Published September 8, 2021
How will climate change impact Earth’s ice sheets in the 21st century? And how much will sea levels rise as a result?
For a decade, glaciologist Sophie Nowicki has played a lead role in coordinating international efforts to answer these and other questions about the Greenland and Antarctic ice sheets.
The resulting research, conducted by a global community of scientists, is now helping to inform decision-making worldwide on issues relating to climate change.
Projections from a major ice sheet modeling project called ISMIP6, which Nowicki co-leads, are among the data included in the latest report from the United Nations’ Intergovernmental Panel on Climate Change (IPCC).
And Nowicki is one of 18 lead authors of a chapter on ocean, cryosphere and sea level change in the new IPCC publication, released in August as the first installment of the IPCC’s Sixth Assessment Report on climate.
Two key takeaways from the analysis: Climate change is widespread, rapid and intensifying. However, we can still slow the warming — if we act now to make deep cuts to emissions of carbon dioxide and other heat-trapping gases.
“It is indisputable that human activities are causing climate change, and climate change is already affecting every region on Earth,” says Nowicki, Empire Innovation Professor of Geology in the College of Arts and Sciences and UB RENEW Institute.
“However, the IPCC report also shows that human actions still have the potential to determine the future course of the climate, as some of the impacts could be slowed and others could be stopped by limiting warming,” she says. “The report stresses the need for immediate, rapid and large-scale reductions in greenhouse gas emissions.”
Consequences of a warming world will include increasing heat waves, longer warm seasons and heat extremes that could endanger health and agriculture more often, according to IPCC projections. Sea level rise will contribute to more frequent and severe coastal flooding in low-lying areas and coastal erosion.
The intensity of these and other impacts will depend on what actions the global community takes today to reduce emissions, Nowicki says.
So, in some ways, this question lies at the heart of the IPCC’s findings: What kind of world do we want to leave behind for our children, for the next generation? The end of the 21st century, a focus for the IPCC assessment, may seem distant, but “it is really a human timescale,” she notes.
“Sea level change affects everyone on the planet,” says Nowicki, who has two school-aged children. “How much sea level will rise by the year 2100, when my children will be in their 90s, depends on what we do in the coming years.
“Sea level will continue to rise in response to the climate change that occurred in my grandmother’s lifetime. This change is already committed (or locked in) and not reversible. But the much larger potential sea level change due to current and future global warming is highly uncertain. We can still slow down changes in the polar regions and corresponding sea level rise, but we need to do so now — before irreversible changes are triggered in the Greenland and Antarctic ice sheets.”
NASA’s Sea Level Change Team has created a simple online tool that helps people envision some of these potential futures, says Nowicki, who is part of the NASA group. The tool shows how sea levels could rise around the world from now through 2150, drawing from the latest data in the IPCC report. Users can view different emissions “scenarios” to see how cutting greenhouse gases emissions could help to lessen the effects of climate change on oceans.
The IPCC is the United Nations’ body for assessing the science related to climate change. The organization’s reports are a key input for international negotiations, providing information on the status of climate change, including impacts and future risks, and options for adaptation and mitigation.
The IPCC has three working groups: Working Group I, dealing with the physical science basis of climate change; Working Group II, dealing with impacts, adaptation and vulnerability; and Working Group III, dealing with the mitigation of climate change.
The August report presents the contributions of Working Group I to the IPCC’s Sixth Assessment Report.
Nowicki has extensive experience with large collaborative projects: As co-lead for ISMIP6 — the Ice Sheet Model Intercomparison Project for phase 6 of the Coupled Model Intercomparison Project — she pulled together over 60 ice, ocean and atmosphere scientists to generate new estimates of how melting ice sheets could impact global sea level by 2100. The effort was born through a workshop she organized several years ago.
Data from ISMIP6 informed the IPCC report, as well as studies like a 2021 paper in Geophysical Research Letters that models future scenarios for the Greenland and Antarctic ice sheets, and a 2021 study in Nature that shows how deep cuts to emissions could dramatically slow down the process of sea level rise this century.
Even with all these past projects, working on the IPCC report was a completely new experience for Nowicki.
“As an IPCC author, your task is to assess the current scientific knowledge on climate change, including our past, present and future climate,” she explains. “You have to be impartial and cannot push forward your favorite research topic or ideas. Your role as an IPCC author is to combine multiple lines of evidence, not create new research.
“Everyone in your chapter needs to agree on what is written, but the assessment goes further than simply your chapter team,” she adds. “Scientists from other chapters and other IPCC reports provide feedback on what you write. In addition, external experts and governments review successive drafts of the reports. Each review comment needs to be addressed. It is a rigorous, transparent endeavor that in the end captures the current state of knowledge.”
Can you comment on the costs of climate policy and what the true impact of these policies will be on reducing temperature rise, as well as on damaging the worldwide GDP? Is Nobel Laureate William Nordhaus' economic modeling still valid? I fear the policy cost will be far greater than the economic cost of climate change and, in turn, will hurt the most vulnerable people on this planet.