"Ecosystem collapse", where trees suddenly fade and die, could happen within 50 years, they warn.

But the 42 experts said if we act now we can avert the catastrophe.

The large-scale loss of forests hit by "wind, fire, pests and disease" has already happened in continental Europe and North America.

"A collapsed forest would be heart-breaking, devoid of its essential life and all the joy and benefits it gives to humanity," said Dr Eleanor Tew of Forestry England and Cambridge University.

But she said we have time to make a difference and we know what to do to make our forests more resilient "so they can continue to thrive for future generations".

Extreme weather events caused by global warming cost the country around US$150 billion in direct damages each year, says the climate report, released on 14 November. From 2018 to 2022, the United States experienced 89 climate disasters that each cost at least $1 billion in damages. That equates to one every three weeks, as compared with one every four months in the 1980s.

“Climate change is here,” says Arati Prabhakar, Biden’s chief science adviser and director of the White House Office of Science and Technology Policy. But Prabhakar says that the United States is stepping up to the challenge with significant new climate investments, “and this gives us hope that we can move at a scale that the climate notices”.

A June study from sustainable transport campaigner The European Federation for Transport and Environment found that 63 cruise ships owned by parent company Carnival Corporation emitted 43% more sulfur oxides, a group of harmful air pollutants, than all the 291 million cars in Europe in 2022.

Though the IMO rule slashes the sulfur emissions of individual ships, it has done nothing to limit the increasing number of cruise ships in recent years. Compared to 2019, cruise ships are also spending more time at European ports and consuming more fuel, per the report. As a result, cruise ships overall emitted 9% more sulfur oxides in 2022 than in 2017, according to Transport & Environment.

Sulfur oxides released into the atmosphere can have adverse effects on human health and air quality, from exacerbating respiratory illnesses such as asthma to contributing to the formation of acid rain. A 2016 study estimated that the IMO's sulfur regulations would prevent 570,000 premature deaths worldwide from 2020 to 2025.