Heated debate

The inhabitants of Evia could hardly believe it was happening. Under a sky bleached orange, wearing masks to protect them from the smoke, they headed for the coast of the Greek island to be evacuated. Elderly people had to be carried onto the ferries. Behind them, fires had destroyed thousands of hectares of land along with houses and offices. "It's like a scene from an apocalypticReferring to the end of the world, or the collapse of civilisation. movie," said one tourist.

The fires that swept through Greece last week were a horrific illustration of the effects of climate change. In recent months there have been still worse fires in the US, and devastating floods in EuropeThe second-smallest of the world's continents. It has a population of 746 million. and ChinaA country in East Asia, home to 1.4 billion people.. And yesterday's report by the Intergovernmental Panel on Climate Change warned that there is worse to come.

Rises in sea levels of almost two metres by the end of the century could not be ruled out, it said. By 2150, they could rise by as much as five metres. Oceans will continue to grow warmer. Glaciers will continue to melt for decades - perhaps even centuries.

"We will see even more intense and more frequent heatwavesIn June Canada's highest ever temperature, 49.6C, was recorded in British Columbia.," says Dr Friederike Otto of Oxford University, one of the report's authors. "And we will also see an increase in heavy rainfall events on a global scale, and also increases in some types of droughts in some regions of the world."

Organised by the UN, the report is the largest ever on climate change. It involved scientists and government officials from 195 countries and drew on over 14,000 scientific papers. "Urgent climate action was needed decades ago," commented Doug Parr, a director of GreenpeaceAn international campaigning organisation based in Amsterdam. Its aim is to  "ensure the ability of the Earth to nurture life in all its diversity".. "Now we're almost out of time."

But the report also contains what another of its authors, Professor Piers Forster of Leeds University, calls "nuggetsSmall lumps. The word is particularly used for precious metals such as gold. of optimism". The latest research shows that if the increase in global temperature since pre-industrial times can be limited to 1.5C, the worst effects can still be avoided. So far, they have increased by 1.2C.

Scientists are also hopeful that if global carbon emissions can be halved by 2030 and reach net zero by 2050, global warming can be halted.

"The thought before was that we could get increasing temperatures even after net zero," says Professor Forster. "But we now expect nature to be kind to us, and if we are able to achieve net zero, we hopefully won't get any further temperature increase. And if we are able to achieve net zero greenhouse gases, we should eventually be able to reverse some of that temperature increase and get some cooling."

Professor Otto agrees that this would minimise the chances of reaching a tipping point. "We are not doomed," he says.

Nevertheless, the report is a "code red for humanity", according to the secretary-general of the UN, Antonio Guterres. "If we combine forces now, we can avert climate catastrophe. But, as today's report makes clear, there is no time for delay and no room for excuses."

Is hope still realistic?

Some say, no. The planet can only be saved if everyone makes major lifestyle changes and if all the industrial nations of the world co-operate. But nobody wants to give up their comforts, and - as the pandemic has shown - governments are bad at working together even in a global emergency. Some - such as Brazil's, with its disrespect for the rainforest - are making the situation even worse.

Others argue that people do change their habits when the situation demands it: we used to not recycle at all, but now everybody does it. The recent weather disasters have finally woken the world to the perils of climate change, and governments and businesses are responding to pressure to behave responsibly. Clean technology is making enormous strides.