Here’s a bit of confusing news: Environmentalists have successfully pressured ExxonMobil to publicly report on how much climate regulations might hurt its business. The New York Times reports:

Energy companies have been under increasing pressure from shareholder activists in recent years to warn investors of the risks that stricter limits on carbon emissions would place on their business.

On Thursday, a shareholder group said that it had won its biggest prize yet, when Exxon Mobil became the first oil and gas producer to agree to publish that information by the end of the month.

In return, the shareholders, led by the wealth management firm Arjuna Capital, which focuses on sustainability, and the advocacy group As You Sow, said they had agreed to withdraw a resolution on the issue at Exxon Mobil’s annual meeting.

It is easy to understand why shareholders would want to know how ExxonMobil is planning for a future in which demand for oil is stunted by global climate treaties and a hodgepodge of national and regional carbon caps and carbon taxes. But Arjuna and As You Sow are committed to sustainability, not just the financial interests of shareholders. So why is this good for the environment? You might imagine that if Exxon reports that it will suffer greatly from carbon pricing, that would hurt, not help, the campaign to pass climate legislation. After all, politicians cower in fear of harming their generous allies in the fossil fuel industry, especially politicians from dirty-energy-producing states.

Activists involved with the shareholder campaign give two reasons that their deal with Exxon could help reduce CO2 emissions. First of all, they predict, Exxon won’t take this opportunity to whine about how a price on carbon would send it to the poorhouse. Companies will always try to put a positive spin on their future outlooks. (Exxon actually endorsed a carbon tax in 2009, in what some saw as a cynical ploy to undermine the Waxman-Markey cap-and-trade bill. Exxon is also heavily invested in natural gas and could benefit from a carbon price that incentivizes electric utilities to switch from coal to gas.)

Second, if Exxon does have promising ideas for producing energy with lower carbon emissions — which is what it will need under a carbon-restricted regime — that could have a cascading effect in the industry. If investors have more confidence that Exxon is prepared for a low-carbon future than other energy companies that have not been so forthcoming, Exxon’s competitors will have to catch up.

“I don’t think the report by Exxon will be negative. It will say, ‘We’re prepared,’” says Danielle Fugere, president of As You Sow. “Shareholders will say that they set the standard for transparency, and ask which companies are prepared.”

By focusing Exxon’s and its shareholders’ minds on the possibility of flatlining or even declining global demand for oil, the activists may encourage a shift in investment priorities. As the more readily accessible oil dries up, oil companies such as Exxon are still plugging away at trying to tap unconventional oil reserves. But unconventional oil tends to be more expensive — and carbon intensive — to extract. That means profit margins are low, and carbon pricing would be a double whammy, making it even more expensive to extract the oil. If that happens, many drilling projects would become unprofitable, and all that money sunk into buying up leases in Alberta’s tar sands and building oil rigs in the ultra-deep waters of the Gulf Coast would go to waste.

If oil companies acknowledge that risk, then maybe they will shift their investments toward renewable energy production, or at least finding efficiencies in oil and gas production that reduce its carbon intensity. “Getting these companies to look at the risk means they may diversify and move into new and cleaner processes, move into new energy sources,” says Fugere.

“There’s renewable energy with costs that are going down dramatically, and a price on carbon would make it even more competitive,” says Natasha Lamb, director of shareholder engagement at Arjuna.

Environmentalists believe that once Exxon contemplates a low-carbon future, it will see its interest in both investing its own money in renewables and encouraging governments to limit emissions. David Hawkins, director of climate programs at the Natural Resources Defense Council, explains in a blog post:

The startling news for many [Exxon] investors is that the current proven reserves held by [Exxon] and other fossil-fuel majors are several times the total cumulative carbon budget that can avoid very damaging climate change. When governments wake up to the true threat of climate disruption, they will act to put a halt to the unlimited release of carbon from the products sold by [Exxon] and other fossil-fuel asset holders. …

[Exxon’s] capital budget should shift promptly to energy options that are sustainable in a carbon constrained world and that will help reduce global carbon burn rates.

In other words, ExxonMobil should switch to making solar panels and wind turbines while it still can.