Coral-dependent Nations Vulnerable to Global Change

Rising sea surface temperatures and ocean acidification are threatening coral reefs worldwide, and humans will feel this loss acutely in a high carbon future.

My colleagues and I recently conducted a new analysis of who is likely to be most harmed by coral reef loss from these global stressors.  Our findings, “Coral Reefs and People in a High CO2 World: Where Can Science Make a Difference to People?” appear in the current issue of the journal PLOS One.

Our new study was led by Duke University and the Université de Bretagne Occidentale.  We built on previous analyses to look at how coral reefs serve ecosystems, and benefit humans. Coral reefs are inextricably intertwined with the people who live near them: through tourism, as storm buffers, and as a critical source of food and shelter for the fish many communities depend on for a source of protein. We looked at storm protection and food from fisheries. (We were not able to assess loss of income from highly-lucrative coral reef-dependent tourism for this study, because the current global data is not adequate).

To evaluate storm protection, we looked at the number of people living at low elevations near a protective coral reef to determine what proportion of a country’s population would be vulnerable if coral degraded. We analyzed fisheries data to determine which countries are most dependent on coral reef fish for food and income.

We found that South-East Asia, Americas, Oceania and Eastern Africa (i.e., the countries shaded brown on the map below), are all places that are highly dependent upon the ecosystem services provided by coral reefs.

Climate change and ocean acidification are a one-two punch. And when we layer these on, here are the areas at highest risk: Northwestern Australia, southern Indonesia, the Coral Triangle countries of Southeast Asia, and Western Mexico. These areas all have high human coral reef dependence and face serious CO2-related threats (See area on map where brown meets red and orange). By 2050, these regions are likely to experience coral reef bleaching and reef loss that affects fisheries and shoreline protection, jeopardizing lives and economic prosperity.

So, why issue this warning?  How is this information useful? For one, countries that are especially dependent on coral reef services may want to invest in mitigation and adaptation strategies.  For example, these countries could begin to identify populations or species of corals that are most resilient to these changes and begin to propagate them. They may want to invest in local mitigation measures such as seagrass restoration. In many cases, better ocean management could also delay these effects through increased ecosystem resilience.

Non-governmental organizations, nonprofits, and labor and trade organizations and other groups that represent people who would be most severely impacted by coral loss can also use this information to advocate for action. Information on sea surface temperatures and ocean acidification in these regions can be helpful in advocating for policy changes to combat these threats.

All countries, not just coral-dependent nations, should hear this as another call to address the severity of the threats posed by runaway carbon pollution. The United Nations Framework Convention on Climate Change (UNFCCC) has unfortunately remained relatively quiet on the serious threat climate change and ocean acidification are posing to our oceans, as I wrote in a previous blog post.

As I explained in the post, the current Paris framework does not adequately address ocean acidification. The agreement permits emission reductions in terms of ‘CO2 equivalencies,’ including other greenhouse gases, such as methane. But solving the problem of ocean acidification will require reductions in carbon dioxide emissions, specifically. Reductions in other greenhouse gases will do nothing to slow ocean acidification. In addition, the Green Carbon Fund, the financial mechanism of the UNFCC which invests in climate-resilient development, might not issue grants for ocean acidification. With this in mind, the next re-evaluation of the Paris agreement should consider the harmful effects of changing ocean chemistry in addition to the impacts from global warming.

I hope that this new research, as it offers yet more evidence that a high carbon future puts human lives at risk, will further spur leaders to global climate action.