The business case for acting on climate change has never been stronger, and the need to act has never been more urgent. For the past three years, worldwide carbon emissions from fossil fuels have stayed flat while gross domestic product (GDP) has grown, demonstrating that emissions and economic growth aren’t inextricably linked. Decoupling emissions and growth is just the first step. To stay within the carbon budget for 2 degrees Celsius warming—and avoid the most catastrophic impacts of climate change—global emissions have to start falling by 2020. While the President of the largest economy in the world blows headwinds at progress, business leaders and investors must act to bend the emissions curve.

Why them? Because the cost of inaction threatens their economic livelihoods. Consider: The world’s current stock of manageable assets is roughly $143 trillion. According to one often-cited report, a business-as-usual future (6 degrees Celsius warming) creates present value losses worth $43 trillion. To put that in perspective, the US Treasury estimated that the 2007-2010 US subprime mortgage crisis wiped out $19.2 trillion in household wealth. But unlike subprime, you don’t have to be an eccentric hedge fund manager to see this one coming.

Also, business leaders and investors are people too. Bill McKibben’s 2012 Rolling Stone article, “Global Warming’s Terrifying New Math,” launched a movement that raised awareness of just how close we are to destroying Earth for future generations. Our kids and grandkids have swallowed the math. CEOs and CIOs must look them in the eye and say they did everything they could to fix that terrifying equation. What’s more, businesses’ employees and customers are also swallowing the math, which means the marketplace for top talent—especially millennials—will reward climate leaders.

Climate leadership is good business

But there are other reasons to act. Climate leadership is profitable—and not just for cash-rich tech companies or companies in the crosshairs of divestment. Walmart, for example, recently joined nearly 300 other companies, including General Mills, Pepsi, Xerox and Ikea, in signing on to the Science Based Targets initiative, which offers a clearly defined pathway to future-proofing growth. The initiative specifies how much and how quickly companies need to reduce emissions to stay within a budget consistent within 2 degrees Celsius warming. By doubling the efficiency of its transportation fleet, growing renewables in its power sourcing, and improving its refrigerant technology, Walmart has saved nearly $1 billion from its 2005 baseline. Now it is going further with its Project Gigaton. With the goal to cut one gigaton (a big number in carbon parlance) of indirect emissions in its supply chain by 2030, Project Gigaton could save billions more dollars , and the equivalent greenhouse gas reductions of 211 million cars for a year.

And there is more. Investors have reached a tipping point in thinking about climate change. The most striking evidence of this came last month, when Exxon shareholders voted 62 percent in favor of requiring the company to report climate-related risks to its business (a similar resolution garnered 38 percent in 2016, a record at the time). Meanwhile, heavy hitters like Blackrock, CalPERS, and New York State Common Retirement Fund are getting more proactive when it comes to climate risk. Even Vanguard, which has previously lagged on voting proxies, voted for the Exxon climate risk resolution. CalPERS has gone so far as to change its governance principles to state that board members of companies it owns should have expertise and experience in climate risk management strategies.

Also, tools to help investors see what they can’t find in quarterly and annual reports are beginning to emerge. For example, Carbon Tracker recently published a study comparing the supply options of publically traded oil and gas companies with demand levels consistent under a 2 degree Celsius carbon budget. They found that $2.3 trillion (roughly one-third) of potential investments in projects through 2025 should not be deployed. On an individual company basis, the range was between 10 to 60 percent of capital expenditure.

From Paris to Walmart

In his announcement to pull the United States out of the Paris Agreement, President Trump argued that he was elected to represent Pittsburgh, not Paris. Trump’s ideological decision was a blow not only to Pittsburg and other cities and states benefitting from the clean economy, but also to US businesses and investors, who played a big role in getting it signed. The business community has been vocal and unified in its message that leaving Paris was bad news, and its actions have been swift and definitive—including full-page ads in the Wall Street Journal criticizing the decision, resignations from Trump Administration advisory boards, and Twitter trolling. As of late June, more than 2,000 businesses and investors, representing more than $2 trillion in revenue and 4.5 million employees, signed the WeAreStillIn pledge to uphold the goals of the Paris Agreement.

Withdrawal from Paris is expensive for the US economy. Stanford’s Marshall Burke produced a great analysis to calculate the price tag, based simply on the temperature impact of a Paris-minus-United States world compared to a Paris-including-United States world, which amounts to a 0.3 degree Celsius temperature differential. That doesn’t sound like a lot, but when you raise warming from 3.3 degrees Celsius to 3.6 degrees Celsius and hit “play” on the US economy, we lose $8 trillion in present value.

Setting aside the wide-ranging implications for the economy, trade, security, and the global world order, withdrawal from Paris has serious implications for US innovation and finance that demand executive attention. Paris is not just a set of voluntary emission reduction targets. It also represents a vast network of public private partnerships and organizations that are building connective tissue through which US capital and innovation could be exported. US companies and investors must continue to fortify these networks to remain competitive.

The absence of federal policy limits the market’s ability to take clear price signals and follow glide paths through a smooth transition to a low-carbon economy. That is annoying but not catastrophic for the electric power sector. However, it is a serious concern for other sectors of the economy—such as the built environment, transportation, industrial processes and agricultural practices—where market forces have yet to take over or where good policy really is the best medicine.

Most critically, lack of federal leadership slows progress toward better data and disclosure. Greater transparency is crucial, as it enables investors to account for asset and portfolio risks that are not yet priced. It also enables the market to reward businesses for future-proofing their operations. The Task Force on Climate-Related Financial Disclosure (TCFD), headed by Michael Bloomberg and housed within the G20 Financial Stability Board, is the leading global effort to create clear, consistent, and comparable information about the risks and opportunities climate change presents. It issued its final recommendations at the end of June in anticipation of July’s G20 meeting in Hamburg. After intense negotiations, on July 8, 19 world leaders declared the Paris accord “irreversible” and included mention of the TCFD’s recommendations in the final statement.

In 2014, the G8 became the G7 due to Russia’s aggression. Who would have imagined that three years later, the G20 would effectively become the G19? As for the fate of the TCFD recommendations, it will be up to the US private sector to ensure their adoption.

Three steps forward

So, what can US business leaders and investors do?

Step 1: Build internal capacity and engage experts. There are lots of great organizations that can help your firm better understand the interface between climate change and business operations or investments, including Ceres, World Resources Institute, We Mean Business, Rhodium Group, Four Twenty Seven Climate Solutions, and 2 Degrees Investing Initiative, to name a few.

Step 2: Conduct a detailed analysis of the risk and innovation opportunities climate change presents to operations, facilities, supply chains, and markets. Develop an understanding of the major disruptions from business as usual (breakthroughs and breakdowns) in a transition to a 2 degree Celsius world. Start with this summer reading list: TCFD recommendations, the Risky Business reports, and Resource Revolution.

Step 3: Get proactive. The world will certainly transition to a low-carbon economy, and vast amounts of wealth will be created (and destroyed) in the process. Those who go first will lose less and gain more.

The business case to act on climate is as strong as it has ever been. But ultimately, we have to look beyond economic arguments if we are to fix global warming’s terrifying equation in time. We need moral leaders to breakthrough inertia and short-termism, and prioritize climate action this week, this month, this year.