Showing posts with label cover. Show all posts
Showing posts with label cover. Show all posts

Wednesday, February 9, 2022

Accelerating loss of global snow and ice cover


Ocean heat is at record levels. As a result, global sea ice extent was only 16.23 million km² on February 9, 2022, the third lowest extent on record. What makes this even more worrying is that we're currently in the depth of a persistent La Niña.


Antarctic sea ice at lowest extent on record since start satellite measurements

Ocean heat is a huge threat for Antarctica at the moment. The image below shows that Antarctic sea ice extent was only 2.091 million km² on February 16, 2022, the lowest on record since the start of satellite measurements.


Ocean heat is reducing the sea ice around Antarctica and is getting underneath floating sea ice. 

The Thwaites Glacier, which is on a retrograde slope, is especially vulnerable to collapse. 

The Thwaites Glacier contains enough ice to raise global sea levels by 65 cm (25.59 inches) if it were to completely collapse.

The animation on the right, created with images from Climate Reanalyzer, shows the retreat of the Antarctic snow and ice cover from January 5 to February 18, 2021. 

The animation underneath, by navy.mil, shows sea ice thickness over 30 days up to February 17, 2022 (with 8 days of forecasts added).

Another danger of a rapid loss of the snow and ice cover on Antarctica is release of methane. Jemma Wadham warned about this in a 2012 study, as discussed at the post methane hydrates. More recently, Jemma Wadham said: “We are sleepwalking into a catastrophe for humanity.

The Thwaites Glacier is often called the Doomsday Glacier because if it collapses it would lead to vast sea level rise, and scientists believe it is likely to fail within a few years, says Cliff Seruntine (the Naturalist) in the video below. 


A recent study concludes that mountain glaciers may hold less ice than previously thought. Their disappearance means less water for drinking and agriculture, and faster temperature rises due to albedo loss. While the study found that the Himalayas contain more water than thought, another recent study, Mt. Everest’s highest glacier is a sentinel for accelerating ice loss, describes how human-induced climate change has a huge impact on the highest reaches of the planet.

The outlook for the Arctic is most threatening, as the post methane hydrates also concluded back in 2013, as described in numerous post here at Arctic-news and as discussed in the video below by Jim Massa.


A huge temperature rise threatens to unfold soon


Above image indicates that the difference between the top of El Niño and the bottom of La Niña could be more than half a degree Celsius.

As said, we're currently in the depth of a persistent La Niña, which suppresses temperatures. As the temperature keeps rising, ever more frequent strong El Niño events are likely to occur, as discussed in an earlier post

A 2019 study analyzes how tipping the ENSO into a permanent El Niño can trigger state transitions in global terrestrial ecosystems.

Currently, the temperature rise is additionally suppressed by low sunspots. Within a few years time, sunspots can be expected to reach the peak of their current cycle and observed sunspots are looking stronger than predicted. 

In the image below on the right, adapted from NOAA, the solar cycle is represented as the number of sunspots (top) and F10.7cm radio flux (bottom). 

In a recent communication, James Hansen repeats that, as reductions take place in the sulfate aerosols that are currently co-emitted by traffic, transport and industry, this is causing the current temperature rise to accelerate and could cause further rapid global warming, referred to in a 2021 presentation as a termination shock.

Furthermore, in addition to a huge temperature rise resulting from sulfate aerosols falling away, there could be a further rise in temperature as a result of releases of other aerosols with a net warming impact, such as black and brown carbon, which can increase dramatically as more wood burning and forest fires take place.

In summary, while the temperatures are accelerating, we'll soon be moving into the next El Niño, with sunspots moving toward a peak, with sulfate aerosols causing a termination shock and with other aerosols further driving up the temperature rise. 

Stop the deception!

In a giant scheme of deception, the temperature rise is all too often presented with images of people playing on the beach on a 'warm' day, as if 'global warming' was making life more 'comfortable'. 

Forest fires are called 'wildfires', biomass burning and associated deforestation is referred to as 'renewable biofuel', fracking-induced earthquakes are called 'natural' disasters and methane eruptions are called seeps and bubbles of 'natural' gas from 'natural' sources such as wetlands. 

This gives the false impression that this was somehow 'natural' as if human activities had nothing to do with it, and as if owning beach-front property was becoming ever more attractive.


Let's stop this deception! In reality, human-caused emissions have a huge short-term impact on temperature and their combination with genuinely natural variability such as El Niño and sunspots can act as a catalyst, causing numerous feedbacks to kick in with ever greater ferocity. 

This can result in collapse of global sea ice and permafrost, resulting in albedo loss and eruption of huge quantities of carbon dioxide, methane and nitrous oxide, further driving up the temperature rise abruptly, as described at the extinction page. Further feedbacks are also described at the feedbacks page

Conclusion

The situation is dire and calls for the most comprehensive and effective action, as described at the Climate Plan.


Links

• Another Record: Ocean Warming Continues through 2021 despite La Niña Conditions - by Lijing Cheng et al. 
https://link.springer.com/article/10.1007%2Fs00376-022-1461-3

• Ocean heat is at record levels, with major consequences - by Kevin Trenberth

• Arctic Data archive System - Vishop extent

• NSIDC: Charctic Interactive Sea Ice Graph

• IPCC: Marine Ice Sheet Instability

• Climate Reanalyzer
https://climatereanalyzer.org/wx/DailySummary/#seaice-snowc-topo

• Antarctica CICE ice thickness

• Antarctica’s ‘doomsday’ glacier: how its collapse could trigger global floods and swallow islands 
https://theconversation.com/antarcticas-doomsday-glacier-how-its-collapse-could-trigger-global-floods-and-swallow-islands-173940

• Methane hydrates (2013)

• Potential methane reservoirs beneath Antarctica - by Jemma Wadham et al. (2012) 
https://www.nature.com/articles/nature11374

• A new frontier in climate change science: connections between ice sheets, carbon and food webs (2021) 

• Ice velocity and thickness of the world’s glaciers - by Romain Millan et al. 
https://www.nature.com/articles/s41561-021-00885-z

• Mountain glaciers may hold less ice than previously thought – here’s what that means for 2 billion downstream water users and sea level rise 
https://theconversation.com/mountain-glaciers-may-hold-less-ice-than-previously-thought-heres-what-that-means-for-2-billion-downstream-water-users-and-sea-level-rise-176514

• Mt. Everest’s highest glacier is a sentinel for accelerating ice loss - by Mariusz Potocki et al. 

• Human-induced climate change impacts the highest reaches of the planet — Mount Everest
• Ocean Heat Content Update 1 - 2022 - Science Talk with Jim Massa
https://www.youtube.com/watch?v=pctkg_LDqcU

• NOAA - ENSO: Recent Evolution, Current Status and Predictions
https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf

• NOAA - Monthly Temperature Anomalies Versus El Niño 
• Human Extinction by 2022? 

• Tipping the ENSO into a permanent El Niño can trigger state transitions in global terrestrial ecosystems - by Mateo Duque-Villegas et al. (2019) 
https://esd.copernicus.org/articles/10/631/2019

• James Hansen - The New Horse Race

• Climate Impact of Decreasing Atmospheric Sulphate Aerosols and the Risk of a Termination Shock - by Leon Simons, James Hansen and Yann duFournet (2021) 

• NOAA - Solar Cycle Progression

• Aerosols

• Feedbacks

• Extinction




Friday, December 28, 2012

Albedo changes in the Arctic

How global warming and feedbacks are causing huge albedo changes in the Arctic.

Snow cover decline

Decline of the snow cover on land in the northern hemisphere is accelerating, as illustrated by the image below and the image underneath on the right. (1)


Image credit: Rutgers University
Fresh snow can have an albedo as high as 0.85, meaning that up to 85% of the sunlight falling on snow can get reflected back into space. As the snow melts, its structure changes making it less reflective, i.e. its albedo will go down, to as low as 40%. (2)

As a result, more sunlight gets absorbed, accelerating the melting process. Eventually, where snow melts away, spots of bare soil become exposed, and dark wet soil has a very low albedo, reflecting only between 5% and 15% of the sunlight. Thus, even more sunlight gets absorbed and the soil's temperature increases, causing more of the remaining snow to melt. (2)

Changes in vegetation can further accelerate this process. Russia's boreal forest - the largest continuous expanse of forest in the world - has seen a transformation in recent years from larch to conifer trees. Larch trees drop their needles in the fall, allowing the vast, snow-covered ground in winter to reflect sunlight and heat back into space and helping to keep temperatures in the region very cold. But conifers such as spruce and fir retain their needles, which absorb sunlight and increase the forest's ground-level heat retention. (3)

Albedo, from Wikipedia
A conversion from larch to evergreen stands in low-diversity regions of southern Siberia would generate a local positive radiative forcing of 5.1±2.6 W m−2. This radiative heating would reinforce the warming projected to occur in the area under climate change. (4)

Tundra in the Arctic used to be covered by a white blanket of snow most of the year. However, as the landscape is warming up, more trees and shrubs appear. Scientists who studied part of the Eurasian Arctic, found that willow and alder shrubs, once stunted by harsh weather, have been growing upward to the height of trees in recent decades. They now rise above the snowfall, presenting a dark, light-absorbing surface. This increased absorption of the Sun's radiation, combined with microclimates created by forested areas, adds to global warming, making an already-warming climate warm even more rapidly. (5 & 6)

Furthermore, encroachment of trees onto Arctic tundra caused by the warming may cause large release of carbon to the atmosphere, concludes a recent study. This is because tundra soil contains a lot of stored organic matter, due to slow decomposition, but the trees stimulate the decomposition of this material. (7)


Sea ice decline

In the Arctic, sea ice volume has fallen dramatically over the years, as illustrated by the image on the right. The trend points at 2014 as the year when Arctic sea ice will first reach zero volume for some time during that year. (8)

The Arctic Ocean looks set to be ice-free for a period of at least three months in 2015 (August, September and October), and for a period of at least 6 months from the year 2020 (June through to November). (9)

Decline of the Arctic sea ice is accelerating, due to numerous feedbacks. As the Arctic atmosphere warms up, any snow cover on top of the ice will melt away ever quickly, decreasing the surface albedo and thus reinforcing the warm-up. As melt ponds appear on top of the ice, the albedo will drop even further.

Sam Carana's Diagram of Doom pictures ten feedbacks that jointly work to accelerate sea ice decline. (10)

The image below shows the three areas where albedo change will be felt most in the Arctic, i.e. sea ice loss, decline of albedo in Greenland and more early and extensive retreat of snow and ice cover in other areas in the Arctic. (8)

Big changes in the Arctic within years, by Sam Carana


References

1. Northern Hemisphere Snow Cover Anomalies 1967-2012 June, Rutgers University
climate.rutgers.edu/snowcover/chart_anom.php?ui_set=1&ui_region=nhland&ui_month=6

2. Albedo, Albedo Change blog
albedochange.blogspot.com/2009/02/albedo-change.html

3. Shift in Northern Forests Could Increase Global Warming, Scientific American, March 28, 2011
scientificamerican.com/article.cfm?id=shift-northern-forests-increase-global-warming

4. Sensitivity of Siberian larch forests to climate change, Shuman et al., April 5, 2011, Wiley.com
onlinelibrary.wiley.com/doi/10.1111/j.1365-2486.2011.02417.x/abstract

5. Warming turns tundra to forest
ox.ac.uk/media/news_stories/2012/120604.html

6. Eurasian Arctic greening reveals teleconnections and the potential for structurally novel ecosystems, Macias-Fauria et al., 2012
nature.com/nclimate/journal/v2/n8/full/nclimate1558.html

7. Expansion of forests in the European Arctic could result in the release of carbon dioxide, University of Exeter news, June 18, 2012
exeter.ac.uk/news/featurednews/title_214902_en.html

8. Big changes in the Arctic within years, Sam Carana, October 26, 2012, Arctic-News blog
arctic-news.blogspot.com/2012/10/big-changes-in-arctic-within-years.html

9. Getting the Picture, Sam Carana, August 2012, Arctic-News blog
arctic-news.blogspot.com/2012/08/getting-the-picture.html

10. Diagram of Doom, Sam Carana, August 2012, Arctic-News blog
arctic-news.blogspot.com/2012/08/diagram-of-doom.html


Further reading

- Albedo change in the Arctic
arctic-news.blogspot.com/2012/07/albedo-change-in-arctic.html

- Greenland is melting at incredible rate
arctic-news.blogspot.com/2012/07/greenland-is-melting-at-incredible-rate.html

- Albedo change in the Arctic threatens to cause runaway global warming
arctic-news.blogspot.com/2012/10/albedo-change-in-the-arctic-threatens-to-cause-runaway-global-warming.html

Sunday, October 14, 2012

Glaciers cracking in the presence of carbon dioxide

Northern Hemisphere snow and ice map , October 14, 2012 (credit: NSIDC, NOAA)

Snow covers more than 33% of lands north of the equator from November to April, reaching 49% coverage in January. The role of snow in the climate system includes strong positive feedbacks related to albedo and other, weaker feedbacks related to moisture storage, latent heat and insulation of the underlying surface, which vary with latitude and season (IPCC, 2007a8).

Albedo or reflectivity of surfaces
wikipedia.org/wiki/Albedo
Ice caps and glaciers cover 7% of the Earth—more than Europe and North America combined—and are responsible for reflecting 80–90% of the Sun’s light rays that enter our atmosphere and maintain the Earth’s temperature7. They are also a natural carbon sink, capturing a large amount of carbon dioxide7.

Snow and ice on the Northern Hemisphere has a cooling effect of 3.3 watts per square meter, peaking in May at ~ 9 watts per square meter. Snow and ice on the Northern Hemisphere has declined over the years and is now reflecting 0.45 watts less energy per square meter than it did in 1979 (Flanner, 2011). As discussed in Albedo change in the Arctic, this compares to warming of 1.66 watts per square meter for the net emission by people (IPCC, 2007b9).

A recent press release7 announced that researchers from the Massachusetts Institute for Technology have shown that the material strength and fracture toughness of ice are decreased significantly under increasing concentrations of carbon dioxide molecules, making ice more fragile and making ice caps and glaciers more vulnerable to cracking and splitting into pieces.

“If ice caps and glaciers were to continue to crack and break into pieces, their surface area that is exposed to air would be significantly increased, which could lead to accelerated melting and much reduced coverage area on the Earth,” said lead author of the study Professor Markus Buehler.

Buehler, along with his student and co-author of the paper, Zhao Qin, used a series of atomisticlevel computer simulations to analyse the dynamics of molecules to investigate the role of carbon dioxide molecules in ice fracturing, and found that carbon dioxide exposure causes ice to break more easily.

Notably, the decreased ice strength is not merely caused by material defects induced by carbon dioxide bubbles, but rather by the fact that the strength of hydrogen bonds—the chemical bonds between water molecules in an ice crystal—is decreased under increasing concentrations of carbon dioxide. This is because the added carbon dioxide competes with the water molecules connected in the ice crystal.

It was shown that carbon dioxide molecules first adhere to the crack boundary of ice by forming a bond with the hydrogen atoms and then migrate through the ice in a flipping motion along the crack boundary towards the crack tip.

The carbon dioxide molecules accumulate at the crack tip and constantly attack the water molecules by trying to bond to them. This leaves broken bonds behind and increases the brittleness of the ice on a macroscopic scale7.

A drop of as little as 1% in Earth’s albedo corresponds with a warming roughly equal to the effect of doubling the amount of carbon dioxide in the atmosphere, which would cause Earth to retain an additional 3.4 watts of energy for every square meter of surface area (NASA, 200510; Flanner et al., 2011b6).

Below, a video by Dr. Peter Carter4, showing loss of snow and ice albedo on the Northern Hemisphere from 1997 to 2009, using NOAA images, and also showing the relationship to global food security and Arctic methane.