"Dear President Biden: Don’t Forget the Ocean on Earth Day!"

That was the message sent to the president today by 15 conservation groups representing millions of Americans concerned about the devastating effects of climate change on the ocean. The groups asked that the Earth Day Climate Summit include a focus on the ocean’s role in mitigating climate change, and key opportunities for international action this year to bolster the ocean’s resilience in the face of climate-related changes already underway.

Why a focus on the ocean at a climate summit? The science is clear that the ocean plays a key role in regulating the climate by absorbing more than 90% of the excess heat and one-quarter of the carbon dioxide humans have generated by burning fossil fuels, helping to shield the planet from the worst ravages of climate change.

But, as the groups noted, this has come at a cost we are only now beginning to understand. Climate change is exerting serious, long-term and far-reaching negative consequences for our ocean. The ocean is now warmer than at any time since measurements began, more acidic than at any time in the last 14 million years, and is losing oxygen, fundamental to virtually all marine life. These changes are already affecting different elements of the marine food web, from the smallest plankton to important fisheries to the largest whales.

Fortunately, there are actions we can take that can help bolster the ability of the ocean to mitigate climate change. These include protecting “blue carbon” ecosystems (salt marsh, mangroves and seagrass) that sequester carbon, reducing CO2 emissions from shipping, halting new offshore drilling and harnessing clean offshore wind energy.

Equally important, there are actions we can take to bolster the resilience of the ocean in the face of climate change. Two major opportunities to do this are slated to take place in 2021:

1. the adoption of new global biodiversity targets at the October meeting of the Parties to the Convention on Biological Diversity (CB) in Kunming, China, and
2. the scheduled final session of negotiations at the United Nations to develop an international treaty to strengthen our ability to protect biodiversity in the ocean beyond national jurisdiction.

Known as the “high seas,” international waters beyond national jurisdiction constitute nearly 2/3rds of the global ocean and cover nearly half the surface of the planet. The current legal regime governing human activities in the high seas is weak, antiquated and lacks modern tools to protect biodiversity that we routinely apply within our waters, such as the ability to create fully protected marine parks and modern environmental assessment and management requirements. Both are urgently needed in the high seas to help the ocean cope with the overwhelming effects of warming, acidification, de-oxygenation and other climate-related impacts.

President Biden’s outstanding leadership on climate needs to be paired with similar leadership on protecting the ocean if we hope to have a sustainable future. The Climate Summit presents a key opportunity to focus global attention on the ocean-climate nexus and the actions needed in 2021 to maximize both the climate-mitigation capacity of the ocean and bolster its climate resilience. These two sides of the ocean-climate nexus—climate mitigation and climate resilience—are essential pieces of a successful climate strategy, and there is no time to lose.

Let’s do this President Biden. We’ll be with you on Earth Day.