Science Understates Dramatically
Half the World’s Population Experiencing Double to 54 Times as Much Extreme Heat As Before We Changed Our Climate, a new extreme heat evaluation by Climate Central dangerously understates reality.
A summary and review based on:
Climate Change Made Extreme Heat Days More Likely
A new attribution study shows every single extreme heat event since last May was made more probable by climate change.
First published in EOS, the journal of the American Geophysical Union, by Grace van Deelen on May 30, 2025
https://eos.org/articles/climate-change-made-extreme-heat-days-more-likely
Based on research by Climate Central on May 29, 2025, Climate Change and the Escalation of Global Heat Extremes
https://www.climatecentral.org/report/climate-change-and-the-escalation-of-global-extreme-heat-2025
(Author’s Note: As a constant consumer of academic climate change literature, it never cease to amaze me how consistently scientists understate and the vast implications for our citizens, lawmakers, and other climate scientists understanding of the realities of climate change. The title of the peer reviewed article this post is based upon is an example, “Climate Change Made Extreme Heat Days More Likely.” Of course it is valid, climate change has certainly made extreme heat days more likely but when one looks at the data, this title is far from accurate and understates greatly. The authors’ back up their understatement even more just down the page with this quote, “The number of days with extreme heat is now at least double what it would have been without climate change in 195 countries and territories.” This is scary enough, right? Extreme heat days have doubled… But this statement pales in comparison to the realities of what the data actually reveal: 80% of the 249 countries and dependent territories evaluated (basically all of them on Earth,) saw extreme heat days double because of climate change, 61% saw them triple, a third saw them increase by six times, and 16% saw extreme heat days increase by over ten times every year. What this understatement means is that consumers of these scientific findings are biased because of the understatements. Please ask your favorite scientists to be at least a little more accurate in their findings. There are light years difference between the authors’ statement of, “extreme heat days being more likely,” and or “doubled,” and the reality of, “more than half of all nations on Earth saw extreme heat days triple, a third increased by six times, and 16% saw them increase by over ten times.”
DEFINITION: Extreme Heat – heat that is greater than the temperature 90 percent of the time.
(EOS) “Sixty-seven extreme heat events have occurred since May 2024. All of these events—including a deadly Mediterranean heat wave in July 2024, an unprecedented March 2025 heat wave in central Asia, and extreme heat in South Sudan in February 2025—broke temperature records, caused major harm to people or property, or did both. The number of days with extreme heat is now at least double what it would have been without climate change in 195 countries and territories [out of 232 evaluated]. Climate change added at least an extra month of extreme heat in the past year for 4 billion people—half the world’s population.”
There are two important takeaways from this research by Climate Central: What the increase in extreme heat days actually means, and how Climate Central misinforms and adds to the problem of future warming. Let’s take the later first:
Climate Central’s research says, “Thanks to developments in attribution science and climate modeling, scientists can now quantify how much heat climate change has added to an extreme temperature event and predict how heat waves will grow more frequent and intense unless emissions are cut drastically.”
The last part of this sentence is false. “…and predict how heat waves will grow more frequent and intense unless emissions are cut drastically.”
This particular statement is repeated time and again in not only popular press reporting, but in academic findings themselves. It is untrue, egregious, and a very sloppy message that allows our world to believe that we can simply limit climate pollution emissions and extremes will abate. They will not. Limiting emissions only limits further warming from future emissions –and– even if we were to halt all of humankind’s emissions this instant, we would experience warming in the pipeline of another 4 degrees C by 2100 and another 3 degrees C or more in the several hundred years after 2100 (Hansen 2024). This is because of the great energy imbalance between the extremely rapidly emitted greenhouse gases that remain in our atmosphere and the cooling effects of our cool oceans and ice sheets.
We cannot just “cut emissions drastically” and expect the effects of warming to diminish when in fact, even with a complete cessation of emissions, almost all effects will become more frequent and intense. . The only way to return the repeatedly unprecedented extremes back to their former rare occurrence rate is to cool our climate back to within the evolutionary boundaries of our Earth systems. Anything warmer than our old climate not only allows effects to continue, but they will definitively worsen.
Example #1: The heat dome feedback, or heat wave evaporative feedback – The hotter it gets, the drier it gets, and drier air can heat up more rapidly, allowing more extreme hot temperatures to develop in a feedback loop.
Example #2: The ecological feedback – Warming beyond our Earth systems evolutionary boundaries at about 1 degree C warmer than normal, where we are at about 1.5 to 1.6 degrees C warmer than normal in 2024, creates ecological stress that persists and amplifies warming in a separate feedback loop. Ecological stress is mainly water stress that is related to the evaporative feedback. Increasing heat increases evaporation from plants and soils nonlinearly; a little more warming does not create a little more evaporation, it creates a lot more. This response to warming has been labelled “Thirstwave.” https://cawaterlibrary.net/wp-content/uploads/2025/04/Earth-s-Future-2025-Kukal-Thirstwaves-Prolonged-Periods-of-Agricultural-Exposure-to-Extreme-Atmospheric-Evaporative.pdf A thirst wave – happens when the three day evaporative potential is greater than it is 90 percent of the time, during summer. The duration, intensity and frequency of thristwaves has typically doubled from 1980 to 2021, and this does not reflect the significant jump in warming in 2023 and 2024 of 0.4 degrees C, or about a third of all warming in the previous 200 years.
Example #3: The event frequency effect – Because our climate has just recently changed beyond its natural variation, or warmed beyond the maximum temperature of our old climate within the last ten years at 1 degree C above normal from the mid- to late 19th century, in general we have only seen weather events that are more frequent than the 10-year event. As time passes, much more extreme events will occur even if we do not warm further, like the 20-, 50- and 100-year events.
This kind of extreme heat kills things. Averages generally don’t kill anything. When plants die in these extremes, because what remains is typically much drier than normal because of the evaporative feedback, the character of the ecology shifts to a drier state with loss or reversal of environmental services, like CO2 sequestration.
These feedbacks together have dramatically altered our planet’s ecologies so that in many places, forests are not regenerating and desertification is increasing nonlinearly. It is simply too warm for our Earth systems to exist in the form they evolved in before humans began geoengineering our world with greenhouse gases.
[BOX] 2024 Global average warming above normal from 1850-1900: NASA 1.47 degrees C, World Meteorological Organization 1.55 degrees C, European Weather Service – Copernicus 1.55 degrees C, Berkeley Earth 1.62 degrees C.
It is also extremely important to understand that warming over land is double the average global warming, or over 3 degrees C (5.4 F).
The other most important takeaway from this work relates exactly what it means that, “The number of days with extreme heat is now at least double what it would have been without climate change in 195 countries and territories.” What does “extreme heat” mean?
Climate Central’s evaluation of our world’s countries hottest one out of ten days every summer shows that this heat has doubled in the US, but quadrupled in the south, south central and southwest. In Europe it is double, with eastern Europe quadruple. UK is up 150 percent. Countries closer to the equator, Barbados is 10 time more: Bolivia eight times more, Congo – nine times, Cuba – five times, Ecuador – eight times, Ethiopia – eight times, Gaza – six times. These are not cherry picked and represent my anecdotal selection. NOrthern ;latitudes are less, with only about a 50 percent increase. It is the island nations close to the equator that are mostly the most extreme because of their more stable temperature in the middle of an ocean and, ocean warming… Cape Verde once per ten days heat is now 15 times more than in our old climate. The Cocos Island are 50 times more. French polynesia is 54 times more; Guam 37, the Maldives – 25 times, Micronesia 17 times, Northern Mariana Island is a whopping 174 times more days as hot or hotter than one out of ten days each summer.
REFERENCES
Warming in the pipeline… Hansen 2023 – Global Warming In the Pipeline… Recent findings telling us that if we stop emissions that warming will cease are not valid. Hansen and his team wrote this paper to show this concept was inaccurate. How they did this was to look at warming in the past when our Earth systems were in balance. The previous recent findings that show no further warming if emissions cease are modelled findings, where modeling has a long history of understatement because of a poor understanding of feedbacks. By looking at direct evidence from the past, Hansen et al eliminate the need to understand feedbacks. The great imbalance of greenhouse gases in our sky will truly be responsible for more warming, or warming in the pipeline, as our cool oceans and ice sheets come into balance with the excess greenhouse gases in our sky. In 100 years, Hansen et al suggest 4.8 degrees C (8.6 F) warming from our current energy imbalance, without further emissions.
Hansen et al., Global warming in the pipeline, Oxford Open Climate Change, November 2, 2023.
https://academic.oup.com/oocc/article/3/1/kgad008/7335889
Thristwave… Kukai and Hobbins, Thirstwaves Prolonged Periods of Agricultural Exposure to Extreme Atmospheric Evaporative, Earth’s future, AGU, March 20, 2025.
https://cawaterlibrary.net/wp-content/uploads/2025/04/Earth-s-Future-2025-Kukal-Thirstwaves-Prolonged-Periods-of-Agricultural-Exposure-to-Extreme-Atmospheric-Evaporative.pdf
Increasing extreme heat… Climate Change and the Escalation of Global Extreme Heat, Climate Central, May 29, 2025.
https://www.climatecentral.org/report/climate-change-and-the-escalation-of-global-extreme-heat-2025