Mammals’ Time on Earth Is Half Over, Scientists Predict
科学家预测，哺乳动物在地球上的时间已过去了一半
It’s been about 250 million years since reptile-like animals evolved into mammals. Now a team of scientists is predicting that mammals may have only another 250 million years left.
自爬行动物进化成哺乳动物以来，已经过去了大约2.5亿年。现在，一个科学家团队预测，哺乳动物可能只剩下2.5亿年的存活时间了。
The researchers built a virtual simulation of our future world, similar to the models that have projected human-caused global warming over the next century. Using data on the movement of the continents across the planet, as well as fluctuations in the chemical makeup of atmosphere, the new study projected much further into the future.
研究人员建立了一个未来世界的虚拟模拟，类似预测下个世纪人类造成的全球变暖的模型。这项新研究利用地球上各大洲移动的数据，以及大气化学成分的波动，对更为遥远的未来做出了预测。
Alexander Farnsworth, a paleoclimate scientist at the University of Bristol who led the team, said that the planet might become too hot for any mammals — ourselves included — to survive on land. The researchers found that the climate will turn deadly thanks to three factors: a brighter sun, a change in the geography of the continents and increases in carbon dioxide.
领导该团队的布里斯托尔大学古气候科学家亚历山大·法恩斯沃斯说，地球可能会热到任何哺乳动物，包括我们人类，都无法在陆地上生存。研究人员发现，因为这样三个因素，气候会变得无法生存：更明亮的太阳、大陆地理的变化和二氧化碳的增加。
“It’s a triple whammy that becomes unsurvivable,” Dr. Farnsworth said. He and his colleagues published their study on Monday in the journal Nature Geoscience.
“这是一个致命的三重打击，”法恩斯沃斯说。他和同事们周一在《自然·地球科学》杂志上发表了他们的研究成果。
Scientists have been trying for decades to foretell the fate of life on Earth. Astronomers expect that our sun will grow steadily brighter and, in about 7.6 billion years, may engulf the Earth.
几十年来，科学家们一直试图预测地球生命的命运。天文学家预计，我们的太阳将变得越来越亮，并在大约76亿年后吞噬地球。
But life probably will not make it that long. As the sun hurls more energy at the planet, Earth’s atmosphere will heat up, causing more water to evaporate from the oceans and continents. Water vapor is a potent greenhouse gas, and so it will trap even more heat. It may get hot enough in two billion years to boil away the oceans.
但生命或许不会持续那么久。随着太阳向地球投射更多的能量，地球的大气层将会升温，导致更多的水从海洋和大陆蒸发。水蒸气是一种强效温室气体，因此会吸收更多的热量。太阳可能会在20亿年后变得足够热，把海洋蒸发干。
In 2020, Dr. Farnsworth turned his attention to the future of Earth as a way to distract himself from the pandemic. He came across a study predicting how the continents will move around the planet far in the future.
2020年，法恩斯沃斯将注意力转向了地球的未来，以此来分散自己对大流行病的关注。他偶然读到一份研究报告，预测在遥远的未来，陆地将在地球上如何移动。
Over the course of Earth’s history, its landmasses have collided to form supercontinents, which have then broken part. The last supercontinent, Pangea, existed from 330 million to 170 million years ago. The study predicted that a new supercontinent — dubbed Pangea Ultima — will form along the equator 250 million years from now.
在地球的历史进程中，大陆板块碰撞形成超级大陆，然后又分裂开来。最后一个超级大陆——盘古大陆——存在于3.3亿到1.7亿年前。该研究预测，2.5亿年后，将沿赤道形成一个新的超级大陆，也就是所谓的终极盘古大陆。
In his primary research, Dr. Farnsworth builds models of ancient Earth to reconstruct the climates of the past. But he thought it would be interesting to use his models to see what life will be like on Pangea Ultima. The climate he ended up with took him by surprise.
经初步研究，法恩斯沃斯建立了古代地球的模型，以重建过去的气候。但他认为，用他的模型来看看终极盘古大陆上的生活会是什么样会很有意思。结果当时的气候让他大吃一惊。
“This world was very toasty,” he said.
他说：“这个世界算是相当温暖舒适了。”
Dr. Farnsworth enlisted Christopher Scotese, a retired geophysicist from the University of Texas who had crafted the Pangea Ultima model, and other experts to run more detailed simulations of that far-off future, tracking the atmosphere moving over the oceans, the supercontinent and its mountains.
法恩斯沃斯请来得克萨斯大学退休地球物理学家克里斯托弗·斯科泰塞以及其他专家，对遥远的未来进行更详细的模拟，追踪海洋、超级大陆及其山脉上空的大气运动。斯科泰塞曾制作了终极盘古大陆模型。
“They did quite a lot, which I’m quite impressed by,” said Hannah Davis, an earth systems scientist at GFZ German Research Centre for Geosciences, who was not involved in the research.
“他们做了很多工作，给我留下了深刻的印象，”德国地质学研究中心的地球系统科学家汉娜·戴维斯说。她没有参与该项研究。
Under a range of possible geological and atmospheric conditions, the researchers found, Pangea Ultima will be much hotter than today’s continents. One reason for the drastic change is the sun. Every 110 million years, the energy released by the sun increases by 1 percent.
研究人员发现，在一系列可能的地质和大气条件下，终极盘古大陆将比今天的大陆热得多。造成这种剧烈变化的原因之一是太阳。每隔1.1亿年，太阳释放的能量就会增加1%。
But the supercontinent will make things worse. For one thing, land heats up faster than ocean. With the continents pushed into one giant landmass, there will be a vast interior where temperatures can soar.
但超级大陆会让情况变得更糟。首先，陆地比海洋升温更快。随着各大洲被挤压成一个巨大的陆块，由此形成一个巨大的内陆，那里的温度会出现飙升。
Pangea Ultima will also influence the climate thanks to its topography, which will include vast stretches of flat land far from the ocean. On today’s Earth, rainwater and carbon dioxide react with minerals on the sides of mountains and hills, which then get carried out to sea to fall to the sea floor. The result is that carbon dioxide is steadily pulled out of the atmosphere. But when Earth becomes home to Pangea Ultima, that conveyor belt will slow down.
由于地形的缘故，包括远离海洋的大片平坦土地，终极盘古大陆也将对气候造成影响。在今天的地球上，雨水和二氧化碳与山脉和丘陵两侧的矿物质发生反应，然后被带到海洋，落到海底。其结果是二氧化碳被稳定地从大气中抽出。但当终极盘古大陆独霸时，传送带就会减速。
If Pangea Ultima behaves like previous supercontinents, it will become studded with volcanoes that belch carbon dioxide, the model found. Thanks to the turbulent movements of molten rock deep in the Earth, the volcanoes may release vast surges of carbon dioxide for thousands of years — blasts of greenhouse gases that will make temperatures rocket up.
模型发现，如果终极盘古大陆与以前的超级大陆一样，那么它将遍布喷发二氧化碳的火山。由于地球深处熔岩的剧烈运动，这些火山可能会在数千年内释放出大量的二氧化碳——温室气体的爆发将使气温急剧上升。
Currently, humans are heating the planet by releasing more than 40 billion tons of carbon from fossils fuels each year. If global warming continues unabated, biologists fear it will lead to the extinction of a number of species, while people will be unable to survive the heat and humidity in large swaths of the planet.
目前，人类每年从化石燃料中释放出400多亿吨碳，导致地球不断升温。生物学家担心，如果全球变暖持续下去，将导致许多物种灭绝，而人类将无法在地球大片地区的炎热和潮湿中生存。
On Pangea Ultima, Dr. Farnsworth and his colleagues concluded, things will probably get far worse for mammals like us. The researchers found that almost all of Pangea Ultima could easily become too hot for any mammal to survive. They might disappear in a mass extinction.
法恩斯沃斯和他的同事得出结论是，在终极盘古大陆，对于像我们这样的哺乳动物来说，情况可能会变得更糟。研究人员发现，几乎整个终极盘古大陆都很容易变得太热，导致所有的哺乳动物都无法生存。它们可能会在大灭绝中消失。
Dr. Farnsworth granted that a few mammals might eke out an existence in refuges on the fringes of Pangea Ultima. “Some areas in the northern and southern peripheries could be survivable,” he said.
法恩斯沃斯认为，少数哺乳动物可能会在终极盘古大陆边缘的避难地勉强生存。他说：“北部和南部边缘的一些地区，可能还能生存。”
Even so, he was confident that mammals would lose the dominance they’ve enjoyed for the past 65 million years. They might be replaced by coldblooded reptiles that could tolerate the heat.
即便如此，他相信哺乳动物将失去它们在过去6500万年中的统治地位。取而代之的可能是耐热的冷血爬行动物。
Wolfgang Kiessling, a climate scientist at University of Erlangen-Nuremberg in Germany, who was not involved in the study, said that the model did not take account of a factor that might mean a lot for the survival of mammals: the gradual decline in the heat escaping from the Earth’s interior. That decline might lead to fewer volcanic eruptions, and less carbon dioxide put in the atmosphere.
德国埃朗根-纽伦堡大学气候科学家沃尔夫冈·基斯林表示，该模型没有考虑到一个可能对哺乳动物生存意义重大的因素：从地球内部逸出的热量逐渐减少。这种下降可能会导致火山喷发减少，大气中的二氧化碳排放减少。基斯林未参与此项研究。
“Mammals may survive somewhat longer than modeled,” he said — maybe 200 million years, give or take.
“哺乳动物的存活时间可能会比模型预测的时间要长一些，”他说。也许是2亿年，大致这个范围。
Eric Wolf, a planetary climate scientist at the University of Colorado, who was not involved in the new study, said that the research could one day help us spot life on other planets. As scientists begin using powerful space telescopes to peer at planets in other solar systems, they may be able to measure their continental arrangements to infer what kinds of life might survive there.
科罗拉多大学的行星气候科学家埃里克·沃尔夫说，这项研究有朝一日可能会帮助我们发现其他行星上的生命。随着科学家开始使用强大的太空望远镜观测太阳系的其他行星，他们或许能够测量行星的大陆布局，从而推断那里可能存在怎样的生命。沃尔夫没有参与该研究。
“We’re trying to prepare ourselves for the many worlds we are going to see,” Dr. Wolf said.
“我们正努力为即将看到的众多世界做好准备，”沃尔夫说。
