At a glance - Is Greenland gaining or losing ice?

On February 14, 2023 we announced our Rebuttal Update Project. This included an ask for feedback about the added "At a glance" section in the updated basic rebuttal versions. This weekly blog post series highlights this new section of one of the updated basic rebuttal versions and serves as a "bump" for our ask. This week features "Is Greenland gaining or losing ice". More will follow in the upcoming weeks. Please follow the Further Reading link at the bottom to read the full rebuttal and to join the discussion in the comment thread there.

fact myth box

At a glance

The interior of Greenland features a huge ice sheet that covers some 80% of that large island. Up to three kilometres thick, the sheet contains a whopping 2.9 million cubic kilometres of ice. If that all melted, global sea level would go up by around seven and a half metres. So it would obviously be good if that didn't happen.

Read any science about ice-sheets and you will soon run into a term that will become familiar: 'mass balance'. Mass balance is an expression of the health of any ice-sheet. Ice-sheets gain mass by snowfall and lose mass by 'ablation', a term covering sublimation, evaporation melt, and meltwater runoff, plus solid ice discharge by the glaciers that drain them. If the value for mass balance of an ice sheet is a positive number, the sheet is growing. But a negative value means the sheet is dwindling.

Since 1991, satellites have obtained continuous data on the Greenland ice-sheet, using radar, lasers and sensitive instruments that can detect changes in local gravity. Such methods allow mass balance to be calculated.

With over 30 years of satellite data now at our disposal, we can step back and look at the big picture. The Greenland ice sheet was close to a neutral state of balance in the 1990s. Since then however, annual losses have risen. One recent paper calculates that Greenland lost almost 4,000 billion tonnes of ice between 1992 and 2018, adding almost eleven millimetres to global sea levels.

Reduction of ice mass balance has occurred for two key reasons. Firstly there is increased meltwater run-off. Have you seen imagery of bright blue pools connected to rivers, flowing across the surface of the ice-sheet, to disappear down into it in spectacular cascades? That's the run-off. Secondly, there is glacier instability - whereby glaciers speed up in their discharge of ice, ultimately to the ocean, with those videos of spectacular calving events many of you will have seen. In Greenland, it's thought that these two processes account for about half of ice-sheet loss each.

Of course, the rate of ice loss varies from year to year. It depends on weather patterns. A cooler year with a lot of snowfall will provide a considerable counter-weight to the loss processes. Then again, in June 2023 the temperature rose to 0.4oC at the Summit Station, a research facility situated 3,216 metres above sea level and near the high-point of the ice-sheet. That has only happened five times in the 34 years since the station was established. Like anywhere else, the year to year pattern is pretty varied: however it's the multidecadal trend that matters and that is very definitely downwards.

It never pays to pick short time-spans when discussing matters of long-term climate trends. Statements like the one by Christopher Monckton in the myth-box above, made in 2009, have simply been made invalid by the march of time.

Please use this form to provide feedback about this new "At a glance" section. Read a more technical version below or dig deeper via the tabs above!


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In case you'd like to explore more of our recently updated rebuttals, here are the links to all of them:

Myths with link to rebuttal Short URLs
Ice age predicted in the 1970s sks.to/1970s
It hasn't warmed since 1998 sks.to/1998
Antarctica is gaining ice sks.to/antarctica
CRU emails suggest conspiracy sks.to/climategate
What evidence is there for the hockey stick sks.to/hockey
CO2 lags temperature sks.to/lag
Climate's changed before sks.to/past
It's the sun sks.to/sun
Temperature records are unreliable sks.to/temp
The greenhouse effect and the 2nd law of thermodynamics sks.to/thermo
We're heading into an ice age sks.to/iceage
Positives and negatives of global warming sks.to/impacts
The 97% consensus on global warming sks.to/consensus
Global cooling - Is global warming still happening? sks.to/cooling
How reliable are climate models? sks.to/model
Can animals and plants adapt to global warming? sks.to/species
What's the link between cosmic rays and climate change? sks.to/cosmic
Is Al Gore's An Inconvenient Truth accurate? sks.to/gore
Are glaciers growing or retreating? sks.to/glacier
Ocean acidification: global warming's evil twin sks.to/acid
The human fingerprint in global warming sks.to/agw
Empirical evidence that humans are causing global warming sks.to/evidence
How do we know more CO2 is causing warming? sks.to/greenhouse
Explaining how the water vapor greenhouse effect works sks.to/vapor
The tricks employed by the flawed OISM Petition Project to cast doubt on the scientific consensus on climate change sks.to/OISM
Is extreme weather caused by global warming? sks.to/extreme
How substances in trace amounts can cause large effects sks.to/trace
How much is sea level rising? sks.to/sealevel
Is CO2 a pollutant? sks.to/pollutant
Does cold weather disprove global warming? sks.to/cold
Do volcanoes emit more CO2 than humans? sks.to/volcano
How do human CO2 emissions compare to natural CO2 emissions? sks.to/co2
Climate scientists could make more money in other careers sks.to/money
How reliable are CO2 measurements? sks.to/co2data
Do high levels of CO2 in the past contradict the warming effect of CO2? sks.to/pastco2
What is the net feedback of clouds? sks.to/cloud
Global warming vs climate change sks.to/name
Is Mars warming? sks.to/mars
How the IPCC is more likely to underestimate the climate response sks.to/underestimat
How sensitive is our climate? sks.to/sensitivity
Evidence for global warming sks.to/warming
Has the greenhouse effect been falsified? sks.to/falsify
Does breathing contribute to CO2 buildup in the atmosphere? sks.to/breath
What is causing the increase in atmospheric CO2? sks.to/CO2increase
What is methane's contribution to global warming? sks.to/methane
Plants cannot live on CO2 alone sks.to/plant
Is the CO2 effect saturated? sks.to/saturate
Greenhouse warming 100 times greater than waste heat sks.to/waste
How will global warming affect polar bears? sks.to/bear
The runaway greenhouse effect on Venus sks.to/venus
What climate change is happening to other planets in the solar system? sks.to/planets
Has Arctic sea ice returned to normal? sks.to/arctic
Was Greenland really green in the past? sks.to/green
Is Greenland gaining or losing ice? sks.to/greenland

 

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Posted by John Mason on Tuesday, 27 February, 2024


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