Earth’s Cryosphere Shrinking by 87,000 Square Kilometers per Year – “A Major Global Change”

Antartica Cryosphere

First global assessment of the extent of snow and ice cover on Earth’s surface—a critical factor cooling the planet through reflected sunlight—and its response to warming temperatures.

The global cryosphere—all of the areas with frozen water on Earth—shrank by about 87,000 square kilometers (about 33,000 square miles), an area about the size of Lake Superior, per year on average, between 1979 and 2016 as a result of climate change, according to a new study. This research is the first to make a global estimate of the surface area of the Earth covered by sea ice, snow cover, and frozen ground.

The extent of land covered by frozen water is just as important as its mass because the bright white surface reflects sunlight so effectively, cooling the planet. Changes in the size or location of ice and snow can alter air temperatures, change the sea level and even affect ocean currents worldwide.

The new study is published in Earth’s Future, AGU’s journal for interdisciplinary research on the past, present, and future of our planet and its inhabitants.

Cryosphere Extent

The percentage of each area that experiences ice, snow or frozen ground at some point during the year (1981-2010). Credit: Peng et al. (2021) Earth’s Future

“The cryosphere is one of the most sensitive climate indicators and the first one to demonstrate a changing world,” said first author Xiaoqing Peng, a physical geographer at Lanzhou University. “Its change in size represents a major global change, rather than a regional or local issue.”

The cryosphere holds almost three-quarters of Earth’s fresh water, and in some mountainous regions, dwindling glaciers threaten drinking water supplies. Many scientists have documented shrinking ice sheets, dwindling snow cover, and loss of Arctic sea ice individually due to climate change. But no previous study has considered the entire extent of the cryosphere over Earth’s surface and its response to warming temperatures.

Contraction in space and time

Peng and his co-authors from Lanzhou University calculated the daily extent of the cryosphere and averaged those values to come up with yearly estimates. While the extent of the cryosphere grows and shrinks with the seasons, they found that the average area covered by Earth’s cryosphere has contracted overall since 1979, correlating with rising air temperatures.

The shrinkage primarily occurred in the Northern Hemisphere, with a loss of about 102,000 square kilometers (about 39,300 square miles), or about half the size of Kansas, each year. Those losses are offset slightly by growth in the Southern Hemisphere, where the cryosphere expanded by about 14,000 square kilometers (5,400 square miles) annually. This growth mainly occurred in the sea ice in the Ross Sea around Antarctica, likely due to patterns of wind and ocean currents and the addition of cold meltwater from Antarctic ice sheets.


Sea ice melting in the Arctic Ocean. Credit: NASA/Kathryn Hansen

The estimates showed that not only was the global cryosphere shrinking but that many regions remained frozen for less time. The average first day of freezing now occurs about 3.6 days later than in 1979, and the ice thaws about 5.7 days earlier.

“This kind of analysis is a nice idea for a global index or indicator of climate change,” said Shawn Marshall, a glaciologist at the University of Calgary, who was not involved in the study. He thinks that a natural next step would be to use these data to examine when ice and snow cover give Earth its peak brightness, to see how changes in albedo impact the climate on a seasonal or monthly basis and how this is changing over time.

To compile their global estimate of the extent of the cryosphere, the authors divided up the planet’s surface into a grid system. They used existing data sets of global sea ice extent, snow cover, and frozen soil to classify each cell in the grid as part of the cryosphere if it contained at least one of the three components. Then they estimated the extent of the cryosphere on a daily, monthly, and yearly basis and examined how it changed over the 37 years of their study.

The authors say that the global dataset can now be used to further probe the impact of climate change on the cryosphere, and how these changes impact ecosystems, carbon exchange, and the timing of plant and animal life cycles.

Reference: “A Holistic Assessment of 1979–2016 Global Cryospheric Extent” by Xiaoqing Peng, Tingjun Zhang, Oliver W. Frauenfeld, Ran Du, Haodong Jin and Cuicui Mu, 16 May 2021, Earth’s Future.
DOI: 10.1029/2020EF001969

14 Comments on "Earth’s Cryosphere Shrinking by 87,000 Square Kilometers per Year – “A Major Global Change”"

  1. Clyde Spencer | July 2, 2021 at 7:25 am | Reply

    “The global cryosphere—all of the areas with frozen water on Earth—shrank by about 87,000 square kilometers (about 33,000 square miles), …”

    Earth is really, really big! What is the percentage loss of the cryosphere? That is more important than some big number!

    “The extent of land covered by frozen water is just as important as its mass because the bright white surface reflects sunlight so effectively, cooling the planet.”

    The impact is commonly overstated because most climatologists are unfamiliar with the behavior of specular reflectors, as water is, with changing angles of incidence of sunlight. Water can have a higher reflectance in the Arctic than snow, reaching 100% at the terminator. The difference is that snow always looks white because of its diffuse reflectance. However, to observe and measure the light reflected from water, one has to be looking towards the sun and at the correct angle. It is like driving on wet pavement, looking into the setting sun.

    • Clyde Spencer | July 2, 2021 at 7:30 am | Reply

      Notice in the third figure above, top center, that the water looks brighter than the surrounding snow/ice!

  2. Wattsupwiththat is a climate change denial site funded by the fossil fuel industry and nothing on it can be trusted as accurate.

    • Clyde Spencer | July 2, 2021 at 12:45 pm | Reply

      You apparently didn’t notice that I’m the author of the article about albedo. I can assure you that I receive no money from anyone, let alone the “fossil fuel industry.” I don’t even get any money from people like you who hypocritically benefit from fossil fuels.

      I would be interested in seeing the evidence you have that WUWT is funded by the FF industry. I presume you can produce it!

      • Per wikipedia, cited and all:
        Watts Up With That? (WUWT) is a blog[1] promoting climate change denial[7]

        • Clyde Spencer | July 2, 2021 at 9:26 pm | Reply

          You didn’t answer the question I asked, which was proof that WUWT was funded by the FF industry. A lack of a response tells me that it is a lie that cannot be backed up.

          Wikipedia does a good job of educating on non-controversial topics such as mathematics and physics. However, it has a poor reputation with respect to politics. I know some teachers that won’t allow students to use Wiki’ for a source for papers for that reason.

          Even the term “climate change denial” speaks to the lack of objectivity of Wiki’ on the topic. It is an ambiguous term that is more of an ad hominem attack than anything. It plays off the term “Holocaust Denial” and does nothing to contribute to an intellectual debate.

  3. Ignore the shill. Albedo is an important measurement for calculation of global heat absorption, just as carbon dioxide, methane and sulfur dioxide levels are important to understanding heat retention. The fossil fuel industry is using the modern equivalent of the same methodology and enjoys the same profit oriented same ethic as the tobacco industry once did. Big tobacco spent monumental sums funding “studies” that killed millions by convincing them that tobacco was safe and unrelated to maladies like Cancer. Big oil, already successfully being sued for global warming, is at the end of that process- having prevented action as we coasted past several tipping points that could have made a huge difference to billions, not millions at this point. Hopefully the consequences and penalties will be proportionate.

  4. Clyde Spencer | July 2, 2021 at 1:05 pm | Reply

    “Albedo is an important measurement for calculation of global heat absorption, …”

    Yes, it is commonly used. However, since you apparently didn’t bother to read my article, you can continue to coast through life ignorant about the difference between albedo and total reflectance.

    “Big oil, already successfully being sued for global warming, …”

    I guess I missed the headline about the successes of those suing. I was of the opinion that all of the cases had been dismissed. Perhaps you could enlighten me and other readers just what the awards were to those “successfully” suing Big Oil.

    It is ironic that you and the other person, TDR, would accuse skeptics of being in denial of climate change when you aren’t willing to read anything that goes against your religion. That is the ultimate denial! Incidentally, for the record, I don’t deny climate change. I believe it is changing all the time! The question is, Why?

    The difference between me, and you and your ilk, is that I’m unwilling to uncritically accept claims by those who obviously are ignorant. I’m also reluctant to accept claims by presumed experts when their claims go against basic physics and observations. I always point out why claims are wrong, based on facts provided in the article itself, or cited from elsewhere. All I see from you are claims in the same category as urban legends without so much as a single citation.

    • Gavin Christie | July 2, 2021 at 2:28 pm | Reply

      You clearly are stating that you know more then the majority of the scientific community even calling them ignorant. You clearly are full of yourself and a global warming denier even though you claim not to be. Additionally you are rude and annoying.

      • Clyde Spencer | July 2, 2021 at 9:40 pm | Reply

        When I used the word “ignorant” I was pointing out that the two initial commenters had not bothered to read the link I provided. “Ignorant” means not knowing something. If someone chooses to not expand their knowledge, then they fit the description of being ignorant. It has been my experience that most climatologists are NOT familiar with Fresnel’s equation for computing the reflectance of light from smooth or polished reflectors. If you want to call that ignorance, so be it.

        I suppose telling proselytes that their leaders are ugly could be annoying. As to being rude, I’m not the one who used pejorative words like “denier” and “troll” right out of the gate.

        Please explain how I could logically be a “global warming denier” when I state that I am convinced that the climate is always changing?

  5. Marcus Quintilian | July 2, 2021 at 2:57 pm | Reply

    So to conclude: anyone who questions a climate change article is in denial and is funded undetectably big oil industry. The majority of the scientific community must be right because all of these climate change articles are right.

    • Clyde Spencer | July 2, 2021 at 10:02 pm | Reply

      You are making claims for which the facts are not in evidence. You don’t make something true by just claiming it is true.

      Not a single one of you who has attacked me has even made an effort to disprove my initial claims or the argument I have put forth in the article I wrote and linked to. That tells me you either are intellectually incapable of mounting an attack, or don’t value facts and are simply responding emotionally. Lucky for me, there are now laws against burning heretics at the stake. You and your ilk have not evolved beyond the level of superstitious ignoramuses that believe in magic and witchcraft. You don’t understand that the essence of the Scientific Method is questioning claims by peers and validating the facts and logic supporting a proposed thesis. It matters not whether the “majority of the scientific community” hold a belief in a common paradigm. What matters is that the facts and evidence support that paradigm, or not.

      Typically, when someone attacks the messenger, rather than the message, it is because they have nothing to use to attack the message.

  6. Video Gamer | July 4, 2021 at 5:13 pm | Reply

    Studies show and experts agree that the Cry-O-Sphere is expanding and is bigger than ever!

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