The world's top scientific authority on climate change was set to adopt a landmark report yesterday that warns that the impacts of global warming are already visible, will accelerate this century and are potentially irreversible.
The document crafted by the UN's Intergovernmental Panel on Climate Change (IPCC) summarizes the first overview on the greenhouse-gas effect since 2001.
It is styled as a guide for politicians facing tough decisions on cutting pollution from fossil fuels, shifting to cleaner energy and bolstering defenses against drought, flood, storms and other problems set to intensify through climate change.
The IPCC was to adopt a 20-page "summary for policymakers" and a 70-page technical document and follow this with a press conference attended by UN Secretary-General Ban Ki-moon, who warned yesterday the world is on the verge of a "catastrophe" because of global warming.
The report encapsulates three phonebook-sized assessments, issued earlier this year, that effectively consigns once-powerful "climate sceptics" to a small and shrinking minority.
The IPCC says the evidence of a human role in observed warming is now "unequivocal."
Retreating glaciers and snow loss in alpine regions, thinning Arctic summer sea ice and thawing permafrost show that climate change is already on the march, it says.
By 2100, global average surface temperatures could rise by between 1.1oC and 6.4oC compared to 1980 to 1999 levels, while sea levels will rise by between 18cm and 59cm, it said.
Heatwaves, rainstorms, water stress, tropical cyclones and surges in sea level are among the events expected to become more frequent, more widespread and more intense this century.
"All countries" will be affected but poorer countries -- ironically those least to blame for causing the problem -- will be hit hardest and they have the least resources for coping, a draft of the new report said.
Publication of the report comes in the runup to a conference in Bali, Indonesia, where the world's countries will gather to ponder the climate crisis.
The Dec. 3 to Dec. 14 conference of the UN Framework Convention on Climate Change is tasked with setting a "roadmap" of negotiations for intensifying cuts in carbon emissions beyond 2012, when the Kyoto Protocol runs out.
Carbon pollution, emitted especially by the burning of oil, gas and coal, traps heat from the Sun, thus warming the Earth's surface and inflicting changes to weather systems.