Global Warming

If I'm not mistaken, global warming is slowly killing earth. It's not only damaging the earth but affecting the way sport is being played. None so is true than the sport of athletics and marathon running.

Runners already face a daunting challenge when they line up at the start of a marathon but they might increasingly find themselves with another obstacle to reckon with: global warming. A new study claims that rising temperatures around the world will make it harder for elite athletes to break the marathon world record or for recreational runners to hit their target times.

Of the 221 races analysed in the report from Climate Central released last week, 86% of them are less likely to have optimal racing conditions for runners by 2045. That includes last Sunday’s New York City Marathon and the other six major marathons around the world — London, Berlin, Tokyo, Chicago, Boston, and Sydney.

For runners, the consequences of running in hot conditions can be extreme. "We’ve seen time and time again where athletes are passing out from dehydration and heat exhaustion during races and taking months to recover," Scottish distance runner, Mhairi Maclennan, said.

“It has really significant impacts on the thickness of your blood, on how quickly your body is able to recover, on your hydration levels for days and also your ability to train after that kind of experience, which can then delay other achievements and goals that you’re pursuing.”

According to the study, the optimal temperature for elite male marathon runners is 39 degrees Fahrenheit (4 degrees Celsius) and 48 degrees F (9 degrees Celsius) for elite women.

This year, the Tokyo Marathon had a 69% chance of optimal race day temperatures for elite men, per the study but those odds are expected to fall to 57% in 20 years. The Boston Marathon’s odds are expected to drop from 61% to 53% for the same category over the same time span; while London’s reduce from 22% to 17%.

For elite women, the likelihood of optimal conditions is also anticipated to fall at five of the seven marathon majors by 2045; with the odds reduced by 10% and 11% or more at the Sydney and Berlin Marathons, respectively.

According to data from climate monitoring agency, Copernicus, 2024 was the hottest year on record — 1.6 degrees Celsius warmer than the period before humans began burning large amounts of fossil fuels. It broke the previous record set in 2023.

Exercising in higher temperatures places greater stress on the body – especially in high humidity – and an athlete’s hydration strategy becomes even more crucial.

Ahead of this year’s race in Berlin, organisers advised that warmer temperatures would "make it harder to achieve personal bests" and told runners to "shift your focus away from chasing records and instead soak up the unique atmosphere along the course." They also gave advice on hydration, cooling strategies, clothing and recovery.

"Some of the exceptional heat experienced at the 2025 Berlin and Tokyo Marathons pushed temperatures far beyond peak performance conditions," said Maclennan, who was the highest-placed British woman at last year’s London Marathon with a time of 2:29:15.

"That’s difficult because at the end of the day, sport is a business and it generates revenue from spectators, and if spectators are there to see fast performances and that’s not happening because of climate change, that’s an issue for the sector."

Maclennan, who lives and trains in the often cold climes of Scotland, said that running in the heat "has and always will be a challenge for me." She explained how elite athletes competing in hot conditions might undertake warm weather training camps, do workouts in heat chambers or take saunas and hot baths straight after training to keep the body temperature high for longer periods.

After heavy rain and flooding in New York City last week, the conditions were good for Sunday’s race, with more than 55 000 runners taking part. Should major marathons continue to take place in warm weather, then it might create a scheduling headache for organisers.

"We have marathons in the spring and in the autumn in the northern hemisphere because those are the times when we get the good, cool temperatures that you need for good running performance," Andrew Pershing, who leads the Climate Central science team and worked on the new study, said.

"As the climate warms, if you have a race that happens at the same week every year, that good climate is moving past you and it’s moving away. Those good conditions are becoming less and less frequent."

One solution for organisers might be to schedule earlier start time for races. An extreme example of that was the 2019 World Athletics Championships in Doha, when the men’s and women’s marathons began at midnight local time to compensate for hot weather during the day. Even then, temperatures for the women’s race reached 88 degrees Fahrenheit (31 degrees Celsius) with humidity at 77%.

As Maclennan explained, athletes rarely have the luxury to choose when and where they compete, especially around events like the world championships and marathon majors.

The 2028 Olympics in Los Angeles, she said, might be another instance where athletes "probably have to do a lot of acclimatisation," adding: "The same is true for any competition where the environment is different to what you train in. There is consideration to be made into how you adapt and how you train your body to compete in those conditions."

The marathon world record has been broken several times on both the men’s and women’s side in recent years, though many attribute the faster times to advancements in shoe technology.

Ruth Chepngetich, who is currently serving a three-year doping ban, set the women’s record of 2:09:56 in Chicago last year, while the late Kelvin Kiptum set the men’s mark of 2:00:35 in 2023; also in Chicago.

With global temperatures rising, athletes and climate experts alike anticipate that those kinds of performances might become more scarce in the future.

"There are more marathons with worsening conditions, which is decreasing the overall opportunities for elite women to potentially break records," said Maclennan. "Overall, that, I guess, reduces the quality of the product … I do think that heat waves are already rewriting race history."

Runners chasing personal bests at Canada’s biggest marathons may soon be racing against the climate itself. A new analysis from non-profit Climate Central finds that rising temperatures are cutting into the number of days with ideal conditions for performance. Races from Vancouver to Ottawa are expected to see hotter, less predictable weather in the years ahead; creating conditions that make running harder, slower and riskier.

The report analysed 221 marathons worldwide, including eight in Canada, and found that 86% will have fewer ideal race-day conditions by 2045. The "sweet spot" for marathon running—the moderate temperature range that helps the human body perform at its best—is shrinking as climate change accelerates.

Researchers paired their findings with an interactive tool showing which events are most likely to maintain that temperature sweet spot and which are slipping out of it. Nearly all the world’s major marathons, including Boston, London, Berlin and New York, are projected to see a steady decline in performance-friendly weather over the next two decades.

The Tokyo Marathon, currently the most favourable of the Abbott World Marathon Majors with a 69% chance of ideal temperatures for elite men, is also expected to experience the steepest drop by 2045. Climate-fueled heat waves are already changing the sport: the 2025 Berlin and Tokyo Marathons were both run in unseasonably hot conditions that scientists say were made two to three times more likely by global warming.

Marathon runners will have less chances of racing in optimal conditions as the planet continues to heat up, according to new research published just weeks after Berlin Marathon runners struggled in unusual heat.

Optimal running conditions vary between women and men, with women at elite level running faster at warmer temperatures (10C/50F) and men at elive level running best in cooler conditions (4C/39F). Optimal running temperatures are slightly lower for recreational female runners and slighly higher for recreational male runners.

With human-made climate change increasing temperatures around the world, the chances of running in these ideal conditions are shrinking, the study concluded. Already this year, the average temperature at the Tokyo Marathon in March was 15.2C – about 8.2C warmer than usual. And in Berlin last month, the average temperature was a whopping 6.7C warmer than normal at 20.7C. In both cases, the abnormal warmth was made more likely by climate change, Climate Central found.

Starting races earlier could reduce the impact of climate change-driven warming on race performance at some locations, according to the study. For marathons in London, Tokyo and Boston, for example, elite male runners would benefit significantly from an earlier start; with chances of peak conditions in 2045 increasing by 44%, 31% and 27%, respectively.

Since elite women perform better in warmer temperatures, earlier starts in Tokyo and Boston would actually decrease their chances of optimal conditions – by 41% and 18%, respectively. In Berlin and Sydney, which have the lowest probability of optimal temperatures on race days among all seven Majors, an earlier start would be beneficial for female elite athletes, too.

Ultimately, however, protecting runners and the future of marathon requires meaningful action to curb fossil fuel pollution, the study concluded.

As global temperatures continue to rise and extreme weather events become more frequent and intense, the sporting world faces an array of challenges that threaten individual events and athletes but also the very future of the industry.

Just last month, extreme heat disrupted the Athletics World Championships in Tokyo and the world’s top tennis athletes competing in the Shanghai Masters in China, who described the baking weather as "very challenging physically." Other major events worldwide, like last year’s Paris Olympics, now face higher risk of cancellations, delays and adjustments brought about by extreme, unpredictable weather.

A recent report warned that 14 of the 16 2026 World Cup venues are already exceeding "safe-play thresholds" for extreme heat, unplayable rainfall and flooding. By mid-century, nearly 90% of host stadiums will face unsafe extreme heat conditions and 11 stadiums will experience unplayable heat.

⁠The "safe-play" benchmark for extreme heat is 35C (95F), which represents the limit of human adaptability to extreme heat. Once this threshold is reached, the body’s natural cooling system begins to fail, heightening the risk of heatstroke and dehydration, both for players and spectators.

According to the report, several of the 2026 World Cup locations are already recording temperatures at or above this threshold. ⁠

It's difficult to fight something you can't control and face. The only thing that people can do is to create safer conditions. Global warming, this shows, is deadly. Extreme heat is quite literally, life threatning. The economy will decrease and the world might suffer through another depression/recession. The continued existence of humanity takes priority over everything else.