Ahead of major climate talks at COP21 this year in Paris, scientists are offering insights to the far-reaching effects of rising carbon dioxide levels on the ocean. Spearheaded by the Oceans 2015 Initiative, which brought together 22 scientists and policy experts from nine different countries, the results were published this week in the journal Science and focus on how warming waters, rising seas, and ocean acidification drive changes to the global ocean. The goal is to arm negotiators with the up-to-date, policy-relevant science that representatives from around the world can use during international climate negotiations.

UW School of Marine and Environmental Affairs’ Ryan Kelly was involved in the study and is one of the coauthors.

“This work brings together all of the best available science on the effects of global change for the world’s ocean, and clearly sets out how our environmental policy decisions today lead to very different future scenarios. Until now, the ocean has largely been left out of the global climate conversation.”

The authors emphasize that the many benefits humans get from the ocean, including seafood and coastal protection from storms, will likely change with increasing CO₂ emissions and warming of the atmosphere. Included in their calculations are what to expect if warming stays under 2 degrees Celsius—the goal set out in the Copenhagen Accord—and what to expect to if emissions continue as they do today, which will cause much greater warming.

In some cases, the impacts are unavoidable no matter what emission-cutting protocols are set in place. However, the authors argue that immediate and substantial reduction of CO₂ emissions is required to prevent massive, and in some cases irreversible, impacts to ocean ecosystems and their services. Smaller-scale fixes such as managing for resilient coastal ecosystems are important steps to take now while they are effective; over the coming decades such options will become untenable if CO₂ continues to build up in the atmosphere.

Upcoming negotiations in December under the United Nations Framework Convention on Climate Change aim to set the course for global decision making around reducing fossil fuel emissions in the coming decades. In past negotiations, little information has been available about climate’s effect on the oceans, thus leaving them largely off the table when planning solutions. The authors’ goal for this work is that it can inform a more sustainable path forward for fossil fuel use that includes thinking about the marine environment.

When it comes to the ocean, what’s happening underwater can be out of sight and therefore out of mind. Yet real changes are happening in the ocean, driven by a 40 percent increase in atmospheric carbon dioxide since the beginning of the industrial period. The effects of this increase on the global ocean include:

• absorbing 93 percent of the Earth’s additional heat since the 1970s, offsetting much atmospheric warming but increasing ocean temperature and rising sea level;
• capturing 28 percent of CO₂ emissions derived from human activities since 1750, again offsetting warming, but generating ocean acidification; and
• accumulating virtually all water resulting from ice melt, further increasing sea level and putting coastal communities at risk.

As societies around the world continue to do business as usual, decision makers are left with fewer choices about how to mitigate the effects of climate on oceans. To get ahead of this, the authors urge policy makers to develop approaches to cutting emissions before the challenge becomes insurmountable.

The University of Washington’s College of the Environment already plays a big role in thinking about how climate change affects the world. Numerous scientists, many in the Department of Atmospheric Sciences, have contributed to or lead chapters of the global assessment IPCC reports on climate change. Kelly’s role and his contributions to this paper add to the growing list of scientists from the UW who are weighing in on this discussion, bringing science to the table to help decision makers develop sound policies.

“The ocean is so big, it’s hard to believe that we can fundamentally change how it works, but every ocean ecosystem we looked at is facing real impacts from CO₂ emissions—from fisheries to coral reefs to oysters. Scientists have a key role to play by distilling everything research tells us, and putting that information where it will do some good,” says Kelly.

Read Kelly’s paper, Contrasting futures for oceans and society from different anthropogenic CO₂ emissions scenarios.

Listen to KUOW’s Tom Banse story on this paper.

By: John Meyer, jjmeyer@uw.edu