The UCU union has launched a campaign demanding the government puts forward a plan to protect universities and colleges.
The “Fund the Future” campaign wants the government to provide financial guarantees to protect education and jobs.
The union has called on others to support the campaign and contact their local MPs over the issue.
In a letter to Boris Johnson, UCU general secretary JoGrady warned that “an estimated 30,000 jobs in higher education are at risk”.
She highlighted a report by London Economics that said universities could face £2.5 billion losses of income from tuition fees and teaching grants. A fall in the number of international students coming to study in Britain could cost the sector around £2 billion.
And the Association of Colleges has estimated that further education could lose up to £2 billion.
Grady said the government has so far taken “very limited actions” that are “inadequate” to protect jobs and education.
“We desperately need a clear and coherent plan that guarantees funding and jobs,” she said.