Scientists and climate experts from around the world have agreed on a report warning that the danger posed by global warming is greater than at first thought.
The report from the UN's Intergovernmental Panel on Climate Change says that while industrialised nations have been responsible for most greenhouse gas emissions, the poor in developing nations will suffer most from climate change.
The new report also stated that climate experts believe the effects of global warming are already visible in the environment.
Many of the warnings about effects of climate change are familiar, but now the IPCC says it is no longer based on models but on what has actually been seen to happen.
The report states that the poor will be hardest hit.
Drinking water will become more scarce, some areas will be flooded by rising sea levels, and death rates from malnutrition, malaria and other conditions will rise.
Ocean and coastal ecosystems are said to be most under threat, including fragile coral reefs.
The European Commissioner for the Environment Stavros Dimas said the report underlined the need for fast action on reducing greenhouse gas emissions.
A further IPCC report on that topic is expected next month.