Litigating climate change is only going to become more topical. These days you cannot open a newspaper or switch on a television without hearing a reference to carbon emissions, melting ice caps or increasingly erratic weather patterns.

Climate change is closely linked to increased levels of greenhouse gases, such as carbon dioxide, in the atmosphere. Furthermore, scientific evidence points to the rapid expansion of key industrial and manufacturing activities and the burning of fossil fuels as major contributing factors.

Against this background, there is potential for legal activity relating to climate change. This affects governments, manufacturers and campaign groups. However, establishing a legal claim based on damage caused by the effects of climate change presents significant challenges – causation being an obvious one.

The US Government displays caution in committing to a protocol for the reduction of emissions produced by its manufacturing and industrial activities. Its failure to ratify the Kyoto Protocol, citing the negative impact that agreeing to its requirements might have on the US economy, was controversial.

Notwithstanding the position of the Federal Government, there has been a greater appetite for regulation of emission levels at a local level in the US. In August this year, the State of California introduced a Bill that will impose farreaching controls on carbon dioxide emissions, with the aim of reducing emissions by 25% by 2020. This step has been seen by many as setting a serious litmus test on regulating emission levels in the US, not only at state level, but also to the Federal Government.

The US has also seen litigation relating to climate change issues. Jurisprudence is in its infancy, but indications are that claims against those contributing to climate change may at least be arguable by a party holding sufficient interest in the issues.

Power companies

One example is the case of Connecticut v American Electric Power Company Inc. The claimants, which included state authorities and environmental groups, brought proceedings against several large power companies in the US District Court in Manhattan on the premise that the emission of greenhouse gases represents a public nuisance.

A motion to dismiss the defendants' petition was granted by the court on the basis that the court's jurisdiction did not extend to a "non-justiciable political question" such as the regulation of greenhouse gas emissions and that policy on such issues should be determined by political authorities. The decision has, however, gone to appeal.

Another instance is Friends of the Earth v Watson, filed in the US District Court for the Northern District of California. The claimants sought a statement from the court that two government bodies, the Overseas Private Investment Corporation (OPIC) and the Export-Import Bank of the United States (Ex-Im), had failed in their obligations to carry out an environmental impact assessment prior to giving over-seas funding to ventures engaged in the burning of fossil fuels.

The court found that the claimants had sufficient standing to pursue the claim. It also indicated that, where the ventures being supported by OPIC and Ex-Im were alleged to make up a projected total of no more than 8% of global emissions in 2003, this level of contribution to emission levels was potentially enough to establish a traceable source of pollution.

Private and public corporations are not the only entities that need to be wary of legal action in this area. One widely reported example is that of the Inuit Circumpolar Conference (ICC), an organisation representing the interests of the indigenous population of the Arctic Circle. In December 2005, the ICC filed a petition with the Inter-American Commission on Human Rights claiming that the US, as the world's largest emitter of carbon dioxide, was threatening the inhabitance of their native land. Its progress should be watched with interest.

In contrast to the US Government, the UK has acknowledged the threat posed by climate change. In the lead-up to the 2005 G8 summit, the Prime Minister stated: "Climate change is… long term, the single biggest issue that we face."

In the UK, attempts to promote environmental awareness in the corporate sphere have come to the fore through the proposed Company Law Reform Bill, due to come into force in 2007. The Bill looks to shift the focus of the key objectives of company activity, setting out a broad range of directors' duties over and above the direct duties traditionally owed to shareholders. It states that, in exercising their powers, directors must have regard to a number of considerations, including "the impact of the company's operations on the community and the environment".

Quite what effect the Bill will have on the approach of companies towards environmental issues is unclear. Notwithstanding this, a proposed legislative provision of this nature hints at the Government's broad intent to encourage companies to take a proactive approach to environmental responsibility.

Flood damage

In terms of litigation, there has not been the same appetite in the UK for pursuing claims based on the effects of climate change as there has in the US. The potential remains – one need only consider the long-term projections of flood damage to areas of the UK, caused by rising sea levels, to see that there may be scope in the future for claims in tort.

In Fairchilds v Glenhaven, the House of Lords took a purposive approach to the issue of causation, moving away from the 'but for' test. This concerned a claimant who developed mesothelioma after having been exposed to asbestos dust during his employment with a number of employers. The claimant could not prove which period of exposure had 'caused' the resulting disease. The House of Lords found that it was sufficient for the claimant to show that the defendant employer's negligence had materially increased the risk of injury. It was not necessary for the claimant to show that 'but for' a particular period of exposure, the illness would not have arisen.

Given the number of potential contributors to climate change, the issue of causation is unavoidable. However, were reliable evidence available showing the emission levels of a particular party to have materially increased the risk of climate change, then the reasoning in Fairchilds provides some food for thought.

Melanie Willems is a partner at Howrey.