Sea turtles are one of several species that have temperature-dependent sex determination. The number of female babies increases when nests are made in warmer sands.

A recent study by the National Oceanic and Atmospheric Administration, California State University and Worldwide Fund for Nature Australia examined two genetically distinct populations of green sea turtles living in the Great Barrier Reef. The study found that a group of about 200,000 turtles living in the northern part of the reef was almost entirely female.

While the southern population was 65 to 69 percent female, females in the northern group accounted for 99.1 percent of young turtles and 86.8 percent of adults.

After combining their results with temperature data, the scientists in charge of the study found that the northern green turtles have been producing mainly females for more than two decades and that the complete feminization(雌性化) of this population is possible in the near future.

The temperature at which the turtles will produce male or female babies can be passed on to the turtles' children. Most sea turtle populations are now producing offspring above the most suitable temperature, making it clear that climate change causes a serious threat to the survival of these populations.

The chief executive Of World Wildlife Fund Australia, Dermot O'Gorman, said this is another sign of the impact of climate change, following recent research that shows that coral bleaching (珊瑚白化) events are occurring far more frequently than in the past.

“We've had two years where we've had mass bleaching events on the Great Barrier Reef,” he told Guardian Australia. “That's a very visible sign of the impact of climate change. But this is a quiet change. We can't see the impact it's having on a turtle population until a study like this shows some long-term trends.”

The lead author of the paper, Dr Michael Jensen, said the findings represent a major environmental conservation issue.

O'Gorman said more urgent action on climate change is clearly needed, adding that some conservationists have already taken practical measures, such as using shade cloth on turtle nesting beaches to lower the sand temperature, and reducing bycatch(误捕) in the fishing industry.

"Shade cloth can be used in certain places, but there's a limit to the scale you can do that, " he said. "Now every large male who can reproduce is going to be even more important.

Teenagers in America know that they’ll possibly need technical skills to find good jobs, but a new survey reveals that interest in technology-related careers may be decreasing.

The percentage of boys aged 13 to 17 who are interested in science, technology, engineering and math—or STEM—careers dropped from 36 percent in 2017 to 24 percent this year, according to a survey by Junior Achievement USA. The amount of girls interested in STEM careers stayed unchanged at 11 percent.

But the 1,000 survey participants still named technology as one of two key skills that will be necessary to prepare them for their future careers.

“Kids don't understand how technology can be applied to careers in addition to computers, and maybe robotics,” said Tammera L. Holmes, president of aviation consulting firm AeroStar Consulting. “That’s all they know, so they can’t really translate that interest to career pathways.”

When Holmes was in high school, her mom sent her to an event that featured the pilots from World War II. One of the pilots took her for a ride and let her take the wheel. “Immediately that was the career for me.” she said.

Women remain outnumbered by men in fields like technology. For people working to increase the number of women in these areas, the lack of growth in girls interest in STEM careers is concerning.

Teenage girls are more interested than their male classmates in running after careers in which they can help others, said Ed Grocholski from Junior Achievement. Even with all the programs aimed at increasing girls' interest in STEM, “I don’t think we really talk that much about how we improve people’s lives through STEM, ” Grocholski said.

Society needs to do better at making those connections for kids, said Katherine Latham, founder of an engineering firm. She used civil engineering as an example of a career that will continue to be important.

However, the fact that students know they will need tech skills in their future careers is encouraging.

The second skill they said they need is relationship-building.

“That's going to be the new type of engineers,” Latham said.

I was a teenager when it first happened. It was the early hours of the morning, still some hours before I had to get out of bed for school. I woke up and tried to turn over in bed, but my body wouldn’t let me — I was unable to move, from head to toe.

Although my brain was conscious, my muscles were still asleep. My bedroom felt hot and restrictive, as if the walls were closing in, and I felt wrapped and panicked. Finally, after about 15 seconds, the paralysis lifted. Later, I found a name for what had happened to me: sleep paralysis (睡眠瘫痪症). It’s a surprisingly common condition in which part of our brain wakes up while our body remains temporarily frozen.

At night, our body cycles through four stages of sleep. The final stage is called rapid eye movement sleep, or REM, a unique phase of sleep when we dream. During REM, our brain paralyzes our muscles, probably to stop us physically acting out our dreams and hurting ourselves.

Although scientists aren’t still sure why the sensory part of our brain emerges from REM ahead of time, which makes us feel awake, doctors say paralysis is more likely to occur when we fail to follow our normal sleep pattern. Some sufferers also find that it happens to them more often when they are sleeping on their backs, though the explanation for this is unclear.

After that initial scary incident, it went on to become a frequent occurrence in my life, with an episode taking place every two or three nights. The more it happened, the less frightening it became for me until it eventually became little more than an inconvenience.

But sleep paralysis can be far more life-affecting. The condition would come with extremely frightening hallucinations, which are also normally the most dramatic and unforgettable episodes of their sleep paralysis. People hallucinate strange species, devils, ghosts, and even threatening aliens.