Earth’s Arctic Ice Disappears, Scientists Study Nearest Exoplanet

Earth’s Arctic Ice Disappears, Scientists Study Nearest Exoplanet

Each year, more ice disappears from the Arctic Ocean.

A new study blames human activity for the loss.

The damage is caused, the study says, by greenhouse gases coming from vehicles, airplanes and other human activities. These gases capture heat and warm the atmosphere, melting the ice.

The study was published in the journal Science.

Greenhouse gases are produced when fuel is burned to take a passenger on a flight from New York to Europe, or a person driving 4,000 kilometers in a gasoline-powered car. These activities emit enough heat-trapping gas to melt three square meters of ice on the Arctic Ocean, according to the study.

Carbon dioxide emissions² warming the planet

There is a “very clear linear relationship” between carbon dioxide emissions and sea ice retreat in September, according to Dirk Notz. He is a climate scientist at Max Planck Institute for Meteorology in Germany, and the study’s lead author. He said this is especially the case at the southern boundaries of the Arctic Ocean.

“It’s very simple. Those emissions from our tailpipes and our coal-fired power plants are all going into the atmosphere,” said Julienne Stroeve, a co-author of the study. She is a climate scientist at both the National Snow and Ice Data Center in Boulder³, Colorado, and University College in London.

The study said limits on the increase in the world’s temperature called for in the Paris Agreement on climate change are not enough for the Arctic summer sea ice to survive. The Paris Agreement calls for keeping the global rise in temperature to below two degrees Celcius. The study said at current carbon emission¹ amounts, the ocean around the North Pole would likely be ice-free in September in about 30 years.

Closest planet may be able to hold life

Our next story comes from a star not too far from our own sun.

More details are coming out about the nearest exoplanet to our own solar system.

In August, a team of astronomers⁴ announced that they had discovered a small planet. They called the planet Proxima b. It orbits the star Proxima Centauri. It is the closest planet to our solar system, a little more than four light years away from our sun.

The scientists said the planet appears to be in the so-called Goldilocks zone—meaning the conditions there could support life.

Last Monday, a group searching for intelligent life beyond Earth called Breakthrough Listen, announced a new effort. Breakthrough Listen said it is using the Parkes Radio Telescope in Australia to listen for possible life on Proxima b. Because the telescope is in the southern hemisphere, it has a direct line to try to reach the planet.

“The chances of any particular planet hosting intelligent life-forms are probably minuscule⁵,” said Andrew Siemion, director of UC Berkeley SETI Research Center. “But once we knew there was a planet right next door, we had to ask the question, and it was a fitting first observation for Parkes. To find a civilization just 4.2 light years away would change everything.”

As the closest known exoplanet, Proxima b is also the main target for Breakthrough Listen's partner program, Breakthrough Starshot. That program is developing technology to send small spacecraft to explore our nearest stars.

More details on Proxima b

A recent study published in The Astrophysical Journal Letters provided more details about Proxima b. It says that the conditions on the planet increase the chances that it can support life.

Researchers say Proxima b could be an ocean planet. It may be covered with the same kind of oceans below its surface that might exist on some of the moons orbiting the planets Jupiter and Saturn⁶.

A team of researchers from the Marseille Astrophysics Laboratory said Proxima b could be an “ocean planet with an ocean covering its entire surface.” The size and qualities of the planet “favor its habitability,” they said.

The study also finds that the Proxima b, like Mercury in our solar system, has a metal core—the inside part of the planet. Researchers say its core accounts for two-thirds of its mass. They add that its mass is similar to Earth.

The U.S. space agency, NASA, says it looks forward to additional research to know about the radius⁷ of the planet. Without knowing the radius, it is “impossible to know what the planet looks like, or what it is made of.”

The radius of a planet sometimes is measured during transit⁸, when it passes in front of a star. But Proxima b is not known to transit.

Words in This Story

emit – v. to send (light, energy, etc.) out from a source

linear – adj. forming a straight line

solar system – n. our sun and the planets that move around it

minuscule – adj. very small

Goldilocks zone – n. a place in outer space that is not too hot, or too cold and could hold life

exoplanet – n. a planet outside our solar system

radius – n. a measure, taken from a straight line from the center of a circle or sphere to a point on the outer edge

1 emission   

n.发出物，散发物；发出，散发

参考例句：

• Rigorous measures will be taken to reduce the total pollutant emission.采取严格有力措施，降低污染物排放总量。
• Finally,the way to effectively control particulate emission is pointed out.最后，指出有效降低颗粒排放的方向。

2 emissions   

排放物( emission的名词复数 )； 散发物（尤指气体）

参考例句：

• Most scientists accept that climate change is linked to carbon emissions. 大多数科学家都相信气候变化与排放的含碳气体有关。
• Dangerous emissions radiate from plutonium. 危险的辐射物从钚放散出来。

3 boulder   

n.巨砾；卵石，圆石

参考例句：

• We all heaved together and removed the boulder.大家一齐用劲，把大石头搬开了。
• He stepped clear of the boulder.他从大石头后面走了出来。

4 astronomers   

n.天文学者，天文学家( astronomer的名词复数 )

参考例句：

• Astronomers can accurately foretell the date,time,and length of future eclipses. 天文学家能精确地预告未来日食月食的日期、时刻和时长。 来自《简明英汉词典》
• Astronomers used to ask why only Saturn has rings. 天文学家们过去一直感到奇怪，为什么只有土星有光环。 来自《简明英汉词典》

5 minuscule   

adj.非常小的；极不重要的

参考例句：

• The human race only a minuscule portion of the earth's history.人类只有占有极小部分地球历史。
• As things stand,Hong Kong's renminbi banking system is minuscule.就目前的情况而言，香港的人民币银行体系可谓微不足道。

6 Saturn   

n.农神，土星

参考例句：

• Astronomers used to ask why only Saturn has rings.天文学家们过去一直感到奇怪，为什么只有土星有光环。
• These comparisons suggested that Saturn is made of lighter materials.这些比较告诉我们，土星由较轻的物质构成。

7 radius   

n.半径，半径范围；有效航程，范围，界限

参考例句：

• He has visited every shop within a radius of two miles.周围两英里以内的店铺他都去过。
• We are measuring the radius of the circle.我们正在测量圆的半径。

8 transit   

n.经过，运输；vt.穿越，旋转；vi.越过

参考例句：

• His luggage was lost in transit.他的行李在运送中丢失。
• The canal can transit a total of 50 ships daily.这条运河每天能通过50条船。