The Hitchhiker’s Guide to the Galaxy declares 42 the answer. But what is the question?

Illustration: Mike Lemanski

For Joeri Rogelj, it’s all about cutting carbon emissions. “If we don’t take drastic action on climate change, the consequences for future generations will be dire,” says Dr Joeri Rogelj, Lecturer in Climate Change and the Environment at the Grantham Institute.

Graphic of a tree next to a gauge of temperatures 0 deg C to 2 deg CAnd he should know. As one of the coordinating authors of the latest Global Warming of 1.5°C Special Report by the UN Intergovernmental Panel on Climate Change (IPCC), Rogelj is at the forefront of efforts to spread this message and mitigate the damage.

The report concluded that the best-case scenario would be to limit global warming to 1.5°C - any higher and developing countries will be particularly badly affected. It says: “The impact of even two degrees of warming is projected to be detrimental to efforts to ensure food security and poverty eradication.”

Achieving this target means that worldwide carbon emissions need to be cut to zero by mid-century. The big question driving Rogelj’s research is how to do that in a holistic way.

“We do not just care about climate change. For example, you can try to solve the climate problem by growing bioenergy crops or plant forests everywhere – but this could negatively impact food security or biodiversity. The challenge is to find out how these different objectives can be tackled together.”

It’s a daunting mission, but one he’s eager to take on. “These are core aspirations of our global society so, as a scientist, I find it incredibly motivating to work towards furthering them. I hope that my research provides a small piece in the puzzle. At the same time, this challenge also provides a great opportunity to choose a more sustainable path.”

He was pleased that the UN’s report reinvigorated the debate around climate change, but now hopes that this will be translated into policy. “I’d like this work to inform both national and international governments to set science-based targets to achieve the most ambitious climate goals.”

Read the full report on the IPCC website.