Pendleton warned that none of the action that is currently being envisaged, including the UK's groundbreaking climate Bill - will be sufficient to keep global temperature rises below the critical 2 degree Celsius level beyond which catastrophic changes are predicted.
He warned that greenhouse gas emissions worldwide must stop rising no later than 2015 and decline by around 5 per cent per year thereafter, with the global economy operating on virtually no carbon emissions by the middle of the century.
"What we do now is what matters because every additional tonne of carbon dioxide that we emit takes us a step closer to irreversible climate change," he said.
"The costs should be borne by those who can afford it and have contributed most to the problem in terms of emissions and not by poor people who now have to focus their efforts on surviving the changes that are already happening.
"This can be worked out easily and with transparency and should form the basis of an agreement that is signed in Copenhagen in 2009."
Christian Aid is calling on the countries meeting in Bangkok to agree a five step emergency programme:
1. Negotiators should agree a way of calculating different countries' responsibility for climate change and their ability to pay to cut emissions.
2. Industrialised countries should each enact national legislation to limit emissions to 40 per cent below 1990 levels by 2020 in advance of a 2009 agreement.
3. Governments in industrialised countries should also take urgent steps to regulate against new sources of emissions, such as coal-fired power plants.
4. Developing countries should write corresponding climate change plans showing how they would deal with climate impacts and limit their own emissions
5. According to the agreed 'responsibility and capability' index of countries, those in a position to pay for emissions cuts should do so both at home and in countries less able to pay, by funding sustainable development initiatives and transferring technology in a measurable, verifiable and reportable way.
