5 ms·

This year has seen both a high melt [1] as well as a high accumulation [2] of snow, the balance of which currently lies clearly at the positive end - Greenland

This year has seen both a high melt [1] as well as a high accumulation [2] of snow, the balance of which currently lies clearly at the positive end - Greenland has far more accumulated snow than average. These images come from the Danish polar portal [3] which I assume to be a canonical source given that Greenland is a Danish province. The explanation with the images reads as follows: The map illustrates what the ice sheet’s total surface gains and losses have been over the year since 1 September compared to the period 1981-2010. It does not include the mass that is lost when glaciers calve off icebergs and melt as they come into contact with warm seawater. The animation shows one frame every seven days going back to the previous 1 September. The blue curve shows the current season, whilst the red curve shows the corresponding development for the 2011-12 season, when the degree of melting was record high. The dark grey curve traces the mean value from the period 1981-2010. The light grey band shows differences from year to year. For any calendar day, the band shows the range over the 30 years (in the period 1981-2010), however with the lowest and highest values for each day omitted. [1] http://polarportal.dk/fileadmin/polarportal/meltarea/MELTA_combine_SM_EN_20210819.png http://polarportal.dk/fileadmin/polarportal/meltarea/MELTA_c... [2] http://polarportal.dk/fileadmin/polarportal/surface/SMB_combine_SM_acc_EN_20210819.png http://polarportal.dk/fileadmin/polarportal/surface/SMB_comb... [3] http://polarportal.dk/en/greenland/surface-conditions/ http://polarportal.dk/en/greenland/surface-conditions/

cs702 5y ago
FYI, there's a school of thought which has concluded that global warming will lead to another glacial period within the current ice age, because higher temperatures disrupt ocean currents -- particularly the Gulf Stream, which redistributes warm water from the Gulf of Mexico to northern Europe. As the Gulf Stream makes its deposits of warm water along the coasts of Great Britain and northwest Europe, it keeps the temperatures in northwest Europe warmer than in eastern Canada, even though they both are roughly the same distance from the equator. The hypothesis is that, if Arctic ice melts as a result of global warming, huge amounts of fresh water will pour into the North Atlantic and slow down the Gulf Stream, cooling Europe, and triggering a feedback loop with colder and longer European winters, and more and more ice building up on the planet's surface.[a][b] [a] The book "Ice Age" by Cambridge-trained astrophysicist John Gribbin and his wife Mary has a good high-level overview of this school of thought: https://reanimus.com/store/?item=1420 https://reanimus.com/store/?item=1420 [b] Recent studies of circulation in the North Atlantic already show a significant reduction in currents flowing north from the Gulf Stream: https://www.realclimate.org/index.php/archives/2020/09/new-studies-confirm-weakening-of-the-gulf-stream-circulation-amoc/ https://www.realclimate.org/index.php/archives/2020/09/new-s...
- the_third_wave 5y ago
  As far as I can tell the slowdown or cessation of the gulf stream will not lead to an "ice age" but to a cooling of north-western Europe. The climate there will be more comparable to that of the southern part of Alaska. While to the inhabitants of this region it may feel like an "ice age" the difference is that in an ice age the global average temperature goes down while this is not the case for the above scenario. It is quite possible - likely, even - for some regions to end up with lower average temperatures while the average global temperature increases.
  - cs702 5y ago
    My understanding is that we're already in an ice age -- specifically, we're in an inter-glacial period of an ice age. What you call the "cooling" of northwest Europe would be a glacial period within this ice age.
    - the_third_wave 5y ago
      We're in an interglacial, awaiting a new ice age. If history [1] is anything to go by we're at the trailing end of the warmest period of the Holocene epoch [2]. Depending on how this interglacial develops the temperature will either gradually decrease into a new ice age (i.e. follow the same pattern as the Pleistocene) or rebound for a second peak (like the Pliocene, Eocene and Paleocene interglacials). At the end of the Holocene interglacial the ice will return for the remainder of the epoch. [1] https://upload.wikimedia.org/wikipedia/commons/c/c9/Co2_glacial_cycles_800k.png https://upload.wikimedia.org/wikipedia/commons/c/c9/Co2_glac... [2] https://upload.wikimedia.org/wikipedia/commons/c/ca/Holocene_Temperature_Variations.png https://upload.wikimedia.org/wikipedia/commons/c/ca/Holocene...
      - cs702 5y ago
        I believe you are using the terminology incorrectly. According to Wikipedia, we currently are in an an ice age that began approximately 2.6 million years ago: https://en.wikipedia.org/wiki/Quaternary_glaciation https://en.wikipedia.org/wiki/Quaternary_glaciation Within this ice age, we've had glacial and inter-glacial periods. For example, Europe's "Little Ice Age" was a glacial period within this ice age: https://en.wikipedia.org/wiki/Little_Ice_Age https://en.wikipedia.org/wiki/Little_Ice_Age Currently, we're in an inter-glacial period.
xaedes 5y ago
> This year has seen both a high melt as well as a high accumulation of snow, the balance of which currently lies clearly at the positive end - Greenland has far more accumulated snow than average. Seems to apply for the whole northern hemisphere. Look at the diagrams for 'the current Northern Hemisphere snow water equivalent relative to the long-term mean and variability' (GCW/FMI SWE Tracker) at https://globalcryospherewatch.org/state_of_cryo/snow/ https://globalcryospherewatch.org/state_of_cryo/snow/ Last year this diagram was similar.

cs702 5y ago

FYI, there's a school of thought which has concluded that global warming will lead to another glacial period within the current ice age, because higher temperatures disrupt ocean currents -- particularly the Gulf Stream, which redistributes warm water from the Gulf of Mexico to northern Europe. As the Gulf Stream makes its deposits of warm water along the coasts of Great Britain and northwest Europe, it keeps the temperatures in northwest Europe warmer than in eastern Canada, even though they both are roughly the same distance from the equator. The hypothesis is that, if Arctic ice melts as a result of global warming, huge amounts of fresh water will pour into the North Atlantic and slow down the Gulf Stream, cooling Europe, and triggering a feedback loop with colder and longer European winters, and more and more ice building up on the planet's surface.[a][b] [a] The book "Ice Age" by Cambridge-trained astrophysicist John Gribbin and his wife Mary has a good high-level overview of this school of thought: https://reanimus.com/store/?item=1420 https://reanimus.com/store/?item=1420 [b] Recent studies of circulation in the North Atlantic already show a significant reduction in currents flowing north from the Gulf Stream: https://www.realclimate.org/index.php/archives/2020/09/new-studies-confirm-weakening-of-the-gulf-stream-circulation-amoc/ https://www.realclimate.org/index.php/archives/2020/09/new-s...

the_third_wave 5y ago
As far as I can tell the slowdown or cessation of the gulf stream will not lead to an "ice age" but to a cooling of north-western Europe. The climate there will be more comparable to that of the southern part of Alaska. While to the inhabitants of this region it may feel like an "ice age" the difference is that in an ice age the global average temperature goes down while this is not the case for the above scenario. It is quite possible - likely, even - for some regions to end up with lower average temperatures while the average global temperature increases.
- cs702 5y ago
  My understanding is that we're already in an ice age -- specifically, we're in an inter-glacial period of an ice age. What you call the "cooling" of northwest Europe would be a glacial period within this ice age.
  - the_third_wave 5y ago
    We're in an interglacial, awaiting a new ice age. If history [1] is anything to go by we're at the trailing end of the warmest period of the Holocene epoch [2]. Depending on how this interglacial develops the temperature will either gradually decrease into a new ice age (i.e. follow the same pattern as the Pleistocene) or rebound for a second peak (like the Pliocene, Eocene and Paleocene interglacials). At the end of the Holocene interglacial the ice will return for the remainder of the epoch. [1] https://upload.wikimedia.org/wikipedia/commons/c/c9/Co2_glacial_cycles_800k.png https://upload.wikimedia.org/wikipedia/commons/c/c9/Co2_glac... [2] https://upload.wikimedia.org/wikipedia/commons/c/ca/Holocene_Temperature_Variations.png https://upload.wikimedia.org/wikipedia/commons/c/ca/Holocene...
    - cs702 5y ago
      I believe you are using the terminology incorrectly. According to Wikipedia, we currently are in an an ice age that began approximately 2.6 million years ago: https://en.wikipedia.org/wiki/Quaternary_glaciation https://en.wikipedia.org/wiki/Quaternary_glaciation Within this ice age, we've had glacial and inter-glacial periods. For example, Europe's "Little Ice Age" was a glacial period within this ice age: https://en.wikipedia.org/wiki/Little_Ice_Age https://en.wikipedia.org/wiki/Little_Ice_Age Currently, we're in an inter-glacial period.

xaedes 5y ago

> This year has seen both a high melt as well as a high accumulation of snow, the balance of which currently lies clearly at the positive end - Greenland has far more accumulated snow than average. Seems to apply for the whole northern hemisphere. Look at the diagrams for 'the current Northern Hemisphere snow water equivalent relative to the long-term mean and variability' (GCW/FMI SWE Tracker) at https://globalcryospherewatch.org/state_of_cryo/snow/ https://globalcryospherewatch.org/state_of_cryo/snow/ Last year this diagram was similar.