The main challenge for survival, or the main threat to sea turtles, is the fact that many humans consider turtle eggs as a delicacy and steal these eggs from their nests. There was also a time when turtle meat was considered a delicacy, most especially in making turtle soup. However, the use of turtle meat then, and now the eggs, are illegal in many countries. This does not keep some people from stealing them from nests anyway.
The challenges to survival for green sea turtles, and other turtles, in the ocean include the turbulence of the ocean waters themselves and certain rough currents. The weather and global warming has taken a huge toll on turtles and other sea life by not only changing their environment, but also the food they need to survive. For the green sea turtles, this includes the dying off large beds of sea kelp which is their main food source when they have become adults. The small fish that young sea turtles mainly feed on while they grow are also affected by global warming in that the schools of these fish are moving/migrating in different patterns that remove them from the usual turtle environments. Although some mature sea turtles may live their lives in the expanse of the deep oceans and seas, most live closer to land and even the land masses are changing for various reasons, including global warming.
Another factor of global warming on sea turtles is how it affects the young. Additional hot temperatures can also make it extremely hard for the younglings to survive as they make the transition from land to the waters. They may become too hot and die as the ocean temperatures rise, which means they have little to no chance of helping to increase the overall number of sea turtles.
The climate is also believed to affect the sex of the younglings. So, if the temperatures continue to significantly increase, it is believed that there will be many more females than males in the world. Yet these males likely won’t be able to keep up with the need of the females when it comes to reproduction. There is also research that shows the younglings can die while still in their eggs due to the extremely hot temperatures in some areas.
Finally, larger green sea turtles along with other larger sea turtles will become a common food supply for both sharks and whales, while they always have been for tiger sharks.