Arctic sea ice extent regime change continues

Investment Analysis Clubs Macro Economic Trends and Risks
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A couple of years ago there was a paper published in Geophysical Research Letters that noted a “regime change” in the minimum Arctic sea ice extent.

Regime Shift in Arctic Ocean Sea‐Ice Extent
H.L. Stern
https://agupubs.onlinelibrary.wiley.com/doi/pdfdirect/10.1029/2024GL114546
Abstract:
A regime shift is an abrupt, substantial, and persistent change in the state of a system. We show that a regime shift in the September Arctic sea‐ice extent (SIE) occurred in 2007. Before 2007, September SIE was declining approximately linearly. In September 2007, SIE had its largest year‐to‐year drop in the entire 46‐year satellite record (1979–2024). Since 2007, September SIE has fluctuated but exhibits no long‐term trend.

This year’s minimum ice extent came in at 4.60 million sq km, the same as last year.

For the last 20 years (2007-2026) the trend is -0.003 per year, not significantly different from zero (p=0.84).

2007   4.16 million sq km
2008   4.59
2009   5.12
2010   4.62
2011   4.34
2012   3.39
2013   5.05
2014   5.03
2015   4.43
2016   4.17
2017   4.67
2018   4.66
2019   4.19
2020   3.82
2021   4.72
2022   4.67
2023   4.23
2024   4.28
2025   4.60
2026   4.60

DB2

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Back in the day, a lot of hay was made over a similar “pause” in global average surface temperatures. Warming has stopped some claimed. Now, many years later, see if you can detect The Pause in the temperature record below:

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For a while now, climate models have predicted that multi-decadal pauses in Arctic sea ice decline are possible and do not contradict global warming.

since the late 2000s, the pace of Arctic sea ice loss has slowed markedly, with no statistically significant decline for about 20 years.

Our findings show that, rather than being an unexpected or rare event, climate model simulations suggest we should expect periods like this to occur relatively frequently.

Were it not for human-caused warming, it is likely that sea ice would have increased over this period.

According to our simulations, the slowdown could even last for another five or 10 years – even as the world continues to warm

None of this contradicts the basic fact that human CO2 emissions are driving global climate change. The natural processes responsible for these pauses are important and scientifically interesting, but do not, in the end, contradict long term climate change.

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Quite true. And at the same time this pause/slow-down/regime change is good news. The rate of decline for the past 40 years (1987-2026) is now half of what it was from 1987-2007.

DB2

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