The debate over climate change is not a straightforward one. To begin with, scientific opinion is still split on whether carbon dioxide and other "greenhouse gases" are the cause of global warming. Moreover, the world's nations are a long way from reaching a consensus on just what needs to be done.

The UN's Intergovernmental Panel on Climate Change follows the growing orthodoxy of blaming humans for global warming - claiming the world is heating up more than expected due to industrial activity. Others argue that rising temperatures are part of a natural phenomenon.

A global strategy on climate change was first agreed under the 1992 United Nations Climate Change Convention and its 1997 Kyoto Protocol. This international legal regime promotes a framework of financial and technical incentives to help all countries to adopt more climate-friendly policies and technologies. It also sets targets and timetables for emissions reductions by developed countries.

To date most governments have still not ratified the 1997 protocol, which means that emissions targets for developed countries - which add up to a planned five per cent reduction compared to 1990 levels during the five-year period 2008-2012 - are not yet in effect. Most are waiting for agreement on how the protocol can be delivered in practice.

The irony of the climate change debate is that it may provide a shot in the arm for atomic power. To the horror of environmentalists, the global warming thesis might rejuvenate the nuclear industry - unlike fossil fuels atomic power does not produce CO2. A key issue at The Hague will be whether to categorise atomic power as a so-called "clean development mechanism" (CDM) - a move that could as act as spur to the commissioning of large scale nuclear projects, particularly in developing countries like India, China, and Vietnam.

The EU will be pushing to exclude atomic power from CDM, seeking to limit it to "safe and environmentally sound technologies'', a move likely to be opposed by coalition of countries including United States and Japan.

Another EU and US clash is likely over the vexed issue of "pollution credits". The US, backed by Latin American countries, is seeking to encourage trading in the credits among countries to meet the required emission levels set by Kyoto. The EU argues that the US is trying to avoid confronting painful measures to cut its own emissions - a cut of over 30 per cent in the next 10 years - by buying up credits from the third world.

A similar faultline exists over the US strategy to soak up CO2 emissions in natural "sinks" by planting forests and crops to absorb the greenhouse gases, another seen by European countries as ducking the issue of tackling the problem at source.

Whatever the science of global warming, and following recent "extreme" weather conditions in the UK, the climate change debate in Hague remains politically heated.