I wrote about your excellent question on my blog.
http://systemsaviour.com/2011/11/11/slashdot-iea-warns-of-irreversible-climate-change-in-5-years/
My answer: I already am doing something about it. There’s room for improvement, but I know I must be doing better than 99% of Australians. Here’s how:
* My wife and I don't have kids. I'll probably get modded down for saying this, but IMO there can be no greater selfishness. It may be said that the significance of all of our environmental problems are directly related to now 7 billion people on this planet. It's been known for decades that the Earth's population growth is unsustainable, and yet here we are.
* We don't own a car. Easily achievable. I know lots of people say "but I live in an area where there is no public transportation" or "I live too far away from work to ride" - but that's because they're selfish. They were not considering the environmental impact of their decision to live in such a location. My wife and I on the other hand have always expected we will not be relying on a car, and have planned our lifestyle accordingly. As such, it is no problem.
If more people chose such a lifestyle, maybe councils around the country and the world would better cater for the needs of people like ourselves who do not drive. For example, the detours I need to take to ride to work are ridiculous - just because my local council didn't pay any significant consideration to cyclists when planing and paving the roads.
* Don't rely on an air-conditioner or heater. Until the Australian summer heat wave of 2009, my wife and I had never owned an air-conditioner. We did buy a portable unit for those few weeks with over 40-degree heat since our apartment tends to get very hot as it is, but I don't think we've ever used it since. Under ordinary circumstances, we have no problem adapting by simply changing to lighter clothing. When it's cold, we wear a jumper and jacket, or dressing gown for night time. If that's still not enough, we'll just get a scarf or even a blanket until we're comfortable. Use thick curtains, keep the windows closed, etc. It's all common sense stuff - and it works.
Contrast this to basically any workplace I've ever worked at. If somebody just came back from a jog, the air-conditioner gets cranked up. Same deal if the air feels 'mucky'. If it's a few degrees too cold, don't bother putting something on - with a couple of button presses it'll magically feel better. It's a sad thing to witness. I usually just bring in a jacket so I can wear it if I'm cold, but almost every day someone will still turn on an air-conditioner. And worse - leave it on when they leave! Meanwhile, I don't think there has ever been a time I have turned on the air-conditioner or heater at any of my workplaces - past or present.
* We're vegetarian (and speaking for myself, I've been vegetarian for around 8 years). That means, we eat a lot of food that isn't processed. My wife is always buying fresh vegetables to cook something for dinner from. Further - and more importantly, we are not contributing to the damage caused by extensive cattle farming - the leading cause of greenhouse gas emissions in places like Brazil, and it makes up about 17 per cent of Australia's emissions. Our choice to be vegetarian certainly isn't because we're religious or too poor - it's because it's unethical from a number of viewpoints not to be at least a strict vegetarian. Some would say the same thing about being vegan, although I haven't taken my diet to that level.
* Limit use of shopping bags and plastic bottles. I personally drink about 1 litre of soft drink each day at work - but I make it at home with my Soda Stream kit and bring it in using a reusable bottle - which I carry in using the pannier on my bike or a backpack if walking/jogging. The main waste created by this is the syrup bottle, although this is small and lasts a few weeks, and is always recycled. By contrast, I know other people who buy a bottle of coke each day from a local cafe! I sure hope they recycle all the plastic they throw out. I also take a backpack with me almost everywhere else I go, and when I do shopping I make sure it's full of reusable shopping bags. Sometimes store clerks give me a plastic bag before I have a chance to tell them that I'd like them to use ones I have specially brought in - in which case I'll keep the bag for use as a rubbish bin later. I always put any bag I receive to use - but do my best to not get them in the first place.
Again, having said all of the above, I know there is still room for improvement in our lifestyle.