Art by James YangOf this year’s Power 100 members, just 29 have signed on to the United Nations-supported Principles for Responsible Investment (PRI). While their assets represent more than a third of the Power 100’s $9.8 trillion total, it is obvious the PRI’s reach is limited when it comes to the leading innovators in institutional investment.

Some investors may feel that such actions are not conducive to making money for retirees, citizens, or students. Sweden’s leading investors disagree—just ask AP4 CEO Mats Andersson (#49), one of the leaders in climate change-oriented investing. His environmental investments are made not “out of charity,” but with “better long-term returns” foremost in mind.

The research into long-term and sustainable investing—notably Mercer’s detailed report published earlier this year—suggests Andersson is on solid footing.

In the report, “Investing in a Time of Climate Change,” Mercer set out four scenarios detailing how the environment could be affected by increasing global temperatures. It gave granular detail on how various asset classes, industry sectors, and sub-sectors would be impacted—and where asset owners can make money.

The same institutions publicly supporting these findings back most such initiatives: Church Commissioners for England (CIO Tom Joy, #65), New Zealand Super (CIO Matt Whineray, #7), and the California State Teachers’ Retirement System (CIO Chris Ailman, #6) were the biggest names attached.

So why aren’t other asset owners engaging as passionately as Andersson and his fellow Swedish asset owners with sustainable investments and activist issues?

The reasons are varied. PRI signatories promise to adhere to six very demanding principles. These include incorporating environmental, social, and governance (ESG) issues into investment processes; holding the companies they own to account over ESG issues; promoting the PRI to other investors; collaborating with fellow signatories to “enhance our effectiveness in implementing the principles”; and reporting fully their engagement records every year.

Some asset owners may disagree with the way PRI encourages them to engage with ESG issues. In 2013, a group of Denmark’s leading investors withdrew their support of the principles, citing the organization’s own lack of good governance.

While the likes of ATP (CIO Henrik Gade Jepsen, #3) and PensionDanmark (Investment Director Claus Stampe, #77) still invest according to the PRI, the movement will be weakened by their continued absence from the list of public supporters.

For many asset owners, even if they do wish to support the principles, a lack of time and resources pushes ESG well down the to-do list, behind funding pressures and performance monitoring. Major long-term projects also take up precious time—these portfolios won’t innovate themselves, after all.

In November, Paris will host the COP21 Sustainable Innovation Forum. Christiana Figueres of the UN’s Framework Convention on Climate Change last year called for widespread action at the summit and declared that “investors have a sacred and legal fiduciary duty to engage with this issue.” In 10 years’ time, she added, it would be too late to make effective changes and too expensive to deal with the consequences.

But the UN has its work cut out if it is to persuade the most powerful asset owners that their time will be well spent at summits such as COP21 when other pressures loom  large. Success will most likely mean having more than a third of CIO’s Power 100 among PRI’s signatories when we check in next year.