英语听力：自然百科 化石改变全球变暖预言？

15 million years ago, New Zealand was a different place. The country was blanketed by dense rainforests and partially submerged under the ocean. Analysis of sedimentary(沉淀性的) rocks has shown that sea temperatures in this part of the world rose between 40 and 50 degreesFahrenheit during a global warming period of a few million years.

"And so this is a time when a massive amount of carbon was rapidly released over a few thousand years. We think something similar to what will be released through fossil fuel combustion(燃烧) over the next several centuries. "

By comparing these data with records from other parts of the world, it may be possible to see how global warming has affected the earth in the past. The finding showed that surface waters in this part of the world exceeded 86 degrees Fahrenheit (or 30 degrees Celsius) during a 2 to 3-million-year period of global warming. That’s about 10 degrees more than previously thought.

This means that previous computer climate models may also be underestimating future rises in sea temperatures. The most surprising aspect is the rate of warming as if it would have required massive levels of greenhouse gases, such as carbon or methane(甲烷) to be released in just a short amount of time.

"And then there is one idea that the earth was slowly warming prior to this time. And that, in the process of warming, gradually it hits some sort of climatic threshold. And as a consequence, you get a jump from one climate state to another. "

However, not everyone is convinced by the report’s findings.

"My interest is in the fossil evidence. And as a paleontologist, I look at the fossil record. And I don’t quite say there’re clear evidence for the extremes. I think it was clearly hot, but was it about 30 degrees? I’ll wait to be convinced."