Tim Nicholson: Mr Nicholson, 42, from Oxford, told a previous hearing that his views were so strong that he refused to travel by air and had renovated his house to be environmentally-friendly. Photo: PA

In a landmark ruling, Mr Justice Michael Burton said that "a belief in man-made climate change ... is capable, if genuinely held, of being a philosophical belief for the purpose of the 2003 Religion and Belief Regulations".

The ruling could open the door for employees to sue their companies for failing to account for their green lifestyles, such as providing recycling facilities or offering low-carbon travel.

The decision regards Tim Nicholson, former head of sustainability at property firm Grainger plc, who claims he was made redundant in July 2008 due to his "philosophical belief about climate change and the environment".

In March, employment judge David Heath gave Mr Nicholson permission to take the firm to tribunal over his treatment.

But Grainger challenged the ruling on the grounds that green views were political and based on science, as opposed to religious or philosophical in nature.

John Bowers QC, representing Grainger, had argued that adherence to climate change theory was "a scientific view rather than a philosophical one", because "philosophy deals with matters that are not capable of scientific proof."

That argument has now been dismissed by Mr Justice Burton, who last year ruled that the environmental documentary An Inconvenient Truth by Al Gore was political and partisan.

The decision allows the tribunal to go ahead, but more importantly sets a precedent for how environmental beliefs are regarded in English law.

Mr Nicholson, 42, from Oxford, told a previous hearing that his views were so strong that he refused to travel by air and had renovated his house to be environmentally-friendly.

But his beliefs led to frequent clashes with Grainger's other managers, while he said that Rupert Dickinson, the firm's chief executive, treated his concerns with "contempt".

Once Mr Dickinson flew a member of staff to Ireland to deliver his Blackberry mobile phone after leaving it in London, Mr Nicholson claimed.

Mr Nicholson hailed the Employment Appeals Tribunal ruling as "a victory for common sense" but stressed climate change was "not a new religion".

He said: "I believe man-made climate change is the most important issue of our time and nothing should stand in the way of diverting this catastrophe.

"This philosophical belief that is based on scientific evidence has now been given the same protection in law as faith-based religious belief.

"Belief in man-made climate change is not a new religion, it is a philosophical belief that reflects my moral and ethical values and is underlined by the overwhelming scientific evidence."

His lawyer Shah Qureshi, head of employment law at Bindmans LLP, argued that if the ruling had gone against them, "the end result would be that the more evidence there is to support your views, the less likely it would be for you to enjoy protection against discrimination".

Grainger now plans to contest Mr Nicholson's claim of unfair dismissal at tribunal.

Dave Butler, its corporate affairs director, said: "This decision merely confirms that views on the importance of environmental protection are capable of amounting to a philosophical belief.

"We are looking forward to addressing the issues at tribunal level and demonstrating that there was no causal link between Mr Nicholson's beliefs and his redundancy."

The grounds for Mr Nicholson's case stem from changes to employment law made by Baroness Scotland, the Attorney General, in the Employment Equality (Religion and Belief) Regulations 2003.

The regulations effectively broaden the protection to cover not just religious beliefs or those "similar" to religious beliefs, but philosophical beliefs as well.