Right-wing lunatics get elected -> things get worse -> people vote for neoliberals who promise to make everything better -> things fail to get better -> Conservatives promise to go even harder this time -> repeat forever.
There was a neat little meme going around illustrating the cycle and pointing out which part of it Canada, the UK, and the USA were in, but I can't find it right now.
Most of the mercury that ends up in the environment due to coal is from emissions that happen when it is burned. It settles all over the land and eventually gets washed into the ocean.
Building renewables does not solve this problem; only ending the use of coal will do that. For now, worldwide coal use remains near record highs.