Apple chief executive Tim Cook has bluntly told climate change sceptic investors to ditch their stocks if they do not support his pledge to slash greenhouse gas emissions, in the latest signal that the company will continue to invest in sustainable energy.

According to witnesses at Apple’s annual meeting on Friday, Cook became visibly angry when questioned by a radical right-wing think tank about the profitability of investing in renewable energy.

Under Cook’s leadership Apple has stepped up its commitment to curbing its environmental impact, pledging to supply 100% of its power from renewable sources and crack down on the use of minerals mined in the Democratic Republic of Congo (DRC) that can fund war and human rights abuses.

At the meeting last week, shareholders voted down a resolution by the National Center for Public Policy Research (NCPPR) - an avid campaigner against action to tackle climate change - that would force Apple to disclose more information about the costs of its investment in tackling climate change.

However, Justin Danhof of the NCPPR pursued the line by asking Cook if Apple’s environmental investments increased or decreased the company’s bottom line. He also asked Cook to commit Apple to only investing in measures that were profitable.

Cook became visibly angry at Danhof’s questions and categorically rejected the NCPPR’s climate scepticism, according to the Mac Observer’s Bryan Chaffin, who attended the event. He told shareholders that securing a return on investment was not the only reason for investing in environmental measures.

“When we work on making our devices accessible by the blind, I don’t consider the bloody ROI,” Cook said, adding that the same sentiment applied to environmental and health and safety issues.

He told Danhof that if he did not believe in climate change, he should sell his Apple shares. “If you want me to do things only for ROI reasons, you should get out of this stock,” he said.

Cook’s comments and visible passion over the issue are one of the strongest signals yet of his commitment to reducing Apple’s environmental footprint. He told shareholders that he wanted to “leave the world better than we found it”.

The NCPPR has reacted angrily to Cook’s put-down, accusing him of denying shareholders the right to know how their money is being invested.

In a statement released after the meeting, Danhof accused Apple of failing to consider the long-term impacts of its environmental investments, arguing that Apple did not have the best interests of its shareholders at heart.

“Too often investors look at short-term returns and are unaware of corporate policy decisions that may affect long-term financial prospects,” he said. “After today’s meeting, investors can be certain that Apple is wasting untold amounts of shareholder money to combat so-called climate change. The only remaining question is: how much?

“The company’s CEO fervently wants investors who care more about return on investments than reducing CO2 emissions to no longer invest in Apple. Maybe they should take him up on that advice.”

However, the NCPPR did not say if it was now planning to sell its Apple shares.