Exxon Mobil Corp has stepped up efforts to persuade investors to vote against climate-related proposals at today’s annual meeting with a campaign of calling, writing and lobbying shareholders in person.

The world's largest publicly traded oil company opposes a proposal requiring it to report on the risks to its business from new technologies and global climate change policies, insisting it already provides the information.

Last year, the same proposal was backed by 38.1 per cent of shares voted.

The stakes are higher this year. The business-impact issue is central to lawsuits by two state attorneys general alleging Exxon soft-peddled the risks to consumers and shareholders. Wall Street support of similar measures also has convinced energy companies including Occidental Petroleum to address the Paris climate accord's goal of keeping global temperature increases under 2-degrees Celsius.

If the proposal garners less than last year's 38 per cent support, it could endorse Exxon's view – which is that its current reporting is appropriate, said Rob Schuwerk, senior counsel for environmental think tank Carbon Tracker Initiative.

But if support this year exceeds 50 per cent, the oil company likely would do more to explain potential business impacts from having to meet the Paris agreement's temperature goal. A result in between the two, he said, would be the "the hazy middle" that would still show growing investor interest in climate issues.

[Company] position that even in world intent on limited temperature rises, it would still need more oil.

Exxon took a conciliatory approach in a letter to investors yesterday. Vice President Jeff Woodbury wrote that on many of the shareholder proposals "the corporation agrees with the underlying objective – we just have a different view on the best means to achieve it."

Prior shareholder letters insisted the proposals were misguided or ignored the company's efforts to spell out its position that even in world intent on limited temperature rises, it would still need more oil.

Anne Sheehan, head of corporate governance at California State Teachers' Retirement System, which backs the additional climate reporting, said Exxon's letter suggests the voting is at least very close and may be going against the company.

"You're not going to do an eleventh-hour shareholder communication if everything was going swimmingly," she said in an interview.

In addition to the vote on the climate-impact report, Exxon holders will consider proposals to shift spending to dividends and buybacks from oil exploration and on a proposal to require a report on its efforts to restrict emissions of methane, a greenhouse gas.

Exxon opposes all these proposals and has actively lobbied shareholders. This campaign "is a lot more intense than normal," said one investor, who spoke on condition of anonymity. "I think they're pulling out all the stops."

Climate campaigners are also active. They have organised rallies and held media briefings. In Dallas, where the meeting takes place, they have put up billboards and signs seeking to sway votes.

Any change likely will be driven by institutional holders shifting their positions. Big investors including State Street Corp and BlackRock Inc, which together hold about 9 per cent of Exxon shares, recently have made clear they are now giving more attention to climate issues.

Bob Litterman, chairman of the risk committee at asset-management firm Kepos Capital LP and who holds derivatives betting that oil companies will underperform the S&P 500 index, said no matter the outcome of the vote today, pressures on Exxon to spell out the potential impact of a global warming on the value of its energy assets will only grow.

"Whether it's shareholders or attorneys general or the passage of time, they're going to have to become honest about the potential for their assets to be stranded," or become uneconomic to pursue, said Litterman.