Temperature

This summer has shown how quickly high temperatures can pose serious health risks, with record-breaking heat waves claiming thousands of lives around the world. However, it’s not just high and low temperatures that matter. How many degrees the temperature swings within a day – the daily temperature variation – itself poses health risks. Studies have found that days with larger than normal temperature swings can increase asthma flare-ups and hospitalizations for respiratory and cardiovascular diseases, leading to an overall higher death rate than normal. One study, based on data from 308 cities from 1972 to 2013, estimates that 2.5% of deaths in that time could be attributed to large daily temperature swings. Although humans can live in a wide range of ambient temperatures, a dramatic shift in temperature can tax multiple systems in the body, including the immune, musculoskeletal and cardiovascular systems. It can be especially taxing on very young and older in...

When summer starts with a stifling heat wave, as many places are seeing in 2024, it can pose risks for just about anyone who spends time outside, whether they’re runners, people who walk or cycle to work, outdoor workers or kids playing sports. Susan Yeargin, an expert on heat-related illnesses, explains what everyone should think about before spending time outside in a heat wave and how to keep yourself and vulnerable family members and friends safe. What risks do people facing running, walking or working outside when it’s hot out? The time of day matters if you’re going for a run, or if you’re walking or cycling to work during a heat wave. Early risers or evening runners face less of a risk – the Sun isn’t as hot and the air temperature is lower. But if your normal routine is to go for a run midmorning or over lunch, you probably want to rethink exercising in the heat. Pretty much everywhere in the U.S., the hottest part of the day is be...

Weather forecasts have gotten quite good over the years, but their temperatures aren’t always spot on – and the result when they underplay extremes can be lethal. Even a 1-degree difference in a forecast’s accuracy can be the difference between life and death, our research shows. As economists, we have studied how people use forecasts to manage weather risks. In a new working paper for the National Bureau of Economic Research, we looked at how human survival depends on the accuracy of temperature forecasts, particularly during heat waves like large parts of the U.S. have been experiencing in recent days. We found that when the forecasts underplayed the risk, even small forecast errors led to more deaths. Our results also show that improving forecasts pays off. They suggest that making forecasts 50% more accurate would save 2,200 lives per year across the country and would have a net value that’s nearly twice the annual budget of the National Weather Ser...

As scorching heat grips large swaths of the Earth, a lot of people are trying to put the extreme temperatures into context and asking: When was it ever this hot before? Globally, 2023 has seen some of the hottest days in modern measurements, but what about farther back, before weather stations and satellites? Some news outlets have reported that daily temperatures hit a 100,000-year high. As a paleoclimate scientist who studies temperatures of the past, I see where this claim comes from, but I cringe at the inexact headlines. While this claim may well be correct, there are no detailed temperature records extending back 100,000 years, so we don’t know for sure. Here’s what we can confidently say about when Earth was last this hot. This is a new climate state Scientists concluded a few years ago that Earth had entered a new climate state not seen in more than 100,000 years. As fellow climate scientist Nick McKay and I recently discussed in a scientific journal art...

Powerful storm systems that hit the U.S. Northeast starting July 9, 2023, dumped close to 10 inches of rain on New York’s Lower Hudson Valley in less than a day and sent mountain rivers spilling over their banks and into towns across Vermont. Vermont Gov. Phil Scott said he hadn’t seen rainfall like it since Hurricane Irene devastated the region in 2011. Extreme water disasters like this have disrupted lives in countries around the world in the past few years, from the Alps and Western Europe to Pakistan, India and Australia, along with several U.S. states in 2022 and 2023. The role of climate change is becoming increasingly evident in these types of deluges. Cars were stranded in floodwater on the campus of the United States Military Academy at West Point, N.Y., on July 10, 2023. U.S. Military Academy via AP Studies by scientists around the world show that the water cycle has been inte...