Greenland Melted Recently, Shows High Risk of Sea Level Rise Today – UConn Today

Greenland’s Past Reveals Vulnerability to Climate Change

During the Cold War, a secret U.S. Army mission, at Camp Century in northwestern Greenland, drilled down through 4,560 feet of ice on the frozen island—and then kept drilling, to pull out a 12-foot-long tube of soil and rock from below the ice. Then this icy sediment was lost in a freezer for decades. It was accidentally rediscovered in 2017 and shown to hold not just sediment but also leaves and moss, remnants of an ice-free landscape, perhaps a boreal forest.

Greenland’s Green Past

An international team of scientists, including UConn Earth Sciences Associate Professor Julie Fosdick, was amazed to discover that Greenland was a truly green land only 416,000 years ago (give or take about 38,000 years). Their new study was published Thursday, July 20 in the journal Science.

‘Bulletproof Evidence’

Until recently, geologists believed that Greenland was a fortress of ice, mostly unmelted for millions of years. But, two years ago, using the rediscovered Camp Century ice core, this team of scientists showed that it likely melted less than one million years ago. Other scientists, working in central Greenland, gathered data showing the ice there melted at least once in the last 1.1 million years—but until this study, no one knew exactly when the ice was gone.

Now, using advanced luminescence technology and rare isotope analysis, the team has created a starker picture: large portions of Greenland’s ice sheet melted much more recently than a million years ago. The new study presents direct evidence that sediment just beneath the ice sheet was deposited by flowing water in an ice-free environment during a moderate warming period called Marine Isotope Stage 11, roughly from 424,000 to 374,000 years ago. This melting caused at least five feet of sea level rise around the globe, and potentially as much as 20 feet, says Fosdick.

Into the Light

At Rittenour’s lab, sediment from the Camp Century core was examined for what is called a “luminescence signal.” As bits of rock and sand are transported by wind or water, they can be exposed to sunlight—which, basically, zeros out any previous luminescence signal—and then re-buried under rock or ice. In the darkness, over time, minerals of quartz and feldspar in the sediment accumulate freed electrons in their crystals. In a specialized dark room, Rittenour’s team took pieces of the ice core sediment and exposed them to blue-green or infrared light, releasing the trapped electrons. With some advanced tools and measures, and many repeated tests, the number of released electrons forms a kind of clock, revealing with precision the last time these sediments were exposed to the sun.

These powerful new data were combined with insight from Bierman’s UVM lab. There, scientists study quartz from the Camp Century core. Inside this quartz, rare forms—called isotopes—of the elements beryllium and aluminum build up when the ground is exposed to the sky and can be hit by cosmic rays. Looking at ratios of beryllium and other isotopes gave the scientists a window into how long rocks at the surface were exposed vs. buried under layers of ice. This data helped the scientists show that the Camp Century sediment was exposed to the sky less than 14,000 years before it was deposited under the ice, narrowing down the time window when that portion of Greenland must have been ice-free.

Further evidence came from Fosdick’s research group, the Basin Analysis & Helium Thermochronology Lab at UConn, which led to the understanding of where the sediments came from through helium isotope analysis,

“We collect helium isotopes from the sediment that allow us to figure out how quickly or slowly those different sediments were eroded from the ancient Greenland hillslopes,” Fosdick says. “Our apatite tracer thermochronology data capture sources across a slowly eroding landscape within Archean crust.”

Sea Level

Camp Century is 138 miles inland from the coast and only 800 miles from the North Pole; the new study shows that the region entirely melted and was covered with vegetation during Marine Isotope Stage 11, a long interglacial period with temperatures similar to, or slightly warmer than, today. With this information, the team’s models show that, during that period, the ice sheet melted enough to cause at least five feet, and perhaps as much as 20 feet, of sea-level rise. The research, supported by the U.S. National Science Foundation, lines up with findings from two other ice cores collected in 1990s from the center of Greenland. Sediment from these cores also suggests that the giant ice sheet melted in the recent geologic past. The combination of these earlier cores with the new insight from Camp Century reveal the fragile nature of the entire Greenland ice sheet—in the past (at 280 parts per million of atmospheric CO₂ or less) and today (422 ppm and rising).

Fosdick says the data gives us valuable information for understanding the risks of future Greenland ice sheet melting and sea level rise in response to climate change today.

“The CO₂ levels during Marine Isotope Stage 11 interglacial were lower than today, but warming was still sufficient to generate major Greenland ice sheet melting.”

“If we melt just portions of the Greenland ice sheet, the sea level rises dramatically,” says Rittenour. “Forward modeling the rates of melt, and the response to high carbon dioxide, we are looking at meters of sea level rise, probably tens of meters. And then look at the elevation of New York City, Boston, Miami, Amsterdam. Look at India and Africa—most global population centers are near sea level.”

“Four-hundred-thousand years ago there were no cities on the coast,” says Bierman, “

SDGs, Targets, and Indicators

1. Which SDGs are addressed or connected to the issues highlighted in the article?

• SDG 13: Climate Action
• SDG 14: Life Below Water
• SDG 15: Life on Land

2. What specific targets under those SDGs can be identified based on the article’s content?

• SDG 13.1: Strengthen resilience and adaptive capacity to climate-related hazards and natural disasters
• SDG 14.1: By 2025, prevent and significantly reduce marine pollution of all kinds, in particular from land-based activities, including marine debris and nutrient pollution
• SDG 15.1: By 2020, ensure the conservation, restoration, and sustainable use of terrestrial and inland freshwater ecosystems and their services, in particular forests, wetlands, mountains, and drylands, in line with obligations under international agreements

3. Are there any indicators mentioned or implied in the article that can be used to measure progress towards the identified targets?

• Indicator for SDG 13.1: Number of countries implementing national disaster risk reduction strategies in line with the Sendai Framework for Disaster Risk Reduction
• Indicator for SDG 14.1: Proportion of coastal and marine areas protected to conserve biodiversity
• Indicator for SDG 15.1: Proportion of important sites for terrestrial and freshwater biodiversity that are covered by protected areas, by ecosystem type

Table: SDGs, Targets, and Indicators

Analysis:

The issues highlighted in the article are connected to multiple Sustainable Development Goals (SDGs). The main SDGs addressed are SDG 13 (Climate Action), SDG 14 (Life Below Water), and SDG 15 (Life on Land).

Based on the article’s content, specific targets under these SDGs can be identified. Under SDG 13, the target is to strengthen resilience and adaptive capacity to climate-related hazards and natural disasters (Target 13.1). Under SDG 14, the target is to prevent and significantly reduce marine pollution of all kinds, including marine debris and nutrient pollution, by 2025 (Target 14.1). Under SDG 15, the target is to ensure the conservation, restoration, and sustainable use of terrestrial and inland freshwater ecosystems and their services by 2020 (Target 15.1).

The article mentions indicators that can be used to measure progress towards these targets. For SDG 13.1, the indicator is the number of countries implementing national disaster risk reduction strategies in line with the Sendai Framework for Disaster Risk Reduction. For SDG 14.1, the indicator is the proportion of coastal and marine areas protected to conserve biodiversity. For SDG 15.1, the indicator is the proportion of important sites for terrestrial and freshwater biodiversity that are covered by protected areas, by ecosystem type.

Behold! This splendid article springs forth from the wellspring of knowledge, shaped by a wondrous proprietary AI technology that delved into a vast ocean of data, illuminating the path towards the Sustainable Development Goals. Remember that all rights are reserved by SDG Investors LLC, empowering us to champion progress together.

Source: today.uconn.edu

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