Climate pollution in the US is up under Donald Trump and threatens to undermine international efforts to stall the crisis, especially if he wins re-election this year and secures a second term in the White House.

While US climate emissions fell 2.1% in 2019, they rose significantly in 2018, according to estimates from the economic analysis firm Rhodium Group. On net, emissions are slightly higher than in the beginning of 2017, when Trump’s administration began enacting dozens of environment rollbacks aimed at helping the oil and gas industry.

Trump is still working to further weaken bedrock standards. This week he proposed to allow major projects like pipelines and highways to bypass reviews of how they will contribute to global warming. The draft rule is unlikely to become final before the November election, but it is yet another reason industries weighing climate choices might delay significant action.

“What they have done is created confusion within the business community and the environmental world as to what are going to be the standards,” said Christine Todd Whitman, who led the Environmental Protection Agency under the Republican president George W Bush. “Essentially every regulation the agency promulgates gets a lawsuit that goes with it, almost inevitably … that’s the only good thing you can say about it.”

Whitman called the approach “mindless” and said “whoever is a bigger donor gets to tell them what the environmental policy should be, it seems”.

In the absence of any federal climate action, states, cities and businesses have pledged their own efforts, seeking to encourage other big emitters like China and India to continue to slow their growing climate pollution.

Andrew Light, a climate negotiator for President Barack Obama’s state department, said the world is taking note of those efforts, but if Trump is re-elected “you are going to see a lot of people who are worried anew about what the US can do”.

Americans choosing Trump would send the signal that they don’t care about the climate, Light said.

America’s Pledge, a project to quantify ongoing US emissions reductions, estimates that non-federal actors – like states and cities – could cut climate pollution 37% below 2005 levels by 2030. A Democrat in the White House could increase that to 49% with what Light described as modest, politically achievable policy changes. Experts are increasingly calling for the US to halve its emissions by 2030 and neutralize them by 2050.

“In the case of a second Trump term, we’ve got to totally double down on the efforts to communicate how serious the non-federal actors are in the United States,” Light said. “And what you really want to try to make sure is that those people in other countries who are not in favor of strengthening their countries’ own climate target are not able to point to the United States and say nothing’s going on there.”

The Trump administration has initiated essentially all of its planned climate rollbacks – from weakening standards for cars to go farther on less gasoline to erasing rules for power companies to shift away from coal. It would be able to defend those changes in court against environment advocates and Democratic states if the president wins election.

“The biggest impact of a second term of a Trump administration would just be more lost time,” said Trevor Houser, a partner at Rhodium Group. “It would be more time in which emissions weren’t really declining when they really needed to be.”

The concentration of climate-heating greenhouse gases is at a record high, according to a report from the UN’s World Meteorological Organization. The planet is already 1C hotter than it was before industrialization.

A train of loaded coal cars heads to the Oak Creek power plant in Oak Creek, Wisconsin, earlier this month. Photograph: Tannen Maury/EPA

Three-quarters of the commitments made by countries under the international Paris agreement are “totally inadequate”, according to a comprehensive expert analysis. Temperatures are still rising and the world is “gravely” unprepared for disasters, crop failures, coastal flooding and heatwaves, according to another review.

Under Trump, the oil and gas industry contributing heavily to the climate crisis is thriving. Oil and gas-related industries in the US are planning to build 157 new or expanded plants and expand drilling over the next five years – releasing as much greenhouse gas pollution as 50 new coal-fired power plants, according to a report from the Environmental Integrity Project.

As the technology for retrieving oil and gas has advanced, with hydraulic fracturing, the cost of production has plummeted. The US is now a net exporter of oil products.

Much of the expansion expected would be for feedstocks to make chemicals and plastics, explained Courtney Bernhardt, the group’s research director.

Bernhardt said the oil and gas expansion would erase about 75% of the progress in the power sector since 2012.

“The US is already struggling to meet climate commitments and transition to a low-carbon future,” Bernhardt said. “This analysis shows that we’re heading in the wrong direction and really need to slow emissions growth from the oil, gas and petrochemical industries.”

It’s not just climate change that is getting worse. Trump has loosened rules for clean water and air and safer chemicals. Air quality is already eroding, linked with 10,000 additional US deaths over two years.

Democrats, meanwhile, are offering a starkly different future for the environment. The House energy and commerce committee last week introduced a discussion draft of legislation for the US to achieve a “100% clean economy” by 2050.

In the race against Trump, all the major Democratic candidates have similarly pledged to seek at least net-zero emissions by 2050.

The League of Conservation Voters’ called the House committee effort encouraging and said the announcement “is further proof that elections have consequences”. But other groups were critical, saying the plan would not transition away from fossil fuels fast enough.