As world leaders and diplomats wrap up the climate negotiations in Scotland in the coming days they will be confronted by new data showing that global carbon dioxide emissions are expected to rise sharply this year, possibly tying the all-time high reached before the Covid-19 pandemic.

The new data, compiled by the Global Carbon Project and published Wednesday in the journal Earth System Science Data, highlights the key factors that are driving global emissions, including China and India’s resurgent use of coal, and points to the big challenges nations face to curb warming.

The most significant driver of climate change is the carbon dioxide emitted by fossil fuels, and such emissions are expected to jump by about 5 percent this year. That’s enough of a leap to return fossil fuel emissions to roughly where they were in 2019, before the pandemic brought the global economy to a halt.

“You park a car or an airplane or a steel plant, for that matter, for a year, and it’s still the same polluting infrastructure when you start using it again,” said Rob Jackson, chairman of the carbon project, professor of earth system science at Stanford University and lead author of an article that accompanied the data and is under review in a separate journal, Environmental Research Letters. “And that’s what happened in the global economy.”

One of the most troubling and surprising trends, Jackson said, is that emissions from coal are expected to surge this year and surpass 2019 levels. Coal use had been on the decline since a peak in 2014, but the new data suggests that trend may have stalled, endangering climate goals.

Meanwhile, global natural gas consumption has continued to grow rapidly. The data shows that the fuel, which burns cleaner than coal and was once considered a bridge to a clean-energy future, is an increasingly significant driver of warming. The new report does not include the methane emissions that result when natural gas leaks from equipment or is released into the atmosphere during production or transmission of the fuel. Methane is a potent greenhouse gas and atmospheric levels have been rising rapidly, though more than 100 nations announced a pledge Tuesday to limit methane emissions by 2030.

Oil is the only fossil fuel for which emissions have yet to return to 2019 levels, largely because air and road travel remain lower than before, Jackson said. 

The new estimates reflect a longer-term trend showing emissions rising in China and India and falling in the United States and Europe. China’s emissions continued to rise even in 2020, when most other countries’ pollution fell sharply due to the pandemic. India’s rapid growth this year is expected to push emissions slightly above 2019 levels. Jackson said the data reflects the fact that those two countries, along with much of the rest of the world, prioritized stimulating existing industries in their pandemic recovery efforts rather than trying to transition to cleaner energy.

Zooming in, the new research points to the critical importance of limiting coal consumption in China, which uses more of that fossil fuel than any other country. In fact, China’s carbon dioxide emissions from coal alone, at an estimated 7.6 billion metric tons this year, are greater than the total carbon dioxide emissions of any other country. Last week, leaders of G20 nations failed to reach an agreement to phase out coal use domestically.

Because of governments’ failure to bend down the global emissions curve, the world’s “carbon budget”—or the amount of carbon dioxide it can emit before reaching critical climate thresholds—is shrinking rapidly. According to the new research, the world has only 11 years at current emissions levels before it eclipses the budget for a 50 percent chance of limiting warming to 1.5 degrees Celsius (2.7 degrees Fahrenheit), and 32 years before exceeding the budget for 2 degrees Celsius (3.6 degrees Fahrenheit).

World leaders could buy more time if they are able to agree in Scotland on more aggressive measures to limit future emissions and follow through with them in coming years. But the window of opportunity is closing rapidly, Jackson said.

“Treading water for global fossil carbon emissions like we’re doing now is closer to drowning when it comes to climate change,” he said.