A geologic field excursion to Death Valley during spring break her first year at Barnard set 玛丽莎Tremblay ’12 on course to becoming a scientist. 她进入大学打算攻读法律学位, 但踏上那广阔, desolate desert landscape marked with sand dunes ignited a curiosity to uncover the stories in stones.
“I ended up falling in love with geology on that trip,” says Tremblay. “I’d never been to a desert environment with basically no vegetation. 你可以看到很多很多的岩石，绵延数英里, and I was captivated thinking about how to go about interpreting what you see in terms of the history of that place over lengthy timescales.”
Nicholas Christie-Blick, professor of earth and environmental sciences at Columbia他带领了这次旅行。. 特伦布雷回忆说，他是唯一一个醒着的学生, 不断地向教授提问, 这群人开着面包车四处转悠. Christie-Blick became a mentor of Tremblay’s as she focused her studies in environmental science.
那年夏天，她在 拉蒙特-多尔蒂地球观测站 下 Sidney Hemming, a geochemist and professor of earth and environmental sciences.
“Having Sidney Hemming as a role model early on was hugely influential in helping me figure out what I wanted to do and the path I would take,特伦布雷说. “She’s one of the few women senior scientists working in our field. It wasn’t always obvious that I would set up a similar lab to hers, 但我很高兴我最终追随了她的脚步.”
现在是地球的助理教授, 大气, 以及西拉斐特普渡大学的行星科学, 印第安纳州, Tremblay studies rock samples to measure the temperature history of continental surfaces. 她使用了她在博士学位期间开发的一种新方法.D. 加州大学的一项研究, 加州大学伯克利分校, which measures historic temperatures using noble gases trapped in minerals. 用这种技术, scientists can determine how warm the planet was during a certain period of history.
Most of her research projects could stretch back only a few tens of thousands of years — until now.
去年秋天, in search of rocks that could tell a story from millions of years ago, Tremblay led an all-women scientific team on a six-week expedition to Antarctica to collect samples from the McMurdo Dry Valleys — a place nearly untouched by time.
麦克默多干谷非常偏远，即使在南极洲也是如此. 到达一些现场, it’s a one-hour flight via helicopter from McMurdo Station — the continent’s largest research facility, which is funded and operated by the National Science Foundation. The team camped for about a week in the western Olympus Range to allow for more time collecting samples and installing instruments. The rock samples were shipped to Purdue in a cold-storage vessel, arriving in May — six months after the team departed Antarctica.
山谷里的天气可能非常寒冷, 平均温度在5到零下22华氏度之间. 虽然南极洲寒冷的气温令人难以置信, it’s global temperatures that shock as they continue to rise — 2022 was one of the hottest years on record.
Understanding how climate change will affect the polar regions in the future can influence policy changes implemented today. 上次冰盖融化时，南极洲有多热? How many degrees would it take for the oceans to rise to catastrophic levels? 通过研究这些石头，特伦布莱希望找到答案.
The two enormous ice sheets that blanket much of Antarctica contain about 70% of all the freshwater on Earth. They are vulnerable to ongoing climate change; a significant increase in temperature could cause them to melt, 导致海平面大幅上升. But how fast and how soon that might occur has been difficult to determine.
To help answer questions about the effects of a warming planet on Antarctica’s ice sheets, Tremblay sought to examine the geologic record during the mid-Pliocene Warm Period, 大约3到3.3 million years ago, when sea levels were about 50 feet higher — the height of a five-story building.
“This period in time is of particular interest because it’s the last time carbon dioxide concentrations in the atmosphere were similar to today’s,特伦布雷说. “It’s a good analog for 下standing where our planet is heading in the next few centuries.”
In other parts of the world, things at the surface erode much faster. 但在麦克默多干谷, the processes acting on the landscape are so slow that these rocks are just sitting there, 见证着气候的变化.
南极冰芯的记录只能追溯到公元800年,000年, and historic ocean records don’t necessarily tell us how warm temperatures were on land. But the rocks in the McMurdo Dry Valleys — which is one of the driest and most remote places on Earth and not covered by ice sheets — have been sitting at the surface eroding at unfathomably slow rates for millions of years. They also contain the noble gases Tremblay uses to study past temperatures. The team identified six sites across the valleys to collect rock samples and set up weather stations to measure present-day temperatures.
“Developing a deeper 下standing in general of the climate system is helping us make better predictions for what’s going to happen in the future,特伦布雷说. “In many ways, our research on the past climate of Antarctica is only just beginning. It will take many months to years studying their chemistry to unlock their climate secrets.”
