A large iceberg calving off from Pine Island Glacier, a channel for rapid ice loss from the West Antarctic Ice Sheet.
(Image credit — NASA)
Geoscientists Call for Reinforcing Glacier and Ice Sheet Research
JUL 24, 2019
A panel of scientists recently warned the House Science Committee about the consequences of accelerating ice sheet and glacier melting around the globe. Given remaining uncertainties surrounding rates of sea level rise and its impacts, they urged Congress to invest in data collection, multidisciplinary research, and research workforce development.
At a hearing this month, the House Science Committee convened a panel of geoscientists to discuss what is known about the global retreat of ice sheets and glaciers and the various threats the situation poses.
The members of the panel were: Pennsylvania State University professor Richard Alley, Columbia University professor and American Geophysical Union President Robin Bell, National Snow and Ice Data Center scientist Twila Moon, Alaska Department of Natural Resources scientist Gabriel Wolkon, and University of Colorado Boulder professor Tad Pfeffer.
The panelists agreed that anthropogenic warming has driven the disappearance of land-based ice in recent decades and that it will remain the dominant contributor to sea level rise this century. However, they emphasized that considerable uncertainty remains surrounding how quickly glaciers and ice sheets will deteriorate. They argued that better data and understanding of the physical mechanisms at work are needed and that federal agencies should encourage multidisciplinary research efforts and help increase the number of scientists who work in the area.
Discussion homes in on uncertainties
Opening the hearing, Committee Chair Eddie Bernice Johnson (D-TX) cited the 2014 Intergovernmental Panel on Climate Change (IPCC) findings that glacier and ice sheet melting is responsible for two-thirds of the rise in sea levels over the past 200 years and that, under a high-emissions scenario, mountain glaciers will lose between 35% and 85% of their ice by 2100. She said the West Antarctic Ice Sheet presents particular worries since its collapse could lead to 11 feet of sea level rise. In addition, she noted concerns that IPCC estimates of melt rates could be too conservative.
Several panelists affirmed that sea levels are expected to increase by at least two to three feet by 2100 under the current global emissions trajectory, but said it is difficult to place an upper bound on the projections. Asked by Rep. Sean Casten (D-IL) to quantify possible rather than projected sea level rise, Alley replied, “I surely wish I knew. This is a frustration for us at a level that is deep. I wake up at two in the morning and I look at the ceiling and I say, ‘What do I tell somebody?’”
Dissatisfied, Casten pressed him, saying, “I started my career — I got a master’s of science in chemical engineering. I get the caution, but we’ve got to sit on this side of the dais and make decisions. So, I’m just asking, if you were in our seats with uncertainty of information, what is the range that we should be thinking about in our zone of possibility?”
After Alley declined to provide specific numbers, saying only that one should not consider figures below those presented by IPCC, Casten explained that numbers matter for questions such as setting 30-year mortgage rates in low-lying coastal areas. “We have a whole host of issues here that go just beyond whether the sea level’s a little higher,” he said.
Casten also inquired about the number of homes at risk due to various climate-related causes. Moon offered estimates about homes endangered specifically by sea level rise, saying, “If we’re looking at one foot by 2035, that would be about 140,000 homes. If we’re looking at four feet of sea level rise, that’s about 1.2 million homes. If we’re looking at two feet, that’s about 300,000 homes. So, it’s in the hundreds of thousands.”
Committee Ranking Member Frank Lucas (R-OK) asked about the consequences that retreating land ice could have for inland regions, mentioning agricultural, economic and geopolitical impacts as examples. Bell replied that “one of the very clear predictions” provided by climate models is that extreme weather events such as droughts and floods will increase. However, she said that the direct connections between weather patterns and disappearing land ice are not as well understood.
Current gaps in ice sheet research charted
Asked by Rep. Jennifer Wexton (D-VA) whether IPCC’s sea level projections have been too conservative, Alley replied, “I have great difficulty finding any evidence that they are overly alarmist and there are certainly things that point to the possibility that they have been low in the past.”
Similarly, Pfeffer, who was a lead author on the sea level rise chapter in the most recent IPCC assessment, told Rep. Bill Foster (D-IL) its projection was “very conservative” owing to a lack of firm knowledge about the mechanics of “tipping points,” at which ice loss becomes self-reinforcing. Earlier in the hearing, he told Johnson that understanding tipping points is a critical research problem, saying,
We can’t model that problem out of the way, with computers or with our knowledge of mathematics and mechanics. We actually have to get in — literally, in and under the glaciers — to see what’s happening.
Pointing specifically to uncertainties surrounding melting on the Greenland Ice Sheet, Moon said, “The United States can lead by supporting targeted research on the physical processes that control ice sheet behavior, by developing systems to collect long-term observations, and by fostering iterative research that connects observations and computer models.”
Addressing the needs of localized research in Alaska, Wolkon said, “Alaska is one-fifth the size of the rest of the United States. We have a lot of area, and we are data poor. We have only a handful of long-term observations in the state, and we have very few long-term records. And when I [say] long-term, I mean beyond 12 years.”
Wolkon also mentioned the recent discontinuation of Operation IceBridge, which had been taking airborne measurements of glacier elevation. “The only way to make the models do better is to actually have data that drive the models,” he said, adding, “We don’t have that right now, and so we’re doing the best we can.”
Workforce and research coordination emphasized
Assessing the needs of their field, all the witnesses expressed a desire for more researchers and for federal agencies to support work that bridges different fields.
In her written testimony , Bell noted there are currently 1,492 members of the AGU Cryosphere Section and contrasted that figure with the more than 100,000 students enrolled in law school each year. She told Johnson,
We really do need to broaden the number of people working on this, and not just glaciologists. We need engineers, we need computer scientists. We need to recognize that this is a significant national security and a national economic issue. It requires all hands on deck.
He also said that work on climate change requires coordination beyond simply allowing scientists to direct their own work. He pointed to the “notable failure ” of the National Science Foundation’s 1970s-era Research Applied to National Needs program, saying, “It’s hard to steer scientists, … but particularly with all these agencies, there needs to be some really imaginative way of figuring out what gets done first, and how long do we have to solve it.”
Bell noted that NSF is currently emphasizing what it refers to as “convergence research ,” bringing people from different disciplines together to address specific problems. “And that’s what we absolutely must do, both within the U.S. and globally. This is a problem we cannot solve by ourselves,” she said.
