Tim Nicholson now works for the Campaign for Green Healthcare
A company has appealed against the decision to allow an employee to claim he was unfairly dismissed because of his views on climate change.
Tim Nicholson, 41, of Oxford, was made redundant in July 2008 as head of sustainability at Grainger Plc, Didcot.
A judge ruled in March he could use employment equality laws to claim unfair dismissal.
The firm said it was appealing because it believed Mr Nicholson's views were political and not covered by the law.
Mr Nicholson, who said his belief in climate change governed his life to the extent that he no longer flies, had said in a written statement that the company's chief executive Rupert Dickinson did not take his concerns about climate change seriously.
He wrote: "He showed contempt for the need to cut carbon emissions by flying out a member of the IT staff to Ireland to deliver his BlackBerry that he had left behind in London."
He was given permission to make his claim under the Employment Equality (Religion and Belief) Regulations 2003 that covers "any religion, religious belief, or philosophical belief".
But Grainger Plc's lawyers said: "A belief about climate change and the environment... is not a religious or philosophical belief", adding it was "a political view about science and/or the world".
They will make their case at an Employment Appeal Tribunal panel in London on Wednesday.
The company has said Mr Nicholson was made redundant because of its "operational needs".