I just finished reading The Man Who Swam the Amazon 3,274 Miles on the World's Deadliest River by Matthew Mohlke and Martin Strel. Click http://www.martinstrel.com/ This is reason enough to participate in The Jeju Big Swim. People do things that are difficult for solutions that may be out of one's control. But no need to worry about what the future holds regarding personal control before the fact. Just do.
There are environmental problems that are concrete and need addressing. Before they can be addressed, awareness has to be raised. Two problems that might be the most overlooked and serious heading into the next 50 years are overfishing and plastic waste in all waterways, which start in the rivers of the world eventually dumping into the oceans and collecting in vast garbage patches thousands of miles in area. The food chain suffers, and ultimately, we suffer. Do the research yourself.
1.) For overfishing, watch "The End of the Line" http://endoftheline.com/ Take a look at the claims made by the film and personally decide if this is a problem.
2.) Plastic garbage may be the most hidden and troublesome environmental problem ever to occur. And from the problem has evolved a new science: flotsametrics. Check out http://flotsametrics.com/
Less talk, more action people.