Editor’s Note: Marc Benioff is chairman and co-CEO of Salesforce. Sir Richard Branson is the founder of Virgin Group. The opinions expressed in this commentary are their own.

The world continues to rally around the urgent fight against climate change. Millions of workers and students are again walking out of their jobs and schools this week in a global strike to demand action by their governments. And at the UN Climate Action Summit, countries around the world announced meaningful steps to avert the worst effects of this impending disaster.

While there is no silver bullet to this existential threat to our way of life, we do already know one of the most effective ways to slow climate change: Protect our ocean.

The ocean is our biggest ally in fighting climate change, absorbing more than 90% of global warming’s heat. The ocean is the world’s largest carbon sink — without it, climate change would be even worse than it already is.

At the same time, the ocean is the biggest victim of climate change. Sucking up so much heat and carbon dioxide has caused the ocean to become hotter much faster than we thought possible, and more acidic. It is melting sea ice at the Poles and driving oxygen out of the seas. This week, more than 100 scientists from more than 30 countries will present the latest summary of the impacts of climate change on the ocean at the United Nations Intergovernmental Panel on Climate Change — a report that promises to be a terrifying read.

Business leaders are uniquely positioned to drive change. It is our responsibility to use our profits and platforms to fight the climate emergency on land and in our seas. It’s not only the right thing to do, it’s good business; our employees, partners and communities are demanding it.

As CEOs we are acutely aware of the economic costs of this climate emergency. Flooding from rising sea levels is expected to soon cause $14 trillion in damage per year. Our global fisheries are projected to lose roughly between $6 billion and $15 billion per year in revenue by 2050. Climate-driven coral bleaching — caused by warming ocean temperatures — risks eroding the value of coral reefs, which have been estimated to generate $36 billion per year in tourism value around the world.

There are also the immense costs on which we can’t put a dollar value. Fishery losses mean not only a loss of profit, but also a loss of access to critically important nutrition for hundreds of millions of people, many of which are among the poorest in the world. Degradation of coral reefs erodes a lucrative tourist asset, but also jeopardizes one-of-a-kind species — corals, tropical fish, sea turtles — that enrich our lives with beauty and add diversity to our planet.

As daunting as this challenge is, we remain optimistic. As pragmatists, we know from experience that in any endeavor, it is essential to have a solid asset base. In the case of our climate and oceans, that means saving and revitalizing the capital that builds that asset base: marine ecosystems. Specifically, we need to urgently accelerate and multiply innovative solutions that invest in nature and regenerate ocean life.

First and foremost, we must follow the science and move as fast as possible to reach net zero carbon emissions. The survival of the essential building blocks of ocean health, like coral reefs, depends on limiting global heating to no more than 1.5 degrees Celsius. We also need to minimize additional risks by not opening new frontiers of exploitation — like drilling for oil in the Arctic or mining in the ocean — that could disturb ancient storehouses of carbon now safely locked away in the deep sea.

The next 18 months will be critical, as they offer multiple opportunities to align the actions needed with bold political decisions. By the end of 2020, we must deliver a strong high seas biodiversity treaty at the United Nations that protects key regions of our shared international waters; we must make sure that vast expanses of Antarctica’s Southern Ocean are protected; and nations must agree at the Convention on Biological Diversity meeting next year to fully protect at least 30% of our ocean by 2030, and then ensure the remaining 70% is sustainably managed.

But even more needs to be done and business leaders will need to step up. At our own companies, we are devising plans to achieve net-zero emissions (which Salesforce has already achieved); identifying opportunities to close the carbon loop in our supply chains that can’t yet be decarbonized; working with our suppliers and adapting business models to remove single-use plastics, and asking that our suppliers and partners also adopt these practices; and actively supporting organizations responding to the climate and ocean crises. Every company can’t do everything. But when it comes to speaking up and acting on behalf of our planet, every company can do something.

Our generation inherited a healthy ocean from our forebearers. But we are passing on a more broken and fragile ocean to the next generation. And our children — like those who will continue to raise their voices over the coming days — know it. In Iceland, a plaque commemorates the first glacier lost to climate change: “This monument is to acknowledge that we know what is happening and know what needs to be done. Only you know if we did it.”

The time for talk has passed. Generations to come will judge us by what we do next and whether, when we had our chance, we took the action that was needed to protect our Blue Planet.