In the past 50 years, the amount of water in the open ocean with zero oxygen has gone up more than fourfold. In coastal water bodies，including river mouths and seas, low-oxygen sites have increased more than tenfold since 1950.Scientists expect oxygen to continue dropping even outside these zones as Earth warms .

“Oxygen is fundamental to life in the Oceans,” said Denise Breitburg, a marine ecologist with the Smithsonian Environmental Research Center. “The decline in ocean oxygen ranks among the most serious effects of human activities on the Earth ’s environment. Actually, it's a great loss to all the support services that rely on recreation and tourism, including hotels and restaurants and taxi drivers and everything else. The reverberations(严重影响) of unhealthy ecosystems in the ocean can be extensive.”

In areas traditionally called “dead zones" , like those in Chesapeake Bay and the Gulf of Mexico，oxygen plummets(大幅下跌) to so low levels that many animals die. As fish avoid these zones, their habitats become smaller and they’ re easier to be attacked or caught. But the problem goes far beyond “dead zones”. Even smaller oxygen decline can prevent growth in animals, hinder reproduction and lead to disease or even death. It also can cause the release of dangerous chemicals such as nitrous oxide, a greenhouse gas up to 300 times more powerful than carbon dioxide. While some animals can boom in “dead zones”，overall biodiversity falls.

Climate change is the key criminal in the open ocean. Warming surface waters make it harder for oxygen to reach the inside of the ocean. Furthermore, as the ocean as a whole gets warmer, it holds less oxygen. In coastal waters, too much nutrient pollution from land creates algal blooms, which use up oxygen as they die and break down.

People's livelihoods are also on the line, the scientists reported, especially in developing nations. Smaller fisheries(渔场)may be unable to relocate when low oxygen destroys their harvests or forces fish to move elsewhere. So we humans have to carry on a war now and win the war.

Sometimes the simplest solution is the best one. That seems to be the case when it comes to the issue of wind turbines (涡轮机）killing birds.

According to a study conducted at a wind farm on the Norwegian archipelago of Smøla, changing the color of a single blade(叶片）on a turbine from white to black resulted in a 70-percent drop in the number of bird deaths.

In the past few years there has been a huge increase in global wind power, with more than 60 GW of new generating capacity(发电量）added worldwide in 2019. If the turbines are placed correctly, wind power is cheaper, cleaner and more sustainable(可持续的). Not to mention that a turbine farm is easier on the eye than a huge power plant.

But these farms aren’t good for everybody - especially not for local bat and bird populations. The US Fish and Wildlife Service calculated that nearly 300,000 birds were killed by wind turbines in 2015, which is a lot fewer than those that die as a result of hitting electrical power lines each year. Yet it still remains an environmental issue, even as bird deaths from turbines seem to be going down as the industry moves to larger turbine blades that move more slowly.

Studies have suggested that birds may not be skillful at noticing obstructions to their flight path, and adding different colored fan blades can increase birds’ chances of spotting a rapidly turning fan.

At the Smøla wind farm, regular checks of four particular wind turbines found the four turbines killed 18 birds that flew into the blades over six years. In 2013, on each of the turbines in the test group, a single blade was painted black. Over the next three years, only six birds were found dead due to hitting the wind turbines.

Researchers said the results are a step in the right direction toward better, more sustainable treatment of our flying friends.

Planting more breadfruit trees could help make food supplies more stable (稳定) as the planet warms. Climate models suggest they will grow well across the tropics. There is an especially big opportunity in tropical Africa, where large areas are suitable for growing breadfruit trees and will remain so until the end of the century.

Breadfruit is a bit like a potato that grows on a tree, says Lucy Yang at Northwestern University in Illinois. The fruits can be cooked in many ways and also turned into a flour. “They are highly productive and very valuable to the body as food,” she says. “In addition, once a tree is planted, it is quite resilient (适应力强的).”

Yang and Daniel Horton, also at Northwestern, worked together to look at where in the tropics breadfruit grows now and to identify the climatic (气候的) conditions the trees require. Next, they used climate models to see where breadfruit could still be grown between 2060 and 2080. They found that the crop will not be affected, with reduction of the overall suitable area by just 4 % globally.

This is important because some studies suggest the production of main crops such as rice could be hard hit by rising temperatures and more extreme weather. There are expected to be many more food shocks like that of 2010, when Russia stopped exporting wheat because of a serious heatwave.

The team’s findings also made known a big opportunity in tropical Africa, where only a little breadfruit is now grown. “There’s possibility there to develop breadfruit production,” says Horton. “This tree may be able to have really positive effect on food resilience and safety.”