On April 29, thousands of demonstrators filled the streets of Washington, D.C. and other cities to show their support for climate change action. Just one week before, scientists marched in cities around the world to underscore the value of objective facts and research, and many of their placards carried climate messages as well.

Demonstrations such as these appear to be getting larger and more frequent, and given the position of the current U.S. administration on climate change (it just removed climate science from the EPA website), the protests are likely to keep growing.

But when was the last time you saw a similarly sized demonstration for the oceans?

It was over four decades ago that the first Greenpeace activists ignited storms of protest to save the whales. Arguably, they succeeded. While some whale species remain vulnerable or endangered, whale populations overall have stabilized and rebounded around the world. This was an enormous victory for marine conservation, one that never has been properly celebrated.

But since those heady days when the first Zodiac boats braved harpoons to capture iconic images of destruction and drive eco-activists into the streets, the ocean has fallen off our radar. With the exception of occasional, specific alarm bells — bleaching coral reefs, failing fisheries — the global ocean, 70 percent of our planet, somehow has remained an immense, silent and distant partner to the atmosphere, which has been our principal object of global environmental concern.

I believe that situation is about to undergo a sea change.

On June 5-9, the United Nations will convene the first global summit meeting on the state of the world’s oceans. While this global call to #SaveOurOceans has come late, it is gathering momentum — driven, unfortunately, by a storm surge of bad news about ocean health, coupled with concerns about a wave of new investment aiming to exploit the sea’s vast resources.

As is well known, the movement to address climate change is still battling frequent challenges to its scientific basis — exaggerated claims of uncertainty propagated by narrow economic interests. This continuing game of deception is made possible by the fact that climate change is a huge, slow and largely invisible process. You can’t look up and see CO2 accumulating like garbage in our atmosphere. Scientists have seen the "smoking gun" of humanity’s impact on climate hundreds of times over, but it requires a fair amount of scientific literacy to read the data and see it for yourself.

Not so with the global oceans. Anybody can get on a boat or put on a dive suit and see many of the problems firsthand. In most cases, there will be no mistaking who is at fault. A sea turtle killed by eating a plastic bag cannot be blamed on "natural variations" in the environment. The estimated 5.25 trillion pieces of plastic polluting the global oceans all had just one possible source: us.

Similarly, a fished-out sea cannot be blamed on extra-hungry dolphins. The extra CO2 in seawater that is causing increasing acidification, damaging the entire ocean food chain, did not arrive from space. No profit-minded oil company or eco-hostile "news" service can sow uncertainty about ocean health with any credibility (although some people are certainly trying).

The problems in our oceans are as deeply serious as they are undeniably real. Did you know that ocean life is responsible for half of the planet’s oxygen production? And that oxygen levels in the ocean itself are dropping (PDF)?

That’s why I keep saying, "Ocean is the new climate."

Like the issue of climate change, the issue of ocean health is deserving of mass attention, intensive journalistic debate and political action on a large scale.

Like the atmosphere, the ocean is a vast system that affects every corner of the planet. Like climate, what happens in the oceans is decisive for the future of humanity — indeed, for the future of life on planet Earth. And like the issue of climate change, the issue of ocean health is deserving of mass attention, intensive journalistic debate and political action on a large scale.

So we had better get more serious about the oceans, and fast. The U.N. Ocean Conference is only a beginning, just as the Earth Summit of 1992 marked the start of serious work on climate change. (The UNFCCC was born then.) But this time around, we cannot afford to wait 25 years to make the long journey from first global summit to a comprehensive, Paris-style global agreement. We have a very short window of time available to us if we are to avoid damage to ocean ecosystems and restore the oceans to health.

That’s why I am spending a lot of time working on ocean issues these days. As a sustainability professional, of course I still work on climate, too (and other topics). Climate change has not become less urgent just because the oceans have become more so. But that urgency is not yet widely shared, so I have personally prioritized ocean issues the past few years, partnering with WWF and other institutions to help advance strategy on ocean sustainability issues.

A key area of focus for me is the "Blue Economy," the part of the global economy tied directly to the oceans — and which many countries around the world are targeting for serious expansion. As mineral resources become scarce on land, as demand for farm-raised ocean fish grows, as ever-bigger cruise ships and cargo freighters carry more people and stuff around our planet (including through seas that used to be frozen and impassable), investment interest in the oceans is seriously heating up. Meanwhile, one in 10 people on our planet still depends on subsistence fishing just to survive.

Humanity’s growing economic interest in the sea, and its continuing dependency on ocean ecosystems, are on a collision course with the declining state of the sea itself.

This is a recipe for catastrophe unfolding in real time. Humanity’s growing economic interest in the sea, and its continuing dependency on ocean ecosystems, are on a collision course with the declining state of the sea itself.

We need to quickly establish new ways of thinking about the oceans, including some "guardrails" for sustainability, and start aiming this growing interest in the oceans in more creative and, indeed, restorative directions.

WWF, as one of the leading voices campaigning to raise the global profile of ocean issues, has been making a huge contribution this process (starting in 2015) with a set of reports documenting the value of the ocean economy, the declining health of ocean life and a new set of "Principles for a Sustainable Blue Economy" that have the potential to help #SaveOurOceans — for their own sake, as ecosystems with their own right to live, as well as for the long-term economic use that we still need to make of them.

The next step in building a truly sustainable and restorative economy in our oceans is to start aiming this growing tide of Blue Economy investment money in the right direction. That’s why WWF recently floated a proposal to develop a global Sustainable Blue Economy Protocol (PDF), a set of voluntary guidelines to help investors create a healthier ocean, rather than spending their money in ways keep paying for its decline.

These are cutting-edge ideas that can accelerate the process of seriously addressing ocean issues — a process that, in the case of climate change, took the better part of three decades (and is far from finished).

But these advances will happen only if we all add the ocean’s enormous, achingly beautiful, painfully damaged and globally essential ecosystems to our collective to-do list. We have to stop treating the oceans as we have treated the atmosphere for centuries: as a vast, freely available garbage dump. We have to help them heal. And we have to do it now.

Ocean is the new climate.