Britain will formally exit the EU at the end of this month.
That date — Jan. 31 — marks the beginning of a transition period that will last until the end of the year, when lawmakers in the EU and Britain hope to hammer out deals on trade, law enforcement security, data-sharing, and more.
One small piece of the puzzle will be how the U.K. funds scientific research, and how easy or hard it will be for scientists — who traditionally are part of an international, mobile workforce — to work outside of their home countries.
Scientists in the U.K. have been feeling the impact of Brexit uncertainty for years already. Lars Boehme, a marine ecologist at the University of St. Andrews in Scotland, noticed the impact of Brexit right away.
"It started on the day of the referendum," he said in the summer of 2016.
Boehme was in the middle of writing a proposal for European grant funding, and when the news broke that the U.K. had voted to divorce itself from Europe, Boehme and his collaborators decided to take his name off the grant proposal.
They figured they might not win the competitive European Union grant if a U.K. professor was listed as lead researcher.
"It's our gut feeling that if they think you are out of the EU next year, then they don't want to fund you for the next five years," Boehme said.
In the end, it will take much longer than a year for the U.K. to fully leave the EU, but since the vote, the uncertainty surrounding Brexit has led many researchers to make the same calculation about applying for funding.
U.K. applicants for the EU's biggest pot of research funding, called Horizon 2020, fell post-referendum. Funding from that source for U.K. researchers dropped by nearly half a billion dollars between 2015, before the Brexit vote, and 2018.
At his university, Boehme also saw applications from potential PhD students from Europe plummet.
"In the past, I had maybe half of the applicants coming from the EU. And in the last two years, I had no applications from the EU," Boehme said. "It's a dramatic loss in numbers."
If it continues, this drop could mark the beginning of a significant workforce trend in the U.K., where almost a third of academic researchers come from abroad and 17 percent from the European Union, according to figures from the Royal Society, Britain's national academy of science.
"It's a very significant fraction," said Venki Ramakrishnan, president of the Royal Society.
Ramakrishnan argues that an international workforce is a good thing.
"Science should be free-flowing," he said. "Science depends on the exchange of ideas, on the exchange of people who bring the ideas."
Ramakrishnan points to how American science flourished after World War II, when researchers flocked to the U.S. to escape war-ravaged Europe. And how big science projects in Europe — like those undertaken at the largest particle accelerator in the world, which spans the border between France and Switzerland — have spurred major new discoveries.
"That just goes to show you how science is, if you have free-flowing information, free-flow of people, that just accelerates science worldwide."
As Brexit becomes a reality, science groups want to keep that flow of people and money as open as possible. Ramakrishnan is optimistic based on what he's hearing from Boris Johnson's government.
In August, the prime minister said he would turn the U.K. into a magnet for scientists from around the world, in part by making it easier for them to get work visas.
Queen Elizabeth made a similar statement in her Queen's Speech last month, saying "a modern, fair, points-based immigration system will welcome skilled workers from across the world to contribute to the United Kingdom's economy, communities, and public services."
So far, Johnson's government has announced an expansion in the number of fellowships that can offer a quick visa for visiting scientists. But he has yet to deliver on other promises he made, such as lifting the cap on visas for highly skilled workers, or streamlining the visa application process for scientists.
The Royal Society is working on a set of recommendations to ease immigration worries for foreign scientists and is advocating for the U.K. to pay its own way in European research funding programs so U.K. researchers can still take part.
But Ramakrishnan fears that if the Brexit negotiations don't go well, Britain could earn an image as insular and unwelcoming to new scientific talent.
"I'm a nonwhite American who came to Britain relatively late in life, and there are not many countries that would take someone who's an outsider, and make them the president of their national academy," Ramakrishnan said.
"In a way, I reflect the traditional openness of Britain and British science. And that is what I hope the country preserves going forward."
It will take at least a year to hammer out the details of Brexit. But the ordeal has already had lasting impacts on science. Aside from drops in EU funding, the U.K. is also attracting fewer EU scientists on a fellowship program designed to increase international mobility for scientists.
For oceanographer Bastien Queste, Brexit changed his career trajectory.
Queste spent 15 years in Britain, but just left his position at the University of East Anglia for a job at the University of Gothenburg in Sweden.
"I wasn't originally looking for jobs at this period," he said. "I had another three years left on my contract."
But then the Brexit vote happened. Queste is French and said he was a little worried about visa issues. But his biggest concern was access to that coveted European research funding.
"It's a competitive career, and you move forward by getting papers and getting research grants," Queste said, "and if you don't have the funding opportunities, it's hard to go out there and do good work."