As Congress returns from recess, a major piece of defence legislation is up for consideration that could prove to be invaluable for those looking to the US to fight climate change.

The annual National Defence Authorisation Act (NDAA), which specifies defence spending as well as foreign policy goals, will be debated in the Senate and the fact it normally gets bipartisan support means it becomes a lightning rod for different policies. This year, one of the amendments - if it is voted through - calls on the Pentagon to produce a report on the security risks posed by climate change.

It will now be up to the Senate to pass the act with or without the Langevin amendment - but if it passes the signal it sends will be at odds with those put out by the Trump adminsitration up unil now.

Debate had been opened on the bill prior to the recess, however it was the same day as a crucial vote on the Republican replacement for Obamacare and debate quickly shifted back to healthcare on the Senate floor.

Donald Trump has begun the formal process to withdraw the US from the Paris Agreement on climate change, a global accord signed by nearly 200 countries to reduce global greenhouse gas emissions and help poorer countries adjust to an already-changed planet.

The move was criticised by several countries’ leaders and in response nearly a thousand CEOs and American mayors vowed to keep fighting climate change, even without the federal government’s help.

At the same time, Mr Trump also increased the US defence budget and recently requested a troop surge for Afghanistan while proposing dramatic cuts to diplomatic functions at the State Department.

These may seem like unrelated issues but as Francesco Femia, President of the Washington-based Center for Climate and Security, reminded The Independent: “the Pentagon has, since at least as far back as 2003, taken climate change seriously.”

At least four of Mr Trump’s top military counsel: Defence Secretary James Mattis, Assistant Defence Secretary Lucian Niemeyer, Secretary of the Navy Richard V Spencer, and Vice Chairman of the Joint Chiefs of Staff Paul Selva have all “reaffirmed” the connection, according to Mr Femia.

Even the 2014 Quadrennial Defence Review, done ahead of the December 2015 Paris Agreement, stated that climate change “will aggravate stressors abroad such as poverty, environmental, political instability, and social tensions – conditions that can enable terrorist activity and other forms of violence.”

However, the Trump administration’s seemingly conflicting policies makes it appear as if it does not see the connection. In the latest draft of the NDAA however, there is hope that Congress does.

In June 2017, the House voted in the Langevin Amendment to the NDAA in what Mr Femia called “the most significant bipartisan action on climate change in about a decade.”

The Amendment, named after Congressman Jim Langevin of the Armed Services Committee, would require the Defence Secretary to provide a report to Congress detailing ten military bases or installations in each service that are facing a threat from climate change within the next 20 years- specifically sea level rise, erosion, drought, increased frequency of natural disasters.

If passed in the Senate it would also require “a discussion of the climate-change related effects...including the increase in the frequency of humanitarian assistance and disaster relief missions and the theatre campaign plans, contingency plans”.

France trolls Trump by annotating White House video about the Paris Agreement

Ohio University Professor Geoff Dabelko told the Wilson Center’s New Security Beat blog that the bipartisan support garnered by the Langevin amendment is just the first step in a process to “heal the political divide on climate change.”

“The security community does not have the luxury to add or drop threats to security when control of Congress or the White House changes hands,” he noted.

He explained, however, that this the “exact opposite” of what the Trump administration has been demonstrating the last seven months.

Part of the criticism of the Langevin amendment was that focusing on climate change - the vast body of science which even Mr Trump’s head of the Environmental Protection Agency Scott Pruitt and Energy Secretary Rick Perry have called into question - would detract from national security properties.

As Representative Liz Cheney - daughter of former Vice President Dick Cheney - said during the House floor debate: “There is no evidence that climate change causes war...North Korea is not developing nuclear tipped ICBMs because the climate’s changing. ISIS and al Qaeda are not attacking the West because of the weather.”

However, that may not be entirely true though academic researchers are still arguing over this climate-conflict connection - particularly when it concerns the sequence of drought, food insecurity, migration, and an outbreak of conflict over more scarce resources.

Republican Representative Scott Perry tried and failed to pass an amendment that essentially said enough federal agencies address climate change that the Defence Department should not be concerned with it.

Several of his party colleagues noted however that the Langevin Amendment is simply a report and information about potential threats is not detrimental.

Neil Bhatiya, a researcher at the Center for a New American Security, also argued against Ms Cheney and Mr Perry’s statements when it comes to focusing on one type of security threat.

He told The Independent that “the military establishment is capable of both responding to immediate threats” like Isis, the Taliban, and North Korea while simultaneously “preparing for future threats like social and political instability arising from climate change impacts.”

Mr Bhatiya said that though “anything is possible” in this political climate, he feels there are more pressing political issues that “are far more controversial” surrounding this year’s NDAA that the climate change amendment will be safe from being taken out of a Senate draft.

Given Mr Trump’s proposed cuts to the US Coast Guard, the maritime security agency which is also tasked with ocean preservation, some experts fear it could still be part of the debate.

10 photographs to show to anyone who doesn't believe in climate change Show all 10 1 /10 10 photographs to show to anyone who doesn't believe in climate change 10 photographs to show to anyone who doesn't believe in climate change A group of emperor penguins face a crack in the sea ice, near McMurdo Station, Antarctica Kira Morris 10 photographs to show to anyone who doesn't believe in climate change Floods destroyed eight bridges and ruined crops such as wheat, maize and peas in the Karimabad valley in northern Pakistan, a mountainous region with many glaciers. In many parts of the world, glaciers have been in retreat, creating dangerously large lakes that can cause devastating flooding when the banks break. Climate change can also increase rainfall in some areas, while bringing drought to others. Hira Ali 10 photographs to show to anyone who doesn't believe in climate change Smoke – filled with the carbon that is driving climate change – drifts across a field in Colombia. Sandra Rondon 10 photographs to show to anyone who doesn't believe in climate change Amid a flood in Islampur, Jamalpur, Bangladesh, a woman on a raft searches for somewhere dry to take shelter. Bangladesh is one of the most vulnerable places in the world to sea level rise, which is expected to make tens of millions of people homeless by 2050. Probal Rashid 10 photographs to show to anyone who doesn't believe in climate change Sindh province in Pakistan has experienced a grim mix of two consequences of climate change. “Because of climate change either we have floods or not enough water to irrigate our crop and feed our animals,” says the photographer. “Picture clearly indicates that the extreme drought makes wide cracks in clay. Crops are very difficult to grow.” Rizwan Dharejo 10 photographs to show to anyone who doesn't believe in climate change Hanna Petursdottir examines a cave inside the Svinafellsjokull glacier in Iceland, which she said had been growing rapidly. Since 2000, the size of glaciers on Iceland has reduced by 12 per cent. Tom Schifanella 10 photographs to show to anyone who doesn't believe in climate change A river once flowed along the depression in the dry earth of this part of Bangladesh, but it has disappeared amid rising temperatures. Abrar Hossain 10 photographs to show to anyone who doesn't believe in climate change A shepherd moves his herd as he looks for green pasture near the village of Sirohi in Rajasthan, northern India. The region has been badly affected by heatwaves and drought, making local people nervous about further predicted increases in temperature. Riddhima Singh Bhati 10 photographs to show to anyone who doesn't believe in climate change A factory in China is shrouded by a haze of air pollution. The World Health Organisation has warned such pollution, much of which is from the fossil fuels that cause climate change, is a “public health emergency”. Leung Ka Wa 10 photographs to show to anyone who doesn't believe in climate change Water levels in reservoirs, like this one in Gers, France, have been getting perilously low in areas across the world affected by drought, forcing authorities to introduce water restrictions. Mahtuf Ikhsan

Mr Trump has repeatedly expressed his commitment to the US coal and manufacturing industries, specifically the workers in those fields.

Coupled with messaging that addressing climate change would have a negative economic impact and several EPA and State Department scientific advisors resigning or being pushed out - political pressure to not include the Langevin amendment or similar language on climate change could mount.

It had done so in the most recent iteration of the healthcare debate, with many Republican Senators initially speaking out against the Trump administration.

However, save for a few, they fell into party line and voted with Mr Trump.

One saving grace may be the deteriorated relationship between Senators Mitch McConnell, John McCain, Lindsay Graham, and Jeff Flake - all of whom have been on the receiving end of Mr Trump’s public, Twitter and private ire according to reports.

“The fact that Chief of Staff John Kelly has been involved in previous [Defence Department] efforts to understand climate impacts as the former Commander-in-Chief of [Southern Command] may ultimately be encouraging on the front,” as well Mr Bhatiya said.

Of course, even with Mr Mattis and Secretary of State Rex Tillerson’s previous comments regarding the need to address climate change, Mr Trump still withdrew the US from the Paris accord.

Mr Femia pointed out that the report required by the Langevin Amendment would also highlight how the civilian communities - both in the US and abroad - are affected by climate change, a selling point for some Senators.

“If this Administration is serious about improving American infrastructure, and supporting our military, it will have to be serious about the climate resilience of that infrastructure” which is not limited to just military bases, Mr Femia said.