Nav: Home

A clearer picture of global ice sheet mass

July 09, 2019

Fluctuations in the masses of the world's largest ice sheets carry important consequences for future sea level rise, but understanding the complicated interplay of atmospheric conditions, snowfall input and melting processes has never been easy to measure due to the sheer size and remoteness inherent to glacial landscapes.

Much has changed for the better in the past decade, according to a new review paper co-authored by researchers at the University of Colorado Boulder, NASA, Utrecht University and Delft University of Technology and recently published in the Review of Geophysics.

The study outlines improvements in satellite imaging and remote sensing equipment that have allowed scientists to measure ice mass in greater detail than ever before.

"We've come a long way in the last 10 years from an observational perspective," said Jan Lenaerts, lead author of the research and an assistant professor in CU Boulder's Department of Atmospheric and Oceanic Sciences (ATOC). "Knowing what happens to ice sheets in terms of mass in, mass out allows us to better connect climate variations to ice mass and how much the mass has changed over time."

Ice sheets primarily gain mass from precipitation and lose it due to solid ice discharge and runoff of melt water. Precipitation and runoff, along with other surface processes, collectively determine the surface mass balance. The Antarctic Ice Sheet, the world's largest, is cold year-round with only marginal summer melting. A small increase or decrease in yearly snowfall, then, can make a considerable difference in surface mass because the addition or subtraction is compounded over a massive area.

"Snowfall is dominant over Antarctica and will stay that way for the next few decades," Lenaerts said. "And we've seen that as the atmosphere warms due to climate change, that leads to more snowfall, which somewhat mitigates the loss of ice sheet mass there. Greenland, by contrast, experiences abundant summer melt, which controls much of its present and future ice loss."

In years past, climate models would have been unable to render the subtleties of snowfall in such a remote area. Now, thanks to automated weather stations, airborne sensors and Earth-orbit satellites such as NASA's Gravity Recovery and Climate experiment (GRACE) mission, these models have been improved considerably. They produce realistic ice sheet surface mass balance, allow for greater spatial precision and account for regional variation as well as wind-driven snow redistribution--a degree of detail that would have been unheard of as recently as the early 2000s.

"If you don't have the input variable right, you start off on the wrong foot," Lenaerts said. "We've focused on snowfall because it heavily influences the ice sheet's fate. Airborne observations and satellites have been instrumental in giving a better view of all these processes."

Ground-based radar systems and ice core samples provide a useful historical archive, allowing scientists to go back in time and observe changes in the ice sheet over long periods of time. But while current technologies allow for greater spatial monitoring, they lack the ability to measure snow density, which is a crucial variable to translate these measurements into mass changes.

The biggest opportunity may lie in cosmic ray counters, which measure surface mass balance directly by measuring neutrons produced by cosmic ray collisions in Earth's atmosphere, which linger in water and can be read by a sensor. Over long periods of time, an array of these devices could theoretically provide even greater detail still.

Overall, Lenaerts said, the field of ice sheet observation has come of age in recent years, but still stands to benefit from additional resources.

"The community of researchers studying these issues is still relatively small, but it's already a global community and interest is growing," he said. "We'd like to get to a point where ice sheet mass processes are factored into global climate and Earth system models, to really show that bigger picture."
-end-
The newly published paper is part of the Grand Challenges special collection created for American Geophysical Union's Centennial, highlighting key areas where major future work and discovery are needed to address fundamental questions in understanding the Earth, its space environment and the history of the planet and its solar system. It was co-authored by Brooke Medley of NASA Cryospheric Sciences Laboratory, Michiel van den Broeke of Utrecht University and Bert Wouters of Utrecht University and Delft University of Technology. NASA provided funding for the study.

University of Colorado at Boulder

Related Climate Change Articles:

Mapping the path of climate change
Predicting a major transition, such as climate change, is extremely difficult, but the probabilistic framework developed by the authors is the first step in identifying the path between a shift in two environmental states.
Small change for climate change: Time to increase research funding to save the world
A new study shows that there is a huge disproportion in the level of funding for social science research into the greatest challenge in combating global warming -- how to get individuals and societies to overcome ingrained human habits to make the changes necessary to mitigate climate change.
Sub-national 'climate clubs' could offer key to combating climate change
'Climate clubs' offering membership for sub-national states, in addition to just countries, could speed up progress towards a globally harmonized climate change policy, which in turn offers a way to achieve stronger climate policies in all countries.
Review of Chinese atmospheric science research over the past 70 years: Climate and climate change
Over the past 70 years since the foundation of the People's Republic of China, Chinese scientists have made great contributions to various fields in the research of atmospheric sciences, which attracted worldwide attention.
A CERN for climate change
In a Perspective article appearing in this week's Proceedings of the National Academy of Sciences, Tim Palmer (Oxford University), and Bjorn Stevens (Max Planck Society), critically reflect on the present state of Earth system modelling.
Fairy-wrens change breeding habits to cope with climate change
Warmer temperatures linked to climate change are having a big impact on the breeding habits of one of Australia's most recognisable bird species, according to researchers at The Australian National University (ANU).
Believing in climate change doesn't mean you are preparing for climate change, study finds
Notre Dame researchers found that although coastal homeowners may perceive a worsening of climate change-related hazards, these attitudes are largely unrelated to a homeowner's expectations of actual home damage.
Older forests resist change -- climate change, that is
Older forests in eastern North America are less vulnerable to climate change than younger forests, particularly for carbon storage, timber production, and biodiversity, new research finds.
Could climate change cause infertility?
A number of plant and animal species could find it increasingly difficult to reproduce if climate change worsens and global temperatures become more extreme -- a stark warning highlighted by new scientific research.
Predicting climate change
Thomas Crowther, ETH Zurich identifies long-disappeared forests available for restoration across the world.
More Climate Change News and Climate Change Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Making Amends
What makes a true apology? What does it mean to make amends for past mistakes? This hour, TED speakers explore how repairing the wrongs of the past is the first step toward healing for the future. Guests include historian and preservationist Brent Leggs, law professor Martha Minow, librarian Dawn Wacek, and playwright V (formerly Eve Ensler).
Now Playing: Science for the People

#565 The Great Wide Indoors
We're all spending a bit more time indoors this summer than we probably figured. But did you ever stop to think about why the places we live and work as designed the way they are? And how they could be designed better? We're talking with Emily Anthes about her new book "The Great Indoors: The Surprising Science of how Buildings Shape our Behavior, Health and Happiness".
Now Playing: Radiolab

The Third. A TED Talk.
Jad gives a TED talk about his life as a journalist and how Radiolab has evolved over the years. Here's how TED described it:How do you end a story? Host of Radiolab Jad Abumrad tells how his search for an answer led him home to the mountains of Tennessee, where he met an unexpected teacher: Dolly Parton.Jad Nicholas Abumrad is a Lebanese-American radio host, composer and producer. He is the founder of the syndicated public radio program Radiolab, which is broadcast on over 600 radio stations nationwide and is downloaded more than 120 million times a year as a podcast. He also created More Perfect, a podcast that tells the stories behind the Supreme Court's most famous decisions. And most recently, Dolly Parton's America, a nine-episode podcast exploring the life and times of the iconic country music star. Abumrad has received three Peabody Awards and was named a MacArthur Fellow in 2011.