Kate Marvel, a widely known climate scientist and author, has resigned from her position at NASA, citing the Trump administration’s attacks on climate science in the United States.

Dr. Marvel, who trained as an astrophysicist before turning to the Earth’s atmosphere, said in an interview that the administration’s actions made it impossible to remain at an agency that she loved.

“It wears you down after a while,” said Dr. Marvel, who announced her resignation on Tuesday. “None of my internally funded science projects were funded. I wrote a couple other proposals, which, as far as I know, have fallen into a black hole.”

Bethany Stevens, a NASA spokeswoman, declined to answer questions about Dr. Marvel’s resignation, saying “it would be inappropriate for the agency to comment on personnel matters.”

Dr. Marvel joins an estimated 95,000 employees who have left federal science agencies through layoffs, retirements or resignations since Mr. Trump returned to the White House last year. Of those, an estimated 10,000 held doctorate degrees in the sciences.

WASHINGTON — Humans are transforming Earth’s natural landscapes so dramatically that as many as one million plant and animal species are now at risk of extinction, posing a dire threat to ecosystems that people all over the world depend on for their survival, a sweeping new United Nations assessment has concluded.

The 1,500-page report, compiled by hundreds of international experts and based on thousands of scientific studies, is the most exhaustive look yet at the decline in biodiversity across the globe and the dangers that creates for human civilization. A summary of its findings, which was approved by representatives from the United States and 131 other countries, was released Monday in Paris. The full report is set to be published this year.

Its conclusions are stark. In most major land habitats, from the savannas of Africa to the rain forests of South America, the average abundance of native plant and animal life has fallen by 20 percent or more, mainly over the past century. With the human population passing 7 billion, activities like farming, logging, poaching, fishing and mining are altering the natural world at a rate “unprecedented in human history.”

Warmer water at the seaside might sound nice for your holiday dip, but recent ocean heat in the Mediterranean Sea has been so intense that scientists fear potentially devastating consequences for marine life.

The temperature of the sea surface regularly passed 30C off the coast of Majorca and elsewhere in late June and early July, in places six or seven degrees above usual.

That's probably warmer than your local leisure centre swimming pool.

It has been the western Med's most extreme marine heatwave ever recorded for the time of year, affecting large areas of the sea for weeks on end.

The heat appears to be cooling off, but some species simply struggle to cope with such prolonged and intense warmth, with potential knock-on effects for fish stocks.

To give you some idea of these temperatures, most leisure centre swimming pools are heated to roughly 28C. Competitive swimming pools are slightly cooler at 25-28C, World Aquatics says.

Children's pools are a bit warmer, recommended at 29-31C or 30-32C for babies, according to the Swimming Teachers' Association.

Such balmy temperatures might sound attractive, but they can pose hidden threats. Harmful bacteria and algae can often spread more easily in warmer seawater, which isn't treated with cleaning chemicals like your local pool.

Major report connects the world's environmental challenges

Climate change, nature loss and food insecurity are all inextricably linked and dealing with them as separate issues won't work, a major report has warned.

Countries agreed to try to hold global warming to 1.5 degrees Celsius. Is that still possible?

An iceberg floats off the coast of Illulisat, Greenland. Ice sheets in Greenland and Antarctica are melting rapidly, and the risks of drastic melting increase as the Earth heats up. The melting of Greenland's ice sheet is the second-largest contributor to global sea-level rise. (The largest contributor is water expanding as it warms.)

The primary focus of international climate negotiations this week in Baku, Azerbaijan, is how to pay for the costs of cutting global climate pollution and adapt to the impacts of climate change.