32 According to the passage, which of the following contributes the most to greenhouse effect?
(A) Methane
(B) Nitrous oxide
(C) Carbon dioxide
(D) Ozone

Climate scientists vigorous充滿活力 debate談論 about how bad global warming will get, how quickly, and how to combat it.

One fight involves包括，包含, 涉及 how much effort to put into stopping leaks液體或氣體, 漏 of methane甲烷，沼氣 gas into the atmosphere.

Some academics學院的；學術 complain that President Obama’s plan to make greater use of natural gas, which consists mostly of methane甲烷，沼氣 ,will lock America into a supposed責任, 預期的 solution to climate change that will be worse than burning coal.

Is that claim說, 聲稱 plausible貌似真實（或可信）的, 花言巧語？ 

The basic scientific facts are clear. The most important greenhouse gas that humans are spewing（使）（液體或氣體）噴出 into the atmosphere is carbon dioxide, which comes from burning fossil fuels礦物燃料. 

The second most important is methane甲烷，沼氣 ,which is released when coal is mined; it escapes when wells are drilled鉆過孔 for oil; and it leaks from pipes that distribute natural gas.

Methane is a far more potent強有力 greenhouse gas than carbon dioxide.

But in stark contrast to CO2, methane breaks down quickly in the atmosphere.

Scientists say, “Methane is like a hangover疾病, （大量飲酒後的）宿醉 that you can get over it if you stop drinking,” said Dr. Pierrehumbert.

“CO2 is more like lead poisoning—it sticks around, you don’t get rid of it, and it causes irreversible不可改變 harm.”

So what has all this got to do with the President’s climate plan? Mr. Obama’s administration管理  intends計劃 to cut carbon dioxide emission（氣體、熱量、光線等的）排放，散發 from power plants by 30 percent, from 2005 levels, by 2030.

That will push states toward much greater use of natural gas to generate electricity—a shift that is seen as combating global warming because, in a power plant, burning natural gas emit發出，射出 roughly不精確的, 大致 half the carbon dioxide as burning coal.

Experts say that it is critical to keep carbon dioxide out of the atmosphere now, even if that requires burning more gas.

If only a limited amount of money is going to be available to tackle global warming, that would weigh in favor of Dr. Pierrehumbert’s argument for ignoring methane leaks for the time being.

Dr. Shindell, a NASA climate scientist, agrees that methane control should not be pursued跟隨 at the expense花費,消費 of CO2 control.

There might be a way out of this conundrum難題. 

The idea would be to promise far more aggressive好鬥 methane control to slow global warming for the benefit of people alive today, along with aggressive CO2 control for the benefit of future generations.

(A) Methane 甲烷/沼氣(化學)
(B) Nitrous oxide 一氧化二氮/笑氣(一種帶甜味的氣體，有輕微的麻醉作用，常用於牙科止痛)
(C) Carbon dioxide 二氧化碳
(D) Ozone 臭氧/清新空氣