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Sea Turtles: Can They Adapt to Global Climate Change?

Sea turtles depend on both water and land. They start their lives on sandy beaches, then journey thousands of miles across the ocean feeding and growing before returning to shore to start the cycle anew.

That cycle is now in peril for the six species of sea turtles found in US waters, all listed as either "threatened" or "endangered" under the US Endangered Species Act. Many of these extraordinary marine animals lose their lives when they are caught incidentally in nets or hooked by fishermen targeting other species, a harmful effect known as "bycatch." Others drown entangled by marine debris or choke to death on trash they may mistake for food. And, as more and more communities develop along coasts, the dark, peaceful beaches sea turtles prefer for nesting are becoming too bright and congested for these quiet beings. Poaching, excessive egg collection, and pollution are also taking a toll.

And now, on top of this crushing load of stresses, climate change brings new threats.

Rising sea levels

Sea levels are rising as glaciers and ice sheets melt at an alarming rate. Sea turtles spend most of their long lives swimming great distances in the ocean, but when it is time to hatch the next generation, they return to the same beaches where they were born, beaches where they can dig their nests and safely deposit their eggs. Studies show that some females are very particular about nesting at specific elevations above the high tide line. As global climate change causes sea levels to rise the world over, many of these critical nesting habitats will be lost or become more susceptible to flooding and erosion from increasingly severe storm surges.

Rising temperatures

Our atmosphere has warmed a little over one degree Fahrenheit in the last 100 years, and the ocean has already absorbed much of the excess heat that has resulted from the emission of greenhouse gases. As a result, sand and water are warming, too. This is key because the temperature of the sand influences which sex the developing turtle embryos become. The warmer the sand, the more female hatchlings. Thus, global warming has the potential to unbalance sex ratios in sea turtle populations, possibly reducing their viability. With fewer males, the future of sea turtles could be problematic. Worse still, if the sand warms too much, hatchlings will die before they even have a chance to emerge from their eggs.

In addition to possible impacts on sea turtle reproduction, warmer ocean temperatures are killing coral reefs, which provide important feeding habitat for some sea turtles along with storm-surge protection for the beaches where they nest. Warmer water causes coral to expel the single-celled algae that help it thrive. The loss of these golden-brown algae reveals the bony white skeleton of the coral beneath—a phenomenon known as "bleaching." If the bleaching persists, the coral will die. Researchers estimate that we've already lost 19 percent of the Earth's coral reefs from the combined effects of pollution, overfishing, and climate change. If our current rate of carbon dioxide emission continues, we may lose most of the world's remaining corals in this century.

Acidification

The ocean has absorbed much of the carbon dioxide we have generated by burning fossil fuels, changing the fundamental chemistry of the ocean by making it more acidic. A consequence of this "acidification" is that shell-building animals and plants are inhibited in making their protective coverings or exoskeletons. Increased acidification could eventually decrease the viability of these shell-building animals, which is bad news for coral reefs, and bad news for sea turtles and the prey they depend on.

Changes in ocean currents

Sea turtles are road warriors of the sea. Though we don't understand a lot about how they navigate, we know that during their long lives they crisscross vast expanses of ocean. Scientists predict that changes in ocean currents caused by climate change could disrupt their migratory corridors. And as those changes in current impact other species like jellyfish and shellfish that turtles rely on for food, sea turtles may struggle to find food in sufficient quantities to survive.

What Ocean Conservancy is doing to help

Climate change is the environmental issue of our time, and it starts with the ocean. Ocean Conservancy's first line of defense is to advocate for reduced greenhouse gas emissions. Scientists say that to avoid severe impacts from climate change—like ocean warming and acidification—we need to keep the concentration of carbon dioxide in the air at a level we exceeded within the last few years, approximately 350 parts per million. Even if we reduce emissions substantially, changes are already in motion and cannot be stopped. Ocean warming, for one, will continue for decades, and a changing world for sea turtles is inevitable.

To give sea turtles a chance to adapt, we must continue the work we have been doing to reduce the other stresses that are sapping their health. This may give them the resilience they need to adapt. Ocean Conservancy is actively involved in reducing the number of sea turtles caught accidentally by fisherman, and our International Coastal Cleanup is removing dangerous marine debris from the ocean. We are also working with coastal residents and businesses in Florida to keep nesting beaches dark and shielded from disorienting lights, and to remove furniture and other obstacles on the beach that can get in the way of females and newly emerged hatchlings.

What you can do to help

• Join our online community to learn more about climate change and find out about direct actions you can take to help sea turtles.
• Reduce your carbon footprint for the sake of sea turtles: take public transportation, turn your heat down, use energy-saving appliances.
• Learn more about ways you can keep beaches safe for nesting turtles and hatchlings through the NESTS program
• Dispose of your trash properly so it doesn't reach the ocean and kill turtles and other sea life. For more information, see the special wildlife section of our report A Rising Tide of Ocean Debris and What We Can Do About It.
• Download Our Sea Turtles Coloring Book (PDF) - it's fun, educational, and free! Kids will discover where sea turtles live and how they nest. They will also learn about the dangers to turtles, and what can be done to help them. This version contains English and Spanish.

© Copyright 2010 Ocean Conservancy
The Ocean Conservancy, International Coastal Cleanup and Ocean Action Network are registered trademarks of Ocean Conservancy.

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The Ocean Conservancy, International Coastal Cleanup and Ocean Action Network are registered trademarks of Ocean Conservancy.

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