Hexbyte Glen Cove Third of Antarctic ice shelf area at risk of collapse as planet warms thumbnail

Hexbyte Glen Cove Third of Antarctic ice shelf area at risk of collapse as planet warms

Hexbyte Glen Cove

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More than a third of the Antarctic’s ice shelf area could be at risk of collapsing into the sea if global temperatures reach 4°C above pre-industrial levels, new research has shown.

The University of Reading led the most detailed ever study forecasting how vulnerable the vast floating platforms of ice surrounding Antarctica will become to dramatic collapse events caused by melting and runoff, as climate change forces temperatures to rise.

It found that 34% of the area of all Antarctic ice shelves—around half a million square kilometers—including 67% of ice shelf area on the Antarctic Peninsula, would be at risk of destabilization under 4°C of warming. Limiting temperature rise to 2°C rather than 4°C would halve the area at risk and potentially avoid significant sea level rise.

The researchers also identified Larsen C—the largest remaining ice shelf on the peninsula, which split to form the enormous A68 iceberg in 2017—as one of four ice shelves that would be particularly threatened in a warmer climate.

Dr. Ella Gilbert, a research scientist in the University of Reading’s Department of Meteorology, said: “Ice shelves are important buffers preventing glaciers on land from flowing freely into the ocean and contributing to sea level rise. When they collapse, it’s like a giant cork being removed from a bottle, allowing unimaginable amounts of water from glaciers to pour into the sea.

“We know that when melted ice accumulates on the surface of ice shelves, it can make them fracture and collapse spectacularly. Previous research has given us the bigger picture in terms of predicting Antarctic ice shelf decline, but our new study uses the latest modelling techniques to fill in the finer detail and provide more precise projections.

“The findings highlight the importance of limiting global temperature increases as set out in the Paris Agreement if we are to avoid the worst consequences of climate change, including sea level rise.”

The new study, published in the Geophysical Research Letters journal, used state-of-the-art, high-resolution regional climate modelling to predict in more detail than before the impact of increased melting and water runoff on ice shelf stability.

Ice shelf vulnerability from this fracturing process was forecast under 1.5°C, 2°C and 4°C global warming scenarios, which are all possible this century.

Ice shelves are permanent floating platforms of ice attached to areas of the coastline and are formed where glaciers flowing off the land meet the sea.

Every summer, ice at the surface of the ice shelf melts and trickles down into small air gaps in the snow layer below, where it refreezes. However, in years when there is a lot of melting but little snowfall, the water pools on the surface or flows into crevasses, deepening and widening them until the ice shelf eventually fractures and collapses into the sea. If there is water collecting on the surface of the ice shelf, that suggests it could be vulnerable to collapse in this way.

This is what happened to the Larsen B ice shelf in 2002, which fractured following several years of warm summer temperatures. Its collapse caused the glaciers behind the ice shelf to speed up, losing billions of tons of ice to the sea.

The researchers identified the Larsen C, Shackleton, Pine Island and Wilkins ice shelves as most at-risk under 4°C of warming, due to their geography and the significant runoff predicted in those areas.

Dr. Gilbert said: “If temperatures continue to rise at current rates, we may lose more Antarctic ice shelves in the coming decades.

“Limiting warming will not just be good for Antarctica—preserving ice shelves means less global sea level rise, and that’s good for us all.”



More information:
Geophysical Research Letters (2021). DOI: 10.1029/2020GL091733

Citation:
Third of Antarctic ice shelf area at risk of collap

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Hexbyte Glen Cove Corn belt farmland has lost a third of its carbon-rich soil thumbnail

Hexbyte Glen Cove Corn belt farmland has lost a third of its carbon-rich soil

Hexbyte Glen Cove

Credit: CC0 Public Domain

More than one-third of the Corn Belt in the Midwest—nearly 100 million acres—has completely lost its carbon-rich topsoil, according to University of Massachusetts Amherst research that indicates the U.S. Department of Agricultural has significantly underestimated the true magnitude of farmland erosion.

In a paper published in the Proceedings of the National Academy of Sciences, researchers led by UMass Amherst graduate student Evan Thaler, along with professors Isaac Larsen and Qian Yu in the department of geosciences, developed a method using to map areas in in the Corn Belt of the Midwestern U.S. that have no remaining A-horizon soil. The A-horizon is the upper portion of the soil that is rich in , which is critical for plant growth because of its water and nutrient retention properties. The researchers then used high-resolution elevation data to extrapolate the satellite measurements across the Corn Belt and the true magnitude of .

Productive agricultural soils are vital for producing food for a growing global population and for sustaining rural economies. However, degradation of soil quality by erosion reduces . Thaler and his colleagues estimate that erosion of the A-horizon has reduced corn and soybean yields by about 6%, leading to nearly $3 billion in annual economic losses for farmers across the Midwest.

The A-horizon has primarily been lost on hilltops and ridgelines, which indicates that tillage erosion—downslope movement of soil by repeated plowing—is a major driver of soil loss in the Midwest. Notably, tillage erosion is not included in national assessments of soil loss and the research highlights the urgent need to include tillage erosion in the soil erosion models that are used in the U.S. and to incentivize adoption of no-till farming methods.

Further, their research suggests erosion has removed nearly 1.5 petagrams of carbon from hillslopes. Restoration of organic carbon to the degraded soils by switching from intensive conventional agricultural practices to soil-regenerative practices, has potential to sequester carbon dioxide from the atmosphere while restoring productivity.



More information:
Evan A. Thaler el al., “The extent of soil loss across the US Corn Belt,” PNAS (2021). www.pnas.org/cgi/doi/10.1073/pnas.1922375118

Citation:
Corn belt farmland has lost a third of its carbon-rich soil (2021, February 15)
retrieved 17 February 2021
from https://phys.org/news/2021-02-corn-belt-farmland-lost-carbon-rich.html

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Hexbyte Glen Cove A third of U.S. families face a different kind of poverty thumbnail

Hexbyte Glen Cove A third of U.S. families face a different kind of poverty

Hexbyte Glen Cove

Credit: CC0 Public Domain

Before the pandemic, one-third of U.S. households with children were already “net worth poor,” lacking enough financial resources to sustain their families for three months at a poverty level, finds new research from Duke University.

In 2019, 57 percent of Black families and 50 percent of Latino families with children were poor in terms of net worth. By comparison, the rate for was 24 percent.

“These ‘net worth poor’ households have no assets to withstand a sudden economic loss, like we have seen with COVID-19,” said Christina Gibson-Davis, co-author of the study and professor of public policy and sociology at Duke University’s Center for Child and Family Policy. “Their savings are virtually nil, and they have no financial cushion to provide the basics for their children.”

The study is among the first to consider in terms of assets, not income. Using 1989-2019 data from the Survey of Consumer Finances, researchers analyzed net worth and income data from more than 19,000 U.S. households with children under age 18.

Among households with children, net worth poverty has been steadily rising over the past 30 years, the authors found. In 2019, a two-parent, two-child household was deemed to be net-worth poor if they had less than $6,500 in assets—or less than one-fourth of the federal poverty line.

Families in that category—those with perilously low levels of net worth—outnumbered families who were poor based on income.

“Uncovering this aspect of poverty, which hinges on wealth, is game-changing,” said Lisa Gennetian, co-author of the study and associate professor of early learning policy studies at Duke’s Sanford School of Public Policy.

“Most policies focus on income and families meeting their day-to-day needs,” Gennetian said. “These efforts are important. But our findings suggest that they are not helping families increase savings that help set children up for success.”

Notably, Black and Latino families were twice as likely to experience net worth poverty than to have incomes.

“Reducing one kind of poverty isn’t helpful if another one is taking its place,” said Lisa Keister, study co-author and a professor of sociology at Duke. “Being net worth poor likely limits parents’ abilities to invest in their kids and shapes how they think about their kids’ future.”

The new research appears in the Journal of Marriage and Family.

“Even before the pandemic, many families with were in a precarious situation,” Gibson-Davis said. “Things are not going to get better in the wake of COVID-19.”



More information:
Christina Gibson‐Davis et al, Net Worth Poverty in Child Households by Race and Ethnicity, 1989–2019, Journal of Marriage and Family (2020). DOI: 10.1111/jomf.12742

Citation:
A third of U.S. families face a different kind of poverty (2021, January 6)
retrieved 8 January 2021
from https://phys.org/news/2021-01-families-kind-poverty.html

This document is subject to copyright. Apart from any fair dealing for the purpose

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