The limits of environmental shareholder activism were highlighted yesterday, after shareholder resolutions demanding that oil giant ExxonMobil take a more proactive approach to tackling global warming were rejected at the company's annual meeting.

However, supporters of the resolutions insisted that they had still proved effective at highlighting environmental issues to the company's board.

Figures showed that only 39.5 per cent of Exxon's investors voted in favour of a motion proposed by the billionaire Rockefeller family that the role of chief executive and chairman should be split, in part to stimulate greater debate on the company's response to global warming.

Similarly, a resolution to limit the company's greenhouse gas emissions secured 30.98 per cent support, while a proposal for increased investment in renewable energy won 27.4 per cent.

The results confirm that a sizable minority of Exxon's shareholders oppose the firm's traditionally hardline approach to climate change and alternative energy. However, the Rockefeller family, who are descendants of the company's founder John D Rockefeller, are likely to be disappointed that the resolutions did not secure wider support.

Speaking at the meeting, which was picketed by a group of environmental protesters, Exxon's chairman and chief executive Rex Tillerson insisted that the company was taking climate change seriously and had undertaken efforts to limit its "environmental footprint".

But he maintained the company's view that soaring energy demands would have to be met in large part by oil and gas, as renewable energy technologies were not yet available in sufficient scale.

"Continuing to do everything we can to supply oil and natural gas is the core of our business," he said at a press conference after the meeting. "That's what we have been doing for 125 years and in my view we do it better than anyone else."

However, Rockefeller family representatives Peter O'Neill and Neva Rockefeller Goodwin said in a statement that the resolutions had an impact.

"Today's vote makes it clear that Exxon Mobil must respect the views of the shareholders and take account of the changing world outside the doors of its executive suite," they said. "We are pleased to have played a role in sending a wake-up call to Exxon Mobil's management and its board of directors."

Rockefeller Goodwin also maintained the dissident shareholder's view that there was a strong business case for investing more in renewable energy technologies, noting that if the cleantech sector develops as rapidly as the IT sector in recent decades it will "seriously undermine Exxon's assumptions in demand for petroleum".

Speaking to BusinessGreen.com, Paul Simpson of environmental reporting lobby group the Carbon Disclosure Project (CDP) agreed that despite being rejected the resolutions had still had a positive impact. "Exxon has said in response to the resolutions that it wants to do a better job of communicating its [environmental] activities and that level of transparency should result in more action," he said. "Also management will have had discussions on these topics and that can only lead to more positive results."

However, he also warned that despite growing pressure from investors for firms to adopt climate change policies long and short term investors were beginning to take differing stances on firms' environmental records. "Longer standing investors such as pension funds tend to look at the risks posed by climate change, but for some investment funds as long as the company is highly profitable the fund managers are just happy picking up their bonuses," he observed.