ON THE GREENLAND ICE SHEET — The midnight sun still gleamed at 1 a.m. across the brilliant expanse of the Greenland ice sheet. Brandon Overstreet, a doctoral candidate in hydrology at the University of Wyoming, picked his way across the frozen landscape, clipped his climbing harness to an anchor in the ice and crept toward the edge of a river that rushed downstream toward an enormous sinkhole.

格陵兰冰盖——凌晨1点，子夜太阳仍在照射着广阔的格陵兰冰盖。怀俄明大学(University of Wyoming)水文学博士研究生布兰登·奥弗斯特里特(Brandon Overstreet)在这片冰面上小心翼翼，将他的安全带系到冰层中的一个锚上，朝着一条向下流入巨大深坑的河流的边缘徐徐前进。

If he fell in, “the death rate is 100 percent,” said Overstreet's friend and fellow researcher, Lincoln Pitcher.

奥弗斯特里特的朋友、同为研究员的林肯·皮彻(Lincoln Pitcher)说，如果他掉进去了，“百分之百会死。”

But Overstreet's task, to collect critical data from the river, is essential to understanding one of the most consequential impacts of global warming. The scientific data he and a team of six other researchers collect here could yield groundbreaking information on the rate at which the melting of Greenland ice sheet, one of the biggest and fastest-melting chunks of ice on Earth, will drive up sea levels in the coming decades. The full melting of Greenland's ice sheet could increase sea levels by about 20 feet.

奥弗斯特里特的任务是从水中收集重要数据，这对了解全球变暖最重要的影响来说是必不可少的。他和其他六名研究员组成的团队在这里收集的科学数据，可能会提供有关格陵兰冰盖融化速度的突破性信息。该冰盖是世界上最大且融化速度最快的冰块之一，会在未来几十年抬高海平面。格陵兰冰盖全部融化会将海平面抬高20英尺。

This summer in Greenland, the scientists set up camp on the ice, where they hoped to capture the first comprehensive measurements of the rate of melting. Their research could yield valuable information to help scientists figure out how rapidly sea levels will rise in the 21st century, and thus how people in coastal areas from New York to Bangladesh could plan for the change.

今年夏季，科学家们在格陵兰冰盖上搭起帐篷，他们希望在这里获取首批有关融化速度的全面测量数据。他们的研究可能会提供具有价值的信息，帮助科学家们了解海平面在21世纪的抬升速度，以及从纽约到孟加拉国等沿海地带的居民该如何应对这种变化。

For years, scientists have studied the impact of the planet's warming on the Greenland and Antarctic ice sheets. But while researchers have satellite images to track the icebergs that break off, and have created models to simulate the thawing, they have little on-the-ground information and so have trouble predicting precisely how fast sea levels will rise.

科学家们多年来一直研究全球变暖对格陵兰和南极冰盖的影响。但当研究人员通过卫星图像追踪破裂冰山的情况，创建模型来模拟这种融化时，他们获得的实地信息很少，因此难以精确预测海平面的抬升速度。

But the research is under increasing fire by some Republican leaders in Congress, who deny or question the scientific consensus that human activities contribute to climate change.

但这项研究遭到国会中一些共和党领袖日益强烈的抨击，他们否认或质疑一个科学共识，即人类活动在一定程度上导致气候变化。

Getting Ready

做好准备

In July, Smith's team arrived in Kangerlussuaq, Greenland, a dusty outpost of 512 people on the island's southwest coast, which serves as a base for researchers to prepare for fieldwork on the ice sheet.

史密斯的团队于今年7月抵达格陵兰岛康克鲁斯瓦格，这是位于西南沿海的一个灰尘漫天的偏远地带，只有512名居民，充当研究人员冰盖实地考察工作的准备基地。

The scientists were excited but anxious as they prepared to travel inland by helicopter to do the fieldwork at the heart of their research: For 72 hours, every hour on the hour, they would stand watch by a supraglacial watershed, taking measurements — velocity, volume, temperature and depth — from the icy bank of the rushing river.

科学家们准备乘坐直升机前往内陆，深入研究的核心地带开展实地考察：接下来72个小时，他们每时每刻都要在一个冰面分水线边值班，站在结冰的河岸上，测量这条湍急河流的流速、流量、温度及深度。

“No one has ever collected a data set like this,” Asa Rennermalm, a professor of geography at the Rutgers University Climate Institute who was running the project with Smith, told the team over a lunch of musk ox burgers at the Kangerlussuaq airport cafeteria.

“从来没有人这样收集数据，”罗格斯大学气候研究所(Rutgers University Climate Institute)的地理学教授阿萨·伦纳马尔姆(Asa Rennermalm)在康克鲁斯瓦格机场餐厅一边吃午餐——麝牛汉堡，一边这样对团队说。伦纳马尔姆与史密斯是项目负责人。

Taking each measurement was so difficult and dangerous that it would require two scientists at a time, she said. They would have to plan a sleep schedule to ensure that a group was always awake to do the job. Everyone knew the team would be working just upriver from the moulin — the sinkhole that would sweep anyone who fell into it deep into the ice sheet.

她表示，获取每个测量数据的过程都很艰难、危险，需要两名科学家同时作业。他们需要制定一个作息时间表，以确保一直有人做这项工作。大家都知道，该团队将在冰川锅穴上游工作——人掉入这个沉洞后就会被卷入水中，坠入冰盖底层。

As the researchers began to set up camp, Overstreet, the University of Wyoming doctoral student, headed toward the river, silent as it sliced through the ice. More than any other member of the team, the success of the mission rested on his shoulders.

在研究人员开始搭建帐篷的同时，怀俄明大学水文学博士研究生奥弗斯特里特向着这条静静地穿过冰层的河流前行。他的工作对这个团队的成败格外关键。

Overstreet, 31, who grew up kayaking and rafting in Oregon, had designed the rope-and-pulley system — modeled on swift-water boat rescue systems — that would be crucial to gleaning data from the treacherous waters. He had spent months refining and practicing his system on rivers in Wyoming.

31岁的奥弗斯特里特在俄勒冈州长大，从小玩皮划艇和木筏。他仿照激流皮划艇救援系统设计了绳索滑轮系统，这对从危险水域中收集数据的工作至关重要。他曾花了数月时间在怀俄明州的河流中对该系统进行改进、操练。

On the Ice

冰上的工作

The team soon got to work. A helicopter pilot flew two of Overstreet's colleagues, Pitcher and Matthew Cooper, across the 60-foot river. On the opposite bank they drilled into the ice, attached an anchor and harnessed themselves to it for safety. They attached a nylon line to the anchor, with the rest of the line coiled in a heavy bag.

团队很快就投入工作。一名直升机飞行员带着奥弗斯特里特的两名同事皮彻和马修·库珀(Matthew Cooper)飞越60英尺宽的河流。在河对岸，他们在冰层上钻洞，将锚放置在冰层中，并将安全带系到锚上，以保证安全。他们将一根尼龙绳系到锚上，剩下的绳子盘绕在一个沉重的袋子中。

Now came the crucial part: The men took turns hurling the bag across the river, but it repeatedly fell into the water. After an anxious half-hour, Cooper finally got the rope across. Overstreet caught it and began setting up the rope-and-pulley system he had been testing for so long.

接下来就是关键部分：他们轮流将袋子扔到河对岸，但袋子多次掉进水中。折腾了半小时后，库珀最终将绳子扔到对岸。奥弗斯特里特拿到了绳子，开始建立他测试了很久的绳索滑轮系统。

On the edge of camp, Johnny Ryan, a doctoral candidate in geography at Aberystwyth University in Wales, launched an airplane-shaped drone from a slingshot-like device, then guided it over a nearly 75-square-mile area. Then the drone went silent. “It stopped talking to me, and now it's crashed in the wilderness,” Ryan said.

在营地的边缘，威尔士阿伯里斯特维斯大学(Aberystwyth University)地理学博士研究生约翰尼·瑞安(Johnny Ryan)用一个类似弹弓的装置把飞机形状的无人机发射出去，然后操控它在一块将近75平方英里的区域上空飞行。接着无人机的声音消失了。“它跟我断绝联系了，现在已经坠毁在旷野里，”瑞安说。

Ryan, who wore a hot-pink knit cap and purple sunglasses that set off his red beard, launched his backup drone. Feeling stressed, he monitored its flight nervously as the hours rolled by, drinking tea to keep warm.

瑞安戴着亮粉针织帽和紫色太阳镜，跟他的红胡子很搭配。他启动了一架后备的无人机。而后的几个小时里，他一边喝茶取暖，一边紧张地监控无人机的飞行。

At the riverbank, Overstreet and Pitcher started the data collection by clipping a device that looked like a boogie board to the line running across the river. Every hour they sent it back and forth to measure the water's depth, velocity and temperature.

在河岸边，奥弗斯特里特和皮彻开始收集数据，将看起来像是滑板的装置系到跨越河流的绳子上。他们每小时都会来回推送该装置，以测量水深、水流速度和水温。

But as the day stretched into night, the device's battery, sapped by the cold, began to die. By now the sun had dropped lower, filling the sky with a spectacular orange glow. The scientists were worried — the death of the battery would mean the death of their mission.

但随着夜幕的降临，在严寒的侵蚀下，装置的电池开始耗尽。现在太阳已经慢慢落下，壮观的橙色光亮照亮整个天空。科学家们担心——电池的耗尽意味着任务的终结。

An idea occurred to Overstreet. He found a roll of heat-reflecting silver sheeting at the camp and wrapped it around the boogie board battery. During the next run across the river, it stayed alive.

奥弗斯特里特想到了一个主意。他在营地里找到了一卷银色的热反射薄膜，裹到电池上。下一次穿越河流时，装置还能运转。

But the battery continued to wane, so Pitcher took gel hand warmers from his gloves and tucked them into the battery's silver jacket. Success. The battery stayed warm and functional.

但电量在继续减少，皮彻拿出了手套中的胶体暖手包，将它们塞进电池的银色外壳。成功。电池得以保持温度，继续起作用。

For three days and three nights, the scientists continued to measure the river, as up to 430,000 gallons of water a minute poured off the ice and into the moulin. On the final morning, the team, tired but elated, gathered by the river as the boogie board made its final trip. By then, Ryan's backup drone had safely completed its mapping mission. Overstreet broke open a celebratory bag of dried mangoes — a lavish treat for the ice campers.

科学家们连续三天三夜对河水进行测量，每分钟多达43万加仑的水从冰层中涌出，流入冰川锅穴。在最后一天的清晨，滑板装置最后一次进行测量时，这个疲惫但又兴奋的团队聚集在河边。此时瑞安的后备无人机也平安完成测绘任务。奥弗斯特里特打开了一包芒果干，以示庆祝——这对于冰上露营者来说是一种奢侈。