Archives par mot-clé : Glaciers

Claim: Svalbard glaciers lost their protective buffer in the mid-1980s and have been melting ever since

by B. Noel & M.  van den Broeke, Sep  23, 2020 in WUWT/U.Utrecht


The archipelago of Svalbard, a land of ice and polar bears, is found midway between mainland Norway and the North Pole. Its capital Longyearbyen on the main island of Spitsbergen is the world’s most northerly city, some 800 miles inside the Arctic Circle.

Svalbard is also home to some of the Earth’s northernmost glaciers, which bury most of the archipelago’s surface under no less than 200 metres of thick ice. Taken together, Svalbard glaciers represent 6% of the worldwide glacier area outside the large ice sheets of Greenland and Antarctica – if they totally melted, they would raise the sea level by 1.7cm.

Svalbard is roughly the size of Ireland or Sri Lanka, but largely covered in ice. Google Maps

Large Increase In Number Of Sunshine Hours Likely Behind Warming, Glacier Retreat In Alps Since 1980

by P. Gosselin, August 9, 2020 in NoTricksZone

Today global warming alarmists insist blaming climate change on man-made CO2 emissions. Yet, everywhere we look it’s difficult to find any correlation between CO2 and warming. Pre-industrial history shows that changes in CO2 in fact followed temperature changes.

Today we look at some climate charts of the European upper Ostalpen to look for hints what may be behind the warming since the late 20th century. We know glaciers there have been receding over the recent decades.

First is a mean temperature chart of the region for the May to September period going back 133 years:

 

Chart cropped from video “Die Alpengletscher im Klimawandel: Status quo“, by Günther Aigner


More Proof That Geologic Forces Are Melting Thwaites and Pine Island Glaciers

by J.E. Kamis, July 20, 2020 in ClimateChangeDispatch


As previously explained before, increased melting/ice loss of Antarctica’s Pine Island and Thwaites glaciers is the result of geologically induced heat flow emitted from underlying bedrock “hotspots,” not climate change (Figure 1).

All but a very minor amount of Antarctica’s glacial ice melting occurs in the western portion of this continent. The most rapid and greatest ice mass loss areas are in West Antarctica.

They are positioned directly above geographically extensive and high heat flow geological features. This association is thought to be strong evidence of a cause and effect relationship.

Discussion of evidence supporting the contention that the melting of Pine Island and Thwaites glaciers is the result of bedrock heat flow begins with a review of the regional geology (refer to Figure 1).

The Pluton Rich “hotspot” is a 61,000-thousand-square-mile area that is home to numerous high-heat-flow lava pockets that are bounded and fueled by deep earth reaching faults.

Several detailed research studies document the existence and configuration of this area. This lies along the West Antarctic Rift.

The Mount Erebus Volcanic Complex “Hotspot” is the most geologically active portion of Antarctica. It is a 25,000-square-mile high-heat-flow area, much of which is absent of glacial ice.

The absence of glacial ice across a huge portion of West Antarctica is extremely unusual and exceedingly difficult to explain by invoking global warming.

Figure 1. NASA map of Antarctica’s ice sheet thickness 1992-2017. Greatest ice thickness losses shaded red. The outline of three regional sub-glacial geological Hotspots” are outlined in red (Image by NASA, most labeling by J. Kamis).

Editorial: Climate Impacts on Glaciers and Biosphere in Fuego-Patagonia

by C. Schneider et al., April 2020 in FrontierEarthScience


The regional climate in Southernmost South America is heavily influenced by the proximity to the oceans. This generates rather weak seasonal cycles with cool to cold summers and moderate to cold winters, especially on the western Pacific side. Slightly more pronounced, continental seasonal cycles are observed in the East of the Andes. While annual mean air temperatures across the region are decreasing from North to South precipitation patterns show very pronounced east-west gradients. The distinctive gradients in precipitation are caused by the north-south striking mountain ranges of the Patagonian Andes, and the northwest-southeast stretching mountain chains of the Cordillera Darwin. Both mountain ranges enforce heavy precipitation on the west and southwest exposed flanks by uplift and dry foehn-like conditions on the leesides (e.g., Holmlund and Fuenzalida, 1995; Schneider et al., 2003; Rasmussen et al., 2007) which produces extremely high drying ratios (Escobar et al., 1992; Carrasco et al., 2002; Smith and Evans, 2007). At inter-annual to decadal time scales atmospheric teleconnections such as the El Niño Southern Oscillation (ENSO) (Schneider and Gies, 2004), Southern Annular Mode (SAM), and Pacific Decadal Oscillation (PDO) are influencing spatial and temporal patterns of both, precipitation and air temperature. For example, positive SAM modes (Garreaud, 2009; Weidemann, Sauter, Kilian et al.) and the PDO (Villalba et al., 2003) are associated with higher air temperatures. Langhamer et al. show that the source of precipitation in the Southern Andes also depends on these teleconnections.

An important aspect is that Patagonia and Tierra del Fuego, together with the sub-Antarctic islands are the only regions where direct proximity between Antarctica and land masses north of the Southern Ocean is given. Such linkages are for example explored with investigations by Hebel et al. on the biosphere and Oppedal et al. for the regional glacier history.

Melting Glaciers Uncover Medieval Artefacts In Norway

by P. Homewood, April 16, 2020 in NotaLotofPeopleKnowThat


Melting glaciers in Norway have revealed ancient artefacts dropped by the side of a road more than 1,000 years ago.

Clothes, tools, equipment and animal bone have been found by a team at a lost mountain pass at Lendbreen in Norway’s mountainous region.

A haul of more than 100 artefacts at the site includes horseshoes, a wooden whisk, a walking stick, a wooden needle, a mitten and a small iron knife.

The team also found the frozen skull of an unlucky horse used to carry loads that did not make it over the ice.

The objects that were contained in ice reveal that the pass was used in the Iron Age, from around AD 300 until the 14th century.

Activity on the pass peaked around AD 1000 and declined after the black death in the 1300s, due as well to economic and climate factors.

The researchers say the melting of mountain glaciers due to climate change has revealed the historical objects, with many more to come.

https://www.dailymail.co.uk/sciencetech/article-8224817/Melting-ice-reveals-lost-Viking-mountain-path.html

 

Unfortunately neither the journalist nor the scientists seem to be capable of adding 2+2!

 

The existence of the Medieval Warm Period in Norway, followed by glacial advance in the Little Ice Age has been long known about, as HH Lamb wrote in 1982:

Denman Glacier–Latest Antarctic Meltdown Scare

by P. Homewood, March 24, 2020 in NotaLotofPeopleKnowThat


Scientists have found a new point of major vulnerability in the Antarctic ice sheet, in a region that already appears to be changing as the climate warms and has the potential to raise sea levels by nearly five feet over the long term.

Denman glacier, in East Antarctica, is a 12-mile-wide stream of ice that flows over the deepest undersea canyon in the entire ice sheet before spilling out into the ocean. That subsea trough is more than 2 miles deep, or double the average depth of the Grand Canyon. While there are far deeper trenches in the open ocean, such as the Marianas Trench, in this case the extreme undersea topography lies right on the outer fringe of the Antarctic continent — making it the “deepest continental point on Earth.”

In reality the scientists who wrote this study do not have a clue whether the retreat of the Denman is anything new or not, or whether the deep ocean temperatures are any warmer than before 1979. Or whether what they are observing is just a natural process.

 

We can then go on to explore sea level implications.

They claim that since 1979, 250 billion tonnes of ice has been lost, equivalent to 0.5mm of sea level rise. In other words, 1.3mm/C, hardly cataclysmic.

They then go on to talk about a potential loss of 540 trillion tonnes, raising sea levels by 5 feet. Yet at current rates, it would take 86400 years for this to occur!

As always with these sort of studies, the authors refuse to say how long all this will take to happen.

 

Studies Show Glaciers Worldwide Were Smaller Than Today

by Die Kalte Sonne & P. Gosselin, February 26, 2020 in ClimateChangeDispatch


19th century glacier retreat in the Alps preceded the emergence of industrial black carbon deposition on high-alpine glaciers

Light absorbing aerosols in the atmosphere and cryosphere play an important role in the climate system. Their presence in ambient air and snow changes the radiative properties of these systems, thus contributing to increased atmospheric warming and snowmelt. High Spatio-temporal variability of aerosol concentrations and a shortage of long-term observations contribute to large uncertainties in properly assigning the climate effects of aerosols through time.

Starting around AD 1860, many glaciers in the European Alps began to retreat from their maximum mid-19th century terminus positions, thereby visualizing the end of the Little Ice Age in Europe. Radiative forcing by increasing deposition of industrial black carbon to snow has been suggested as the main driver of the abrupt glacier retreats in the Alps. The basis for this hypothesis was model simulations using elemental carbon concentrations at low temporal resolution from two ice cores in the Alps.

Here we present sub-annually resolved concentration records of refractory black carbon (rBC; using soot photometry) as well as distinctive tracers for mineral dust, biomass burning and industrial pollution from the Colle Gnifetti ice core in the Alps from AD 1741 to 2015. These records allow precise assessment of a potential relation between the timing of observed acceleration of glacier melt in the mid-19th century with an increase of rBC deposition on the glacier caused by the industrialization of Western Europe. Our study reveals that in AD 1875, the time when rBC ice-core concentrations started to significantly increase, the majority of Alpine glaciers had already experienced more than 80 % of their total 19th-century length reduction, casting doubt on a leading role for soot in terminating of the Little Ice Age. Attribution of glacial retreat requires expansion of the spatial network and sampling density of high alpine ice cores to balance potential biasing effects arising from transport, deposition, and snow conservation in individual ice-core records.”

Also, a glacier history of the Alps since the end of the last ice age was published in 2009 by Susan Ivy-Ochs and colleagues.

Between 10,500-3300 years before today, glaciers were mostly smaller than today and ended 200 meters above modern levels. The Alpine glaciers expanded during the cold period of migration and the Little Ice Age.

Want to know more about glacier history? Here’s the abstract:

New Study: Greenland’s Largest Glacier Has Rapidly Thickened Since 2016…Fueled By 1.5°C Regional Ocean Cooling

by K. Richard, February 17, 2020 in NoTricksZone


Greenland’s largest glacier (Jakobshavn) has quite abruptly thickened since 2016. The thickening has been so profound the ice elevations are nearly back to 2010-2011 levels. The nearby ocean has cooled ~1.5°C – a return to 1980s-era temperatures.

The world’s glaciers have not been following along with the CO2-driven catastrophic melting narrative.

Alaska

For example, in a study of 50 Alaskan glaciers for the warming period between 1972-2012, researchers (McNabb and Hock, 2014) found there was
“…no corresponding change in the number of glaciers retreating nor do we see corresponding acceleration of retreat rates. To the contrary, many glaciers in the region have advanced…”

Patterns of thinning of Antarctica’s biggest glacier are opposite to previously observed

by University of Bristol, January 27, 2020 in ScienceDaily


Using the latest satellite technology from the European Space Agency (ESA), scientists from the University of Bristol have been tracking patterns of mass loss from Pine Island — Antarctica’s largest glacier.

They found that the pattern of thinning is evolving in complex ways both in space and time with thinning rates now highest along the slow-flow margins of the glacier, while rates in the fast-flowing central trunk have decreased by about a factor of five since 2007. This is the opposite of what was observed prior to 2010.

Pine Island has contributed more to sea level rise over the past four decades than any other glacier in Antarctica, and as a consequence has become one of its most intensively and extensively investigated ice stream systems.

However, different model projections of future mass loss give conflicting results; some suggesting mass loss could dramatically increase over the next few decades, resulting in a rapidly growing contribution to sea level, while others indicate a more moderate response.

Identifying which is the more likely behaviour is important for understanding future sea level rise and how this vulnerable part of Antarctica is going to evolve over the coming decades.

The results of the new study, published in the journal Nature Geoscience, suggest that rapid migration of the grounding line, the place where the grounded ice first meets the ocean, is unlikely over that timescale, without a major change in ocean forcing. Instead, the results support model simulations that imply that the glacier will continue to lose mass but not at much greater rates than present.

Lead author Professor Jonathan Bamber from the University of Bristol’s School of Geographical Sciences, said: “This could seem like a ‘good news story’ but it’s important to remember that we still expect this glacier to continue to lose mass in the future and for that trend to increase over time, just not quite as fast as some model simulations suggested.

“It’s really important to understand why the models are producing different behaviour in the future and to get a better handle on how the glacier will evolve with the benefit of these new observations.

“In our study, we didn’t make projections but with the aid of these new data we can improve model projections for this part of Antarctica.”

World Leading Alps Glaciologist Shows “Today’s Climate, Vegetation And Glacier Situation Nothing Special”

by H.J. Lüdecke & K.E. Puls, January 25, 2020 in NoTricksZone


Prof. Gernot Patzelt is an internationally renowned glaciologist with numerous publications and lectures. Now he has, as it were, presented his life’s work with the book “Gletscher: Klimazeugen von der Eiszeit bis zur Gegenwart“ (Glaciers: Climate Witnesses from the Ice Age to the Present” (Hatje Cantz-Verlag, Berlin, 2019, 266 pages). It combines the overwhelming artistic aesthetics of Alpine glaciers in painting with scientific glaciology.

Gernot Patzelt, Professor of High Altitude Research at the University of Innsbruck and Head of the Alpine Research Centre Obergurgl in Tyrol, was not and is not retired after his retirement in 2004. His lectures, especially those at EIKE climate conferences (here, here) and his writings, which are listed here, bear witness to this. He was also co-author of the book “A. Fischer und G. Patzelt: Gletscher im Wandel: 125 Jahre Gletscher-Meßdienst des Alpenvereins, Springer, 2018″.

His book “Klimazeugen von der Eiszeit bis zur Gegenwart” (Climate Witnesses from the Ice Age to the Present), which is discussed here, breaks new ground by making the otherwise rarely attempted connection between natural aesthetics and scientific description. The Austrian glaciologist  has convincingly succeeded in this attempt, namely the connection of painting history with Ice Age history, glacier history, landscape history, vegetation history, climate history, cultural history … and more!

Major Greenland Glacier Is Growing

by NASA (Earth Observatory), June 6, 2019 in NASA.E.Observ.


Jakobshavn Glacier in western Greenland is notorious for being the world’s fastest-moving glacier. It is also one of the most active, discharging a tremendous amount of ice from the Greenland Ice Sheet into Ilulissat Icefjord and adjacent Disko Bay—with implications for sea level rise. The image above, acquired on June 6, 2019, by the Operational Land Imager (OLI) on Landsat 8, shows a natural-color view of the glacier.

Jakobshavn has spent decades in retreat—that is, until scientists observed an unexpected advance between 2016 and 2017. In addition to growing toward the ocean, the glacier was found to be slowing and thickening. New data collected in March 2019 confirm that the glacier has grown for the third year in a row, and scientists attribute the change to cool ocean waters.

“The third straight year of thickening of Greenland’s biggest glacier supports our conclusion that the ocean is the culprit,” said Josh Willis, an ocean scientist at NASA’s Jet Propulsion Laboratory and principal investigator of the Oceans Melting Greenland (OMG) mission

False Alarm: Glacier National Park Changes ‘Gone By 2020’ Signs

by Chris White, January 9, 2020 in ClimateChangeDispatch


Officials who manage Glacier National Park are swapping out signs warning visitors that climate change would cause the park’s glaciers to disappear by 2020.

The U.S. Geological Survey told the park in 2017 that the complete melting off of the glaciers was no longer expected, park spokeswoman Gina Kurzmen told CNN.

Forecast models over the years show the glaciers were no longer at risk of disappearing by that date, she noted.

Placards at the St. Mary’s Visitor Center, located in Montana’s mountain ranges, were reportedly changed in 2019. The park is waiting for budget authorization to update the park’s full set of signs, Kurzman noted.

The signs will be changed to say: “When they will completely disappear depends on how and when we act. One thing is consistent: the glaciers in the park are shrinking.”

SEE ALSO: National Park Stealth Removes Warning That All Glaciers Will Be Gone By 2020

SEE ALSO: Himalayan Glacier Loss Caused By Many Factors, Not Just Warming

USGS noted in a report to the Daily Caller News Foundation in 2019 that recent harsh winters had significantly changed forecasts from years past.

“Glacier retreat in Glacier National Park speeds up and slows down with fluctuations in the local climate,” a representative with the USGS told the DCNF at the time. The agency is responsible for managing the park.

“Subsequently, larger than average snowfall over several winters slowed down that retreat rate and the 2020 date used in the NPS display does not apply anymore,” the representative said.

 

 

Also : National Park Stealth Removes Warning That All Glaciers Will Be Gone By 2020

If “Greenland is catastrophically melting”, how do alarmists explain NASA’s growing Greenland glacier?

by A. Watts, June19, 2019 in WUWT


It turned out to be a weather event, unrelated to “climate change”. The next year, there was no “insta-melt“.

In fact. we’d not even know about the melting in Greenland before satellites came on the scene. So how many times in the history of the Earth has Greenland has a quick melt spike? I’m guessing hundreds of thousands of times.

Jakobshavn Glacier in western Greenland is notorious for being the world’s fastest-moving glacier. It is also one of the most active, discharging a tremendous amount of ice from the Greenland Ice Sheet into Ilulissat Icefjord and adjacent Disko Bay—with implications for sea level rise. The image above, acquired on June 6, 2019, by the Operational Land Imager (OLI) on Landsat 8, shows a natural-color view of the glacier.

Jakobshavn has spent decades in retreat—that is, until scientists observed an unexpected advance between 2016 and 2017. In addition to growing toward the ocean, the glacier was found to be slowing and thickening. New data collected in March 2019 confirm that the glacier has grown for the third year in a row, and scientists attribute the change to cool ocean waters.

June 6th, 2019 Jakobshavn Glacier in western Greenland . Image acquired on June 6, 2019, by the Operational Land Imager (OLI) on Landsat 8, shows a natural-color view of the glacier.

PATAGONIA ICE SHEETS THICKER THAN PREVIOUSLY THOUGHT

by GWPF, June 05, 2019


After conducting a comprehensive, seven-year survey of Patagonia, glaciologists from the University of California, Irvine and partner institutions in Argentina and Chile have concluded that the ice sheets in this vast region of South America are considerably more massive than expected.

hrough a combination of ground observations and airborne gravity and radar sounding methods, the scientists created the most complete ice density map of the area to date and found that some glaciers are as much as a mile (1,600 meters) thick. Their findings were published today in the American Geophysical Union journal Geophysical Research Letters.

Glacier National Park Quietly Removes Its ‘Gone by 2020’ Signs

by Roger I. Roots, May 30, 2019 in WUWT


Founder, Lysander Spooner University

May 30, 2019. St. Mary, Montana. Officials at Glacier National Park (GNP) have begun quietly removing and altering signs and government literature which told visitors that the Park’s glaciers were all expected to disappear by either 2020 or 2030.
In recent years the National Park Service prominently featured brochures, signs and films which boldly proclaimed that all glaciers at GNP were melting away rapidly. But now officials at GNP seem to be scrambling to hide or replace their previous hysterical claims while avoiding any notice to the public that the claims were inaccurate. Teams from Lysander Spooner University visiting the Park each September have noted that GNP’s most famous glaciers such as the Grinnell Glacier and the Jackson Glacier appear to have been growing—not shrinking—since about 2010. (The Jackson Glacier—easily seen from the Going-To-The-Sun Highway—may have grown as much as 25% or more over the past decade.)

Montana Glacier National Park Mountains Cracker Lake

Greenland Glaciers Growing Again

by P. Homewood, May 22, 2019 in NotaLotofPeopleKnowThat


European satellites have detailed the abrupt change in behaviour of one of Greenland’s most important glaciers.

In the 2000s, Jakobshavn Isbrae was the fastest flowing ice stream on the island, travelling at 17km a year.

As it sped to the ocean, its front end also retreated and thinned, dropping in height by as much as 20m year.

But now it’s all change. Jakobshavn is travelling much more slowly, and its trunk has even begun to thicken and lengthen.

“It’s a complete reversal in behaviour and it wasn’t predicted,” said Dr Anna Hogg from Leeds University and the UK Centre for Polar Observation and Modelling (CPOM).

“The question now is: what’s next for Jakobshavn? Is this just a pause, or is it a switch-off of the dynamic thinning we’ve seen previously?”

The rapid flow, thinning and retreat of Jakobshavn’s front end in the mid to late 2000s were probably driven by warm ocean water from Disko Bay getting into the fjord and attacking the glacier from below.

The phase change, scientists think, may be related to very cold weather in 2013. This would have resulted in less meltwater coming off the glacier, which in turn might have choked the mechanism that pulls warm ocean water towards Jakobshavn.

Greenland Has Been Cooling In Recent Years – 26 Of Its 47 Largest Glaciers Now Stable Or Gaining Ice

by K. Richard, May 20, 2019 in NoTricksZone


A new analysis of recent trends for the Greenland ice sheet reveals that since 2012 there has been an abrupt slowing of melt rates and a trend reversal to cooling and ice growth.
• In 2018, 26 of Greenland’s 47 largest glaciers were either stable or grew in size.
• Overall, the 47 glaciers advanced by +4.1  km² during 2018.  Of the 6 largest glaciers, 4 grew while 2 retreated.
• Since 2012, ice loss has been “minor” to “modest” due to the dramatic melting slowdown.
• Summer average temperatures for 2018 were lower than the 2008-2018 average by more than one standard deviation.
• Since 2000, the extent of the non-snow-covered areas of Greenland has increased by 500 km² per year.

Inconvenient: NASA says a Greenland glacier did an about-face – growing again

by Anthony Watts, March 25, 2019 in WUWT


“…scientists were so shocked to find the change.”

From NASA JPL: Cold Water Currently Slowing Fastest Thinning Greenland Glacier

NASA research shows that Jakobshavn Glacier, which has been Greenland’s fastest-flowing and fastest-thinning glacier for the last 20 years, has made an unexpected about-face. Jakobshavn is now flowing more slowly, thickening, and advancing toward the ocean instead of retreating farther inland. The glacier is still adding to global sea level rise – it continues to lose more ice to the ocean than it gains from snow accumulation – but at a slower rate.

The researchers conclude that the slowdown of this glacier, known in the Greenlandic language as Sermeq Kujalleq, occurred because an ocean current that brings water to the glacier’s ocean face grew much cooler in 2016. Water temperatures in the vicinity of the glacier are now colder than they have been since the mid-1980s.

See also here in NBS

Greenland’s Glaciers Expanding Again

by P. Homewood, March 11, 2019 in NotaLotofPeopleKnowThat


As I reported last  September, Greenland’s ice sheet mass balance had grown at close to record levels for the second year running.

To clarify again, the mass balance calculation accounts for:

1) Snowfall

2) Ice melt

3) Ablation

 

In other words, it does not include calving.

http://www.dmi.dk/en/groenland/maalinger/greenland-ice-sheet-surface-mass-budget/#

..

Geological ‘Hotspot’ Melting Pine Island And Thwaites Glaciers, Not Global Warming

by J.E. Kamis, February 25, 2019 in ClimateChangeDispatch


SUMMARY

Research study after research study has now proven beyond any doubt that the 350,000-square-mile subglacial Marie Byrd Mantle Plume and its associated geological features that are emitting massive amounts of ice melting heat and heated fluid onto the base of the Pine Island Glacier and Thwaites Glaciers.

Failure of the media to include in their numerous articles this telling scientific evidence which substantiates the significant and likely dominant role of this subglacial geologically induced heat flow in melting of West Antarctic glaciers is difficult to reconcile with proper scientific methodology.

A methodology which states that new and relevant data should be used to review old supposedly 100% settled theories.

Most of these research studies have been released one by one during the last three years which has led to minimizing their collective importance.  Numerous previous Climate Change Dispatch articles written by this author beginning in 2014 have inexplicably been ignored by mainstream media outlets.

It’s time for the media to inform the public that by tying all this information together that a clear picture emerges concerning the significant impact of Antarctic subglacial geologically induced heat flow.

Observing glaciers in “real time”

by Anthony Watts, August 20, 2018 in WUWT


From ETH Zurich and the “slow as molasses in winter” department.

Hot summers cause glaciers to melt. That not only changes the makeup of the landscape and hence the maps of Switzerland, it also affects every area of society. A new, dynamic glacier inventory makes the impact of climate change and the changing landscape visible.

The last time Swiss glaciers managed to grow at all was in 2001. Since then, the country’s 1,500 glaciers – as well as others elsewhere – have been suffering a slow but inexorable death. Until now, though, we have understood only partially how quickly they are really disappearing, and what effect that has on the landscape, people and animals. That is about to change, thanks to the Glacier Monitoring in Switzerland (GLAMOS) project. GLAMOS is working on behalf of various Swiss federal offices to put together a comprehensive inventory of the country’s glaciers – at an unprecedented level of detail.

Glacier observation under the spell of several Valais four-thousand-metre peaks. (Photograph: GLAMOS)

The coloured lines show where the edge of the Aletsch glacier once was (red line 1850, green=1973, blue=2010). (Graphic: Swisstopo/GLAMOS)