2 . Raising livestock (牲畜) is a big part of the carbon emission from agriculture. But it is hard to change people’s habits and get them to give up their hamburgers, especially since more than one-third of Americans eat fast food every day. We previously called for carbon labels on everything from buildings to burgers. Now, a new study from the Johns Hopkins Bloomberg School of Public Health found that labels on fast food affected people’s choices.

The study said shifting current dietary patterns to more sustainable diets with less red meat could reduce food-related greenhouse gas emissions by 55% and have health benefits.

The 5,000 participants in the study were shown fake menus. One group got menus with high climate impact labels on red meat items and another had low climate impact labels on fish or plant-based burgers. Both menus were effective in reducing the orders for red meat. But interestingly, the high-impact labels were far more effective, with 23% of the participants choosing a more environmentally sustainable selection, while menus listing low-impact choices encouraged only 10% participants to change.

“We found that labeling red meat items with high-climate impact labels was more effective in increasing sustainable selections than labeling non-red meat items with low-climate impact labels,” wrote the authors of the study.

Lead author, Julia Wolfson, said, “These results suggest that menu labeling, particularly labels warning that an item has high climate impact, can be an effective strategy for encouraging more sustainable food choices in a fast food setting.”

The study points out negative labels might be unpopular: “It is unlikely that the industry would voluntarily adopt a negative label approach; such an approach needs to be carried out via law. However, high climate impact labels may easily be adopted in settings like universities and hospitals.”

They have a point that this label is aggressively negative, more like a cigarette warning than a food label. In the study, the authors note that future research should test more label designs using qualitative and quantitative research on how people understand different climate impact labels.

3 . Dandelion (蒲公英) seeds are some of the best flyers in nature, catching the wind and spreading as far as 100 kilometers. Each dandelion seed is tied by a thin tube to around 100 hairs, which form the parachute-like (类似降落伞的) structure. When seeds break free from the flower head, these hairs catch the wind and carry their seeds. This hairy parachute closes when the air is humid (潮湿的), which often means the wind is weak. In drier and windier conditions, dandelions widen their parachutes to better catch the wind so the seeds can fly freely.

However, in the past, nobody knew how they sense and respond to their environment so effectively.

Now researchers have uncovered the secret “thinking” behind dandelions’ spreading seeds. Their work, published in Nature Communications, found the seed-carrying parachutes open and close using something like actuators — devices that change signals into movement — without using active input of energy. The center of the parachutes senses the humidity of their immediate environment by absorbing water molecules (分子) from the air. Responding to these humidity signals, they either open their parachutes and fly away, or close their parachutes and stay put.

Study author Dr. Naomi Nakayama of the Department of Bioengineering who led the work said that their findings reveal how the dandelion ensures the survival of its species by making perhaps the most important decision in a plant’s life — to stay or go to seek a better habitat.

“Understanding how dandelions work is fascinating because the dandelion is the foundation of ecosystems. It feeds insects and birds,” Nakayama says. “So, the environmental sensitivity of their flight is an important topic for us to understand how nature will change in future climates.”

7 . Away from the bright lights of the city, if you look up at the night sky you will see an ocean of bright stars. But in the illuminated concrete jungles we humans have built ourselves, it’s a different story.

This year, Earth Hour was observed on March 26. The annual tradition, started by the World Wildlife Fund (WWF) in 2007 in Sydney, Australia, was created to raise awareness for climate change. Those celebrating turn off all their electrical appliances for one hour. It also draws attention to another serious problem that the world is currently facing — the threat of light pollution.

Light pollution happens when too much man-made light harms nature. Scientists have found that it is especially harmful to nocturnal animals. These creatures rely on the natural light cycle provided by the movement of the sun to help coordinate their sleep cycles. When this is disturbed by constant bright lights from man-made structures, it can seriously disorientate the animals and harm their physical health. “Wildlife species have evolved on this planet with biological rhythms — changing that has profound effects,” said Travis Longcore, a biogeographer with the Urban Wildlands Group in Los Angeles, US. A lack of darkness at night can also cause difficulties for animals in other ways.

Newly hatched (孵化) baby sea turtles rely on the brighter horizon over the ocean to guide them from the beach to the sea. However, with artificial lights next to the oceans, the small animals are easily led away from the right path. “Hatchlings are attracted to lights and crawl inland, or crawl aimlessly down the beach, sometimes until dawn, when predators or birds get them,” said Michael Salmon, a biologist at Florida Atlantic University in Boca Raton, Florida.

Artificial light has caused a “drastic change” to the natural environment of animals, research scientist Christopher Kyba told the International Dark-Sky Association. “Predators use light to hunt, and prey (猎物) species use darkness as cover,” Kyba explained. If a predator has such an extra advantage in hunting its prey, this can lead to an imbalance in the ecosystem as the hunted species are no longer able to maintain their population when they become over-hunted.