Humanity still has a chance, close to the last one, to prevent the worst of climate change ’s future harms, a top United Nations panel of scientists said Monday.

But doing so requires quickly slashing carbon pollution and fossil fuel use by nearly two-thirds by 2035, the Intergovernmental Panel on Climate Change said. The United Nations chief said it more bluntly, calling for an end to new fossil fuel exploration and rich countries quitting coal, oil and gas by 2040.

“Humanity is on thin ice — and that ice is melting fast,” United Nations Secretary-General Antonio Guterres said. “Our world needs climate action on all fronts — everything, everywhere, all at once.”

Stepping up his pleas for action on fossil fuels, Guterres not only called for “no new coal” but also for eliminating its use in rich countries by 2030 and poor countries by 2040. He urged carbon-free electricity generation in the developed world by 2035, meaning no gas-fired power plants too.

That date is key because nations soon have to come up with goals for pollution reduction by 2035, according to the Paris climate agreement. After contentious debate, the U.N. science panel calculated and reported that to stay under the warming limit set in Paris the world needs to cut 60% of its greenhouse gas emissions by 2035, compared with 2019, adding a new target not previously mentioned in the six reports issued since 2018.

“The choices and actions implemented in this decade will have impacts for thousands of years,” the report, said calling climate change “a threat to human well-being and planetary health.”

“We are not on the right track but it’s not too late,’’ said report co-author and water scientist Aditi Mukherji. “Our intention is really a message of hope, and not that of doomsday.’’

With the world only a few tenths of a degree away from the globally accepted goal of limiting warming to 1.5 degrees Celsius (2.7 degrees Fahrenheit) since pre-industrial times, scientists stressed a sense of urgency. The goal was adopted as part of the 2015 Paris climate agreement and the world has already warmed 1.1 degrees Celsius (2 degrees Fahrenheit).

This is likely the last warning the Nobel Peace Prize-winning collection of scientists will be able to make about the 1.5 mark because their next set of reports will likely come after Earth has either breached the mark or locked into exceeding it soon, several scientists, including report authors, told The Associated Press.

After 1.5 degrees “the risks are starting to pile on,” said report co-author Francis X. Johnson, a climate, land and policy scientist at the Stockholm Environment Institute. The report mentions “tipping points” around that temperature of species extinction, including coral reefs, irreversible melting of ice sheets and sea level rise on the order of several meters (several yards).

“The window is closing if emissions are not reduced as quickly as possible,” Johnson said in an interview. “Scientists are rather alarmed.”

“1.5 is a critical critical limit, particularly for small islands and mountain (communities) which depend on glaciers,” said Mukherji, who’s also the climate change impact platform director at the research institute CGIAR.

Many scientists, including at least three co-authors, said hitting 1.5 degrees is inevitable.

“We are pretty much locked into 1.5,” said report co-author Malte Meinshausen, a climate scientist at the University of Melbourne in Australia. “There’s very little way we will be able to avoid crossing 1.5 C sometime in the 2030s ” but the big issue is whether the temperature keeps rising from there or stabilizes.

Guterres insisted “the 1.5-degree limit is achievable.” Science panel chief Hoesung Lee said so far the world is far off course.

“This report confirms that if the current trends, current patterns of consumption and production continues, then … the global average 1.5 degrees temperature increase will be seen sometime in this decade,” Lee said.

Scientists emphasize that the world, civilization or humanity won’t end if and when Earth hits and passes the 1.5 degree mark. Mukherji said “it’s not as if it’s a cliff that we all fall off.” But an earlier IPCC report detailed how the harms – from coral reef extinction to Arctic sea ice absent summers to even nastier extreme weather – are much worse beyond 1.5 degrees of warming.

“It is certainly prudent to be planning for a future that’s warmer than 1.5 degrees,” said IPCC report review editor Steven Rose, an economist at the Electric Power Research Institute in the United States.

If the world continues to use all the fossil fuel-powered infrastructure either existing now or proposed Earth will warm at least 2 degrees Celsius since pre-industrial times, blowing past the 1.5 mark, the report said.

Because the report is based on data from a few years ago, the calculations about fossil fuel projects already in the pipeline do not include the increase in coal and natural gas use after Russia’s invasion of Ukraine, said report co-author Dipak Dasgupta, a climate economist at The Energy and Resources Institute in India. The report comes a week after the Biden Administration in the United States approved the huge Willow oil-drilling project in Alaska, which could produce up to 180,000 barrels of oil a day.

The report and the underlying discussions also touch on the disparity between rich nations, which caused much of the problem because carbon dioxide emissions from industrialization stay in the air for more than a century, and poorer countries that get hit harder by extreme weather.

If the world is to achieve its climate goals, poorer countries need a “many-fold” increase in financial help to adapt to a warmer world and switch to non-polluting energy. Countries have made financial pledges and promises of a damage compensation fund.

If rich countries don’t cut emissions quicker and better help victim nations adapt to future harms, “the world is relegating the least developed countries to poverty,” said Madeline Diouf Sarr, chair of a coalition of the poorest nations.

Risk vs Opportunity

The report offers hope if action is taken, using the word “opportunity” nine times in a 27-page summary. Though opportunity is overshadowed by 94 uses of the word “risk.”

The head of the IPCC said the report contains “a message of hope in addition to those various scientific findings about the tremendous damages and also the losses that climate change has imposed on us and on the planet.”

“There is a pathway that we can resolve these problems, and this report provides a comprehensive overview of what actions we can take to lead us into a much better, livable future,” Lee told The Associated Press.

Lee was at pains to stress that it’s not the panel’s job to tell countries what they should or shouldn’t do to cap global temperature rise at 1.5 Celsius.

“It’s up to each government to find the best solution,” he said, adding that scientists hope those solutions will stabilize the globe’s temperature around 1.5 degrees.

Asked whether this would be the last report to describe ways in which 1.5 C can be achieved, Lee said it was impossible to predict what advances might be made that could keep that target alive.

“The possibility is still there,” he said. “It depends upon, again I want to emphasize that, the political will to achieve that goal.”

Activists also found grains of hope in the reports.

“The findings of these reports can make us feel disheartened about the slow pace of emissions reductions, the limited transition to renewable energy and the growing, daily impact of the climate crisis on children,” said youth climate activist Vanessa Nakate, a goodwill ambassador for UNICEF. “But those children need us to read this report and take action, not lose hope.”