President Donald Trump has presided over the biggest increase in energy-related U.S. carbon emissions in eight years, according to preliminary estimates released by New York research firm the Rhodium Group.

After three years of decline, U.S. carbon emissions increased by 3.4 percent in 2018, according to the data, marking the second-largest annual gain in two decades and the largest in eight years.

The surge in emissions was down to increased natural gas use filling the gap left by retiring coal power plants, alongside growth in electricity demand, leading to a 1.9 percent increase in overall power sector emissions.

Meanwhile, transport remained the largest source of U.S. emissions for the third year running, with "robust" growth — more than 3 percent — in demand for diesel and jet fuel more than offsetting a slight decline in passenger car fuel.

And buildings and industry, often the "forgotten sectors" in clean climate policymaking according to Rhodium, saw large increases in emissions. Direct emissions from residential and commercial buildings shot up 10 percent last year, to their highest level since 2004, while the industrial sector emitted an extra 55 million tonnes of carbon in 2018.

Official EPA data on U.S. emissions will not be available until 2020, but the worrying preliminary results, coupled with Trump's public skepticism of the threat climate change poses, means the U.S. is drifting further off course from its goals under the Paris Agreement.

To meet its goals under the Paris Agreement to deliver a 26-28 percent reduction in greenhouse gas emissions on 2005 levels by 2025, energy-related CO2 emissions in the United States will need to fall by 3.3 percent a year — well above the 1.2 percent average reduction seen since 2007.

It is certainly feasible, but will likely require a fairly significant change in policy in the very near future and/or extremely favorable market and technological conditions.

"It is certainly feasible, but will likely require a fairly significant change in policy in the very near future and/or extremely favorable market and technological conditions," Rhodium Group warned.

But the president has made clear curbing emissions is far from his priority in office — and has taken steps to roll back policy measures that experts say will lead to a direct increase in emissions. Last year, he took steps to reverse new fuel emissions standards for passenger cars, moved to relax emissions rules for coal power plants and pulled funding for international climate efforts. 

It has been left to America's private sector, and states and cities, to step up to the plate. The We Are Still In movement has hundreds of major supporters, but outside the climate action strongholds of California and New York, many areas of the country may well need cajoling from the federal or state governments to take more ambitious action. 

Cutting U.S. emissions, particularly in its industrial heartlands, will be a challenge but is not an impossible task. America's industrial sector could take its cues from Scotland — fresh data this week revealed greenhouse gases from industry in the country have hit a 10-year low. The update from the Scottish Environment Protection Agency (SEPA) reveals greenhouse gas emissions have dropped 57 percent between 2007 and 2017, from 26 metric megatons of pollutant a year to 11 metric megatons.

Carbon dioxide emissions dropped 6 percent between 2016 and 2017, as did methane, while nitrous oxide emissions fell 28 percent over the course of the year. Together, 2016-2017 represents the largest drop in emissions since 2007, largely thanks to the retirement of Longannet, the last Scottish coal power station.

But stricter regulation is also forcing Scottish industry to become more efficient, SEPA chief executive Terry A'Hearn pointed out. "The most successful countries in the 21st century will function within our planet's means to support us," he said. "Through our regulatory strategy, One Plant Prosperity, SEPA is helping business grow sustainably while reducing their environmental burden."

Stricter regulation is also forcing Scottish industry to become more efficient.

It is clear that if the international community is to get a handle on carbon emissions, all sectors of the economy will need to pull their weight. But the trend is heading in the wrong direction, with global emissions rising last year.

New data suggests the toll on the climate is already clear. The European Union's Copernicus Climate Change Service said that 2018 was the fourth warmest year on record, as the concentration of greenhouse gases in the atmosphere hit record levels.

Last year was 32 degrees F off being crowned as the hottest year of all time, Copernicus said, with 2019 expected to be just as hot.

"Dramatic climatic events like the warm and dry summer in large parts of Europe or the increasing temperature around the Arctic regions are alarming signs to all of us," said Jean-Noël Thépaut, head of Copernicus.

Rising greenhouse gases also have a grim impact on the world's oceans. More than 90 percent of the heat caused by manmade emissions have been trapped in the world's oceans, according to new research from the University of Oxford reported in The Guardian.

The paper's analysis suggests global warming has heated the oceans by the equivalent of one atomic bomb explosion per second for the past 150 years.

If the world is to avert the catastrophic impacts of more than 1.5C of warming, global emissions must start falling soon. By 2030 global emissions must have dropped 45 percent, before then transitioning to a net zero emission economy by 2050, according to the world's top climate scientists.

Some leading analysts, such as Bloomberg New Energy Finance founder Michael Liebreich, have suggested global carbon emissions could fall this year as the recent surge in U.S. economic growth proves itself to be a tax cut induced "Trump bubble" and clean technology deployments continue to accelerate. But even if emissions do tick downwards following two years of stalled progress, the need for a step change in decarbonization rates has never been clearer.