The National Snow & Ice Data Center (NSIDC) follows conditions in the polar regions, including the Arctic minimum sea ice extent each September. This year’s number is 4.23 million sq km.
For the last 17 years (2007-2023) the trend is -0.009 per year, not significantly different from zero (p=0.70).
Why make a claim about a time trend using the last 17 years when the article mentions 45 years of data?
A “pause” is not the wording in the article referenced.
The article says:
In the 45-year-satellite record, 17 of the lowest minimums have all occurred in the last 17 years.
The overall, downward trend in the minimum extent from 1979 to 2023 is 12.5 percent per decade relative to the 1981 to 2010 average. The loss of sea ice is about 77,800 square kilometers (30,000 square miles) per year, equivalent to losing the state of Nebraska or the Czech Republic annually.
Key words and phrases:
45-year
17 lowest measurements in last 17 years
downward trend
12.5% per decade
loss of sea ice
losing
Because the trend changed over the last 17 years compared to the earlier years. Which raises the question: why the dramatic change in trend? I remember posts by Peter and Loren on the Climate Change board which were projecting “ice free” September conditions (less than a million square kilometers of ice extent) in only a few years. Perhaps a change in some arctic oscillation?
At any rate, good news compared to a continuation of the previous trend.
Trend change analysis is a robust field of statistics. Showing the slope is not significantly different from zero over a short period does not indicate a trend change. One tool is the Chow Test
This change of trend is mirrored in a way in the spring. Schmidt et al. measured the onset of spring in the Arctic over 25 years (1996-2020) looking at flowering plants, arthropods, and birds. They found no trend but rather large inter-annual changes. A previous study 15 years ago reported extreme rates of phenological change in the High Arctic. The longer follow-up study found little overall change.
Actually, one can see that the last 17 years have been not so much “flat” but abnormally unstable, with all that variation tending to mask any short-term trends. You can decide whether to believe the 17 year trend or the 40 year trend.
The “little overall change” is due to many Arctic species reaching the limit to which they can adapt to warming temperatures and the high weather instability observed during the last two decades, which is also likely related to climate change. As we have seen, the world is getting both warmer and less predictable with its weather. When species reach the limit of their ability for “phenological change” they are left with the option of either move or die.
If you care, this is a continuation of a post from the Renewables board two years ago.
It is also something we tracked on a regular basis for many years on the now-disappeared Climate Change board.
" I remember posts by Peter and Loren on the Climate Change board which were projecting “ice free” September conditions (less than a million square kilometers of ice extent) in only a few years."
Peter and Loren are no doubt very smart people. But let’s see what the scientific community thinks. Back in 2000, the IPCC models projected 80% loss of Arctic ice by 2050. The current IPCC “prediction” is that the Arctic will be ice free at least once before 2050 and mostly ice free by that year.
The Arctic ice observations appear to be well within the bounds of the IPCC projections. Wattsupwiththat is making a big deal about nothing, which is pretty much par for the course with that site.
There was a thread on the Climate Change board where the various predictions were collected over the years. Unfortunately gone. But some can still be found out there.
Only a few years ago, climate modellers predicted the Arctic sea ice would not melt out in summer until at least the end of the century. “Then they said 2070, and then they said 2050 and then they said 2030,” said Robie Macdonald, a leading Canadian Arctic scientist on board the Louis…
“There’s a group that makes a very strong case that in 2012 or 2013 we’ll have an ice-free (summer) Arctic, as soon as that. It’s astounding what’s happened,” said Ted Scambos, another research scientist from the Snow and Ice Data Centre.
Fang et al. studied the correlation between surface temps and the mass balance of the Greenland ice sheet. Not surprisingly they found a high correlation, some 94% over the last 20 years.
Looking at their Figure 9, the time series in red shows the average summer temperatures. Over 20 years there is no significant trend.
Air temps only ONE potential source of heat. Direct sunlight adds heat to the ice and may not add much to air temps due to the cooling action of the ice. So does warmer water under the ice.
Using data from both poles, it looks quite clear that the amount of ice is declining. We don’t need to bother with statistical tests to get the trend, just apply an eyeball test (if these charts were of stock prices, we would agree that the trend is down).
Result = less ice on earth.
Here’s a quote from the ice sheet team that sums it up:
Glaciologists have found, in study after study, that both of the planet’s remaining ice sheets are losing overall mass at an accelerating rate.
Temperatures don’t need to increase for ice to melt, although it does affect the rate of melt.
Something changed in the Arctic earlier in this century; ice extent and temperature trends are different than they were. One of those multi-decadal oscillations?
Overall what matters is the amount of energy the earth has absorbed (and then the resulting impacts on the biosphere). Temperature is one (but not the only) way to measure change in energy content.
I would also argue that measuring global (all regions) ice mass is a good way to measure if the earth’s total water is shifting from solid to liquid and thereby absorbing more energy.
Maybe, but a more parsimonious answer based on the simple theory of how greenhouse gases are produced (humans are producing a lot more of them) and act to warm the earth (they insulate the earth like a blanket) is my, and many other’s, preferred explanation.
Oscillation?
Why twist into a pretzel to avoid a simpler explanation that doesn’t suite your personal narrative?
Also, 2 or more factors can be happening at once: we could have a warming trend and a multi-decadal oscillation.
There are likely many kinds of oscillations present in global ocean and atmospheric patterns.
By the time we have the data to understand multi-decadal oscillations, the warming trend will be far, far along.
Dear children: I’m sorry all of the forests are burning. We need 300 years maybe to check if this is solely a transitory thing and you just happened to be born in the wrong part of the cycle. Never mind the impact of 8 billion (and growing) humans.
There have been some papers. It is difficult to tease out the separate influences as they are interlinked.
The PDO (Pacific Decadal Oscillation) has been linked to changes in arctic amplification. Screen and Francis write “the contribution of sea-ice loss to wintertime AA appears dependent on the phase of the Pacific Decadal Oscillation (PDO).”
Simon et al. write “the warm PDO phase therefore enhances the response to sea-ice loss, while the cold PDO phase reduces it.”
Fan and Yang examined connections with the eastern Atlantic. “The wintertime Arctic temperature decreased from 1979 to 1997 and increased rapidly from 1998 to 2012, in contrast to the global mean surface air temperature. Here aspects of circulation variability that are associated with these temperature changes are examined…”
