The world needs a new approach to environmental crises threatening the health of people and the planet by adopting policies to jointly tackle climate change, biodiversity loss, land degradation and pollution, according to a U.N. report released Tuesday.

Those issues are inextricably linked and require solutions that include increased spending and financial incentives to transition away from fossil fuels, encourage sustainable agricultural practices, curb pollution and limit waste, the authors of the U.N. Environment Programme’s quadrennial Global Environment Outlook said.

“You can’t think of climate change without thinking of biodiversity, land degradation and pollution,” said Bob Watson, one of the lead authors and a former top NASA and British climate scientist. "You can’t think of biodiversity loss without thinking about the implications of climate change and pollution."

They’re “all undermining our economy," worsening health and poverty and threatening food and water security and even national security, Watson said.

Almost 300 scientists from 83 countries contributed to this year’s report — called the most comprehensive global environment assessment ever undertaken — which was released during the U.N. Environment Assembly in Nairobi, Kenya.

Experts have warned that the world is nearing a tipping point on climate change, species and land loss and other harms. But efforts to address those problems largely have been pursued through individual agreements that haven’t made nearly enough progress, they said.

Instead, they advocate an approach that involves every area of government, the financial sector, industry and citizens and a circular economy that recognizes that natural resources are limited.

“What we’re saying is we can become much more sustainable, but it will take unprecedented change to transform these systems,” Watson said. “It has to be done rapidly now because we’re running out of time.”

Global tipping point

The report lays out a dire future if the world continues on its current path.

Emissions of heat-trapping greenhouse gases — primarily from burning fossil fuels such as coal, gas and oil — reached a new high in 2024, despite decades of negotiations between countries to curb emissions.

Ten years ago, almost 200 nations signed the Paris Agreement with the goal of limiting future warming to no more than 1.5 degrees Celsius (2.7 degrees Fahrenheit) since preindustrial times to avoid or lessen the most catastrophic effects of climate change. But on the current trajectory, the climate could warm by 2.4 degrees Celsius (4 degrees Fahrenheit) by 2100, Watson said.

Scientists say climate change is contributing to wilder weather extremes, including more intense storms, drought, heat and wildfires.

What’s more, climate change is a threat multiplier, meaning that it makes things like land degradation, deforestation and biodiversity loss worse, said Katharine Hayhoe, a climate scientist at Texas Tech University and chief scientist at the Nature Conservancy, who wasn’t involved in the report.

“If we don’t fix climate change, we’re not going to be able to fix these other issues too,” Hayhoe said.

Among other challenges: Up to 40% of land area globally is degraded; more than 1 million plant and animal species face extinction; and pollution contributes to an estimated 9 million deaths a year.

Adopting a comprehensive approach would be expensive, scientists acknowledge, but cost far less than the harms that otherwise could result.

The report says that to achieve a goal of net-zero emissions by 2050 and restore biodiversity, about $8 trillion in global investment is needed every year. But starting in 2050, economic benefits will surpass spending, growing to $20 trillion a year by 2070 and $100 trillion a year thereafter.

Nations also must look beyond gross domestic product as a barometer for economic health, because it doesn’t measure whether growth is sustainable or recognize its potential harms, Watson said.

Environmental issues aren’t the only things interlinked, Watson said. He also said governments, nonprofits, industry and the financial sector also must ensure that there are incentives and funding for renewable energy and sustainable agricultural practices, for example.

University of Pennsylvania climate scientist Michael Mann, who wasn’t involved in the report, welcomed its emphasis on tackling issues across governments and society.

“We must do what is right, rather than what seems politically expedient,” Mann said. “The stakes are simply too great."

International cooperation falters

Despite the report’s urgent call for action, international cooperation is anything but guaranteed, scientists say — especially as U.S. President Donald Trump has refused to participate in many of the discussions.

Trump, who withdrew the United States from the Paris Agreement, has called climate change a hoax. He’s promoted fossil fuel use, canceled permits for renewable energy and is abandoning automobile fuel-efficiency standards.

“International action and agreements are becoming harder and harder,” Watson said, noting that this year’s U.N. climate conference in Brazil failed to “move in the direction we needed it to move” with stronger commitments to reduce greenhouse gas emissions and other issues.

Talks this summer on a treaty to address plastic pollution in Geneva ended without an agreement, though a U.N. conference earlier in the year garnered commitments for funding to protect global biodiversity.

Watson said that the U.S. didn’t attend the intergovernmental meeting in Nairobi, but joined discussions on the last day and "said they didn’t agree with anything in the report.”

“Some countries might say if the U.S. is not willing to act, why should we act?” Watson said.

Still, he believes that some countries will move forward, while others, including the U.S., could fall behind.

Hayhoe, the Texas Tech scientist, said that she’s confident changes will happen, because the stakes are becoming too great.

“It is not about saving the planet. The planet will be orbiting the sun long after we’re gone,” Hayhoe said. “The question is, will there be a healthy, thriving human society on that planet? And the answer to that question is very much up for grabs at this point.”

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