1 . It’s not easy to swim 109 miles when you’re starving to death. It’s not easy either to try to survive when you’re losing body weight at a rate of 2. 2 lb. a day. And it might be the hardest of all if you’re a nursing mom and your calorie intake has dropped so low that you can no longer produce the milk you need to care for your young.

As a newspaper in Nature Communications reveals, all of those challenges and more are facing the world’s polar bears, thanks to disappearing sea ice in our warming world, denying the animals a platform that they need to hunt for seals. If the trend isn’t reversed (扭转) soon, the estimated 26, 000 polar bears in the wild could start to lose their hold on survival before the middle of this century.

The researchers followed 20 different polar bears in Manitoba, Canada, from 2019 to 2022, fitting them with GPS trackers and video collars and periodically tranquilizing(麻醉) them to analyzes their blood, body mass, and daily energy consumption.

“The polar bears in Hudson Bay are probably at the edge of the range at which they can survive right now,” says Anthony Pagano, a research biologist with the U. S. Geological Surrey and the lead author of the paper. “Most of the modeling work suggests that around 2050, they are going to be on land and away from their primary habitat on the ice.”

According to the study, the data gathered was troubling. Weight loss varied among bears, with the daily loss of 2. 2 1b. representing an average; some of the subjects dropped up to 3. 75 lb. every 24 hours.

The bears are efficient hunters when they’ve got the purchase of ice beneath them, but they are clumsy when they are going after seals and trying to swim at the same time.

That leaves them searching on land for foods they would not ordinarily eat and getting little payoff for their efforts. Polar bears are feeding on ducks, geese, and eggs. Other foods on the desperate bears’ menus include berries and other vegetation. None of that food is as calorie-rich as seals.

3 . The impact of fast fashion on the environment is significant. Recently Zara, one of the largest fast-fashion retailers (零售商) in the world, put forth a concept that only sustainable fabrics are used in clothing production. But how can Zara ever be sustainable? They produce around 450 million garments (衣服) a year and release 500 new designs a week, about 20,000 a year. Zara’s fast-fashion model has been so successful it has inspired an entire industry to follow them.

Clothing production doubled from 2012 to 2022. The average consumer bought 60 percent more clothing in 2022 than in 2012, but kept each garment half as long. And less than one percent of all clothing produced globally is recycled.

I spend a lot of time reading the corporate social responsibility reports of large brands and interviewing micro-to-small sized enterprises to see how they approach sustainability. The largest significant difference between them is culture.

Small brands focus on creating a culture of sustainability by using strategies like producing made-to-order, so they are not making more than what is sold. Most small brands are opting to work under, an “anti-fashion calendar”. They choose not to follow the intense seasonal calendar that fashion functions under. They do this because waste is one of their biggest concerns. They also design clothing to be of the highest quality, ensuring durability and longevity, so you may keep it longer.

Fast fashion is a “grow or die” business, and the fast-fashion growth model used by all large companies is predicated on limitless growth. Large global corporate retailers are not seeking to change their fundamental business model or create cultures of sustainability. That would require re-working their entire business structure and ultimately hurt their bottom line.

I would start to believe Zara and other large fashion brands had good intentions to fight climate change if they started to look at how to move away from their continuous offerings of weekly new products. They need to introduce alternative sustainable business model practices. One small step could be to offer repair or tailoring services. Tailoring creates clothes that fit perfectly, subsequently increasing their emotional value, so that we love them and keep them longer.

4 . Until recently, gravitational waves could have been the stuff of Einstein’s imagination. Before they were detected, these waves in space time existed only in the physicist’s general theory of relativity, as far as scientists knew. Now, researchers are on the hunt for more ways to detect the waves. “The study of gravitational waves is booming,” says astrophysicist Karan Jani of Vanderbilt University in Nashville. “This is just remarkable. No field I can think of in fundamental physics has seen progress this fast.”

Just as light comes in a variety of wavelengths, so do gravitational waves. Different wave lengths point to different types of origins of the universe and require different kinds of detectors. Gravitational waves with wavelengths of a few thousand kilometers—like those detected by the United States, Italy and Japan—come mostly from pairs of black holes 10 or so times the mass of the sun, or from collisions of dense cosmic blocks called neutron stars (中子星). These detectors could also spot waves from certain types of exploding stars and rapidly moving neutron stars.

In contrast, huge waves that span light-years are thought to be created by orbiting pairs of bigger black holes with masses billions of times that of the sun. In June, scientists reported the first strong evidence of these types of waves by turning the entire galaxy (星系) into a detector, watching how the waves make slight changes to the timing of regular blinks from neutron stars throughout the Milky Way.

Physicists now hope to dive into a vast, cosmic ocean of gravitational waves of all sorts of sizes. These waves could reveal new details about the secret lives of exotic objects such as black holes and unknown parts of the universe.

Physicist Jason Hogan of Stanford University thinks there are still a lot of gaps in the coverage of wavelengths. “But it makes sense to cover all the bases. Who knows what else we may find?” he says. The search for capturing the full complement of the universe’s gravitational waves exactly could take observatories out into the moon, to the atomic area and elsewhere.

5 . Historical accounts often described the now-extinct California grizzly bears as huge beasts ready to attack humans and livestock at any time. But according to a new paper, scientists say the truth might have been less dramatic: The bears ate a mostly vegetarian diet and were smaller than previously described. California grizzly bears once roamed in the Golden State. But European settlers often hunted, poisoned and trapped the creatures. Over time, because of these human activities, the California grizzly population declined. The last reliable sighting of a California grizzly bear occurred 100 years ago in 1924, and the animals disappeared completely sometime after that.

Researchers wanted to get a better understanding of the factors that accelerated the bears’ extinction. They also hoped to gain more insight into the creatures’ behavior, size and diet. To do so, they turned to documents and California grizzly specimens in natural history collections. They measured the animals’ skulls and teeth and analyzed their bones and pelts. The researchers found that California grizzly bears were much smaller than the 2,000 pounds often reported at the time. Historical accounts might not necessarily have been wrong, but they might have only included the largest bears. In addition, analyses of the animals’ bones and skins suggest the bears were primarily eating plants, which stands in contrast to their fear some hyper carnivorous (超级食肉的) reputation. “The bears likely increased meat consumption due to landscape changes coupled with the arrival of livestock,” says study co-author Alexis Mychajliw. However, researchers found the animals still ate a majority vegetarian diet and killed far less livestock than historical accounts suggested.

By digging beyond the bears’ reputation, the researchers gained a more accurate understanding of the California grizzly’s biology and natural history. And since scientists and land managers often rely on historical accounts when reintroducing animals to their former habitats, the study serves as a reminder that those old newspapers and journals do not tell the whole story.

8 . A dog’s behavior is far more influenced by environment and upbringing, according to a new study published in the journal Science.

Lead author Kathleen Morrill, a Ph. D. candidate at the University of Massachusetts Medical School, and her numerous co-researchers surveyed owners of 18,385 dogs and examined 2,155 dogs’ DNA as part of the citizen science project Darwin’s Ark.

For the project, participants were given a battery of surveys to fill out about their dogs. They then received a DNA kit to collect their dogs’ saliva (唾液) and send it back to the lab for DNA testing. The information was stored in a large database that was freely shared with researchers around the world. In return, curious dog owners were sent a DNA and breed (品种) profile of their dogs.

With the data provided to them by citizen scientists, Morrill and her team presented a number of interesting findings, but the biggest was this: Breeds offer little predictive value for individuals, explaining just 9% of variation in behavior.

The researchers broke down dog behavior into eight categories: comfort level around humans, case of stimulation or excitement, affinity (喜爱) toward toys, biddability (also known as response to human training), how easily the dog is affected by a frightening stimulus, comfort level around other dogs, engagement with the environment, and desire to be close to humans. Of these behavioral characteristics, biddability and toy affinity were most linked with breeds, but the associations were slight.

The study’s findings call into question laws that target specific, supposedly “dangerous”, breeds. More than 900 cities in the U.S. currently have some breed-specific laws.

“We now have demonstrated that breed-specific laws are ineffective at protecting the public or reducing dog attacks,” Elinor Karlsson, a senior author of the study, said. “Any dog has the potential to be dangerous, regardless of its size or breed background. Because of this, dogs should not be declared dangerous based on their appearance. Instead, they should be assessed as individuals based on their behavior.”

9 . Sharks

Engage yourself in the world of Sharks! In this great exhibition created by Australian Museum experts, visitors will go back in time to meet sharks’ ancient ancestors, come face-to-face with life-size shark models ranging from the 50cm epaulette shark to the 8m whale shark, explore the contents of a shark’s stomach, play with a whale shark and uncover its extraordinary adaptation with interactive displays.

Visitors are advised to pre-book their preferred session time in advance to avoid disappointment.

Purchase your tickets now at Ticketek.com.au.

Ticket prices

Adult: $29

Child (3-15 years old): $17.50

Family (admits 4) 2A+2C / 1A+3C: $76

AM Member: 50% off; first visit FREE

Exhibition highlight

Extraordinary adaptations

In your mouth, you have 16 teeth in one neat row. The white shark has 300 teeth in five rows and can easily replace teeth lost while hunting and eating.

And what do you know about sharks amazing skin? It’s not skin at all. Sharks are covered in tiny denticles, which are closer to teeth than anything else!

You’ll see:

• The biggest fish - a life-size model of a whale shark, which can grow to 16m long.

• The fastest shark-a life-size model of the shortfin mako shark, which can reach speeds of up to 70km/hour and jump as high as 9m out of the water.

• A wet sample of the third-smallest shark-the Moller’s Lanternshark, reaching just 46cm long.

• A life-size model of the 270-million-year-old Helicoprion, known as the buzzsaw shark.

• Real, touchable shark samples from the Australian Museum collection.