As US President Donald Trump unveils his plans to roll back his predecessor Barack Obama's climate change policies and end his "war on coal", it's worth a reminder the basic science has been settled for decades no matter what politicians do.

The Earth had an "effective temperature" that was a balance of solar radiation it received and what it radiated back to space, I learnt as a Harvard freshman in my Science A-30 atmosphere course.

Our atmosphere was "an insulating blanket" keeping the planet's surface at about 298 degrees Kelvin (25 degrees) compared with space's 3 degrees K, according to class notes I found while sorting some old boxes.

Alter the amount of carbon dioxide in the atmosphere - back then it was rising at 1.2 parts per million a year or less than half the present rate - and you would warm it up.

Other consequences included melting tundra that would release the more potent greenhouse gas, methane, while oceans would become more acidic as they absorbed more carbon from the air.

'Exceedingly bad'

Among my notes was a 1983 paper by the US National Research Council that argued global warming impacts from burning fossil fuels on poorer nations "could be exceedingly bad news".

The paper warned of "claims for compensation as a matter of right may emerge" from affected populations, requiring "welfare aid".

Those lecture notes were unremarkable - if alarming - decades ago.

Since then, politicians in nations such as the US and Australia - often at the bidding of fossil industry donors and certain media outlets - have seeded sufficient voter doubt to stymie the introduction of consistent policies needed to curb carbon emissions.

Trump's rollback of US policies fit the pattern even if they face fierce legal battles and are likely to be delayed or made less radical in the process.

And his efforts to open up federal lands to coal miners and scrap other limits on coal-fired power plants are unlikely to lead to a massive jump in coal output because gas and increasingly renewable energy are already pricing coal out of the market.

As in Australia, Trump will find investors are wary of building new coal-fired power that may face a future carbon price or other curb.

Trump has so far failed to fulfil his campaign promise to pull the US out of the Paris climate pact. His executive order signed on Tuesday, though, will make it harder for America to meet its promise to cut emissions by 26 per cent on 2005 levels by 2025. (Australia has a similar goal - but is aiming to reach it five years later.)

The damage may be mostly economic in the short term if American support for renewable energy research is cut - as the Trump budget seeks - and the energy market gets tilted more in favour of fossil fuels over clean sources such as wind and solar.

China, the world's leader in most renewable energy rollout, will likely extend its lead.

Science moves

Some politicians, mostly on the right, in places such as Australia are already lining up to say their country should follow the US in depleting already insufficient efforts to tackle climate change.

National pledges made in Paris in 2015 fall far short of keeping global temperature increases to 1.5-2 degrees above pre-industrial times. Even if fully implemented - an outcome make less likely by Trump's policies - warming is headed towards three degrees or more by century's end.

For the planet, the science hasn't shifted but only become more refined.

Each rise of one degree in the atmosphere lifts its capacity to hold moisture by 7 per cent. That means the potential for bigger storms increases, as any first-year lecturer will tell her students.

Big storms such as Cyclone Debbie are projected to become more common, with a bigger clean-up bill for all of us to pay - even if media commentators and most politicians would prefer not to mention the link.

The fact the world's coral reefs - including our Great Barrier Reef - will largely be long gone if the temperature rises anywhere near 3 degrees - and we are one degree there already - is also well understood to scientists.

More complex changes are also afoot with new research regularly improving our partial understanding of the consequences of climate change.

These include signs that the jetstream over the northern hemisphere is weakening, allowing weather patterns to get stuck more often - bringing more extreme warm and cold spells.

Science, in other words, is moving on. It's time we demanded our politicians kept pace.