Ahead of climate talks, a crucial voice is missing

sunrise, Mozambique

A man walks through the shallows at sunrise in Mozambique. More than 500 million people depend directly on reefs for coastal protection, food and sustained livelihoods. (© William Crosse)

In early December, world leaders will gather in Paris to hammer out a pact to confront climate change.

But one voice representing nearly 75% of the Earth’s surface is being left off the agenda: the ocean.

This has drawn the attention of renowned ocean champions such as Dr. Sylvia Earle, oceanographer and National Geographic Explorer-in-Residence, who is calling for a voice for oceans at climate change negotiations.

Giving decision-makers the benefit of the doubt, how can they begin to combat climate change across the world’s vast oceans? One way is by better understanding the links between major climate-induced impacts.

Assessment tools like the Ocean Health Index provide insight into overall pressures on oceans, including climate change, and offer a clear way forward for policies to relieve those pressures.

The Index defines a healthy ocean as one that sustainably delivers a full range of benefits to people both now and in the future. It is the first assessment tool that both measures and communicates key elements from all dimensions of the ocean’s health using 10 holistic benefits, such as carbon storage, food provision, and tourism and recreation.

The Ocean Health Index calculates the overall impact of climate change by breaking it down into three primary measures: sea surface temperature, sea-level rise and ocean acidification. The Index demonstrates that climate change disrupts the ocean’s ability to provide all 10 of the benefits we track.

Now, as it enters its fifth year, the Index highlights five key reasons protecting oceans can play a major role in helping humanity fight and adapt to climate change:

  1. The ocean is fighting climate change right now.

The ocean produces half of the oxygen we breathe and acts as the planet’s largest “sink,” or repository, of carbon and heat. In fact, the ocean stores 93% of all carbon on Earth.

Based on the current rate of degradation of coastal mangrove, tidal marsh and seagrass ecosystems, the Index predicts a 14% decline in the ability of these coastal areas to store carbon. Although they cover less than 2% of the ocean’s total area, these ecosystems account for more than 50% of the ocean’s total carbon storage. Approximately one-third of coastal habitats have already been lost and the remainder are severely threatened, weakening the ocean’s ability to absorb carbon and accelerating the rate of global climate change.

  1. The ocean influences weather on land.

The oceans have already absorbed almost 90% of the heat added to Earth’s system by rising greenhouse gas emissions — but they’re reaching their limit. By absorbing, storing and slowly releasing these large quantities of heat, the ocean regulates local temperatures and, over time, the entire planet. Ocean currents also play a major role in maintaining Earth’s climate. Changes in these currents have global implications, including irregular rainfall — excessive rain in some regions, extreme drought in others — more intense and longer-lasting storms, and changes in local air and water temperatures. These changes will alter habitats for countless terrestrial and marine species, as well as make crop-growing seasons more unpredictable.


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  1. Climate change is already having disastrous impacts on marine ecosystems.

 A massive chemical reaction is underway in the ocean. As it absorbs large amounts of carbon dioxide, the ocean’s pH is changing; in fact, the ocean has become 30% more acidic since the start of the Industrial Revolution.

Not only does increased acidity inhibit the growth of organisms such as corals, clams and crabs, it also affects the larval development of certain commercial fish and shellfish. Thus, fisheries that many humans depend upon may experience serious declines. For example, it is estimated that a 10%–25% decrease in U.S. mollusk harvest could result in a loss of up to US$ 187 million per year.

Similarly, the Ocean Health Index shows that climate change has led to increased sea surface temperature, affecting the Index’s biodiversity, natural products and coastal protection goals. More specifically, warming waters alter migration patterns of species, food webs, predator-prey relationships and reproduction success. Increased sea surface temperatures are also likely to cause nearly half of coral reefs to experience severe bleaching — and potentially die — within just 20 to 30 years.

More than 500 million people depend directly on reefs for coastal protection, food and sustained livelihoods. The total net benefit per year of the world’s coral reefs is estimated to be nearly US$ 30 billion. The effects of climate change on marine ecosystems drastically inhibit their ability to provide crucial benefits to communities both locally and globally.

lemon shark in mangrove forest, Bahamas

A young lemon shark hunts in a mangrove forest in the Bahamas. In addition to providing habitat for species, mangroves and other coastal ecosystems help buffer coasts from storms — saving human lives and property in the process. (© Matthew D Potenski 2011/Marine Photobank)

  1. Coastal habitats offer protection to coastal communities.

As mentioned above, climate change will likely cause more intense hurricanes and tropical storms due to higher ocean temperatures, resulting in the destruction and devastation of coastal communities.

Healthy coastal habitats including mangrove forests, seagrass meadows, salt marshes and coral reefs can provide protection from storms, erosion and flooding — saving human lives and property in the process. For example, mangroves absorb wave energy, reducing the depth, velocity and force of waves that reach the shores.

As the Index demonstrates, coastal habitats also provide other benefits to humans. In addition to providing coastal protection, mangrove forests are also vital for carbon storage and biodiversity, yet they are declining rapidly due to coastal development.

  1. Climate change eclipses all other pressures on oceans.

Out of the five major pressures on ocean health — fisheries exploitation, habitat destruction, pollution, spread of invasive species, and climate change — climate change is the most all-encompassing, reaching across all aspects of ocean health: biological, physical, economic and social.

As Sylvia Earle has said, “No ocean, no life. No blue, no green. If not for the ocean, there would be no climate to discuss … we must give the ocean a voice!”

Lindsay Mosher is the coordinator of the Ocean Health Index, a collaboration between Conservation International and the University of California, Santa Barbara.

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