”

This study underscores the urgency for accelerated global climate action to reduce emissions and protect vulnerable populations from escalating heat risks.