Absolutely nothing. The amount of difference
you as an individual can make by choosing 'eco-friendly' products is minute, negligible in comparison to the emissions of industry.
Even just the ability to inform yourself
which products are produced with limited CO2 emissions is difficult. You'll look for some particular label on the product showing some independent approval of its 'green status', and the conditions required for this approval is very lax and encompasses all sorts of issues as well as CO2 emissions. For example, free range eggs have a much bigger carbon footprint than battery farmed eggs (
2007, Cranfield University)), but the free range eggs will get the 'organic' stamp of approval. This may represent a moral dilemma within the green movement, as 'ethical' farming practises are not necessarily sustainable and some of the dogma surrounding the green movement and 'organic' foods is incompatible with solutions to anthropogenic climate change (as certain decidedly 'non-green' topics, such as nuclear power, genetically modified crops, and nanoscience may play an important part).
And locally sourced produce is not necessarily good either, if it's grown in a climate it isn't used to. Many products now display the 'food miles' to give an indication of how far the product has flown from its origin. But the actual contribution to CO2 emissions from transportation can be very low (
2008, New Scientist)), and some foods grown locally can have much bigger carbon footprints than those overseas (and bigger than that of the transportation as well).
So actually working out which product has less CO2 emissions is very difficult, very expensive, the contribution made is tiny, the underlying problem of electricity generation by burning fossil fuels still remains, and most importantly there's no actual incentive for
you to do anything.
In the US and western Europe, climate change probably isn't going to affect us until later this century, after our lifetimes. It's certainly affecting
some people right now, but these are poor people in poor countries that we never cared about before and we're probably not going to start caring now. Relying on the charity of the masses is an unreasonable expectation of a capitalist society.
The only fundamental long-term solution to a global problem is some sort of economic sanction based on an international political treaty between
governments.
The most important thing you can do is
vote. Not change what coffee you drink, or what car you drive, but simply to
vote on matters that affect climate change and inform your friends and get them to vote on those matters too. The climate change deniers currently have some footing in public opinion, but no real political influence. If left unchallenged, they may well find some political footing and cause a great step backwards for science and disrupt any reasonable agreement on a very real global challenge.