Climate change is the biggest threat to all our futures. It will affect every individual, every family, every community, every business and every country.
So it is fitting that today people from all over the world are coming together to blog on climate change for Blog Action Day.
In less than two months, politicians will meet in Copenhagen to forge a critical new deal on tackling climate change.
I will go to the talks in December if it means we will get an agreement and I am urging other leaders to join me. But it must be the start of something not the end.
And it is not just about what governments do; we all have to take responsibility to cut emissions from our homes, our cars and our places of work.
Sarah and I are trying to do our bit. In Downing Street, we are composting, recycling, using energy-saving light bulbs and buying locally-sourced and sustainable food whenever possible. It’s little things like this which will make a big difference if we all do them.
Like every parent, I want to leave a safe and secure world for my children. And I want to be able to look them in the eye because our generation stood up for their future.