Labour did introduce some legislation/measures to combat climate change, most notably the Climate Change Act in 2008, also 'feed in tarrifs'. I am not sure of the top of my head what the Tory governments have done though?
However I would say it is a matter of fact that a Labour government is...
What should people do, if anything, if asking people to have less/no children doesn't significantly affect population increase?
Either you do nothing or you do something, what would you do?