New paper and of course it’s worse than we thought.
New estimates of snow depth, from a combination of lidar and radar, improve sea-ice thickness estimates, according to a new study in AGU’s Geophysical Research Letters. Arctic sea ice has lost 16% of its thickness in the last three years, the study finds.
Credit: NASA/Kathryn Hansen
According to the press release:
– End-of-season Arctic multiyear sea ice is about 1.5 feet thinner in 2021 than in 2019
– Arctic Ocean sea ice lost one-third of its volume in the past 18 years
– New pan-Arctic snow depth suggests previous estimates of sea ice thickness may have been overestimated
https://news.agu.org/press-release/new-observations-from-icesat-2-show-remarkable-arctic-sea-ice-thinning-in-just-three-years
and
WASHINGTON—Over the past two decades, the Arctic has lost about one-third of its winter sea ice volume, largely due to a decline in sea ice that persists over several years, called multiyear ice, according to a new study. The study also found sea ice is likely thinner than previous estimates.
Seasonal sea ice, which melts completely each summer rather than accumulating over years, is replacing thicker, multiyear ice and driving sea ice thinning trends, according to the new research.
https://news.agu.org/press-release/new-observations-from-icesat-2-show-remarkable-arctic-sea-ice-thinning-in-just-three-years
And straight out of Rick’s Cabaret, I’m shocked I tell you.
“We weren’t really expecting to see this decline, for the ice to be this much thinner in just three short years,” said lead study author Sahra Kacimi, a polar scientist at the California Institute of Technology’s Jet Propulsion Laboratory.
https://news.agu.org/press-release/new-observations-from-icesat-2-show-remarkable-arctic-sea-ice-thinning-in-just-three-years
First published: 10 March 2022 | https://doi.org/10.1029/2021GL097448
Abstract
Using ICESat-2 and CryoSat-2 freeboards, we examine the variability of monthly Arctic sea ice snow depth, thickness and volume between October 2018 and April 2021. For the 3 years, satellite-derived estimates captured a decrease in mean April snow depth (∼2.50 cm) and ice thickness (∼0.28 m) equivalent to an ice volume loss of ∼12.5%. Results show greater thinning of multiyear ice with an end-of-season thickness in 2021 that is lower by ∼16.1% (0.50 m), with negligible changes over first-year ice. For the period, sea ice thickness estimates using snow depth from climatology result in thicker ice (by up to ∼0.22 m) with a smaller decrease in multiyear ice thickness (∼0.38 m). An 18-year satellite record, since the launch of ICESat, points to a loss of ∼6,000 km3 or one-third of the winter Arctic ice volume driven by decline in multiyear-ice coverage in the multi-decadal transition to a largely seasonal ice cover.
Plain Language Summary
Ice thickness and volume are critical variables for assessing the evolution and response of the polar sea ice cover to a warming climate. Retrieval of sea ice thickness from altimeter freeboards (i.e., the vertical height of the floating ice and snow above the local sea level) requires knowledge of loading due to snow. Until recently, snow depth has been prescribed with a climatology based on historical field records. Using freeboard differences from ICESat-2 and CryoSat-2, we are now able to derive snow depth estimates. In this paper we examine the differences between climatological and satellite-derived snow depth as well as the retrieved ice thicknesses from the two altimeter missions. Their changes for three winters between 2018 and 2021 are documented. Derived ice volume estimates are placed within the context of an 18-year satellite record.
1 Introduction
As of December 2021, ICESat-2 has completed its 3-year prime mission (Markus et al., 2017) and is currently in extended operation. For the ice-covered Arctic Ocean, the lidar on the ICESat-2 observatory is tasked to provide the heights of sea ice and local sea surfaces for the calculation of freeboard—the vertical height of the floating ice above the local sea level. The retrieved total freeboard (snow plus ice) facilitates the estimation of thickness of the Arctic and Southern Ocean ice covers. The non-stop operations (with only a few interruptions) have provided all season coverage of the polar oceans. Here, we examine estimates of Arctic snow depth and ice thickness between October 2018 and April 2021.
Time-varying snow depth over sea ice, for computing snow loading, has been a limiting factor in the accuracy of sea ice thickness estimates. Prior to the launch of ICESat-2, the potential of combining ICESat-2 (IS-2) and CryoSat-2 (CS-2) freeboards to provide estimates of snow depth was recognized by Kwok and Markus (2017). The measurement concept is based on differencing the freeboards from IS-2 (which measures the height of the air-snow interface above the local sea surface) and CS-2 (which measures the height of the snow-ice interface above the local sea surface). For one Arctic growth season (October 2018 to April 2019), Kwok et al. (2020) provided a first examination of the snow depth retrievals using IS-2 and CS-2 freeboards. Results showed that the snow depths compared well with airborne estimates and spatial patterns of reconstructed snowfields. As well, the variability of the freeboards, derived snow depth, and ice thickness estimates was assessed in the Antarctic (Kacimi & Kwok, 2020).
In this paper, we examine the interannual variability of the freeboard-derived snow depth, ice thickness and volume over the first three winters of IS-2 operations (between October 2018 and April 2021). The paper is organized as follows. The next section describes the data used in this analysis. Section 3 briefly describes the two different estimates of snow depths used here – one from the IS-2 and CS-2 freeboards and the other from a modified Warren climatology (Kwok & Cunningham, 2015; Warren et al., 1999) – followed by an analysis of their spatial variability and seasonal evolution. In Section 4, we describe the calculated sea ice thickness and volume from IS-2 and CS-2, and the observed interannual variability. Section 5 summarizes the record of ice volume estimates since the launch of ICESat in 2003. The last section concludes the paper.
https://doi.org/10.1029/2021GL097448
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The Arctic warming at the pole is behaving differently to the Antarctic continent due to the following reasons.
1) The Arctic is mainly ocean whereas Antarctica mainly land.
2) The Arctic has an ocean current (AMOC) moving through the middle of it whereas Antarctica (ACC) has an ocean current surrounding it.
Which warm or cools the quickest, ocean or atmosphere?
Answer = atmosphere
The atmosphere warms much quicker than the ocean so why was the Arctic warming significantly whereas there has been no or little warming in Antarctica?
The atmosphere can’t be doing this because this would had also happened in Antarctica where it is out of the influence from ocean currents. The warming from CO2 is not visible in the area where most warming should take place. Antarctica is the coldest and driest place on Earth so should have the most warming from the atmosphere if the control was changed from normal.
So what is the cause?
Answer = ocean current
The Antarctic Circumpolar Current (ACC) has very cold ocean water that circulates the continent preventing any warm ocean current from reaching it.
The Atlantic Meridional Overturning Circulation (AMOC) is a large system of ocean currents that carry warm water from the tropics northwards into the North Atlantic Ocean and eventually pass through the Arctic ocean.
If the Arctic was cut off from a warm ocean current it would also show no or little warming. Antartica would warm like the Arctic if it had a warm current directly influencing it.
So what should be expected by atmospheric warming only?
The Arctic would warm much slowly than Antarctica due to one being significantly moderated by water and the other being land based.
So what should be expected by ocean warming only?
Global cloud albedo has shown to have decreased by at least 4% between the 1980’s and 2000’s. This warms the oceans most where the highest solar energy penetrates the closest to the Tropics. Water moving north from the tropics is warmed the most, so when this flows into the Arctic ocean it warms the underneath of the floating ice surrounding the ocean surface. This has been occurring since the early 1980’s and is no coincidence that Arctic ocean ice has been declining since this period started.
Antarctica on the other hand the ocean warms the least with a decline in cloud albedo because the solar energy is considerably weaker closer to the poles. With no ocean current to move warm water towards it this option only applies. Therefore little or no warming over Antarctica and no sea ice decrease around it because this mechanism relies on warmer solar energy from the Tropics to provide the energy the Arctic has been receiving.
So what are the observatons showing over both poles, an atmospheric warming or an ocean warming?
Answer = ocean warming
This leads to a conclusion that there has been no signal at the poles of atmospheric warming and whatever there has been is within error.
Is no sea ice in Summer in the Arctic ocean a possible disaster that alarmists claim?
Answer = no
The melting of ice around the Summer season due to latent heat keeps the ocean surface very cold only slighly above 0c. If this was to occur, it would be only be for a very short time in Summer and ice would form quickly later at the end of the season. Surface ocean temperatures only need to drop around another 2c for freezing to return. Winter sea ice even from a Summer with no ice would return to similar area extents that have been seen for recent decades.
I suppose we had better take “action” because this undoubtedly means more ice tornadoes and jet-stream ice-melt bomb-vortex blasts.
Once again, the alarmists proclaim that the natural state of the world is for everything to stay the same from one year to the next, and if anything changes, it must be CO2 that caused it.
This ^
So, much like annual sea ice melt which reaches it’s peak near the end of Summer which is well past the peak of maximum insolation, would you expect most of the long term sea ice decreases to occur more near the end of the interglacial which would be well past the peak of the maximum temperature era?
After posting, I re-read my comments and realized I need to re-phrase it as such:
“much like the annual lowest sea ice volume occurs near the end of Summer which is well past the peak of maximimum insolation, would you expect the lowest sea ice volume years to occur towards the end of the interglacial”
And of course I am referring to northern hemisphere ice.
Here’s a question. If the new estimates show that ice is thinner than previous estimates, wouldn’t the older previous estimates be in error by a similar amount, such that everything was thinner and there has been, basically, no change?
Dusty
They should have continued the old method to compare and calibrate. I wonder why they did not?
Oh dear! Satellites!
The following is from the technical files at this page:
https://icesat-2.gsfc.nasa.gov/science/specs
“91-day exact repeat orbit with monthly sub-cycle for the polar regions and oceans. Operational off-nadir pointing over land areas to generate a dense grid of data over 2 years”
It takes 91 days for the Satellite to get back to its starting point on the surface of the earth.
What has changed on the surface during those 3 months? Ice comes or goes or both?
Averaging lots of measurements of something that is changing gives you a number that means very little.
Not bad for climate change science.
Three months is a season the last time I researched it. I think both temps and resulting phenomena change a lot during that time.
“The profiles provide a consistently referenced elevation data set with unprecedented accuracy and quantified measurement errors that can be used to generate GCPs with sub-decimeter vertical accuracy and better than 10 m horizontal accuracy.”
https://ntrs.nasa.gov/api/citations/20100026470/downloads/20100026470.pdf
So accuracy of about 100mm.
Well you gotta figure they would come up with something like this because extent has been pretty good the last couple years. In fact this winter it got pretty close to Iceland.
So know how they have operated in the past it is reasonable to expect them to come up with a “study” that claims that ice is thin, rotten, no good ice.
Probably a dumb question, but where has all this melting ice gone?
Surely there should be a considerable, and noticeable, rise in sea levels.
As the annual maximum arctic ice has been growing since 2015 they have to make it thinner.
Not a neutral source.
Their findings appear to me, modeled using personal opinions.
Estimates of estimates compared to believed erroneous earlier estimates… From the linked paper; “The researchers found using climatology-based estimates of snow depth can result in overestimating sea-ice thickness by up to 20%, or up to 0.2 meters (0.7 feet).“
Their approach to determining ice height above sea water sounds remarkably like NOAA’s satellite measurements of sea level. They radar and Lidar sea ice, then estimate how high the ice is, smoothing out irregular surfaces. From this they calculate subsurface ice and total ice volume…
The author’s opinion summarizes the lack of quality behind this research.
Such confidence and precision hints at huge error bounds that are not displayed or cited.
The study makes two claims: 1. Arctic sea ice is thinner than thought, and 2. It is losing volume faster than thought.
But if 1 is correct then 2 can only be relative to the Adjusted(TM) thinner baseline. At 3yrs long this is clearly an insufficient reference period to enable meaningful conclusions to be drawn, even if everything else in the study is correct.
In this regard, given the researchers involved have seen fit to publish conclusions arising from such an extremely short measurement series, this hardly encourages confidence in the extent of rigour underlying the rest of the research.
There is always one statistic to p
ick from many to prove what you want. Isn’t it called the green jelly bean hypothesis?