Study: Cheetahs Become More Nocturnal on Hot Days as Climate Change Takes Toll 

In this photo provided by Briana Abrahms, a female cheetah and her cub sit watchfully in front of a herd of zebra in northern Botswana on Aug. 23, 2011. (Briana Abrahms via AP)
In this photo provided by Briana Abrahms, a female cheetah and her cub sit watchfully in front of a herd of zebra in northern Botswana on Aug. 23, 2011. (Briana Abrahms via AP)
TT

Study: Cheetahs Become More Nocturnal on Hot Days as Climate Change Takes Toll 

In this photo provided by Briana Abrahms, a female cheetah and her cub sit watchfully in front of a herd of zebra in northern Botswana on Aug. 23, 2011. (Briana Abrahms via AP)
In this photo provided by Briana Abrahms, a female cheetah and her cub sit watchfully in front of a herd of zebra in northern Botswana on Aug. 23, 2011. (Briana Abrahms via AP)

Cheetahs are usually daytime hunters, but the speedy big cats will shift their activity toward dawn and dusk hours during warmer weather, a new study finds.

Unfortunately for endangered cheetahs, that sets them up for more potential conflicts with mostly nocturnal competing predators such as lions and leopards, say the authors of research published Wednesday in the journal Proceedings of the Royal Society B.

“Changing temperatures can impact the behavior patterns of large carnivore species and also the dynamics among species,” said University of Washington biologist Briana Abrahms, a study co-author.

While cheetahs only eat fresh meat, lions and leopards will sometimes opportunistically scavenge from smaller predators.

“Lions and leopards normally kill prey themselves, but if they come across a cheetah’s kill, they will try to take it,” said Bettina Wachter, a behavioral biologist who leads the Cheetah Research Project at the Leibniz Institute for Zoo and Wildlife Research.

“The cheetahs will not fight the larger cats, they will just leave,” said Wachter, who is based in Namibia and was not involved in the study.

Hunting at different times of the day is one long-evolved strategy to reduce encounters between the multiple predator species that share northern Botswana’s mixed savannah and forest landscape.

But the new study found that on the hottest days, when maximum daily temperatures soared to nearly 45 degrees Celsius (113 degrees Fahrenheit), cheetahs became more nocturnal — increasing their overlapping hunting hours with rival big cats by 16%.

“There’s a greater chance for more unfriendly encounters and less food for the cheetahs,” said co-author Kasim Rafiq, a biologist at the University of Washington and the nonprofit Botswana Predator Conservation Trust.

For the current study, researchers placed GPS tracking collars on 53 large carnivores — including cheetahs, lions, leopards and African wild dogs — and recorded their locations and hours of activity over eight years. They compared this data with maximum daily temperature records.

While seasonal cycles explain most temperature fluctuations in the study window of 2011 to 2018, the scientists say the observed behavior changes offer a peek into the future of a warming world.

In the next phase of research, the scientists plan to use audio-recording devices and accelerometers — “like a Fitbit for big cats,” said Rafiq — to document the frequency of encounters between large carnivores.

In addition to competition with lions and leopards, cheetahs already face severe pressure from habitat fragmentation and conflict with humans.

The fastest land animal, cheetahs are the rarest big cat in Africa, with fewer than 7,000 left in the wild.

“These climate changes could become really critical if we look into the future — it's predicted to become much warmer in this part of Africa where cheetahs live, in Botswana, Namibia and Zambia,” said Wachter of the Cheetah Research Project.



Study Says Climate Change Will Even Make Earth’s Orbit a Mess

In this satellite image provided by CSU/CIRA & NOAA taken 1:10 GMT on Feb. 25, 2025, shows three cyclones, from left, Alfred, Seru and Rae east of Australia in the South Pacific. (CSU/CIRA & NOAA via AP, File)
In this satellite image provided by CSU/CIRA & NOAA taken 1:10 GMT on Feb. 25, 2025, shows three cyclones, from left, Alfred, Seru and Rae east of Australia in the South Pacific. (CSU/CIRA & NOAA via AP, File)
TT

Study Says Climate Change Will Even Make Earth’s Orbit a Mess

In this satellite image provided by CSU/CIRA & NOAA taken 1:10 GMT on Feb. 25, 2025, shows three cyclones, from left, Alfred, Seru and Rae east of Australia in the South Pacific. (CSU/CIRA & NOAA via AP, File)
In this satellite image provided by CSU/CIRA & NOAA taken 1:10 GMT on Feb. 25, 2025, shows three cyclones, from left, Alfred, Seru and Rae east of Australia in the South Pacific. (CSU/CIRA & NOAA via AP, File)

Climate change is already causing all sorts of problems on Earth, but soon it will be making a mess in orbit around the planet too, a new study finds.

MIT researchers calculated that as global warming caused by burning of coal, oil, gas continues it may reduce the available space for satellites in low Earth orbit by anywhere from one-third to 82% by the end of the century, depending on how much carbon pollution is spewed. That's because space will become more littered with debris as climate change lessens nature's way of cleaning it up.

Part of the greenhouse effect that warms the air near Earth's surface also cools the upper parts of the atmosphere where space starts and satellites zip around in low orbit. That cooling also makes the upper atmosphere less dense, which reduces the drag on the millions of pieces of human-made debris and satellites.

That drag pulls space junk down to Earth, burning up on the way. But a cooler and less dense upper atmosphere means less space cleaning itself. That means that space gets more crowded, according to a study in Monday's journal Nature Sustainability.

“We rely on the atmosphere to clean up our debris. There’s no other way to remove debris,” said study lead author Will Parker, an astrodynamics researcher at MIT. “It’s trash. It’s garbage. And there are millions of pieces of it.”

Circling Earth are millions of pieces of debris about one-ninth of an inch (3 millimeters) and larger — the width of two stacked pennies — and those collide with the energy of a bullet. There are tens of thousands of plum-sized pieces of space junk that hit with the power of a crashing bus, according to The Aerospace Corporation, which monitors orbital debris. That junk includes results of old space crashes and parts of rockets with most of it too small to be tracked.

There are 11,905 satellites circling Earth — 7,356 in low orbit — according to the tracking website Orbiting Now. Satellites are critical for communications, navigation, weather forecasting and monitoring environmental and national security issues.

“There used to be this mantra that space is big. And so we can we can sort of not necessarily be good stewards of the environment because the environment is basically unlimited,” Parker said.

But a 2009 crash of two satellites created thousands of pieces of space junk. Also NASA measurements are showing measurable the reduction of drag, so scientists now realize that that “the climate change component is really important,” Parker said.

The density at 250 miles (400 kilometers) above Earth is decreasing by about 2% a decade and is likely to get intensify as society pumps more greenhouse gas into the atmosphere, said Ingrid Cnossen, a space weather scientist at the British Antarctic Survey who was not part of the research.

Cnossen said in an email that the new study makes “perfect sense” and is why scientists have to be aware of climate change's orbital effects “so that appropriate measures can be taken to ensure its long-term sustainability.”