2 . Every spring, as the weather warms, trees up and down the East Coast explode in a display of bright green life as leaves fill their branches, and every fall, the same leaves provide one of nature’s great color displays of vivid yellow, orange and red.

Thanks to climate change, the timing of these events has shifted over the last two decades, Harvard scientists say.

Andrew Richardson, an associate professor of organismic and evolutionary biology, and research associate Trevor Keenan worked with colleagues from seven different institutions on a study which found that forests throughout the eastern United States are showing signs of spring growth dramatically earlier, and that the growing season in some areas extends further into the fall.

Richardson said, “Climate change isn’t just about warmer temperatures. It’s also about changes in precipitation (降水) patterns... so in the future, an earlier spring might not help forests take up more carbon dioxide if they end up running out of water in mid-summer.”

The research combined information from three sources. Using satellite data, Keenan tracked when forests across the region began to turn green in the spring, and when leaves began to turn yellow in the fall. Ground observations made every three to seven days at the Harvard Forest in Petersham and a long-term research site in New Hampshire provided information about the state of buds, leaves and branches. When combined with records from instrument towers, the data sets allowed the researchers to paint a richly detailed picture that shows spring starting earlier, and the growing season lasting longer than at any point in the past two decades.

Another important result, Richardson said, was the discovery of a significant source of error in existing computer models on how forest ecosystems work.

“This shows an opportunity to improve the models and how they simulate how forests will work under future climate scenarios forecast.” he said.

The real power of the findings, however, may be in helping to make the effects of climate change clearer to the public, the researchers said.

3 . We’re shopping online more than ever now, including various personal care and food items. Of U.S. Internet users, one-third do it at least once a week. Seeing your limited toilet paper (TP), you might pull up your smartphone and after a few taps have a fresh order of TP set to arrive in a day, maybe even less, and all done right from the toilet seat.

But this type of shopping — numerous small, quick-to-ship orders placed through e-tailing companies like Amazon — might be the worst for the environment, according to a recent study in Environmental Science & Technology. With their current business model of free shipping and fast delivery, greenhouse gas emissions linked with transporting “fast consumer goods” are high. “The online-only retailers are growing rapidly,” says lead author Sadegh, a scientist at Radboud University in the Netherlands.

Previous analyses haven’t agreed on whether online or in-store shopping is better. In fact, some studies have found that online shopping has a lower impact, because it saves the emissions associated with driving your car to the store (95 percent of Americans drive to go shopping). But this benefit can vary, or even disappear, depending on how fast we want that TP to arrive. And if you’re shopping in real life, factors like how you transport those items, how far you travel, and how much you buy at once all affect the carbon footprint of your purchase. “There have been some contradicting results, with some saying online shopping is better and some saying traditional shopping is better,” says Sadegh. So he tried to settle the debate with an approach that showed how likely one option was to be better than the other.

Sadegh and his team compared three shopping styles: traditional in-store shopping, online ordering from a physical store (which they called “bricks and clicks”), and ordering through an online-only retailer. Nearly two-thirds of the time, bricks and clicks shopping resulted in fewer emissions per item than in-store shopping — and was better than online shopping 97 percent of the time. In-store shopping had fewer emissions than online — only 81percent of the time.