With global warming getting worse, urgent action is needed, climate scientists say

Following the landmark United Nations report released Monday, climate scientists said the path is clear — an immediate and sustained campaign to transform our energy system and reduce greenhouse gases.

“Ultimately, what it comes down to is that we need to dramatically reduce emissions and stop burning fossil fuels,” said Peter Frumhoff, director of science and policy at the Cambridge-based Union of Concerned Scientists.

He and others urged lawmakers and regulators to enact laws and rules that would:

Reduce carbon emissions by half what they were in 2010 by the end of the decade and effectively eliminate them by 2050.
Stop the burning of fossil fuels such as oil and gas; ramp up the use of clean energy, such as wind and solar power; curb deforestation; and use agricultural lands more sustainably.
Reduce the consumption of beef and dairy products, which contribute to deforestation and a significant amount of emissions from cattle.
Impose a tax or other fees on carbon pollution.
Encourage farmers to better manage their soil and land, so they sequester more carbon dioxide.
Invest in research to find ways to remove large amounts of carbon from the atmosphere, at reasonable costs.
Prepare for the unavoidable impacts that the United Nations report says will happen no matter what policymakers do, including sea levels rising by a foot by the middle of the century, more intense storms, greater flooding, and increased droughts.
Invest in helping the most vulnerable adapt to all the consequences of a warming world, especially the impoverished and those who have the least ability to move or make changes to protect their homes or livelihoods.

The United States and other countries stand to learn from some smaller nations that have taken bold action, such as Costa Rica, which two years ago pledged to produce no more carbon emissions than it could offset by 2050, said Bob Chen, interim dean at the School for the Environment at the University of Massachusetts Boston

“We all need to take that kind of responsibility,” he said.

The United States has sent the world mixed signals over the years.

Pledges and policies designed to reduce emissions during the administrations of Presidents Clinton and Obama were overturned by their Republican successors. Most notably, President Trump in 2017 pulled out of the Paris climate accord, which the Obama administration helped create and persuaded nearly 200 other nations to sign.

President Biden has once again moved the nation back into a leading role to address climate change. Since taking office in January, he has pledged to reduce US emissions by at least 50 percent below 2005 levels by the end of the decade.

But it’s unclear whether the country can achieve that without Republican support. Some of the measures that might have moved the country in that direction were stripped recently from a bipartisan infrastructure bill that some viewed as a potential legislative vehicle to curb emissions.

The United States — the largest source of cumulative greenhouse gas emissions over the past 150 years — has also failed to live up to its promises to help provide billions of dollars to help developing countries make the transition to a carbon-free future, experts said.

“The bottom line is that we have a lot of catching up to do,” said Mindy Lubber, president of CERES, a Boston-based environmental group that promotes climate action in the corporate world. “We need to make commitments and put money on the table.”

Still, Lubber and others said the United States could only do so much to wrest the planet from the worst outcomes forecast in Monday’s report by the Intergovernmental Panel on Climate Change.

The report found that the planet has already warmed 1.1 degrees Celsius since the preindustrial era and is rapidly approaching the 1.5-degree threshold that the Paris agreement was designed to prevent. The consequences are expected to become more severe after the planet passes that threshold, which the report said is now likely to occur in the next 20 years — a decade earlier than previously thought.

Bill Moomaw, a retired professor of international environmental policy at Tufts University, noted that other major countries, such as China, India, and Brazil, must do much more as well. China and India, he noted, continue to build coal power plants, which produce an inordinate amount of carbon pollution, while deforestation has accelerated in Brazil, which has often been described as the planet’s lungs.

And while European countries have made significant pledges to reduce emissions, they still rely on coal and burning trees and other vegetation for heat, he said.

“It’s hard to find a single country that has done the full range of things that have to be done,” he said. “We all need to do better.”

David Abel can be reached at david.abel@globe.com. Follow him @davabel.