U.S. carbon dioxide emissions rose by a striking 3.4 percent in 2018, in the midst of an otherwise downward trend since 2005, a new analysis suggests. It’s likely the second-largest emissions jump since 1996, topped only by a 3.6 percent spike in 2010.

The findings were published Monday by the Rhodium Group, an independent research firm, largely drawing on data from the U.S. Energy Information Administration.

The uptick occurred during one of the biggest years for coal plant closures on record. This means declines in coal aren’t enough to keep pace with increasing demand for electricity—largely fed by natural gas over renewables last year, the report points out—and increasing emissions from other sources, including transportation and industry.

On a global scale, multiple reports in the last year have concluded that the world is not on track to meet its climate targets under the Paris Agreement—namely, keeping global temperatures within 1.5 degrees Celsius, or 2 C at the very most, of their preindustrial levels.

A December report from the research consortium Global Carbon Project found emissions grew worldwide by about 2.7 percent to reach an all-time high in 2018, at a time when scientists warn they should be dramatically falling (Climatewire, Dec. 6, 2018).

The GCP report also suggested an increase in U.S. emissions in 2018, although it projected a slightly more modest uptick of about 2.5 percent.

And a November report from the United Nations warned that individual nations will need to substantially strengthen their carbon-cutting pledges under the Paris Agreement within the next decade or so to meet the global temperature targets.

As the world’s second-largest emitter of carbon—topped only by China—the United States plays a pivotal role in the global ability to meet these targets.

President Trump has vowed to withdraw the country from the Paris Agreement, and his administration has worked to unravel a variety of environmental and climate regulations, including the Obama administration’s Clean Power Plan. The 2018 emissions spike underscores the gap between current policies and the dramatic declines in carbon output that experts say the United States should be pursuing in order to stay on track with its original Paris pledge.

Still, as per the rules of the Paris Agreement, the United States can’t actually officially exit the agreement until November 2020—the day after the next presidential election. A new administration could potentially re-enter it right away and begin work to get back on track.

In that case, the findings from 2018 may provide some important insight into the areas emissions most need to be tackled.

Continued work on the power sector—where emissions rose by 34 million metric tons last year, even after they’d declined by more than twice that amount in 2017—is a major priority.

But as the report points out, there are other less obvious areas where emissions are on the rise, as well.

Weather warnings

Both the Global Carbon Project’s December report and the Rhodium Group’s new analysis suggest the weather played a significant part in 2018’s emissions spike.

An unusually cold winter caused U.S. “heating degree days,” or the number of days in a season when buildings need to be heated, to increase by about 15 percent during the first few months of the year. The GCP report also suggests that a warm summer may have driven up air conditioning and electricity demand in 2018, as well.

Overall, the Rhodium Group report suggests that direct building-related emissions—including natural gas burned onsite for heating and cooking—increased by about 10 percent last year, hitting their highest levels since 2004.

There are several takeaways from these findings. The reports both imply that fluctuations in the weather—which, itself, is influenced by climate change—can have surprisingly large effects on nationwide carbon emissions, as long as heating and air conditioning remain as carbon-intensive as they are.

That’s important to consider in a world where summers are getting hotter and heat waves are on the rise. It may also be important to consider in places like the U.S. East Coast, where some research suggests that individual winter storms may actually be worsening under climate change even as temperatures continue to rise overall.

The Rhodium Group analysis also generally points to improvements in building efficiency as a so-far under-addressed strategy for cutting emissions.

Efficiency improvements in oil and gas furnaces have made some strides but are as yet “not enough to offset the emissions impact of population growth and increased demand for heating and other non-electric building energy services,” the authors note. And other strategies—electrifying buildings entirely, for instance—have also made slow progress on the ground.

Industry and transportation

Industrial emissions saw the greatest leaps in 2018, the report notes, rising by about 55 million metric tons. That’s mainly linked to an overall increase in industrial activity—and the report suggests that “absent a significant change in policy or a major technological breakthrough,” industry’s share of U.S. emissions is likely to continue growing. In some states, such as Texas, the authors suggest it may actually become the leading source of carbon emissions within the next few years.

Transportation remains the largest source of carbon dioxide emissions in the United States for the third year running, according to the report.

Continued improvements in vehicle efficiency and the expansion of electric cars are the obvious priority when it comes to decarbonizing the transportation sector. In fact, these kinds of improvements may already be making a modest difference—gasoline demand actually fell slightly in 2018, despite a small increase in total vehicle miles traveled.

But there are other areas to tackle, as well. The report points out that both trucking and air travel are on the rise, and that demand for diesel and jet fuel both rose by about 3 percent last year. As a result, even with the gasoline declines, total transportation emissions rose by about 1 percent last year.

Reprinted from Climatewire with permission from E&E News. E&E provides daily coverage of essential energy and environmental news at www.eenews.net.