New study analyses roughly 220,000 glaciers
ETH ZURICH
Glaciers are a sensitive indicator of climate change – and one that can be easily observed. Regardless of altitude or latitude, glaciers have been melting at a high rate since the mid-?20th century. Until now, however, the full extent of ice loss has only been partially measured and understood. Now an international research team led by ETH Zurich and the University of Toulouse has authored a comprehensive study on global glacier retreat, which was published online in Nature on 28 April. This is the first study to include all the world’s glaciers – around 220,000 in total – excluding the Greenland and Antarctic ice sheets. The study’s spatial and temporal resolution is unprecedented – and shows how rapidly glaciers have lost thickness and mass over the past two decades.
Rising sea levels and water scarcity What was once permanent ice has declined in volume almost everywhere around the globe. Between 2000 and 2019, the world’s glaciers lost a total of 267 gigatonnes (billion tonnes) of ice per year on average – an amount that could have submerged the entire surface area of Switzerland under six metres of water every year. The loss of glacial mass also accelerated sharply during this period. Between 2000 and 2004, glaciers lost 227 gigatonnes of ice per year, but between 2015 and 2019, the lost mass amounted to 298 gigatonnes annually. Glacial melt caused up to 21 percent of the observed rise in sea levels during this period – some 0.74 millimetres a year. Nearly half of the rise in sea levels is attributable to the thermal expansion of water as it heats up, with meltwaters from the Greenland and Antarctic ice sheets and changes in terrestrial water storage accounting for the remaining third.
Among the fastest melting glaciers are those in Alaska, Iceland and the Alps. The situation is also having a profound effect on mountain glaciers in the Pamir mountains, the Hindu Kush and the Himalayas. “The situation in the Himalayas is particularly worrying,” explains Romain Hugonnet, lead author of the study and researcher at ETH Zurich and the University of Toulouse. “During the dry season, glacial meltwater is an important source that feeds major waterways such as the Ganges, Brahmaputra and Indus rivers. Right now, this increased melting acts as a buffer for people living in the region, but if Himalayan glacier shrinkage keeps accelerating, populous countries like India and Bangladesh could face water or food shortages in a few decades.” The findings of this study can improve hydrological models and be used to make more accurate predictions on a global and local scales – for instance, to estimate how much Himalayan glacier meltwater one can anticipate over the next few decades.
To their surprise, the researchers also identified areas where melt rates slowed between 2000 and 2019, such as on Greenland’s east coast and in Iceland and Scandinavia. They attribute this divergent pattern to a weather anomaly in the North Atlantic that caused higher precipitation and lower temperatures between 2010 and 2019, thereby slowing ice loss. The researchers also discovered that the phenomenon known as the Karakoram anomaly is disappearing. Prior to 2010, glaciers in the Karakoram mountain range were stable – and in some cases, even growing. However, the researchers’ analysis revealed that Karakoram glaciers are now losing mass as well.
Study based on stereo satellite images As a basis for the study, the research team used imagery captured on board NASA’s Terra satellite, which has been orbiting the Earth once every 100 minutes since 1999 at an altitude of nearly 700 kilometres. Terra is home to ASTER, a multispectral imager with two cameras that record pairs of stereo images, allowing researchers to create high-?resolution digital elevation models of all the world’s glaciers. The team used the full archive of ASTER images to reconstruct a time series of glacial elevation, which enabled them to calculate changes in the thickness and mass of the ice over time.
Lead author Romain Hugonnet is a doctoral student at ETH Zurich and the University of Toulouse. He worked on this project for nearly three years and spent 18 months analysing the satellite data. To process the data, the researchers used a supercomputer at the University of Northern British Columbia. Their findings will be included in the next Assessment Report of the United Nations Intergovernmental Panel on Climate Change (IPCC), which is due to be published later this year. “Our findings are important on a political level. The world really needs to act now to prevent the worst-?case climate change scenario,” says co-?author Daniel Farinotti, head of the glaciology group at ETH Zurich and the Swiss Federal Institute for Forest, Snow and Landscape Research WSL.
Alongside the University of Toulouse, ETH Zurich and WSL, other institutions that participated in the study include Ulster University in the UK, the University of Oslo in Norway and the University of Northern British Columbia in Canada (please refer to the study for a complete list).
Reference Hugonnet R, McNabb R, Berthier E, Menounos B, Nuth C, Girod L, Farinotti D, Huss M, Dussaillant I, Brun F, Kääb A. Accelerated global glacier mass loss in the early twenty-?first century, Nature, published online April 28th 2021. DOI: 10.1038/s41586-?021-03436-z
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I thought that the main driver of glacier movement was the weight of snow at the top rather than a small change in temperature at the bottom.
If so, that would mean the real “problem” would be reduction of precipitation rather than increase in temperature, so is “the climate emergency” supposed to reduce precipitation or increse it
Faster than when?
The NH was cooling in the mid 20thC – 1960s and 70s, consequently sea level rise slowed down.
However, sea levels were rising as fast as now in the early 20thC, suggesting glaciers are melting no faster than then
Wow glaciers shrink in an interglacial period. Shocking
The shocking part is that the interglacial is cold enough to maintain glaciers in the first place.
Are they really sensitive indicators of climate change?
Sounds like a stretch that these huge structures are sensitive to minuscule temperature change…
They are sensitive indicators of climate change, but not necessarily air temperatures. The rate of snow accumulation, the presence of dark volcanic ash on the surface, warm rain, windiness, and most importantly cloudiness, all impact glacial ablation in addition to air temperatures.
From the article: “Glaciers are a sensitive indicator of climate change – and one that can be easily observed. Regardless of altitude or latitude, glaciers have been melting at a high rate since the mid-?20th century.”
This should be expected since “the mid-20th century” was one of the coldest periods since the Little Ice Age, so when it warms up from one of the coldest periods since the Little Ice Age, we can expect some ice to melt. It has nothing to do with CO2. At least, the alarmists can’t prove it has anything to do with CO2.
It’s Mother Nature, not CO2, until proven otherwise.
Mid 20th Century or a century or two earlier?
Geoff S
The authors of this study haven’t thought through the implications of their results. Sea level rise is a combination of aquifer extraction, thermal expansion of sea water and glacial melting. This means that if the amount of glacial melting is greater than previously thought, the amount of thermal expansion must be less than previously thought to obtain the same amount of sea level rise. So I wish to congratulate the authors for their evidence that the amount of global warming is much less than previously imagined. Climate alarmists will not be pleased with this study.
BT,
Sea level rise as currently understood requires no change in the shape and volume of the basin formed by the surrounding rocks. Does not take a huge change to affect levels by a millimetre. And we know the basins are changing because there is underwater volcanism moving some rock around. As yet, we do not know by how much it changes basin volume.
Here is an interesting exercise for you. Try to find the figure that represents the change in sea level globally for a 1 degree C change in the global air temperature. Happy hunting!! Geoff S
Geoff
And we can reasonably expect that as the ice-loading responsible for isostatic depression of land, and subsequent rebound, is transferred to the ocean basins, the basins will isostatically adjust to the increased load by deepening the basin(s).
Is there such a thing as permanent ice?
It depends on one’s definition of permanence. From a geologic perspective, the answer is “No.” There might be permanent ice on the moon.
SA,
In terms of phase changes, this is the same question as “Is there such a thing as permanent water?”. Or even permanenmt water vapour. Geoff S.
When glaciers in some regions of the world melt, it’s “climate change”, and when others either don’t melt or grow, it’s a “weather anomaly”. Got it.
The volume of meltwater estimated by this study is claimed to have contributed to sea level rise. But how much of this flow actually gets to the oceans? Evaporation and aquifer replenishment among other factors are in play. Have the waters of the Rhine, Rhone, Yangzi, Indus and other rivers increased?
The article is a talking point. It is meaningless, but alarmists, such as AlGore, will simply drop the line in a long list of ‘alarms’ with no attribution, and no validation. Glacial melting, along with sea levels rising, temperatures rising and CO2 rising.
“The findings of this study can improve hydrological models and be used to make more accurate predictions on a global and local scales”
The study certainly cannot predict the AMO cycle which drives the advances and retreats of Alpine glaciers.
“The world really needs to act now to prevent the worst-?case climate change scenario,” says co-?author Daniel Farinotti”
The world needs to act now to prevent the worst case anti-science, the warm AMO phase driving the glacier retreat, is due to lower indirect solar forcing since 1995, not rising CO2 forcing.
Ulric,
The Climastrologists will soon be claiming that the AMO, the PDO, the ENSO and other cycles are driven by CO2! They should be required to heat their bath water with a blow dryer!
Soon? Mikey Mann has started that particular line of drivel already – statistically insignificant increases due to volcanic eruptions only – the only significant increases due to CO2. Transparent, desperate and complete bullsh!t.
Truly a disgrace to his profession! Mikey Mouse!
While they are sitting in the tub? 🙂
If only! 🤪
When people stop believing the environista lies they just screech them louder. Very pathetic and totally predictable.
A better metric would be olympic swimming pools, and doing the math, that’s enough to fill about 97 million olympic swimming pools per year. Yowza. Then we just need to know how many hiroshimas worth of energy melting that much ice would be. Now where did I put my hiroshima calculator?
The bomb dropped on Hiroshima was c. !5 kilotons. That on Nagasaki c. 21 kilotons. The Castle Bravo H bomb used on Bikini atoll was about 1000 times more powerful than the Hiroshima bomb.
Hope this helps wth the calculation!
Funny how those numbers have changed through the years. The original estimates were around 20 Ktons.
Ice Sheets and Sea Level Rise
By: Claire L. Parkinson, Oceans and Ice Branch, Code 971, NASA Goddard Space Flight Center,
Greenbelt MD 20771 e-mail: clairep@neptune.gsfc.nasa.gov
From: The PUMAS Collection http://pumas.jpl.nasa.gov
©1997, California Institute of Technology. ALL RIGHTS RESERVED. Based on U.S. Gov’t sponsored research.
I found this document above that appears to be a write up for Middle School curriculum that correlates cryo melt and SLR.
Parkinson concludes that the complete melting of Greenland, 2,343,728 Gt and Antarctica, 26,384,368 Gt, would raise sea levels 79.6 m or 260 feet.
So, 100 Gt of cryo melt would raise sea level 2.77 E-4m, .277 mm.
“Table Al summarizes the compiled information on glacierized surface areas of the world. The large ice sheets of Antarctica (85.7%) and Greenland (10.9%) together represent 96.6% of the total area. Within 2 the remaining 3.4% (roughly 550,000 km ), slightly less than two thirds (about 2.1%) concern smaller ice caps at higher latitudes and only about 1.3% mountain glaciers (Shumskii et al. 1964). Such moun[1]tain glaciers, however, are those features of perennial surface ice most closely related to human activities at lower latitudes.”
https://wgms.ch/downloads/wgi_1988_small.pdf
96.6% of the cryo is Greenland and Antarctica and glaciers are about 1.5% or 446,088 Gt and if 100% melted producing a SLR of 1.2 m.
267 Gt would be 0.06% of the total glacial amount.
The only real use of the word accelerating in climate science would be.
Climate scientists accelerate societies complete rejection of objective reality.
Again numbers presented out of context in order to alarm, rather than inform. For example:
All the fuss is about <1% of global land ice, which itself is measured with a wide error range.
Full discussion is at https://rclutz.com/2021/04/29/zombie-melting-glacier-hype-again/
Cherry picking is in full effect on glacial melt. I was on a family trip to the Columbia Ice Field in Alberta as a kid in the 60’s. At one point the highway passed close to the toe of a massive glacier. You could get out and walk down to the edge and there were bus tours out onto the glacier. On the walk down there were signposts set up with photographs showing the retreat of the glacier since the mid=1800’s. They wee melting back a hundred years before 1950. Just another artifact of the recovery from the completely unexplained Little Ice Age.
And most of the melting of glaciers in the US Glacier National Park are on south facing slopes, with some of the ice fields in the shadows on north-facing slopes having shown little change in a century. It argues for cloudiness being more important than actual average air temperature.
Clyde,
is Grinell glacier (north facing) the among those not covered with
“some of the ice fields in the shadows on north-facing slopes having shown little change in a century.”
https://www.usgs.gov/media/images/grinnell-glacier-1938-2019-glacier-national-park
When I first got interested in this topic, I found a statement on the NPS site about the north-facing slopes being static. A couple years later I tried to find the statement and it was gone.
The images you link to demonstrate clearly that Grinell is not in the shade of the mountains, and would therefore by impacted by decreasing cloudiness.
This smacks of a simple model where the researchers claim to divine many absolutes depending upon their fancy analyses model.
Now they need to provide real proof their model works.
Ideally for every single one of the 220,000 glaciers.
Glacier melt only accounts for 4% of the water in the Ganges.
R. Armstrong, D. Alford, and A. Racoviteanu, A preliminary assessment of the role of glaciers in the hydrologic regime of the Nepal Himalaya, Geophysical Research Abstracts, Vol. 11, EGU2009-10794, 2009
One thing that is ‘super ‘ about super computers is the way models from them can be claimed to tell you all about history for which there is little to no actual valid measured values. From temperatures, to sea heights to animal populations and glaciers. We live in a age where there is no need for boring honest science, with its concerns over accurate and valid data and good experimentally design ,with measurements. All we now need is ‘models’ and you can prove the value of something from a thousand years ago which people did not even known existed , let alone measured, until the last 100 years. Simply amazing !
Right, never mind that the Earth is struggling to get out of an ice age, any climate changes must be due to humanity trying to survive by using fuels to stay warm and for their livelihood to stay fed.