What can an ordinary person do to be more sustainable?

Chris Smith put this to climate scientist Doug Crawford-Brown from the University of Cambridge...

Doug - Yeah, we've packed a lot of questions in there. When I was born there were 2.5 billion people on the Earth, and I'm not that old.

Chris - Is that back when you had your first Brontosaurus?

Doug - When I hear that fact, I fell off my dinosaur, yeah. If we were to go back to that number of people - problem sorted. Every time we discuss this at the conference of the parties meetings on climate change, it gets into a big argument between the United States saying "well, you China produce more CO2," and China saying "but we have more people," and the United States saying "oh, but your are producing more CO2," and back and forth.

So population has been on the table for a long time. People worry about discussing it simply because it causes such discord between the developed and developing nations.

Chris - I suppose it's a hard nut to crack isn't it, because you've basically got to tell people how many kids they can have, which has always been something people have regarded as an almost God given right, isn't it?

Doug - In the US, I used to go round to churches and give these presentations. And every time I would talk about climate and talk about all sorts of mitigation measures, which is what the first half of the question was, everybody was fine. The minute I talked about population control, the response was uniformly 'God will tell me how many children to have' and I just learned to back away from that.

What can we do to make the changes? The example I always use is on the 7th of March, 2008 at 07.05 am, my carbon footprint went down by 60 percent. And I'm always asked by people "well what happened" and well, what happened was that was the time at which my wife and myself and my son migrated from the US to here. Any my life in Cambridge is just as good as my life in Chapel Hill, North Carolina, but it's 60 percent less CO2. Smaller house, we don't drive a car, because you can't really drive one in Cambridge, and so forth. So those are the things: make your house smaller, make your house a little bit cooler in the winter, and so on.

Chris - You say cooler in the winter. Do you mean like fairly light, Christmas lights, that kind of thing? Georgia.

Georgia - Well speaking of Christmas actually, that is like if you think about reducing the amount of waste, Christmas has so many things that we just throw away immediately. Think about crackers - you pull them and they immediately go in the bin. Wrapping paper - so much paper that is there to look nice. So things like recycle so boring - recycle your wrapping paper and things like that.

Chris - But you raise a good point about wrapping paper because I was pretty horrified when I just didn't put the bin out for a couple days at home, and I looked at how much packaging, like plastic packaging, that everything. You cannot buy something these days without it coming with impenetrable layers of plastic packaging. What's with that?

Peter - The Germans started about 25/30 years ago when I was living there they changed that quite a bit. There wouldn't be much packaging and you would take off the packaging before you left the supermarket. Obviously, you're taking a risk then that you damage an item on the way home but the reduction in packaging, I assume they're still doing it, was considerable compared with other countries.

Chris - So Doug, just wrap up the question then. Could you give us a little checklist of say your top five tips for what Heath, and the average person, can do to cut their carbon footprint.

Doug - Well, the biggest one, by far, is how much temperature you have in you house and turn the thermostat down if you even have a thermostat - a 3 or 4 degrees centigrade temperature drop.

Number two. Don't do what I do, which is fly all over the world and lecture people about how they can reduce their carbon footprint.

Chris - About climate change.

Doug - I think St Peter and I are going to have a conversation about that at some point in time.

I mean number three is consumption patterns. And, ultimately, I think people need to understand that they are the ones driving this system. You know, quite blaming the producers, the companies, the countries that produce this stuff. We turn that system on every time we consume refrigerator, computers, and so forth.

That's not five, but it's three.