We believe urgent action is needed to reduce emissions of greenhouse gases into the atmosphere. This is the only way we can avoid or slow 'dangerous' levels of climate change. For the people who have already suffered from the effects of extreme weather, failed crops, flash floods and heat related illnesses, and for the species and ecosystems that are struggling to adapt to changes in temperatures, the level of climate change we are experiencing (a 0.7 °C increase in global average temperatures) is already proving dangerous. And thanks to the time lag between emissions and the temperature increasing - the 'inertia' of the climate system - we know we have more changes ahead of us.

The challenge we face is to avoid causing levels of change in global temperatures that will bring about catastrophic consequences over relatively short timescales. The kind of changes that will result in the melting of the Greenland ice sheet, adding 7 meters to global sea levels, or the loss of the Amazon rain forests - the home of more than a third of the world's species, or the desertification of large parts of Asia, Africa and the Americas.

Latest scientific thinking tells us that we need to act quickly - ie within ten years - to reverse global trends in emissions which are rising faster than ever.

But if the climate system has an inbuilt inertia then so does our political system: what ambitious yet realistic changes can be made in such a short space of time?