Greenhouse gas pollution dropped this year

Emissions of man-made greenhouse gases appear to have declined slightly in 2015, scientists said Monday, reflecting what experts say is an encouraging, though likely temporary, pause in the steady rise in pollutants blamed for climate change.

The projected dip of 0.6 percent over 2014 levels, if confirmed, marks the first decline in heat-trapping pollutants in a year when the world economy was not in recession, a new analysis shows. Scientists say the drop is tangible evidence of changing behavior as more countries invest in renewable energy such as solar and wind power.

The single biggest factor appears to be a marked reduction in China's use of coal to make electricity. But other countries, from North America to Europe, also emitted less carbon dioxide from fossil fuel burning as governments and consumers shifted to cleaner fuels and more fuel-efficient vehicles, according to a report published Monday in the scientific journal Nature Climate Change.

"We can't yet call it a long-term trend, but we do see really encouraging signs over the last couple of years," said coauthor Robert Jackson, the Douglas Provostial professor at Stanford University's School of Earth Sciences. "From the data for 2015, it looks like we could even see a decline in fossil-fuel emissions this year."

The authors cautioned that this year's "pause" is not likely to last, as developing economies in India and elsewhere around the world are projected to increase emissions from coal and oil in the coming decades. But those higher emissions are beginning to be offset elsewhere as more people turn to the sun and wind to provide electricity, the analysis said, suggesting that a "peak" in the world's output of greenhouse gases could be achieved in the foreseeable future.

"We have shown that the high growth rates in global CO2 emissions prevalent since the early 2000s ceased in the past two years, at least temporarily, despite robust growth in global economic activity," the report stated. "Underlying trends in some emerging and established economies suggest that structural changes in their economies and energy systems are already leading to emissions reductions."

The report is likely to provide a psychological lift to negotiators at this week's climate talks in Paris, where diplomats from more than 190 countries are seeking to forge a global agreement on reducing emissions of from fossil-fuel burning. The goal is to prevent global temperatures from rising by more than 2 degrees Celsius (3.6 degrees Fahrenheit) over historical averages. Scientists warn that without substantial cuts in emissions, the planet will likely experience much higher temperature increases that could endanger humans and natural ecosystems for centuries to come.

Todd Stern, the diplomat who heads the U.S. delegation at the Paris talks, welcomed the new figures as "good news" but said the report was not likely to be a factor in the negotiations. "At this point in a negotiation like this, people are pretty focused on the business at hand," he said.