When we finally flew over the front of the enormous glacier after weeks of travelling, I found myself staring down at an epic vision of shattered ice. //

I was surprised how moved I was by what I'd seen. In the weeks it took to travel home, I tried to process my emotions.

I thought about the men and women who had set our camp, who flew the planes, cooked the meals, processed the rubbish and groomed the ice runways. And I thought about the scientists who have been studying the processes at work for decades.

Our research trip was only possible because of a huge chain of human enterprise culminating with the hardworking people in the UK and US whose taxes paid for it all. //

Satellite monitoring shows that the overall rate of ice loss from West Antarctica has increased five-fold over a 25-year period. This one glacier - Thwaite's glacier - alone now accounts for 4% of global sea level rise.

Needless to say, this acceleration is a result of us humans polluting the air with greenhouse gases. That fact explodes any impression that the ice is overwhelming. The opposite is true, we are overwhelming the ice. //

But I will not forget what I saw in Antarctica. It reminds us that climate change is a process that is likely to take centuries to play out, and tens of thousands of years to reverse.

Consider this: the last time CO2 levels were this high is reckoned to have been around four million years ago and it is estimated that the sea level then could have been as much as 30-40 metres higher than it is now.

That's a measure of how important the climate issue is and also explains why I'm so pleased to be given this opportunity to play a role in covering it for the BBC.

Tackling global warming will be the central project of the 21st Century and it is an incredible privilege to have been given a front row seat.