As speculation has continued to swirl about what Presidents Donald Trump and Vladimir Putin discussed in their second conversation at the G-20 earlier this month, one thing seems certain: The topic was not climate change, a subject Trump has so little time for, it drove him to pull the U.S. out of the Paris climate agreement just weeks before the G-20 gathering.

That decision was a blow for climate activists but also raised an obstacle for the many parties working to make climate-change disclosures mandatory for companies in their financial statements. Investors are increasingly clamoring for information on how increased flooding, tornadoes, droughts, such as the recent one in California, and other weather-related phenomena are impacting the businesses in which they own stakes.

A special task force, commissioned by the group of global regulators known as the Financial Stability Board and led by former New York City Mayor Michael Bloomberg, presented the G-20 meeting with its final recommendations on the issue.

The Task Force on Climate-related Financial Disclosures, or TCFD, had spent most of 2016 consulting a wide variety of stakeholders to come up with what would initially be a set of voluntary disclosure recommendations that would help investors, lenders and insurance underwriters understand more about climate-related financial risks.

TheG-20 communiquéacknowledged a commitment to sustainable growth and protecting the environment, but, with the U.S. out of the Paris agreement, it lacked the teeth advocates were seeking.

“The G-20 highlighted two things,” said Leonardo Martinez-Diaz, global director of the Finance Center at the World Resources Institute, which conducts research and makes recommendations on ways to protect Earth’s natural resources.

“One is how united 19 of 20 countries are, with many regions of all levels of development and income in agreement on climate action, including many parts of the Hamburg climate and energy plan, which includes elements relating to disclosure.

“The second is that the U.S. is isolated, and when the second biggest [carbon] emitter is missing, it’s a problem.”

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The TCFD has broad support from industry, including many of the energy companies and property and casualty insurers that are on the front line of climate change. But those are not the only sectors that are affected. WRI cites as examples a Cargill beef processing plant that was forced to shut down in 2013 because of drought, at the cost of 2,000 jobs. And about 60% of U.S. shale gas plants are in arid or extremely water-stressed regions.

Investors are waking up to the issue, too. This year, shareholders at Exxon Mobil Corp.’sannual meeting voted to ask the company to make limited disclosures about how climate change could hurt its business. The proposal was brought by climate activists in the past but failed to win enough support. This time around, 62% of shareholders voted in favor.

The disclosure relates to how goals set in the 2015 Paris Accord are affecting Exxon’s business. It was proposed by the New York State Common Retirement Fund, the pension fund for New York’s teachers, police officers and firefighters, and backed by Vanguard Group and BlackRock Inc. , the world’s biggest asset manager. Vanguard is Exxon’s biggest shareholder, with a 7% stake, according to FactSet. BlackRock ranks third, with a stake of 4.3%.

“Increasingly, investors are demanding disclosure of climate risks and strategies for addressing them in understanding whether their portfolio companies are prepared for the carbon constrained future envisioned by the Paris Agreement,” said Cook ESG Research, a firm that develops data-driven tools to track company disclosures.

The Securities and Exchange Commission acknowledged in 2010 that climate change poses a material risk for companies and issued interpretive guidance about how that risk should be handled in financial statements. The guidance includes disclosures about how regulation related to climate change, international treaties, business trends or physical impacts would affect business. Since then, it has been mostly silent on the matter.

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Hopes for a renewed push were revived in January by Trump’s pick for SEC chairman, Jay Clayton, a legal expert who played a key role at his law firm to get clients, which included Exxon, to follow rules for full disclosure of climate-change impact, as MarketWatch’s Francine McKenna has reported.

Clayton and his firm, Sullivan & Cromwell, sounded the siren on climate-change disclosure in more than one memo, strongly encouraging corporations to disclose climate-change-related risks to the SEC and investors. The memos also highlighted the legal consequences companies like Exxon and Peabody Energyhave faced when failing to do so.

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Exxon is still the subject of probes by the attorneys general of New York and Massachusetts for allegedly suppressing climate science. The New York attorney general is also investigating it for misleading investors by using a different set of data on climate in public disclosures to those it circulated in house.

Dave Anderson, policy and communications manager of the Energy and Policy Institute, an industry watchdog, said such state-level actions may be the best way to improve climate-risk disclosures, particularly if probes lead to costly settlements.

“Money talks, [and] that may be the best hope,” he said. “The states could lead in policies on the environment and the same on enforcement.”

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The stakes are high.

The TCFD forecasts that the transition to a lower-carbon world needs about $1 trillion of investments a year for the foreseeable future. It cites a 2015 study that estimates the value at risk from climate change to the total global stock of manageable assets ranges from $4.2 trillion to $43 trillion between now and the end of the 21st century.

“Investors may not be able to avoid climate-related risks by moving out of certain asset classes as a wide range of asset types could be affected,” the task force wrote in its recommendations report. “Both investors and the organizations in which they invest, therefore, should consider their longer-term strategies and most efficient allocation of capital.”

The TCFD’s recommendations are based on four areas that the task force believes are core to how companies operate: governance, strategy, risk management, and metrics and targets. They favor companies developing scenario planning as a means of placing emphasis on longer-term thinking.

The next step is working with asset managers, to try to understand their needs in terms of data and analytics for this type of financial reporting and to help encourage a consistent and comparable regime, said WRI’s Martinez-Diaz.

Exxon shares have fallen 11% in 2017, while the Dow Jones Industrial Averagehas gained 9% and the S&P 500has risen 10%. The Energy Select Sector SPDR exchange-traded fund has fallen 14% so far in 2017.