Florida, as seen from the ISS, is one of the most vulnerable states to climate change - but it's ironically unlikely to ever join the Alliance. NASA

Trump may have decided to pull out of the Paris climate agreement, but his administration is looking quite isolated on this issue. Thousands of companies, universities, world leaders and a clear majority of the population of the planet have declared that they will abide by the climate accord with or without the federal government.

This also includes the US, of course: plenty of politicians, from mayors to Governors, have pledged to abide by their carbon-cutting targets regardless. Three of them – the Democratic Governors of Washington, New York and California – have formed a Climate Alliance, a group designed to help individual states coordinate their climate advocacy actions.

Although it was seen as fairly unlikely that any Republican states would join the Alliance – primarily because of the sort of funding many GOP lawmakers receive – it appears that Trump’s actions on Paris have crossed a line. At the time of writing, two Republican Governors – those of Massachusetts and Vermont – have joined the Alliance.

“As the Commonwealth reiterates its commitment to exceeding the emission reduction targets of the Paris Climate Agreement, today we join the US Climate Alliance to expand on our efforts while partnering with other states to combat climate change,” Massachusetts Governor Charlie Baker said in a statement.

Baker added that he expects bipartisan cooperation “to protect the environment, grow the economy and deliver a brighter future to the next generation.”

Governor Phil Scott of Vermont said that “growing our economy and protecting our environment by supporting cleaner and more affordable energy and transportation choices can go together.”

In total, this brings the total number of states joining the “green wall” to nine, with the Democratic Governor-controlled states of Oregon, Rhode Island, Connecticut, and Hawaii making up the rest.

Blue = Alliance states; Green = states likely to join. thekiller160/Wikimedia Commons; CC BY-SA 4.0

The West Coast states, plus New York, have long been pioneers of low-carbon infrastructures, and Hawaii has been making some inroads – but their efforts combined will make a huge difference to cutting the country’s carbon emissions.

All in all, these member states represent 27 percent of the US population and 31 percent of US GDP. They also make up 14.3 percent of the total US carbon dioxide emissions. Essentially, at present, more than a quarter of the US is still going along with the Paris agreement, which will hold more weight than most individual nations.

The Alliance will likely not stop at these nine states either. Several others have also expressed interest or seem likely to eventually join, although they’ve yet to make an official declaration. These include the Democratic Governor-run states of Colorado, Delaware, Minnesota, Montana, North Carolina, Pennsylvania, Virginia and Washington DC.

The Republican Governor-run states of Ohio, Maryland and New Jersey have also hinted that they wish to join, as has Puerto Rico.