Staging a global forum on climate change is a dilemma, for it adds to very problem it is trying to solve.

Around 13,000 tonnes of carbon dioxide (CO2) will add to Earth's greenhouse effect from the December 1-12 meeting of the UN Framework Convention on Climate Change, the UNFCCC said.

That estimate is based on a turnout of 8,000 people, but as of Sunday 10,657 people had registered for the talks.

Poland, which is hosting the meeting, "plans to offset the total emissions resulting from the conference once a final calculation has been made," the UNFCCC said.

Under offsets, anyone emitting carbon can invest in a scheme that mitigates the pollution by the same amount.

Typical projects involve reforestation or transferring cleaner technology to developing countries in order to ease their own emissions of greenhouse gases.

The UNFCCC, based in Bonn, is sending 200 people to the Poznan talks, who are travelling by the most "carbon-friendly means possible," either by train or bus, it said.

The Poznan talks are a stepping stone to a new global treaty on climate change, scheduled to be concluded in Copenhagen in December 2009.

Greenhouses gases are so called because they linger in the atmosphere and trap the heat from the Sun, instead of letting it radiate out into space.

As a result, Earth's surface is slowly warming, inflicting potentially dangerous impacts on its climate system.

Most greenhouse gases come from the burning of oil, coal and gas. Emissions from the Poznan talks come principally from delegate travel and heating and lighting the conference venue.