Weather experts gathered yesterday in The Hague to discuss how to stop man-made gases affecting world climate just days after widespread flooding, blamed on global warming, hit Europe.
Underlining the passions stirred by debate on so-called "greenhouse gases", 20 people were arrested for trying to stage a demonstration in the grounds of the conference, police said.
Delegates from 180 nations are meeting for two weeks, with discussion focusing on a 1997 deal on curbing greenhouse gases reached in Kyoto, Japan.
"The evidence is mounting," said the Dutch Environmental Minister and conference head, Mr Jan Pronk, in his opening statement. "The greenhouse gases we produce are having a visible impact on the environment."
The Kyoto agreement aimed to reduce greenhouse gas emissions by more than 5 per cent from 1990 levels by 2008-2012. While 180 nations signed the agreement, only 30 have ratified it.
"We need to bring negotiations to a successful close, so that we can ratify the Kyoto Protocol and start putting it into practice," Mr Pronk said.
Those greenhouse gases have contributed directly to climate change, according to Dr Robert Watson, chairman of the Intergovernmental Panel on Climate Change.
"The Earth's surface temperature is now the highest level in 1,000 years," Dr Watson said, with the northern hemisphere warming slightly more than the southern. "The weight of the evidence is that we humans are at least partially responsible for climate change," he said.
New forecasts put the expected temperature increases for the coming century at 1 1/2to 6, double the previous estimates, he added.
In addition, ocean levels are expected to rise 50 cm by 2100, threatening 200 million people who live in coastal areas of China, south-east Asia and Africa alone, he said. None of the major industrialised nations has tackled the targets set at Kyoto. Many are awaiting a clearer set of rules before tying themselves to binding targets.
The conference is officially called the Sixth Conference of Parties (CoP6) to the UN Framework Convention on Climate Change.
Its early days will be largely devoted to hearings by two UN working groups, one devoted to assessing the science behind the proposals and the other to creating practical ways of implementing emissions cuts.
Much of the cutting is likely to be carried out by the private sector, according to Mr Michael Zammit Cutajar, assistant UN Secretary-General.
"We are creating new markets, new businesses and new commodities through the development of carbon trading," he said.
However, the overall costs of reaching the Kyoto targets are difficult to estimate.
"It will probably cost less than we think, but the costs of inaction tend to be overlooked," he said.
Under consideration are so-called flexibility mechanisms designed to offer states a number of ways of reaching their emission-cutting targets without actually trimming their output. Those include the clean development mechanisms, or CDMs, which promote investments by firms or governments in developing countries and could include the use of "sinks", or reforestation projects, to help absorb carbon dioxide, the main greenhouse gas.
Another mechanism is joint implementation, under which credits for emissions targets are shared by developing states and the industrialised countries that helped them achieve the goals either by investments or technology transfers.
A third method is emissions trading, where countries such as Russia, which is expected to meet its emissions targets easily, can sell some credits to countries not meeting their limits.