Electric cars are dirty. In fact, not only are they dirty, they might even be more dirty than their gasoline-powered cousins.

People in California love to talk about “zero-emissions(排放) vehicles”, but people in California seem to be clueless about where electricity comes from. Power plants mostly use fire to make it. Aside from the new folks who have their roofs covered with solar cells, we get our electricity from generators(发电机). Generators are fueled by something--usually coal, oil, but also by heat generated in nuclear power plants. There are a few wind farms and geothermal

In other words, those "zero-emissions" cars are likely coal-burning cars. It’s just because the coal is burned somewhere else, it looks clean. It is not. It's as if the California Greens are covering their eyes—“If I can't see it, it's not happening.” Gasoline is an incredibly efficient way to power a vehicle; a gallon of gas has a lot of energy in it. But when you take that gas (or another fuel) and first use it to make electricity, you waste a nice part of that energy, mostly in the form of wasted heat—at the generator, through the transmission lines, etc.

A gallon of gas may propel your car 25 miles. But the electricity you get from that gallon of gas won't get you nearly as far—so electric cars burn more fuel than gasoline-powered ones. If our electricity came mostly from nukes or geothermal, or hydro or wind or solar, then an electric car truly would be clean. But for political, technical, and economic reasons, we don't use much of those energy sources.

In addition, electric cars' batteries which are poisonous for a long time will eventually end up in a landfill. And finally, when cars are the polluters, the pollution is spread across all the roads. When it's a power plant, though, all the junk is in one place. Nature is very good at cleaning up when things are too concentrated, but it takes a lot longer when all the garbage is in one spot.

The Sahara is the world’s largest and most magic desert, but knowledge about it is surprisingly limited. Even estimates of when it formed vary widely, from more than five million years ago to mere thousands. Now, however, geographers studying wind-carried Saharan dust on the Canary Islands have come closer to settling this: it is, they report, close to five million years old.

One reason for the uncertainty over the Sahara’s age is that researchers use different methods to estimate it. These include studying desert dust found in sediment (沉积物) under the Atlantic Ocean, analyzing sandstone and modeling the ancient climate. To help settle the uncertainty, Daniel, geographer of the U.S. Geological Survey, and his workmates looked at sediment on Spain’s Canary Islands. They found evidence of Saharan dust. The dust appeared in ancient soil layers (层), whose age they assessed on the basis of fossils (化石) found in the same layers — and that age agreed with the earlier ocean’s sediment studies. The researchers reported their findings in November in Palaeogeography.

“The conclusion of the study is very good,” says Zhongshi Zhang, a climate modeler at the University of Bergen in Norway, who was not involved in the work. “Because the dust found on the islands is distinct from the ocean’s record,” Zhang adds, “it helps to build the case for a five-million-year age.”

The Sahara is the biggest source of wind-carried dust in the world — and that dust’s journey does not end in the Canary Islands, which lie just off the western coast of Africa. It continues onto places such as the Amazon rain forest in South America, Daniel notes. Amazon soils are poor in nutrients, and he says the new results help to show how rich dust from Africa could have been supporting the South American region’s incredible biodiversity for millions of years — adding to the Amazon’s own origin story.

The days when art was an Olympic sport

Did you know that creating works of art used to be an Olympic competition? 【小题1】 In the first year, Walter Winans became the first and the only Olympian to win medals for both art and sports. Despite this seemingly optimistic start, the idea of the arts being included in the Olympic Games soon met with disinterest, finally resulting in the removal of the art competition from the Olympic Games.

The idea to include art in the Olympics came from Baron Pierre de Coubertin, who was the founder of the International Olympic Committee, which created the modern Olympics. Coubertin believed that the arts and sports were linked and was impressed by anyone who had a firm command of both a sport and an artistic discipline(项目).

For starters, only amateurs were allowed to compete in the arts part of the Olympics. 【小题3】 Having artists of average quality competing while only the most competent athletes were allowed to compete created a dramatic divide and gave the impression that the arts were not as important as sports.

Secondly, works of art created had to have sports as the subject matter. 【小题4】 Limiting the subjects also contributed to making the arts part of the Olympic Games boring to the general public.

Finally, one of the biggest reasons was that the arts are subjective. Sports can be judged by time and distance, making it easy to determine who is the winner. 【小题5】 This difficulty in judging a definite winner resulted in the arts part becoming a non-competitive exhibition that ran for the duration of the Olympic Games.