U.K. researchers and their organizations have reacted with dismay to last night’s decision by the U.K. electorate to leave the European Union. Science and technology were not a major talking point during the referendum campaign, but numerous scientists and research organizations urged voters to preserve the United Kingdom’s E.U. membership.

“This is a really serious worry for me. … I fear desperately for U.K. science,” says Steve Cowley, director of the Culham Centre for Fusion Energy near Oxford, U.K., home of the Joint European Torus (JET), a fusion reactor that is one of a handful of European facilities sited in the United Kingdom. “There is no way I can pretend to be anything other than dispirited and disappointed," says Simon Wessely, president of the Royal College of Psychiatrists in London. "Whilst I don’t believe that people voted to leave the E.U. with science and health foremost in their minds, I fear that the consequences for both will be serious over the coming year unless we take firm and decisive action now.”

"Personally, I’m a bit bewildered and ashamed by my own country. I never thought this would happen," the European Commission's former science adviser, Anne Glover, who is now vice principal for external affairs and dean for Europe at the University of Aberdeen in the United Kingdom, tells ScienceInsider.

Although the amount of funding channeled through Brussels to scientists is small compared with national grant systems, the United Kingdom has generally done very well in the race for European money. Europe’s Horizon 2020 research program plays an important role in fostering cross-border collaboration and boosting research in scientifically less well-developed countries. The European Union also guarantees free movement of researchers across the continent and regulates the pharmaceutical industry and clinical trials.

“The U.K.’s vote to leave the European Union is understandably causing considerable uncertainty for British science and research," Jeremy Farrar, head of the Wellcome Trust biomedical research foundation in London, said in a statement. "Wellcome is committed to ensuring that science and research are properly considered in the exit negotiations, that existing public funding is maintained and that international collaboration is not hindered.”

"It’s a bad day for Europe, the U.K., and European science. I think the E.U. funding was such a significant part of U.K. science funding. I think this will really lead to a dramatic drop in funding, and it will not be made up by charities or national government. This will disproportionately affect young European researchers, who are largely funded on soft money. I find this extremely worrying,” says Helga Nowotny, a former president of the European Research Council and professor emerita of social studies of science at ETH Zurich in Switzerland.

Around the United Kingdom, foreign scientists were left wondering this morning what their future in the United Kingdom will be once the divorce is complete and freedom of movement becomes restricted. The Imperial College London (ICL) acknowledged the uncertainty in an email to staff and students today that said: "We are urgently seeking clarification from the government on the visa and fee status of non-UK European Union students, as well as other key policy areas for the College as the UK negotiates its future relationship with Europe."

For the first few months at least, nothing will change in the United Kingdom’s relationship with Europe. To start the process of withdrawal, the U.K. government must invoke Article 50 (the exit clause) of the Lisbon Treaty. Negotiating the terms of withdrawal and untangling financial ties with Brussels is expected to take 2 years—no country has quit the European Union before, so it is unknown territory. Following Prime Minister David Cameron's announcement this morning that he will resign in the fall, the decision to invoke Article 50 will likely wait till a new Conservative Party leader is elected in September or October.

Researchers will be hoping that the United Kingdom decides to continue participation in Horizon 2020, which it can do by becoming an “associate” and paying a share of the program’s costs in proportion to gross domestic product. Membership of organizations such as CERN, the European Space Agency, the European Southern Observatory, and the European Molecular Biology Laboratory will be unaffected because they operate outside the E.U. framework. “The U.K. will try to obtain an association agreement, but this will take time. And I don’t know what the overall conditions will be to grant them the same status,” Nowotny says.

A withdrawal from the European Union almost certainly means that the United Kingdom can no longer host the European Medicines Agency (EMA), the bloc's medical watchdog, currently headquartered in London's Canary Wharf. An EMA spokesperson today declined to discuss the Brexit's implications, but speculation has already begun about which of the remaining 27 member states might host the agency, which has 890 employees.

When it comes to drug regulation, the European Union does not have to go it alone. EMA also serves Iceland, Norway, and Liechtenstein, three countries that aren't in the European Union but are part of the European Economic Area. The United Kingdom could go that route, too. There has also been speculation that it might somehow join forces with the U.S. Food and Drug Administration. Whatever the outcome, the Brexit may spell additional headaches for Europe's pharmaceutical industry. "Our companies will have to make major efforts to overcome the new bureaucratic obstacles," the German Pharmaceutical Industry Association said in a statement today.

The role of the United Kingdom in European fusion research is also in question. JET is operated by the Culham Centre on behalf of Euratom, the nuclear arm of the European Union. Its current contract runs out at the end of 2018 and the Brexit vote means that there is now uncertainty over what happens after that. “They can’t move JET to Denmark [for example],” Cowley says. In 2019 and 2020, JET researchers are planning key experiments in support of the international ITER fusion project in France (currently under construction). “We’ve got to do it, having spent all this money” making JET as ITER-like as possible, Cowley says. “To have a €2 billion piece of kit and throw it away because no agreement can be reached would be foolish in the extreme.”

“Even though it might not be easy, I am confident that we can find ways to continue the very successful collaboration with the U.K. This is a process that now needs to be started,” says Tony Donné, head of EUROfusion, a collaboration of European fusion labs that carries out research on JET on behalf of Euratom.

Others, too, expressed their determination to remain prominent on the international scene, even while their country is in retreat. "Imperial is, and will remain, a European university, whatever your view of the referendum outcome," ICL's email today said. "We are very proud of the innovations, ideas and inspiration that come from the European members of Imperial’s global community… We will vigorously defend our international values if they are threatened and will continue to think and act internationally."

With reporting by Martin Enserink, Kai Kupferschmidt, Tania Rabesandratana, and Gretchen Vogel.