【推荐2】Tropical(热带的)birds deep in Brazil’s Amazon rainforest are shrinking as the world’s climate changes. Researchers studied data for 77 tropical bird species over the past 40 years and found that all of them had lost body mass, with some species losing nearly 2% of their weight per decade.

A 2019 study of birds that had crashed into buildings in Chicago, Illinois, found that they’d lost mass over a 40—year period, but those species were migratory(迁徙的). However, why the birds changed in that way was unknown. Therefore, researchers decided to examine the records of 15, 000 non-migratory birds living in a rainforest within a few hours’ drive from Manaus in Brazil.

The average temperature of the birds’ habitat is 1℃ warmer in the wet season and 1. 65℃ warmer in the dry season compared with that in 40 years ago. What’s more, 13% more rain falls in the wet season and 15% less in the dry season. The birds have lost mass more sharply following extremely dry or wet seasons. This could be a short-term response to changes in their environment, such as a lack of rainfall causing a decline in the number of insects that the birds feed on.

“Mass is a generally good indication of body condition in birds, says Vitek Jirinec at the Integral Ecology Research Center in California, who led the study. "If they’re simply not getting enough to eat, you’d expect them to lose weight.”

Birds of the same species are generally larger at higher latitudes. The leading theory is that their smaller surface — area — to — volume ratio（表面积和体积比）allows them to better conserve heat. The opposite would help smaller species in hot climates to cool and could explain why birds are getting smaller as the climate warms, says Jirinec.

The marked physical change during just four decades show why stopping destroying trees alone won’t prevent the ongoing extinctions of animal species across the world, says Camila Gomez, a scientist who studies evolutionary changes in birds. "This study also shows how human-caused changes in climate are contributing to observed population declines in tropical birds," says Gomez.

Goal 13:Tackling(应对)Climate Change

Goal 13 calls for urgent action to fight climate change and its impact.    1    .

To address climate change, countries adopted the Paris Agreement to limit global temperature rise to well below 2 degrees Celsius. Learn more about Goal 13, and for the latest United Nations climate news, visit un. org/climatechange.

Why we need action

Climate change is now affecting every country on every continent. It is disrupting(扰乱) national economies.    2    

The greenhouse gas emissions(排放)from human activities are driving climate change and continue to rise.    3     Without action, the world’s average surface temperature is projected to rise over the 21st century and is likely to surpass 3 degrees Celsius this century—with some areas of the world expected to warm even more.

A race we can win

Affordable, scalable(可攀登的)solutions are now available to enable countries to turn to cleaner, more resilient(有弹性的)economies. The pace of change is quickening as more people are turning to renewable energy.    4    

But climate change is a global challenge that does not respect national borders. Emissions anywhere affect people everywhere. It is an issue that requires solutions that need to be managed at the international level and it requires international cooperation to help developing countries move toward a low-carbon economy.

To address climate change, countries adopted the Paris Agreement on 12 December 2015.    5     In the agreement, all countries agreed to work to limit global temperature rise to well below 2 degrees Celsius.

【推荐2】Australian researchers are creating electronic “smart” gloves which should finally enable surgeons (外科医生) to pass on their hard-earned perfect skills to trainees.

Biomedical engineer Gough Lui, from the MARCS Institute for Brain said that the smart gloves contain tiny electronics to record the hand movements of experienced surgeons. When worn by trainees, the gloves collect data, including the tiniest movements. Then it’s passed on to a screen to see where the students’ hand movements differ from their teachers’.

The inspiration behind the gloves was a conversation between Lui and Les Bokey, one of Australia’s most famous surgeons and educators. They realized that surgery was requiring an ever-growing range of skills to master modern techniques such as robotic surgery, but teaching methods couldn’t keep up with them. In the traditional training, the experienced surgeon usually stands over a student’s shoulder to provide advice during operation. “Often, the surgeon might say, ‘that wasn’t very good’, but can’t tell exactly what is wrong,” Lui said. “That’s very annoying when you’re trying to master a skill.”

One recent training advance has been surgical simulators (模拟器), but Lui said they are “hugely expensive” and are not always accessible to hospital trainees. In contrast, Lui hopes the gloves will eventually be coupled with a smartphone app, so trainees will be able to practice tasks at home for as little as $225.

Work continues on creating the perfect gloves. The next stage for Lui and his team is to find the best way for the gloves to provide guidance through a feedback such as a sound to the fingertips, or some form of audio feedback. The glove models with more versions (版本) continue to be tested at Liverpool Hospital later this year.