Global carbon emissions crept upward in 2017 at a time when the world needs to rapidly reduce greenhouse gas emissions to limit future warming, yet the trends were not entirely bad news as the world's two biggest emitters, China and the United States, made progress in their own ways.
Energy-related CO2 emissions increased worldwide by 1.4 percent in 2017 after remaining flat for the previous three years, according to an International Energy Agency (IEA) report released Thursday.
While most countries' emissions increased, some, including the United States, saw declines driven largely by renewable energy deployments.
Emissions in China, the world's largest emitter of greenhouse gases, increased by 1.7 percent, yet the country continued to make progress toward its emissions goals under the Paris climate agreement.
More than 70 percent of new global energy demand was met by fossil fuels in 2017, a significant departure from recent years when renewable sources such as solar and wind energy met the majority of new energy needs, the IEA reported.
"The robust global economy pushed up energy demand last year, which was mostly met by fossil fuels, while renewables made impressive strides," IEA Executive Director Fatih Birol said in a statement.
2 Surprises: The U.S. and China
The biggest decline in absolute emissions came in the United States, where greenhouse gas emissions dropped by 0.5 percent in spite of efforts by the Trump administration to bring back coal, develop offshore oil, and withdraw from the Paris climate accord.
Market forces, including the low price of renewables and natural gas, as well as a growing appetite for renewable energy fueled the decrease in U.S. emissions.
Renewable energy provided a record 17 percent of U.S. electricity generation in 2017. That's a percentage that will likely continue to grow, said Glen Peters, researcher director at the Center for International Climate Research in Oslo.
In the U.S., the increase in renewables has been driven in part by increasing pressure on utility companies to reduce emissions, even though the Obama-era Clean Power Plan regulations are in limbo. Duke Energy, one of the largest power providers in the U.S. and a company that has opposed some renewable energy projects in the past, outlined what a "two-degree policy" would look like in a report to shareholders on Thursday. Such a policy would, by 2050, phase out existing coal generation and reduce Duke's CO2 emissions 72 percent from its 2010 levels, the company said. Duke said its current emissions reduction goals for 2030 are consistent with that pathway.
For its part, China's economy grew nearly 7 percent in 2017 but carbon dioxide emissions increased by just 1.7 percent due to the continued development of renewable energy and the replacement of coal with natural gas, according to the IEA report. The low growth in emissions relative to economic growth is in line with the country's pledge under the Paris Agreement to reduce its carbon intensity, or emissions per unit of GDP.
Overall, Asia's growing economies contributed about two-thirds of the global increase in carbon emissions, the IEA found. India's emissions grew, the IEA said, but at half the rate seen in the past decade.
Among the other standouts: The United Kingdom's emissions fell 3.8 percent, with a 20 percent drop in demand for coal, and Mexico's emissions were down 4 percent with growth in clean energy and efficiency gains.
WMO Warns of Costs of Global Warming
The unprecedented buildup of mankind's greenhouse gases in the atmosphere is already wreaking costly damages, a trend that's expected to increase as temperatures continue to warm.
2017 had the highest economic losses associated with severe weather and climate events of any year to date, the World Meteorological Organization wrote in a separate report published Thursday. It cited reinsurance giant MunichRe's calculation of a record $320 billion in climate- and weather-releated disaster losses worldwide in 2017, and noted that government agencies had reported even higher numbers for some of the disasters, including U.S. losses from three destructive hurricanes.
Global average temperatures reached about 1.1 degrees Celsius above pre-industrial times in 2017, and 30 percent of the world's population now lives in conditions with potentially deadly temperatures at least 20 days a year, the WMO said.
Just stopping the increase in global greenhouse gas emissions and leveling it off won't be enough, said Peters, who contributed to the WMO report. "It's like you are turning up the bath tap and then you stop turning, the water is still blasting out of the tap, so the bath is still filling up at the maximum rate," he said. "To stop the carbon problem, you've got to start turning the tap down."