Climate change will lead to a "fortress world" in which the rich lock themselves away in gated communities and the poor must fend for themselves in shattered environments, unless governments act quickly to curb greenhouse gas emissions, according to the vice-president of the intergovernmental panel on climate change (IPCC).

Mohan Munasinghe was giving a lecture at Cambridge University in which he presented a dystopic possible future world in which social problems are made much worse by the environmental consequences of rising greenhouse gas emissions. "Climate change is, or could be, the additional factor which will exacerbate the existing problems of poverty, environmental degradation, social polarisation and terrorism and it could lead to a very chaotic situation," he said.

The scenario, which he termed "barbarisation" was already beginning to happen, he said. "Fortress world is a situation where the rich live in enclaves, protected, and the poor live outside in unsustainable conditions.

"If you see what is going on in some of the gated communities in some countries you do find that rich people live in those kind of protected environments. If you see the restrictions on international travel you see the beginnings of the fortress world syndrome even in entering and leaving countries," he said.

The Sri Lankan-born expert on climate change and sustainable development was delivering the annual Clare College Distinguished Lecture in Economics and Public Policy. He said the IPCC's fourth assessment in 2007 predicted that developing countries would be hit hardest by climate change, especially rising sea levels.

"One of the most distressing aspects is that developing countries are the most vulnerable to climate change and the poorest people will be the hardest hit. This is in fact rather unfair because they had least to do with the problem – apparently they will pay the biggest costs," he said.

Bangladesh, for example, could lose 17% of its land – mostly highly populated areas – to rising seas, according to Munasinghe. But, he was positive about international efforts to tackle the problem. "I tend to be optimistic because I believe this can be done through rational processes, but I also feel that the consequences of failure are unimaginable and that's really the bottom line."