Hexbyte Glen Cove Arctic sea ice thinning faster than expected thumbnail

Hexbyte Glen Cove Arctic sea ice thinning faster than expected

Hexbyte Glen Cove

The research vessel Polarstern drifting in Arctic sea ice. Source: MOSAiC website image library https://multimedia.awi.de/mosaic/ . Credit: Alfred-Wegener-Institut

Sea ice in the coastal regions of the Arctic may be thinning up to twice as fast as previously thought, according to a new modelling study led by UCL researchers.

Sea ice thickness is inferred by measuring the height of the ice above the water, and this measurement is distorted by snow weighing the ice floe down. Scientists adjust for this using a map of snow depth in the Arctic that is decades out of date and does not account for .

In the new study, published in the journal The Cryosphere, researchers swapped this map for the results of a new computer model designed to estimate snow depth as it varies year to year, and concluded that sea ice in key coastal regions was thinning at a rate that was 70% to 100% faster than previously thought.

Robbie Mallett (UCL Earth Sciences), the Ph.D. student who led the study, said: “The thickness of sea ice is a sensitive indicator of the health of the Arctic. It is important as thicker ice acts as an insulating blanket, stopping the ocean from warming up the atmosphere in winter, and protecting the ocean from the sunshine in summer. Thinner ice is also less likely to survive during the Arctic summer melt.”

“Previous calculations of sea ice thickness are based on a snow map last updated 20 years ago. Because sea ice has begun forming later and later in the year, the snow on top has less time to accumulate. Our calculations account for this declining snow depth for the first time, and suggest the sea ice is thinning faster than we thought.”

3D picture of the floe based on highly resolved aerial imagery from the helicopter nadir camera. Source: MOSAiC image gallery https://multimedia.awi.de/mosaic/#1622663686901_1 . Credit: Alfred-Wegener-Institut / Niels Fuchs

Co-author Professor Julienne Stroeve (UCL Earth Sciences) said: “There are a number of uncertainties in measuring sea ice thickness but we believe our new calculations are a major step forward in terms of more accurately interpreting the data we have from satellites.

“We hope this work can be used to better assess the performance of climate models that forecast the effects of long-term climate change in the Arctic—a region that is warming at three times the global rate, and whose millions of square kilometres of ice are essential for keeping the planet cool.”

To calculate sea ice thickness researchers used radar from the European Space Agency’s CryoSat-2 satellite. By timing how long it takes for radar waves to bounce back from the ice, they can calculate the height of the ice above the water, from which they can infer the ice’s total thickness.

In the new study, researchers used a novel snow model previously developed by researchers at UCL and Colorado State University, SnowModel-LG, which calculates snow depth and density using inputs such as air temperature, snowfall and ice motion data to track how much snow accumulates on sea ice as it moves around the Arctic Ocean. By combining the results of the snow model with satellite radar observations, they then estimated the overall rate of decline of sea ice thickness in the Arctic, as well as the variability of sea ice thickness from year to year.

Polar bears close to the research vessel Polarstern. Source: MOSAiC image gallery https://multimedia.awi.de/mosaic/#1622663686901_1 . Credit: Alfred-Wegener-Institut

They found that the rate of decline in the three coastal seas of Laptev, Kara and Chukchi seas increased by 70%, 98% and 110% respectively, when compared to earlier calculations. They also found that, across all seven coastal seas, the variability in from year to year increased by 58%.

Sea ice in the coastal seas typically varies from half a metre to two metres thick. Increasingly, the ice in this region is not surviving the summer melt. The faster thinning of sea ice in the coastal Arctic seas has implications for human activity in the region, both in terms of shipping along the Northern Sea Route for a larger part of the year, as well as the extraction of resources from the sea floor such as oil, gas and minerals.

Mallett said: “More ships following the route around Siberia would reduce the fuel and carbon emissions necessary to move goods around the world, particularly between China and Europe. However, it also raises the risk of fuel spillages in the Arctic, the consequences of which could be dire. The thinning of coastal sea ice is also worrying for indigenous communities, as it leaves settlements on the coast increasingly exposed to strong weather and wave action from the emerging ocean.”

Mallett, Professor Stroeve and co-author Dr. Michel Tsamados (UCL Earth Sciences) spent several weeks investigating and ice in the Arctic onboard the German research vessel Polarstern, which explored the central Arctic Ocean in 2019 and 2020.



More information:
“Faster decline and higher variability in the sea ice thickness of the marginal Arctic seas when accounting for dynamic snow cover”, The Cryosphere (2021). tc.copernicus.org/articles/15/2429/2021/

Citation:
Arctic sea ice thinning faster than expected (2021, June 3)
retrieved 4 June 2021
from https://phys.org/news/2021-06-arctic-sea-ice-thinning-faster.html

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part may be reproduced without the written permission. The content is provided for information purposes only.

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Hexbyte Glen Cove Cerium sidelines silver to make drug precursor thumbnail

Hexbyte Glen Cove Cerium sidelines silver to make drug precursor

Hexbyte Glen Cove

A mild process discovered by Rice University chemists could replace difficult, silver-based catalysis to create valuable fluoroketones, a precursor in the design and manufacture of drugs. Credit: Renee Man/@chemkitty

Save your silver! It’s better used for jewelry than as a catalyst for drugs.

Rice University scientists have developed a greatly simplified method to make fluoroketones, precursors for drug design and manufacture that typically require a silver catalyst.

Rice chemist Julian West and graduate students Yen-Chu Lu and Helen Jordan introduced a process for the rapid and scalable synthesis of fluoroketones that have until now been challenging and expensive to make.

Their open-access work graces the cover of the Feb. 21 issue of the Royal Society of Chemistry journal ChemComm.

The lab’s new process replaces silver with cerium-based ceric ammonium nitrate (CAN), which produces functional precursors under mild conditions in about 30 minutes.

“We could make batches of this in a bathtub,” West said.

Cerium has demonstrated such potential in other labs, and the fact that it’s 800 times more abundant in the Earth’s crust than silver made it of great interest to the Rice team.

“Ketones are a gateway functional group in molecules that you can use to make different things, like anti-cancer compounds,” said West, who came to Rice in 2019 with funding from the Cancer Prevention and Research Institute of Texas and was named a Forbes 30 Under 30 science “game changer” last year.

“They’re a great foothold to turn into an alkene or an aromatic ring,” he said. “The important part of this paper is that we’re incorporating into these fragments. Fluorine is an interesting element and quite abundant, but it’s barely used in biology.

“Fluorine has some extreme properties: It’s incredibly electronegative, so it holds onto its electrons,” West said. “That makes it hard for enzymes in to deal with them in pharmaceuticals like anti-cancer molecules.”

Hydrogen atoms in molecules are easy for the liver to process, but replacing them with fluorines “is like armor plating at that position,” he said. “That helps drugs last far longer in the body, so you don’t have to take as much. That’s desirable for chemotherapeutics.” He noted that atorvastatin (aka Lipitor), one of the most commonly prescribed drugs in the United States, incorporates fluorine for the same purpose.

“We want to put fluorine in specific places in the molecule where we know it will make a difference, and this ketone functional group allows us to do it,” West said. “People have been using a silver catalyst, but the process requires a lot of , it takes a long time at high temperature and it has to be done under a carefully controlled nitrogen or argon atmosphere.

“Our process is cheap bucket chemistry, and we think the reaction is done in about five minutes,” he said. “But we leave it for 30, just to be safe.”

The process is highly scalable. “When Yen-Chu tripled the initial recipe, he got the exact same result,” West said. “That’s rare in these kinds of reactions.”



More information:
Yen-Chu Lu et al, Rapid and scalable synthesis of fluoroketones via cerium-mediated C–C bond cleavage, Chemical Communications (2021). DOI: 10.1039/D0CC08183C

Citation:
Cerium sidelines silver to make drug precursor (2021, February 26)
retrieved 2 March 2021
from https://phys.org/news/2021-02-cerium-sidelines-silver-drug-precursor.html

This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information p

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