【推荐1】Growing up, Chelsea Wood dreamed of becoming a sea biologist and studying large, exciting animals like sharks. Instead, she later found herself looking through a microscope at the organs of a snail(蜗牛) and saw thousands of little white sausage-shaped parasites(寄生虫). Through the microscope, each parasite had two dark eyespots, which made them surprisingly attractive. “I couldn’t believe that I’d been looking at snails for as long as I had and missing all the cool stuff happening inside them,” says Wood, now a parasitologist at University of Washington.

Nearly half of all known animals on Earth are parasites. According to one study, a tenth of them may already be certain to extinction due to climate change, loss of their hosts, and intentional attempts of wiping them out. But now it seems that few people care.

By definition, parasites live in or on a host and take something from that host. But not all parasites cause harm, and only a small percentage affect their hosts. In fact, parasites play essential roles in ecosystems, keeping some populations in check while helping to feed others. Without parasites keeping them in check, populations of some animals would explode. Many parasites move into their next host by controlling the host they’re in, which drive that host into an animal’s mouth so that the animal can be fed.

Even human health wouldn’t entirely benefit from wiping out parasites. The human immune system(免疫系统) evolved with a group of parasites, and when we killed them off, our immune systems began attacking ourselves. Some people with Crohn’s disease have even purposely infected themselves with intestinal(肠道的) parasites live deserves our attention. If you get to understand them, you may find the bravery and attraction of parasites. They’ve evolved clever means of survival, from becoming a fish’s tongue to controlling the mind of cockroach(蟑螂).

However, scientists aren’t eager to save all the parasites. The guinea worm, for instance, gets a hard pass from even the most stubborn conservationists. It grows to adulthood inside a person’s leg, causing harm to one’s health. Ultimately, the goal of promoting parasite conservation isn’t to make everyone fall in love with them. Instead, it’s to call a relaxation in our war against all of them, because there’s still so much we don’t understand about their value to ecosystems and maybe even to people.

【推荐3】Nowadays mail delivery is a little different. I still get my mail from my mailbox. Nothing, but my neighbors’ mail. I thought that was curious.

I proceeded to take my neighbors’ mail to them. I was about to put the mail in their mailbox when a tall man came running out shouting about messing with his friend's mail. He snatched (夺过) the mail from my hand, opened the mailbox and pointed to the mail inside.“You were after this.

I shook my head, “No, believe me. I got this mail by mistake in my box today. I was just bringing it to them.” He gave me a funny look and went back into his house.

I got the knock on the door the next morning by two very polite officers. The annoyed tall man had phoned the police and told them I was a crazy old woman going around mixing up everyone's mail. Before I could finish telling them about what was going on, the officers had watched a dog approach my mailbox with mail in his mouth. He took out the mail that was in my box and put letters in. He pushed the door closed with his nose, picked up the new pile of mail he had gotten from my box, and repeated this all the way down the next street. We all started laughing.

The dog had belonged to a mail carrier who had died. No one thought to check (the carrier lived alone) on the man’s dog. The dog had been trained to put mail in and take mail out of the boxes. When he got loose, he assumed his duties.

I went by to talk to the annoyed tall man to fill him in on what had happened. He was very pleased when he realized I was not a mail thief. He did, however, adopt the little guy.

【推荐1】The effect of climate change extends beyond ruining Earth’s environment and our physical safety. A report published this week suggests that climate change has a negative effect on our mental health, too.

The study, published in the journal Proceedings of the National Academy of Sciences of the United States(PNAS), links an increase in monthly temperatures to a rise in mental health issues. The experimental evidence stems from meteorological (气象的) data paired with information collected from nearly 2 million randomly sampled residents in the United States. The data was collected over the span (跨度) of a decade.

“We find that experiences with hotter temperatures and added rainfall each worsen mental health, that long-lasting warming associates with an increased popularity of mental health issues, and that exposure to tropical cyclones(热带气旋), likely to increase in frequency in the future, is linked to worsened mental health,” authors of the study stated. “These results provide added large-scale evidence to the growing link between climate change and mental health.”

The report specifically focused on mental health outcomes due to the effects of environmental stress - such as temperature, rainfall, and tropical cyclones - but other climate change-related issues are likely to affect mental health as well - specifically, the stress and anxiety of knowing natural disasters could be more frequent as temperatures rise.

【推荐1】Researchers are using an underwater drone (无人机) to measure CO₂ levels in the ocean. It is believed to be the first time such a vehicle has been used specifically to test CO₂ levels. The vehicle, which the team also calls a glider (滑翔机), is designed to dive down to 1,000 meters in deep ocean areas and can operate for weeks at a time.

The goal of the research is to provide scientists with data about how climate change is affecting the ocean’s chemistry. The self-swimming drone was deployed in the Gulf of Alaska this spring.

The team says the project could be a major step forward in measuring the environmental health of oceans. Scientists are most interested in levels of ocean acidification (酸化). This happens when CO₂ emissions in the atmosphere make their way into the ocean. Ocean acidification can harm or kill some kinds of sea life.

In a way, oceans have done humans a big favor by taking in (吸收) some of CO₂. If this were not the case, there would be much more CO₂ in the atmosphere. This would trap more of the sun’s heat and further warm the Earth.

“But the problem is now that the ocean is changing its chemistry because of this uptake,” said team member Claudine Hauri.

One of the best ways to measure ocean acidification is to collect CO₂ measurements. Until now, these collections were mostly done from ships or with floating devices at the ocean surface or equipment on the ocean floor.

McDonnell said his goal is to have a large number of similar robotic gliders operating in oceans across the world one day. “Such efforts will be important in helping scientists understand much more about what’s going on in the ocean than we have before,” he said.

【推荐2】Take a period of limited rainfall. Add heat. And you have what scientists call a ‘hot drought’ — dry conditions made more intense by the evaporative power of hotter temperatures.

A new study, published in the journal Science Advances, Wednesday, finds that hot droughts have become more common and severe across the western U.S. as a result of human-caused climate change. “The frequency of compound warm and dry summers particularly in the last 20 years is unprecedented,” said Karen King, lead author of the study and an assistant professor at the University of Tennessee in Knoxville.

For much of the last 20 years, western North America has been under the control of a huge drought that has strained crop producers, city planners and water managers. Scientists believe it to be the driest period in the region in at least 1,200 years. They reached that determination, in part, by studying the rings of trees collected from thousands of sites across the Western U.S..

Cross-sections or cores of trees, both living and dead, can offer scientists windows into climate conditions of the past. Dark scars can show where fires have burned. Pale rings can indicate insect outbreaks. “Narrow rings mean less water,” said King, a dendrochronologist, who specialized in tree ring dating. “Fatter rings, more water.” Scientists have looked at tree ring widths to understand how much water was in the soil at a given time. King and fellow researchers did something different. They wanted to investigate the density (密度) of individual rings to get a picture of historical temperatures. In hotter years, trees build thick walls to protect their water.

By combining that temperature data with another tree-ring-sourced dataset looking at soil moisture (湿度), the researchers showed that today’s hotter temperatures have made the current western huge drought different from its past ones.

It also suggests that future droughts will be worsened by higher temperatures, particularly in the Great Plains, home to one of the world’s largest aquifers, and the Colorado River Basin, the source of water for some 40 million people.