【推荐1】For millions of years, Arctic sea ice has expanded and shrunk in a rhythmic dance with the summer sun. Humans evolved in this icy world, and civilization relied on it for climatic, ecological and political stability. But now the world comes ever closer to a future without ice. The National Snow and Ice Data Center reported that 2019’s minimum arctic sea ice extent was the second lowest on record. Arctic summers could become mostly ice-free in 30 years, and possibly sooner if current trends continue. As the northern sea ice declines, the world must unite to preserve what remains of the Arctic.

Although most people have never seen the sea ice, its effects are never far away. By reflecting sunlight, Arctic ice acts as Earth’s air conditioner. Once dark water replaces brilliant ice, Earth could warm substantially, equivalent to the warming caused by the additional release of a trillion tons of carbon dioxide (CO₂) into the atmosphere and declining sea ice threatens wildlife, from the polar bear to algae that grow beneath the sea ice, supporting the large amount of marine life.

To avoid the consequences the scientific community should advocate not just for lowering greenhouse gas emissions, but also for protecting the Arctic from exploitation. The Antarctic shows the way. In the 1950s, countries raced to claim the Antarctic continent for resources and military installations. Enter the scientists. The 1957-1958 International Geophysical Year brought together scientists from competing countries to study Antarctica, and countries temporarily suspended their territorial disputes (争议). In 1959, 12 countries signed the Antarctic Treaty to preserve the continent for peaceful scientific discovery rather than territorial and military gain.

Sixty years later, we must now save the Arctic. A new Marine Arctic Peace Sanctuary (MAPS) Treaty would protect the Arctic Ocean as a scientific preserve for peaceful purposes only. Similar to Antarctica, MAPS would prohibit resource exploitation, commercial fishing and shipping, and military exercises. So far, only 2 non-Arctic countries have signed MAPS; 97 more need to sign on to enact it into law. Scientists can help—just as they did for the Antarctic—by giving statements of support, asking scientific organizations to endorse (支持) the treaty, communicating the importance of protecting the arctic to the public and policy-makers, and above all, by convincing national leaders to sign the treaty. In particular, Arctic nations must agree that recognizing the arctic as an international preserve is better than fighting over it. In 2018, these countries successfully negotiated a 16-year moratorium on commercial fishing in the Arctic high seas, demonstrating that such agreements are possible.

Humans have only ever lived in a world topped by ice. Can we now work together to protect Arctic ecosystems, keep the northern peace, and allow the sea ice to return?

【推荐2】Scientists say seagrasses can be a valuable tool in fighting climate change. But many of these plants are being harmed as mining and fishing pollute the seawater.

In March, scientists went on an expedition (考察) to an area in the Indian Ocean thought to contain the largest field of underwater seagrass in the world. The team collected data to learn more about what affects the health of seagrasses.

Studies have shown that a big benefit seagrasses bring is that it can store up to two times the amount of carbon that forests do. If seagrasses can stay heathy and grow, they can remove carbon dioxide, or CO₂, from the environment. CO₂ is one kind of greenhouse gas that scientists have linked to rising temperatures in Earth’s atmosphere.

The Indian Ocean expedition, led by environmental group Greenpeace, traveled to Saya de Malha near the island nation of Seychelles. The field of seagrass at Saya de Malha is about the size of the European nation of Switzerland. Because the area is far from coastlines, it has stayed well protected from pollution and digging activities that can harm sea life. The seagrasses are also closer to the surface, meaning they take in more sunlight. This environment provides shelter and rich feeding grounds for thousands of different living things in the ocean.

Among those taking part in the expedition were scientists from Britain’s Exeter University. They say they were able to collect some of the firsthand field data on the area’s wildlife, including its little-studied seagrass beds. The team gathered up pieces of grass floating in the water to examine later in the laboratory. It isn’t yet known how much carbon is being stored in Saya de Malha. But experts estimate that worldwide, the root systems of seagrasses trap more than 10 percent of the carbon buried in oceans sediment (沉积物) per year. Therefore, the carbon-storing abilities of seagrass have massive implications (影响) for worldwide efforts to limit climate change.

This year, Seychelles began looking at its coastal seagrass carbon supply for the first time. And at least 10 countries have said seagrasses would play a part in their climate action plans.

The Effects of a Warmer World Are Visible in Animals’ Bodies

For humans, adapting to climate change will mostly be a matter of technology. More air conditioning, better-designed houses and bigger flood defences may help mitigate the effects of a warm world.     1     In a paper published in Trends in Ecology & Evolution, a team led by Sara

Ryding, a phd candidate at Deakin University, in Australia, shows that is already happening. Climate change is already altering the bodies of many animal species, giving them bigger beaks, limbs and ears. In some species of Australian parrot, for instance, beak size has increased by between 4 % and 10 % since 1871.

All that dovetails (吻合)nicely with evolutionary theory. “Allen’s rule”, named for Joel Asaph Allen, who suggested it in 1877, holds that warm-blooded-animals in hot places tend to have larger appendages (附属物) than those in less hot regions.    2     For example, Fennec foxes, which are native to the Sahara desert, have strikingly large ears, especially compared with their Arctic cousins.

Ms Ryding examined museum specimens, comparing their bodies to those of their modern counterparts. She is not the first researcher to take that approach.     3     All sorts of other factors, from changes in prey to the evolving reproductive preferences of males or females, might possibly have been driving the changes. Her team combined data from different species in different places.Since they have little in common apart from living on a warming planet, she says, climate change is the most reasonable explanation.

    4     Researchers have already seen changes in the geographical range of many species, from insects to fish. Another evolutionary rule-of-thumb, Bergmann’s rule, holds that animals in hotter places tend to have smaller bodies, another way to boost the ratio between surface area and volume. Other animals may alter their behaviour as well as their bodies, such as by seeking shelter at hot times of the day.

Studying a broader range of animals will help firm up exactly what is happening. Much of Ms Ryding’s data concern birds, with less information available for other taxa (类群). But it seems clear that the world of the future is not just going to be hotter than humans are used to.    5