deglaciation – Page 4 – Desdemona Despair

Atlantic Meridional Overturning Circulation (AMOC) sea surface temperature (SST) fingerprint. Multimodel mean correlation map between the low-frequency AMOC at 26°N and SST (12). Stars numbered 1 to 16 denote location of sites referred in the figures. The reconstructed AMV at South Sawtooth Lake (1), August temperature in Vøring Plateau off Norway (2), Eastern Fram Strait IRD (3), Atlantic water influence based on C. neoteresis in Western Fram Strait (4), East Greenland Strait N. labradorica (5), North Icelandic shelf temperature based on δ18O from bivalve shells (6), IRD in Denmark Strait (7), the RAPiD-35-COM δ18O T. quinqueloba (8), percentage of Atlantic species in Disko Bugt (9), the RAPID-21-COM sortable silt in the ISOW (10), Gulf of Maine reconstructed SST from bivalve shells (11), titanium (%) in the Cariaco Basin (12), Quelccaya ice record δ18O (13), Huagapo speleothem δ18O (14), and Lake Bosumtwi lake level inferred from δ18O (15). The James Ross Island ice core record with annually resolved δD is shown (16). Graphic: Lapointe and Bradley, 2021 / Science Advances

December 25, 2021

Researchers uncover the surprising cause of the Little Ice Age – “We may be underestimating future ice loss from the Greenland ice sheet”

AMHERST, Massachusetts, 15 December 2021 (University of Massachusetts Amherst) – New research from the University of Massachusetts Amherst provides a novel answer to one of the persistent questions in historical climatology, environmental history and the earth sciences: what caused the Little Ice Age? The answer, we now know, is a paradox: warming. The Little Ice […]

Satellite view of changes to the Sierra Nevada snowpack, 2006-2021. Photo: NASA

December 25, 2021

Sierra Nevada snowpack, a crucial water resource, could disappear in 25 years – “A low-to-no-snow future has massive implications for where and when water is stored in the western U.S.”

By Denise Chow 1 December 2021 (NBC News) – The Sierra Nevada snowpack, a major source of water for California, could largely disappear in 25 years if global warming continues unchecked, according to a recent study. The worrisome findings, published 26 October 2021 in the journal Nature Reviews Earth & Environment, have serious implications for California’s […]

(a) Linear sea surface temperature (SST) trend (°C yr-1) for August of each year from 1982 to 2021. The trend is only shown for values that are statistically significant at the 95 percent confidence interval; the region is shaded gray otherwise. White shading is the August 2021 mean sea ice extent, and the yellow line indicates the median ice edge for Aug 1982-2010, (b, c) Area-averaged SST anomalies (°C) for August of each year (1982-2021) relative to the 1982-2010 August mean for (b) Baffin Bay and (c) Chukchi Sea regions shown by blue boxes in (a). The dotted lines show the linear SST anomaly trends over the period shown and trends in °C yr-1 (with 95 percent confidence intervals) are shown on the plots. Mean August SST warming trends from 1982 to 2021 persist over much of the Arctic Ocean, with statistically significant (at the 95 percent confidence interval) linear warming trends of up to +0.1°C yr-1 (a). Overall, Baffin Bay SSTs are becoming warmer in August with a linear warming trend over 1982-2021 of 0.05 ± 0.01°C yr-1 (b). Similarly, Chukchi Sea August mean SSTs are warming, with a linear trend of 0.06 ± 0.03°C yr-1 (c). Mean August SSTs for the entire Arctic (the Arctic Ocean and marginal seas north of 67° N) exhibit a linear warming trend of 0.03 ± 0.01°C yr-1. Graphic: Timmermans and Labe / NOAA

December 24, 2021

NOAA’s 2021 Arctic Report Card: Rapid and pronounced warming continues to drive the evolution of the Arctic environment

By T. A. Moon, M. L. Druckenmiller, and R. L. Thoman 6 December 2021 (NOAA) – As the influences of human-caused global warming continue to intensify, with the Arctic warming significantly faster than the globe overall, the 2021 Arctic Report Card (ARC2021) brings a broad view of the state of the Arctic climate and environment. […]

$Satellite view of Antarctica’s Thwaites Glacier on 28 December 2015 (left) and 31 March 2021 (right). On 13 December 2021, Ice scientists at the American Geophysical Union (AGU) meeting in New Orleans warned that great cracks and fissures had opened up both on top of and underneath the Thwaites glacier, one of the biggest in the world, and it may fracture and collapse, possibly within five years. Photo: ESA Sentinel-1$

December 22, 2021

Antarctica’s “doomsday” glacier: how its collapse could trigger global floods and swallow islands – “If Thwaites were to collapse, it would drag most of West Antarctica’s ice with it”

By Ella Gilbert 22 December 2021 (The Conversation) – The massive Thwaites glacier in West Antarctica contains enough ice to raise global sea levels by 65 centimeters if it were to completely collapse. And, worryingly, recent research suggests that its long-term stability is doubtful as the glacier haemorrhages more and more ice. Adding 65 centimeters to global sea levels […]

Map showing the near-surface air temperature differences from the 1981-2010 average for January to September 2021. Data are from the ERA5 reanalysis product. Graphic: C3S / ECMWF

December 12, 2021

State of the Climate in 2021: Past seven years are on track to be the seven warmest on record – “Extreme events are the new norm”

GENEVA, 31 October 2021 (WMO) – Record atmospheric greenhouse gas concentrations and associated accumulated heat have propelled the planet into uncharted territory, with far-reaching repercussions for current and future generations, according to the World Meteorological Organization (WMO). The past seven years are on track to be the seven warmest on record, according to the provisional WMO […]

Map showing trends of early-warning indicators of Atlantic Meridional Overturning Circulation (AMOC) collapse. a, Linear trends of the corrected restoring rate λ estimated from the HadISST dataset assuming autocorrelated noise. b, Same as (a) but for the EN4 salinity dataset. c, Linear trends of the variance estimated from the HadISST dataset. d, Same as (c) but for the EN4 salinity dataset. e, Linear trends of the AC1 estimated from the HadISST dataset. f, Same as (e) but for the EN4 salinity dataset. Note the high positive values in the northern Atlantic and the subpolar gyre region in particular for λ and AC1, but also in the southern Atlantic ocean where a salinity pileup has recently been associated with an AMOC slowdown. Graphic: Boers, 2021 / Nature Climate Change

August 22, 2021

Gulf Stream could be veering toward irreversible decline, a new analysis warns – Atlantic current “approaching a critical threshold beyond which the circulation system could collapse”

By Ben Turner 6 August 2021 (LiveScience) – One of the most crucial ocean current systems for regulating the Northern Hemisphere’s climate could be on the verge of total collapse due to climate change, a new study has revealed. The Atlantic Meridional Overturning Circulation (AMOC), which includes the Gulf Stream and is responsible for moderating […]

Time series of climate-related responses to anthropogenic drivers, 1990-2020. Out of the 31 tracked planetary vital signs, 18 were at new all-time record lows or highs in 2020. Data obtained before and after the publication of Ripple and colleagues (2020) are shown in gray and red respectively. For variables with relatively high variability, local regression trend lines are shown in black. The variables were measured at various frequencies (e.g., annual, monthly, weekly). The labels on the x-axis correspond to midpoints of years. Sources and additional details about each variable are provided in the supplemental material. Graphic: Ripple, et al., 2021 / BioScience

July 31, 2021

World scientists’ warning of a climate emergency 2021 – Humans face untold suffering from “the consequences of unrelenting business as usual”

28 July 2021 (BioScience) – In 2019, Ripple and colleagues (2020) warned of untold suffering and declared a climate emergency together with more than 11,000 scientist signatories from 153 countries. They presented graphs of planetary vital signs indicating very troubling trends, along with little progress by humanity to address climate change. On the basis of […]

In a grim commentary on climate change, in 2009, British artist Banksy creatively vandalized this 1890 painting by Hudson River School painter Albert Bierstadt. The artwork, now titled Subject to Availability, has a surprise for Northwest locals — Mount Rainier. It sold at auction Wednesday, 28 June 2021, for 4,582,500 pounds, or $6,342,180. Photo: Christie’s Images Limited 2021

July 3, 2021

Artist Banksy’s “hijacked” painting of Mount Rainier sells for more than $6 million as global warming roasts the Pacific Northwest

By Megan Burbank 30 June 2021 (The Seattle Times) – As the Puget Sound region coped this week with extreme heat caused by climate change, one of the art world’s most audacious commentaries on the issue reemerged across the Atlantic. A 2009 work of creative vandalism from British artist and agitator Banksy, Subject to Availability, was sold […]

Deep water underneath the Thwaites ice shelf front is lighter than water outside the ice shelf. (A) Map of trough T3 showing the AUV path color coded by latitude. Shaded region indicates the ice shelf front, and black contours are depth contours. (B) Conservative temperature θ (in degrees Celsius) versus absolute salinity SA (in grams per kilogram) for the AUV data points shown in (A), colors as in (A). Contours show potential density (9) relative to 900 m, and blue arrow indicates isopycnal mixing, i.e., water that has the same density but different temperatures and salinities. Green circles in (A) and (B) show the dense saline deep water found in trough T3 discussed in the main text. (C) Absolute salinity SA (in grams per kilogram) as a function of depth for the AUV data in trough T3 and the CTD data (colors indicate station as in Fig. 3). (D) Potential density (in kilograms per cubic meter) as a function of depth for the AUV data in trough T3 and the CTD data (colors indicate station as in Figs. 3 and 4). Red and blue arrows indicate the two deep water masses discussed in the main text from Pine Island Bay and Thwaites Trough. Dissolved oxygen versus θ and SA is shown in fig. S6. Graphic: Wåhlin, et al., 2021 / Science Advances

April 11, 2021

Exploration of ocean currents beneath the “Doomsday Glacier” by an autonomous underwater vehicle – Net melting of 75 cubic km of ice per year means “the glacier is not stable over time”

9 April 2021 (University of Gothenburg) – For the first time, researchers have been able to obtain data from underneath Thwaites Glacier, also known as the “Doomsday Glacier”. They find that the supply of warm water to the glacier is larger than previously thought, triggering concerns of faster melting and accelerating ice flow. With the […]

Millennium-scale evolution of the Atlantic Meridional Overturning Circulation (AMOC), 400 - 2020. SST-based AMOC reconstructions (light and dark blue) compared to various proxy reconstructions, including land and sea surface temperature reconstructions, sortable silt data, δ18O in benthic foraminifera, δ15N of deep-sea gorgonian corals, and relative abundance of Turborotalita quinqueloba. Since at least 400 AD relatively stable, the AMOC began to decline during the 19th Century which is evident in all proxy records. Around 1950 a phase of particularly rapid decline started that is found in several, largely independent proxies. A short-lived recovery is evident in the 1990s before a return to decline from the mid-2000s. Together these data consistently show that the modern AMOC slowdown is unprecedented in over a thousand years. Graphic: Levke Caesar

March 21, 2021

Gulf Stream System at its weakest in more than a millennium – “This could bring us dangerously close to the tipping point at which the flow becomes unstable”

25 February 2021 (PIK) – Never before in over 1000 years the Atlantic Meridional Overturning Circulation (AMOC), also known as Gulf Stream System, has been as weak as in the last decades. This is the result of a new study by scientists from Ireland, Britain, and Germany. The researchers compiled so-called proxy data – taken […]