VOA科学技术2024--Has Earth Warmed More Than We Thought?

Has Earth Warmed More Than We Thought?

　　Old sponges from deep in the Caribbean Sea are causing some researchers to think human-caused climate change began sooner than scientists have thought. But, if a recent study is correct, world temperatures are increasing faster than United Nations' estimates suggest.

　　The researchers from American and Australian universities published their sponge findings recently in Nature Climate Change. They said, if their findings are correct, the world has already gone past a temperature limit set by international negotiators. Negotiators of the Paris Agreement on climate change set 1.5 degrees Celsius¹ as a limit for the increase of the world's temperature from pre-industrial times. Pre-industrial times are from about 1850 to 1900. But the American and Australian researchers said that the world hit a 1.7-degree Celsius increase in 2020.

　　The scientists looked at six special sponges that are known to live hundreds of years. They examined the sponges' growth records to find very small levels of the elements calcium² and strontium. The scientists said that the amount of calcium and strontium changes, depending on the water temperature.

　　Malcolm McCulloch is an ocean scientist at the University of Western Australia. He was the lead writer of the study. McCulloch noted³ that the currently accepted temperature estimates for the 1850-1900 period were too high. That means that present-day temperature increases are larger and the Earth's temperature is warming faster than scientists have believed. He said, "We have a decade less than we thought."

　　In the past several years, many scientists have noted that there seems to be more extreme weather than they had expected. One explanation would be that the Earth is warming faster than scientists had first believed, said Amos Winter.

　　Winter helped write the study. He is an ocean scientist at Indiana State University. He said the study supports the theory that climate change is quickening. Former top NASA scientist James Hansen also has proposed that theory.

　　Sponges get water flowing from all over them so they can record a larger area of environmental change, Winter and McCulloch said. The research team examined sponges that lived in a special "mixed" area of the ocean that is 33 to 91 meters deep. The researchers were able to estimate nearly the exact atmospheric⁴ temperature of the Earth from the amount of calcium and strontium in the deep-sea sponges.

　　Their results were different from the scientifically accepted temperature estimates used by the United Nations' Intergovernmental Panel on Climate Change (IPCC). The IPCC temperature estimates are the basis for the U.N. temperature goals.

　　The Nature Climate Change study finds that the mid-1800s were about half a degree Celsius cooler than believed. It also found that warming from heat-trapping gases started about 80 years earlier than the measurements the IPCC uses. IPCC numbers show warming started just after 1900.

　　McCulloch and Winter said it makes sense that the warming started earlier than the IPCC stated because by the mid-1800s industries had begun polluting the air with carbon dioxide.

　　For pre-industrial temperatures, the IPCC and most scientists use data that came from ships whose crews would take the temperature of water near the surface. Some of the measurements could change based on how the collection was done.

　　The researchers said sponges provide better information because of the way they store chemical elements in their skeletons. When waters are warmer, there is more of the element strontium and less of the mineral calcium, Winter said.

　　University of Pennsylvania climate scientist Michael Mann, who was not part of the study, has thought warming started before the IPCC said it did. But he doubted the study's findings.

　　"In my view it begs credulity to claim that the instrumental record is wrong based on paleo-sponges from one region of the world," Mann said.

　　But Winter and McCulloch have defended their use of sponges to identify world temperature change. They said, except for the 1800s, their temperature findings based on sponges follow global records from other devices. These include scientific instruments and measurements from things like coral, ice, and tree rings.

　　Princeton University climate scientist Michael Oppenheimer was not part of the sponge study either. He said, even if the McCulloch team is right, it should not change warnings from scientists. He said that the danger level is not tied to the exact "value of preindustrial temperatures."

　　McCulloch added that "...the only way to stop this is to reduce emissions⁶. Urgently. Most Urgently.

　　Words in This Story

　　sponge – n. a type of sea animal from which natural sponges are made

　　decade – n. a period of 10 years

　　beg – v. to cause someone to ask a specified⁷ question as a reaction or response

　　credulity – n. ability or willingness to believe something

　　paleo- – prefix⁸ connected with ancient times

　　region – n. a part of a country or of the world that is different or separate from other parts in some way

　　emission⁵ – n. a gas, such as carbon dioxide, that is sent out or produced by a process like burning

1 Celsius   

adj.摄氏温度计的，摄氏的

参考例句：

• The temperature tonight will fall to seven degrees Celsius.今晚气温将下降到七摄氏度。
• The maximum temperature in July may be 36 degrees Celsius.七月份最高温度可能达到36摄氏度。

2 calcium   

n.钙(化学符号Ca)

参考例句：

• We need calcium to make bones.我们需要钙来壮骨。
• Calcium is found most abundantly in milk.奶含钙最丰富。

3 noted   

adj.著名的，知名的

参考例句：

• The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
• Jim is noted for arriving late for work.吉姆上班迟到出了名。

4 atmospheric   

adj.大气的，空气的；大气层的；大气所引起的

参考例句：

• Sea surface temperatures and atmospheric circulation are strongly coupled.海洋表面温度与大气环流是密切相关的。
• Clouds return radiant energy to the surface primarily via the atmospheric window.云主要通过大气窗区向地表辐射能量。

5 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。

6 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。

7 specified   

adj.特定的

参考例句：

• The architect specified oak for the wood trim. 那位建筑师指定用橡木做木饰条。
• It is generated by some specified means. 这是由某些未加说明的方法产生的。

8 prefix   

n.前缀；vt.加…作为前缀；置于前面

参考例句：

• We prefix "Mr."to a man's name.我们在男士的姓名前加“先生”。
• In the word "unimportant ","un-" is a prefix.在单词“unimportant”中“un”是前缀。