The color of the ocean has changed significantly over the last 20 years, for which human-caused climate change may take the responsibility, and more than 56% of the world’s oceans have changed color to an extent that cannot be explained by natural variability, according to a new study published Wednesday in the journal Nature. It also mentioned that tropical oceans close to the equator in particular have become greener, reflecting changes in their ecosystems.

The color of the ocean is from the materials found in its upper layers. For example, a deep blue sea will have very little life in it, whereas a green color means there are ecosystems there, based on phytoplankton (浮游植物), plant-like microbes which contain chlorophyll (叶绿素). The phytoplankton form the basis of a food web which supports larger organisms such as fish, seabirds and marine mammals.

It’s not clear exactly how these ecosystems are changing. Ocean ecosystems are finely balanced and any change in the phytoplankton will impact on the whole food chain. “All changes are causing an imbalance in the natural organization of ecosystems. Such imbalance will only get worse over time if our oceans keep heating,” said study co-author Stephanie Dutkiewicz. “It will affect the ocean’s ability to act as a store of carbon, because different phytoplankton absorb different amounts of carbon.”

While the researchers are still working to find out exactly what the changes mean, what is clear is that the changes are being driven by human-caused climate change. The researchers analyzed color variation data from 2002 to 2022 and then used climate change. models to simulate (模拟) what would happen to the oceans both with additional planet-heating pollution and without. The color changes matched almost exactly what Dutkiewicz predicted would happen if greenhouse gases were added to the atmosphere—that around 50% of our oceans would change color.

2020 is a leap year, and as we all know leap years happen every four years, right? Wrong. That extra day in February is designed to keep the earth in sync (同步的) with the seasonal year. But, what you might not realize is that the maths isn’t that simple and occasionally we have to wait eight years.

The method behind calculating when leap years occur might be a bit more complicated than you think. Way back in 1582 the calendar we now use was first applied. The Gregorian calendar was named after the authority at the time, Gregory XIV. The people who created it realized it wasn’t perfect to just add an extra day every four years.

Here’s where the maths comes in. A day, of course, is measured by the amount of time it takes for the earth to complete one full cycle on its axis (轴). A year is the number of days it takes the earth to orbit the sun, which most people assume is 365. However, the earth actually takes just under 365 and a quarter days to complete one full revolve (旋转) around the sun.

So, every four years we get an extra day, which falls on the 29th February. However, as mentioned earlier, it is in fact just under a quarter of a day. So, by rounding it up (四舍五入), we put the calendar out of sync again—which means that after a while we have too many days.

That imbalance has to be dealt with again, otherwise after 400 years you’d end up with three extra days. So back in 1582, they realized that every turn of a century should skip their extra day to remove those three extra days. This is why the years 1700, 1800, and 1900 weren’t leap years. But wait, there’s more. The year 2000, the millennium, was a leap year. That’s because over a period of four hundred years we only need to remove three days. So, every 400 years the turn of the century is a leap year.

The next time you hear someone saying “leap years happen every four years”, you can tell them why they’re wrong.

Everyone procrastinates(拖延). “It's part of the human condition, ”says procrastination researcher Tim Pychyl. “We want to feel good now. The way to do that is avoid the task.” He admits that in the short term, procrastination is powerfully rewarding. The present self-benefits, of course, but not the future self.

His research has shown that people can procrastinate on nearly anything, even enjoyable tasks such as planning a vacation. Some people procrastinate cleaning. Some people procrastinate by cleaning. The top tasks people delay are advancing their careers, taking care of their health, and planning their finances.

One big factor for them is fear of failure, of not living up to expectations. Kelli Saginak, a 57-year-old health coach from Wisconsin, procrastinated about looking for a new job for years. That inability to take action only confirmed her belief that she would never do any better. “It's totally fear of judgment,” says Saginak. “If I don't take the risk, I don't have to face the judgment. Yet it's simply me judging myself.”

Some people embrace procrastination, insisting that the white-hot pressure of a last-minute completion makes his or her work better. But researchers have proved it wrong. “I did an experiment, putting procrastinators under restrictions of time. They did worse than non-procrastinators, but they thought they did better.” says Joseph Ferrari, a psychology professor. “Non- Procrastinators focus on the task that needs to be done. They have a stronger personal identity and are less concerned about what psychologists call social esteem's how others like us.”

Procrastination is usually not going to be good for you. Just thinking about what you haven't done may cause discomfort. So if you have been procrastinating on starting an exercise routine, just put on your walking shoes. If you've been putting off a work project, reread your boss's notes about it.