As the latest chapter of the UN's climate change report is launched, Christian Aid notes that the way in which poor countries industrialise and develop will make or break the planet.
The report of the third working group of the Inter-Governmental Panel on Climate Change considers how world emissions of greenhouse gases must decline in order to keep global warming below two degrees celsius.
Poor communities in the regions most vulnerable to climate change will struggle to cope even with this level of warming, Christian Aid says, but anything greater would spell catastrophe.
Christian Aid is campaigning for the UK and other rich countries to reduce their own emissions but also to repay their effective carbon debt in order to help the poorest countries develop sustainably and without increasing their greenhouse gas emissions.
"Poor people have a right to development and to a life of dignity and opportunity. But because industrialised nations such as the UK and US have spent the global carbon budget on their development, they will be denied that right unless we completely rethink what development means and how it is done," said Paul Brannen, head of campaigns at Christian Aid. "The old ideologies of economic globalisation must now be replaced with a new focus on human development and well-being achieved within environmental constraints.
"The report underlines the absolutely Herculean effort that is now required if global warming is to be kept below 2 degrees, but for the sake of the world's poorest, this must be our aim,' said Mr Brannen. 'But the message is one of optimism; if world leaders seize the initiative and agree a crash programme of emissions reductions then the 2 degree target is still possible.
"Rich countries have to redouble their efforts to reduce emissions and must aim to make cuts of at least 80 per cent by 2050,' said Mr Brannen. 'But the fresh challenge spelt out by the report is that of clean, sustainable development in poor countries. Without this, the climate system, many species and habitats and also the lives of millions of poor people are under profound threat."
Climate change issues were discussed at a crucial preparatory meeting 4 May for the G8 summit in Germany in June.
