Lord Browne of Madingley last night vowed to put the drama and distress of the past few days behind him, saying that a person's identity was defined only in part by his or her "passions and personal relationships".

He made the comments in Brussels during his first public appearance since being forced to resign as head of BP on Tuesday after having been found to have lied about his love life. Lord Browne delivered a lecture on sustainable development and global warming to an audience of diplomats, European officials and academics, including the Nobel prize-winning economist, Amartya Sen.

Lord Browne quoted Prof Sen's insight that any human being's identity is made up of multiple factors, pointing out that it was dangerous to frame people's identities by colour or creed. Factors that helped to define human identities included professional life, occupation, and "our individual passions and personal relationships".

The former BP chief, seen as the outstanding British businessman of his generation, introduced his lecture with a rueful observation about the last few days during which his reputation had been sullied by newspaper investigations of his private life and his flawed attempt in the courts to prevent publication of the details.

"It's a great pleasure to be back in Brussels and a great honour," he said. "The past few days have been testing for me personally. I'd like to express deep gratitude for all the enormous support I've received."

He was greeted with generous applause from an audience of around 200 after arriving with the British ambassador to the European Union, Sir John Grant.

The Cambridge and Stanford-educated physicist and entrepreneur was forced to resign on Tuesday after telling a court he met a former lover, Jeff Chevalier, in a London park, rather than through a gay dating website. He was seeking an injunction preventing the Mail On Sunday publishing details of his four-year affair.

Lord Browne's lecture focused on the challenges thrown up by global warming. He argued that an international solution binding the EU, US, and China was needed to reduce greenhouse gases.

The answer was "not about telling people you can't fly or drive. It's about offering people better choices."