Barack Obama insisted forcefully before his newly empowered opposition on Tuesday that he would hold the line against attacks on his domestic and international climate agenda. But even though he called out climate deniers once again, the president offered no concrete sign of new initiatives on the horizon in his remaining two years in power.

After repeatedly using his executive authority to advance climate measures, Obama pivoted in his State of the Union address to making sure that Republicans did not undo what he has sought to accomplish on climate change.

That crucially applies to the international arena, where Obama recommitted America to help lead efforts in forging an international climate deal.

“I will not let this Congress endanger the health of our children by turning back the clock on our efforts,” Obama said. “I am determined to make sure American leadership drives international action,” Obama said.

In the last 18 months, Obama has used his executive authority to introduce the first rules cutting carbon pollution from power plants, a joint US-Chinese emissions cutting deal, a pledge of $3bn to an international climate fund for developing countries and – just last week – new curbs on methane emissions from the oil and gas industry.

As on other high-visibility occasions, Obama used the speech to re-affirm climate change is occurring and to stick it to Republicans for climate denial. That will score Obama points with environmental groups heading into a year that set to culminate with climate talks in Paris.

In June 2013, when rolling out his climate action plan, Obama dismissed climate deniers as members of “the Flat Earth society”.

In Tuesday night’s address, he stepped on the Republicans’ new “I am not a scientist” meme, which casts doubt on climate change while avoiding outright denial.

In one of his best lines of the night, Obama said: “I’ve heard some folks try to dodge the evidence by saying they’re not scientists – that we don’t have enough information to act. Well, I’m not a scientist, either. But you know what? I know a lot of really good scientists at Nasa, and Noaa, and at our major universities.”

Calling out climate deniers – and appropriating Republican talking points – was popular with environmental groups. But they were lukewarm about his other climate remarks.

Greenpeace applauded the tough talk and Obama’s some of recent initiatives – but said he had still not done enough.

“The president has worked to address climate change in certain areas,” the group said in a statement. “Unfortunately, these advances are overshadowed by a weak proposed rule on methane emissions and subsidies for the continued extraction and export of climate-polluting fossil fuels. Advancements can no longer be negated by setbacks elsewhere. Addressing global climate disruption requires immediate global action.”

The World Wildlife Fund said: “Tonight’s words not only signal that climate change is a legacy issue for the President, but it is also a clear and present danger to America’s national security. Now, he must continue his push to reduce the United States’ greenhouse gas pollution and work with Congress to fully fund our promised fair share of the Green Climate Fund.”

Republicans, as might be expected, objected to Obama’s comments. “The president’s war on fossil fuels and nuclear energy,” said Jim Inhofe, the new Republican chair of the Senate environment and public works committee.

However, Inhofe held back from dismissing climate change as a hoax – as he has done in the past – arguing instead that Obama’s climate plan would be ineffective.

“The president’s climate agenda would only reduce CO2 concentration by less than one-half of a percent; it would only reduce the average global temperature by less than 2/100th of a degree; and it would only reduce the rise of sea levels by 1/100th of an inch – or the thickness of three sheets of paper.”

Unlike previous addresses of this magnitude, Obama did not tout his “all of the above” energy strategy or play up the expansion of oil and gas drilling through fracking technology. Indeed, the president gave fairly short shrift to fossil fuels or clean energy – except for a passing reference to “converting sunlight into liquid fuel”.

He made only indirect reference to the Keystone XL pipeline, suggesting the Republicans were misguided to focus on the project: “Let’s set our sights higher than a single oil pipeline.”

But after the fast pace of climate initiatives, it seemed Obama has just about exhausted the use of his executive authority to fight climate change in the US.

Recapping November’s breakthrough emissions deal with China, Obama hinted at a way forward with international negotiations.

“Because the world’s two largest economies came together,” he said, “other nations are now stepping up, and offering hope that this year the world will finally reach an agreement to protect the one planet we’ve got.”

The president offered no specifics on what he might do in the remaining two years in the White House – beyond what is already becoming obvious in his showdown with Congress over the Keystone XL pipeline, debate on which was expected to reopen on Thursday.

For now, at least, Obama has no intention of backing down.