Bill Thompson's fight to stop offshore wind farms was once confined to the tiny U.S. state of Rhode Island where he lives.

Today, he is part of a global movement. In April, Thompson, who is director of the activist group Green Oceans, got an email from a fellow anti-offshore wind group more than 10,000 miles (16,000 kilometers) away called Responsible Future (Illawarra Chapter). They were looking for advice on ways to combat projects off Australia’s southeast coast.

In August, he got another request, this time from French group PIEBIEM fighting projects in Brittany. "It's always nice to know that other people are thinking the same way you are," he said. These groups are among a dozen or more local activist organizations across the U.

S., Europe and Australia who said they have begun sharing tactics, talking points and other resources in their common mission to derail offshore wind — a development they hope will transform what was once a disorganized scattering of local activists into an increasingly sophisticated global network. Several anti-offshore wind groups said they believe governments and wind developers, such as Orsted, Avangrid and Shell, are downplaying the environmental damage caused by projects as they promote the renewable energy source as a solution to climate change.

In most cases, the groups are looking to anti-offshore wind activists on the U.S. East Coast for advice, citing their years of success in slowing or cutting the size of major projects, eroding p.