(This accompanies SPECIAL REPORT-Online activists are silencing us, scientists say)

LONDON, March 13 (Reuters) - Social media platforms have supercharged battles over scientific evidence on a range of issues, including:

Climate Change

A United Nations panel of climate scientists says it is at least 95 percent certain that human activity is the dominant cause of climate change since the mid-20th century. Climate sceptics challenge that consensus daily on social media, arguing that fluctuations in global temperatures have occurred in previous era and are natural events.

Vaccines

The World Health Organization has now ranked "vaccine hesitancy" as one of 2019's top 10 global health threats. Outbreaks of measles, for example – which had been all but wiped out in many wealthy countries thanks to the introduction of preventative vaccines – are now becoming more common again. Anti-vaccine groups use social media to fuel doubts about vaccines, often citing concerns about side effects or recycling long-debunked suggestions about links to autism.

Genetically Modified Organisms

Hundreds of scientific studies have shown genetically modified foods to be safe to eat and GM crops are widely grown across the world, including in the United States. Supporters say GM crops can help feed a growing world population with cheaper, more plentiful food. But opponents believe they are risky and say tampering with crops' genes could have unknown future impacts.

(reporting by Kate Kelland; editing by Janet McBride and John Blanton)

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