The loss of Arctic sea ice has been identified as a tipping point.

Exeter researchers star in climate change series

Exeter academics Professors Tim Lenton and Peter Cox recently starred in a major new television series about tipping points – events that could permanently ‘tip’ the Earth’s climate into a new state.

The series was inspired by Professor Lenton’s research into the phenomenon. He identified a number of locations around the globe where a tipping point event might occur and the series took a number of leading climate researchers to those locations.

Tim expanded: “The tipping points work started in 2005 when I was collaborating with German colleagues. We brought together a group of experts to get their views on some of our early work into the phenomena.

“Then after a couple of years’ work identifying tipping points we published a paper in early 2008, which is a landmark in the field – it’s been cited about 500 times.”

TV producer Liz Courtney became interested in Tim’s work after seeing a tipping points webpage he worked on with Allianz and the Worldwide fund for Nature (WWF). The concept was a series of climate change experts from around the globe would each visit a tipping point location and investigate the probability of a tipping event occurring.

Tim had been doing some work on the melting of both the Arctic sea ice and the Greenland ice sheet – while filming in the country he got to mingle with the locals.

“We went dog sledging on the sea ice with Inuit hunters and spent time working with them. The lead presenter, Bernice Notenboom, is a climate journalist - she’s dragged a sledge to the North Pole and was meant to get us in adventure situations.” Tim explained.

But some serious science was also done.

“We were looking at how the Arctic sea ice around Greenland is melting – when we went out on the ice it was far retreated from the norm for the time of year.

“The impact is severe – we think the loss of Arctic sea ice is a cause of some of the recent extreme weather we’ve seen in the UK – the extremely wet weather, and the string of cold winters before that.”

Meanwhile Professor Cox visited the Amazon rainforest to investigate how it may be vulnerable to a tipping event.

Speaking about filming the show, he said: “They took me on a two day boat trip and to a number of sites in Brazil, over an intense period of 10 days. The Amazon programme was motivated by climate model projections that we carried-out when I worked at the Met Office. These suggested that the rainforest could dieback under some global warming scenarios, due to extreme drying.

“The first site we visited was a huge field site set-up by our collaborators at the Universities of Edinburgh and Oxford who had covered the forest floor in acres of plastic sheeting to see what happened if tree roots are deprived of moisture. Then we flew to the eastern Amazonia to a site where researchers were carrying out controlled burns of the forest to see when this tips the forest to savannah.”

It wasn’t all work, no play, though: “We also went to some towers set up to measure carbon uptake by the intact forest – then abseiled 50 metres down through the canopy of the rainforest. That was pretty scary, but not quite as scary as falling-out of a canoe close to where an anaconda had been spotted the day before!”

Professor Lenton is continuing his research into tipping points. Working with PhD students, he is investigating where to look for early warning signals of a possible collapse of the Atlantic Ocean’s overturning circulation (which keeps the UK relatively warm).

Professor Cox has been finding out what year-to-year variations in carbon dioxide reveal about the vulnerability of tropical rainforests to climate change.

The series is being broadcast worldwide. It has already aired in in the Netherlands and the US, but no broadcast has yet been agreed for the UK.