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The Walrus

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #200 on: September 25, 2020, 01:39:54 PM »
How is DMI N80 heavily skewed?

As I understand it, not all areas N of 80 are equally weighted in their "average."  Weighting increases as you approach the pole.  I can't fathom why it was set up this way.  But having started with this algorithm, it needs to be continued to enable direct year-to-year comparisons.

It was done to relate temperature to equal measures of latitude, instead of area.

The Walrus

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #201 on: September 25, 2020, 01:52:39 PM »

Your intuition is supported by the data.  The last few winters have been almost 4C above average, while there has been little temperature change during the summer.

Well, that is only true for the heavily skewed and therefore not really relevant DMI 80N temp data. For the broader Arctic, summers are egetting warmer, just like winters:

Even the broader definition shows much more warming in winter than summer.  From your graph, winters warmed from ~-1C in the 1950s to ~2.5C in the 2010s, an increase of 3.5C.  Conversely, the summers warmed from ~025C to ~1.25C, an increase of 1C.  Your graph also excludes the temperature increase of the early twentieth century, which would eliminate that rise.

https://journals.ametsoc.org/jcli/article/17/20/4045/30396/The-Early-Twentieth-Century-Warming-in-the-Arctic

Archimid

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #202 on: September 25, 2020, 02:10:16 PM »
It was a trick question. N80 is weighted more heavily towards the north pole than the outer latitudes. This "skewness" makes N80 an outstanding marker for  the most central, most northern Arctic.

Air temperatures 2 meters above the surface of the ice, averaged over N80, weighted more heavily towards the North Pole.

DMI N80 and is the "heart" of the Arctic.
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kassy

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #203 on: September 25, 2020, 02:35:28 PM »
Even the broader definition shows much more warming in winter than summer.

And that is because the remaining Arctic ice has a damping effect on summer temps.
Toms question mentions daily temperature swings which don´t really work there (compare summer and winter solstice f.e.).

When the ice is gone the central arctic temps will jump up.

I think that if you interpret the cycle on a year it will become more equal because it is all water.

If you look at actual daily temperature swings in the future at the pole well i don´t know but since Arctic ice was such a strong control on temps i will play for bigger. Now all we need is to wait some years.

Another open question is what the big scale weather will be like without arctic ice. I bet that is going to be really interesting.
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Re: The Climatic Effects of a Blue Ocean Event
« Reply #204 on: September 25, 2020, 04:55:28 PM »
Is that “interesting” in the Chinese sense, kassy?
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oren

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #205 on: September 26, 2020, 12:58:33 AM »
DMI N80 is weighted by latitude rather than by area. So the circle 89-90 gets the same weight as the 80-81 belt, which has an area 19 times larger. Badly skewed.

Archimid

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #206 on: September 26, 2020, 07:45:02 AM »
Badly skewed towards exactly the right direction one wants if one is trying to get a snapshot of the "heart" of the Arctic.
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El Cid

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #207 on: September 26, 2020, 09:05:49 AM »
Another open question is what the big scale weather will be like without arctic ice. I bet that is going to be really interesting.

That is the gazillion dollar question. Will there be a rearrangement of NH atmospheric circulation without the ice? And if so, then how? Noone knows the answer.

I still say that Greenland will take the role of the Central Arctic, as Greenland will stay a bastion of ice for centuries to come (due to inertia and 100s of meters of ice there)

A-Team

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #208 on: September 26, 2020, 10:42:54 AM »
Quote
I cannot fathom why DMI 80N was set up so biased
Me either. Terrible idea. Ever look at their own description?

"Since the data are gridded, it is straightforward to deduce the average temperature North of 80 degree North. However, since the model is gridded in a regular 0.5 degree grid, the mean
temperature values are strongly biased towards the temperature in the most northern part of the Arctic! Therefore, do NOT use this measure as an actual physical mean temperature of the arctic."

http://ocean.dmi.dk/arctic/documentation/arctic_mean_temp_data_explanation_newest.pdf

In other words, the lat lon grid is a completely inappropriate choice of coordinate system here unfit for purpose but the global data came that way so they foolishly used it rather than take a moment to re-grid. A biased average, dependent on coordinate system choice, is scientifically unacceptable, perhaps explaining why DMI 80N analysis has never appeared in a peer-reviewed journal.

Denmark has 5.8m people, a quarter of Los Angeles. What can be expected?

It is merely a ECMWF reanalysis product called ERA40 that you can get anywhere for any place on earth (eg the whole Arctic Ocean basin) as a colored time series map (2D+T data) for the same time span of years. If what you want is ice surface temperature variation or ice temperature profile with thickness, we have satellites and buoy thermistor chains for that.

In the bigger picture, it is a poor idea to believe the state of the Arctic Ocean can be reduced to single numbers. This made some sense in the pre-computer age when journals had minimal ability to dot print even b/w graphics and simple pre-spreadsheet tasks like averaging were tedious. However today analysis of 2D+T displays is preferable as all information is retained, unlike with the single number approach 0D+T.

There's another issue here called pipeline immortality. Once a product algorithm is set up to run unattended, no matter how flawed, that's what it does. The project automator may have moved on or even died but, as long as the institutional electric bill is paid, the daily product continues to be served indefinitely from some nook or cranny in storage. Someone has to actively intervene to take it down. However inaction is a whole lot easier. Innocents come along later on the internet and are duped.

The 2m amsl level is by far the least accurate atmospheric choice because of topographic effects of rough ice on wind and boundary layer. Ask yourself how many instruments exist offshore actually measuring it for assimilation, typically none. How many 80º+ weather stations on land: 4-5 and diminishing. The Polarstern does not measure it; their mast is at 36m. It is model-driven assumption, not observation.

The case cannot be made that north pole is somehow the "heart" of the Arctic Ocean. It's representative of it in any way becing such an asymmetric basin, both at current sea level and for continental shelf bathymetry. The ice is not centered there at any time of year, the cold pole is not centered there, the geographic center of the the ocean is not there, the last remnant ice will not be located anywhere near it. (In 2016 it was already open water; see Jim H's photo.)

DMI 80 is an inappropriate product for detecting climactic impacts of incipient BOE (this forum) because it leaves out so much of the open water of the excluded ESS, Chukchi, Beaufort and Laptev where the insolation of large area, low albedo early open water counts the most. The low area NP region is where it matters least because of the lower angle longer path through the atmosphere and poor match to peak insolation even when it is melt pond (this year) or open water.

Thus the Bering Strait is at 65.9º which is 1,234 ignored km below 80º, causing a whole lot of Arctic Ocean to be left out. Meanwhile 80º north is tainted by its inclusion of the anomalous localized area impacted by incoming Atlantic Waters.

The slides below show the highly variable 80th parallel enclosure on Sept 15 for the years 2012-20. The bottom image shows how poorly this enclosure characterizes actual basin percentages of land, water, ice on that date.
« Last Edit: September 26, 2020, 01:53:48 PM by A-Team »

Tor Bejnar

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #209 on: September 26, 2020, 08:20:29 PM »
Great post, A-Team.
In the last graphic, it looks like about 75% ice and 25% water within 80N (ignoring land).  I presume the boxed percentages are derived from the entire rectangular graphic (not 80N), and therefore shows that "80N" just isn't a reasonable representation of the Arctic.  ["But what about the CAA?" I hear someone complain.  :)]

Why doesn't somebody make an easily accessed daily Arctic surface Temp website with a 'more reasonable' set of boundaries (etc.)?  If we had that, we wouldn't go to DMI. [Ideas:  ~85N equal area [where solar gain is minimal at the equinoxes), entire Arctic Ocean sea surface, a 10^6 km2 circle selected as being the mostly likely area to find ice in mid-September over the past decade)]

It's like atmospheric CO2 data from Mauna Loa, Hawaii.  It's not representative of the world, but it's not bad and the continuous record is worth a lot.
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Archimid

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #210 on: September 26, 2020, 08:26:26 PM »
Quote
I cannot fathom why DMI 80N was set up so biased
Me either. Terrible idea. Ever look at their own description?

I do. I think they were trying to capture the most central arctic but with small effects added at the lower latitudes.  I like to think of it as heavy center weight that fades as it reaches lower latitudes.

"Since the data are gridded, it is straightforward to deduce the average temperature North of 80 degree North. However, since the model is gridded in a regular 0.5 degree grid, the mean
temperature values are strongly biased towards the temperature in the most northern part of the Arctic! Therefore, do NOT use this measure as an actual physical mean temperature of the arctic."



Good thing we are not taking it as an actual physical mean temperature of the arctic. We are using it as a marker for oceanic vs desert conditions above the Arctic.
 

Quote
In the bigger picture, it is a poor idea to believe the state of the Arctic Ocean can be reduced to single numbers.


If there was one single number that could represent a state change of the Arctic is temperatures close to the surface very close to the North Pole. I can't think of a better one. That said, I agree that a simple number is not nearly enough to explain the event and its consequences.

Quote
There's another issue here called pipeline immortality.

I'm not defending any particular research group. I'm defending the concept that temperatures near the ocean/atmosphere interface, near the pole, during the summer, will be a very good indicator of when a tipping point in Arctic Sea Ice and world climate has occured.

Exactly how that temperature is calculated is up for debate, but I think DMI's tradeoffs are particularly excellent to mark the departure of the Arctic from cold frozen desert to open, relatively "warm"ocean.

Like I said before, these temperatures are fixed to the ice during summer. When temperatures depart variability it means that the ice is not serving its function as the NH refrigerator. This concept is independent from research groups or model vs observation or methodology.

Quote
The case cannot be made that north pole is somehow the "heart" of the Arctic Ocean.

The incident radiation of the Sun upon Earth is the ultimate driving force behind all the climate on Earth.  That radiation hits the Earth that spins around it's own axis, a day/night cycle. The Earth is also tilted 23.5 degrees from the plane of its orbit around the sun with the North Pole and the South Pole as the pivot points and global minimums for global insolation. This creates the winter/summer cycle.

The north pole is the darkest point in the NH, where the light of the sun is gone first and arrives last. The poles are global extremes.

I think that's a good case to call the latitudes N80 the heart of the Arctic.

Quote
DMI 80 is an inappropriate product for detecting climactic impacts of incipient BOE (this forum) because it leaves out so much of the open water of the excluded ESS, Chukchi, Beaufort and Laptev where the insolation of large area, low albedo early open water counts the most.


I believe the opposite. All the seas you mention are already seasonally ice free. Any measure of temperature that includes the regions mentioned above would be affected by the "noise of those seasonally ice free regions. Temperatures N80 excludes those regions. N80 has very likely been mostly ice-covered since the eemian.

Quote
The low area NP region is where it matters least because of the lower angle longer path through the atmosphere and poor match to peak insolation even when it is melt pond (this year) or open water.

For the topic of climatic consequences, the long term permanence of ice cover and relative non-variance of temperatures of air above the surface is what matters most.

Since the Eemian, the air above N80 has been a relatively fixed size during summer due to the presence of ice.  A BOE will change the size of the air above by virtue of warming the air above to levels that have not happenned since the eemian.
A BOE has two main compoents. 

1. Albedo
2. Enthalphy of fusion.

Temperatures will increase not just because there is less albedo, they will increase because there is no ice to melt so not only there will be more albedo, but all the energy that goes to melt ice will go to warm the water, which in turn will warm the atmosphere above all the way up to space, increasing it's size.

This changes the gradients of atmospheric and changes pattern that have been basically unchanged for thousands of years.

Quote
Thus the Bering Strait is at 65.9º which is 1,234 ignored km below 80º, causing a whole lot of Arctic Ocean to be left out. Meanwhile 80º north is tainted by its inclusion of the anomalous localized area impacted by incoming Atlantic Waters.

But being skewed towards the North minimizes Atlantic water influences. If Atlantification occurs   N80 surface temperatures will shoot up.
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oren

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #211 on: September 27, 2020, 09:48:41 AM »
Archimid, all that your reply to A-Team's excellent post achieved is explain why the biased and non-physical DMI N80 product will be a severely lagging indicator. When BOE arrives we will have plenty of indicators, one more of those is not overly interesting except it would make for a good headline. What should be more interesting are leading indicators marking the Arctic transition as it occurs.

I do see the merit of single numbers (0D+T) as easy to chew on indicators for non-scientists, but at least these numbers should be constructed properly. Following on from Tor:
* North of 85 2m temps.
* North of 85 850 HPA temps.
* Arctic Basin (non-land) 2m temps.
* Arctic Basin (non-land) 850 HPA temps.
* Siberian land/island stations north of 70 and within 50km of the Arctic ocean (Kara to ESS, Chukchi, CAB), surface temps.
* North American land/island stations north of 70 and within 50km of the Arctic ocean (Chukchi, Beaufort, CAA, CAB), surface temps.

All the above of course, averaged and weighted properly.

Like Sep minimum extent, these single numbers will not capture the complexity of the Arctic and will not tell the whole story. But they could be useful as a popular indicator with a long history.
I still hope "someone with a website" will take some of these up.

Archimid

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #212 on: September 27, 2020, 10:16:25 AM »
Quote
DMI N80 product will be a severely lagging indicator.

Yes, it will be. That is why is such a great marker to mark a BOE and a great starting point to theorize about consequences of a BOE. I have made no claim of its predictive power, in fact, I have been very clear that if that number departs summer variability it will be too late.
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kassy

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #213 on: September 27, 2020, 11:19:18 PM »
Another open question is what the big scale weather will be like without arctic ice. I bet that is going to be really interesting.

That is the gazillion dollar question. Will there be a rearrangement of NH atmospheric circulation without the ice? And if so, then how? Noone knows the answer.

I still say that Greenland will take the role of the Central Arctic, as Greenland will stay a bastion of ice for centuries to come (due to inertia and 100s of meters of ice there)

I am not sure just Greenland is the same as the old Arctic system + Greenland. Wayne used to write about the cold poles moving around. One was usually on Greenland and the other(s) moved over the ice or where on it. The connection to the siberian side has broken and the cold pole also cannot be on the central arctic anymore so this opens up the siberian side to more long range connections.

Yes Greenland will stay cold for a bit but that is just not the same as the system staying the same when we lose the central arctic ice.
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A-Team

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #214 on: September 27, 2020, 11:55:05 PM »
"do NOT use this measure as an actual physical mean temperature -- DMI"
Quote
Tor asks: it looks like about 75% ice and 25% water within 80N (ignoring land).  I presume the boxed percentages are derived from the entire rectangular graphic (not 80N), and therefore shows that "80N" just isn't a reasonable representation of the Arctic.
That's correct. We are well over half way to a full-on BOE restricted to the Arctic Ocean proper, with 55% open water and 45% ice using NSIDC's standard end of season, 15 Sep 2020 (first image below). There is still insolation on the open water today but it's inconsequential in September.

The problem is, there's a surprising amount of open water even before summer solstice peaks on June 20th. Gerontocrat posted to the melt forum the key sine-like graphic that furnishes the bottom-of-atmosphere heat input to each high latitude, with the peripheral basin seas getting hit harder earlier, the idea being to weight the weekly open water areas by the weekly heat input graph. I provided that rainbow tool for doing this on that same forum.

One aspect of Arctic Amplification is higher open water percentages creeping back earlier in the season, thus better matching the insolation season and worsening reflection back out to space. It's not easy though to take clouds and adjacent land albedo into consideration but that was done in the trillion tons of Co2e and 2035 first BOE papers above. People have also wondered if increasing fog and rain-on-snow are additional unfavorable feedbacks:
 
Trends and spatial variation in rain-on-snow events over the Arctic Ocean during early melt season
T Dou et al
https://tc.copernicus.org/preprints/tc-2020-214/

"Rain-on-snow (ROS) events can accelerate the surface ablation of sea ice, thus greatly influencing the ice-albedo feedback. However, the variability of ROS events over the Arctic Ocean is poorly understood due to limited historical station data in this region. In this study early melt season ROS events were investigated based on four widely-used reanalysis products (ERA-Interim, JRA-55, MERRA2 and ERA5) in conjunction with available observations at Arctic coastal stations.

The performance of the reanalysis products in representing the timing of ROS events and the phase change of precipitation was assessed. Our results show that ERA-Interim better represents the onset date of ROS events in spring and ERA5 better represents the phase change of precipitation associated with ROS events.

All reanalyses indicate that ROS event timing has shifted to earlier dates in recent decades (with maximum trends up to −4 to −6 days/decade in some regions in ERA-Interim), and that sea ice melt onset in the Pacific sector and most of the Eurasian marginal seas is correlated with this shift."

The graphic in #208 is done with a rectangular crop mask that works for almost all Arctic Ocean data products. It does pick up a portion of the Bering Sea that often has ice via its transport coupling with the Chukchi as well as some CAA but not much of the Kara, Barents or Greenland seas (those crops are just corner extensions retaining 'Greenland down').

The coastline being rather irregular, it takes a detailed google earth polygon to reproducibly specify the many lat lon coordinates of the AO basin mask. I've posted that editable .kml before and have attached it again.

On the AMSR2_AWI mask, different days or years are layered into a stack, the light blue and gold mask applied, leaving the color picker tool free to count the pixels of open water and ice (of all concentrations). The latter pixels are the inverse of the combined selection of gold, light blue, and dark blue. If the color radius is increased, more of the concentration palette is picked, increasing the pixel count; however not by much.

The 80N product has no applicability to anything before its three errors are fixed: incorrect masking, false thermodynamic reasoning about non-laminar (turbulent) 2m flow of 7m/s, and non-utilization of one-click weighted zonal averaging. Some time back, the ice season moderator booted the 80N posts off to their own forum (with solar cycle collapses and sudden ice ages) to give yhe angle trisectors unlimited space of their own (if only they would use it!). For what it's worth, this is in line with US case law (Judge Posner's 1995 ruling):

"A crank is a person inexplicably obsessed by an obviously unsound idea—a person with a bee in his bonnet. To call a person a crank is to say that because of some quirk of temperament he is wasting his time pursuing a line of thought that is plainly without merit or promise … to say a person a crank is just a colorful way of expressing disagreement and it therefore belongs to the language of controversy rather than to the language of defamation."
« Last Edit: September 28, 2020, 12:26:15 AM by A-Team »

El Cid

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #215 on: September 28, 2020, 08:28:13 AM »
...
I still say that Greenland will take the role of the Central Arctic, as Greenland will stay a bastion of ice for centuries to come (due to inertia and 100s of meters of ice there)

I am not sure just Greenland is the same as the old Arctic system + Greenland.
...
Yes Greenland will stay cold for a bit but that is just not the same as the system staying the same when we lose the central arctic ice.
I am not saying that it would be the same as the "old system", but even it is worth noting that even after a BOE there will be plenty of ice  in the Arctic (=Greenland). How that new cold pole will rearrange the atmospheric circulation is anyone's guess.
Any research on that  would be very interesting

Archimid

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #216 on: September 28, 2020, 10:05:57 AM »
A BOE != an Ice Free Arctic.

Ice free arctic = less than a million square kilometers of ice on the Arctic ocean

BOE = a departure of the long term variability of summer temperatures right above the surface of the central arctic ocean.


If the ice reaches less than a million km2  in mid September, temperatures above the surface will not increase much for long, they might even drop significantly.

However, if by July/Aug temperatures N80 depart natural variability and warm up it will mean that there is no ice and albedo plus enthalpy are changing the state of the atmosphere above the most central Arctic.

This will change hydrologic cycles in a geological instant, even if it takes a few years. This is abrupt climate change.
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Shared Humanity

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #217 on: September 28, 2020, 04:04:33 PM »
Thank you A-Team. I never fail to learn things from your posts.

metalreflectslime

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #218 on: November 13, 2020, 12:26:05 PM »
Will a BOE destroy soil?

Tom_Mazanec

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #219 on: November 13, 2020, 12:40:52 PM »
Will a BOE destroy soil?
My uneducated guess...
No, not directly. Possibly through some indirect effect.
Anyone with a better educated guess?
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El Cid

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #220 on: November 13, 2020, 01:14:27 PM »
Will a BOE destroy soil?

Why and how would it?

Soil is mostly destroyed by human activities unfortunately (industrial agriculture, tillage, etc). We have the solution to these problems though (regenerative agriculture) but implementation is way too slow

vox_mundi

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #221 on: December 03, 2020, 04:58:42 PM »
Is Arctic Warming Behind a Monster Saharan Dust Storm?
https://phys.org/news/2020-12-arctic-monster-saharan-storm.html

The June 2020 dust storm set records in terms of its geographic size and its aerosol optical depth—essentially a measure of its thickness determined by the ability of satellites to see through it. It reached an altitude of 6,000 meters (19,600 feet). In certain locations over the Atlantic Ocean, its thickness was double what had ever been recorded during the month of June during the history of the satellite record, which dates back to 1995.

The researchers analyzed what made it happen in a study appearing today in the journal Geophysical Research Letters

.Evan, lead author Diana Francis of Khalifa University of Science and Technology in the United Arab Emirates, and colleagues attributed the dust storm's magnitude to conditions set up by the development of a type of high-pressure system called a subtropical high off the coast of the Sahara. This increased the north-south pressure gradient over West Africa leading to record-strength, persistent northeasterly winds. The intensification of the northeasterly winds over the Sahara generated continuous dust emissions over several days in the second half of June 2020.

The researchers found that the subtropical high was embedded in a circumglobal wavetrain, a chain of wind patterns that extended around the planet, and was present in the Northern Hemisphere for most of June 2020. This wavetrain may have been caused by record-low Arctic sea ice extent observed in June 2020 as well. The warming of the Arctic region is believed to be altering the course of wind patterns in the mid-latitudes and subtropics and causing severe weather events, though there is controversy among scientists about this concept.

"The development of the subtropical high off the African coast had a deterministic role in both dust emissions and rapid westward transport of the airborne dust across the tropical Atlantic," said Francis. "The clockwise circulation associated with the high, intensified the African Easterly Jet, a jet stream present over the Sahara around five kilometers (3.2 miles) in altitude, which rapidly transported the dust towards the Caribbean and southern United States."

The study also touches on a controversial topic within the science community. Though not the main focus of study, the wavetrain pattern that set the Godzilla dust storm in motion looked very similar to one observed in 2010 when sea ice in the Arctic Ocean was substantially diminished, Francis' team noted.

"As the Arctic sea-ice cover was rather low in June 2020, around the lowest on record in the period of satellite observations, it may have contributed to the observed large-scale anomaly pattern," the study concludes. "Thus, if such patterns become more common in a warmer world, it is plausible that these extreme dust outbreaks will increase in frequency in the future."

Diana Francis et al. The Atmospheric Drivers of the Major Saharan Dust Storm in June 2020, Geophysical Research Letters (2020)
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020GL090102
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Re: The Climatic Effects of a Blue Ocean Event
« Reply #222 on: February 06, 2021, 06:20:10 AM »
How would a BOE cause famines?

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #223 on: February 06, 2021, 12:35:45 PM »
How would a BOE cause famines?
By changing weather patterns in the Northern Hemisphere, leading to crop failures.
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jai mitchell

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #224 on: February 07, 2021, 07:38:22 PM »
Lawrence et. al 2008 still has the best projection of regional temperature impacts during summer ice free conditions.

One of the several inherent modeling conservatisms in this area is the use of an annual average temperature to project impacts on permafrost.  This is not realistic as the summer warming will be much greater, and the impacts much stronger.

https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2008GL033985

Accelerated Arctic land warming and permafrost degradation during rapid sea ice loss
GEOPHYSICAL RESEARCH LETTERS, VOL. 35, L11506, doi:10.1029/2008GL033985, 2008


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Re: The Climatic Effects of a Blue Ocean Event
« Reply #225 on: March 03, 2021, 03:28:20 PM »
Ice Age Testing Reveals Challenges In Climate Model Sensitivity
https://phys.org/news/2021-03-ice-age-reveals-climate-sensitivity.html

... Climate models have traditionally forecast an increase of 1.5°C–4.5°C for a doubling of atmospheric CO2 from the preindustrial climate. However, many of the latest models are finding values in excess of 5°C, which, if correct, would have significant negative implications for our ability to overcome the planet's ongoing warming. Zhu et al. investigated this trend by using one of the high-ECS models, the Community Earth System Model version 2 (CESM2), to simulate the climate during the culmination of the last ice age, called the Last Glacial Maximum (LGM).

The LGM, occurring 21,000 years ago, is sufficiently recent that there is widespread geologic evidence of both climate forcings and resulting surface temperature changes.

The authors configured CESM2 to closely mirror its use in modern climate change research, omitting only those parts (such as vegetation biogeochemistry) for which good data for the LGM are not available. Within 500 model years after initialization, CESM2's global mean surface temperature plunged to 11°C below the preindustrial era, roughly 5°C cooler than what the geological proxies indicate. In comparison, the model's predecessor, CESM1, produced values several degrees warmer and within the uncertainty ranges of the proxies.



The authors attribute the discrepancy between CESM1 and CESM2 to how the latter handles clouds. The atmospheric model in CESM2 has been updated so that the computer-simulated clouds behave more like real-world observations, which affects the shortwave cloud feedback, the ability of clouds to reflect incoming sunlight back to space under climate change. When CESM2 was configured to use the older model's atmospheric package—which lacks these updates—much of the excess temperature decrease disappeared. The authors suggest that CESM2 likely overestimates the shortwave cloud feedback and therefore the ECS.

Morgan Rehnberg. Ice Age Testing Reveals Challenges in Climate Model Sensitivity, Eos (2021)
https://eos.org/research-spotlights/ice-age-testing-reveals-challenges-in-climate-model-sensitivity
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vox_mundi

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #226 on: March 03, 2021, 10:33:47 PM »
High End of Climate Sensitivity In New Climate Models Seen As Less Plausible
https://phys.org/news/2021-03-high-climate-sensitivity-plausible.html



The researchers found that models with lower climate sensitivity are more consistent with observed temperature differences, particularly between the northern and southern hemispheres. The graph shows changes in the annual global-mean surface temperature (a) and the temperature difference between the northern and southern hemispheres (b) from 1850 to 2000. The red line represent high climate-sensitivity models, while the blue line represents models with low climate sensitivity. The black line shows observed temperature fluctuations collected by NASA's Goddard Institute for Space Studies Surface Temperature Analysis project, which more closely follow the blue line when it comes to interhemispheric temperature. The gray backgrounds indicate years when the difference between the high and low climate-sensitivity models are significant. Credit: Chenggong Wang, Program in Atmospheric and Oceanic Sciences, Princeton University

Researchers at Princeton University and the University of Miami reported that newer models with a high "climate sensitivity"—meaning they predict much greater global warming from the same levels of atmospheric carbon dioxide as other models—do not provide a plausible scenario of Earth's future climate.

Those models overstate the global cooling effect that arises from interactions between clouds and aerosols and project that clouds will moderate greenhouse gas-induced warming—particularly in the northern hemisphere—much more than climate records show actually happens, the researchers reported in the journal Geophysical Research Letters.

Instead, the researchers found that models with lower climate sensitivity are more consistent with observed differences in temperature between the northern and southern hemispheres, and, thus, are more accurate depictions of projected climate change than the newer models. The study was supported by the Carbon Mitigation Initiative (CMI) based in Princeton's High Meadows Environmental Institute (HMEI).

These findings are potentially significant when it comes to climate-change policy, explained co-author Gabriel Vecchi, a Princeton professor of geosciences and the High Meadows Environmental Institute and principal investigator in CMI. Because models with higher climate sensitivity forecast greater warming from greenhouse gas emissions, they also project more dire—and imminent—consequences such as more extreme sea-level rise and heat waves. ...

Chenggong Wang et al, Compensation Between Cloud Feedback and Aerosol‐Cloud Interaction in CMIP6 Models, Geophysical Research Letters (2021)
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020GL091024
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Re: The Climatic Effects of a Blue Ocean Event
« Reply #227 on: March 09, 2021, 11:04:47 AM »
Besides famines, how else would humans die due to a BOE?

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #228 on: March 09, 2021, 11:12:29 AM »
Besides famines, how else would humans die due to a BOE?
Could have worse heat waves in places not used to it?
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Re: The Climatic Effects of a Blue Ocean Event
« Reply #229 on: March 09, 2021, 12:02:46 PM »
Evidence for recent abrupt climate change and its implications. A BOE should have a similar impact.

A global environmental crisis 42,000 years ago

https://www.researchgate.net/publication/349448597_A_global_environmental_crisis_42000_years_ago

Quote
Abstract
Geological archives record multiple reversals of Earth’s magnetic poles, but the global impacts of these events, if any, remain unclear. Uncertain radiocarbon calibration has limited investigation of the potential effects of the last major magnetic inversion, known as the Laschamps Excursion [41 to 42 thousand years ago (ka)]. We use ancient New Zealand kauri trees (Agathis australis) to develop a detailed record of atmospheric radiocarbon levels across the Laschamps Excursion. We precisely characterize the geomagnetic reversal and perform global chemistry-climate modeling and detailed radiocarbon dating of paleoenvironmental records to investigate impacts. We find that geomagnetic field minima ~42 ka, in combination with Grand Solar Minima, caused substantial changes in atmospheric ozone concentration and circulation, driving synchronous global climate shifts that caused major environmental changes, extinction events, and transformations in the archaeological record.
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Re: The Climatic Effects of a Blue Ocean Event
« Reply #230 on: March 09, 2021, 12:14:51 PM »
Besides famines, how else would humans die due to a BOE?
If BOE accelerates global heating then

Plague -  many tropical diseases will spread to higher latitudes (as is already happening) even faster.

War - as food gets scarce humans will fight to secure that which is left.

Extreme weather events - though the death toll is relatively light the economic damage is large.

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #231 on: March 09, 2021, 12:31:58 PM »
BOE is expected to disrupt weather around the globe. Results could be as varied as floods, severe snowstorms, hurricanes, wildfires, failure of the electricity grid (e.g. Texas), all with the potential for human casualties. Longer term effects could include accelerated sea level rise and its resulting disasters. But yeah, famines are eventually the biggest threat.

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #232 on: March 09, 2021, 01:28:55 PM »
BOE is expected to disrupt weather around the globe. Results could be as varied as floods, severe snowstorms, hurricanes, wildfires, failure of the electricity grid (e.g. Texas), all with the potential for human casualties. Longer term effects could include accelerated sea level rise and its resulting disasters. But yeah, famines are eventually the biggest threat.

Although this is still somewhat controversial.  From this recent paper: 

"Arctic warming, regardless of its driver, has increased geopotential height thickness, which in turn has weakened the thermal wind.  It is not clear, however, how much these atmospheric changes have influenced the jet stream or the influence on storm tracks and occurrence of blocking events.  It is entirely possible that such a link exists, yet its manifestation in the real world is likely only of minor importance given the substantial year-to-year variability arising from internal variability of the climate system."

https://iopscience.iop.org/article/10.1088/1748-9326/aade56/pdf

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #233 on: March 09, 2021, 01:40:46 PM »
Depends on how you read it.

While it is understood that changes happening
within the Arctic do not stay there, it is less certain
whether current Arctic warming is already driving an
increase in storm frequency and extreme weather
events across the mid-latitude


So this is about the current changes and attribution is always problematic with these things.
It does not discuss BOE conditions when attribution will be much less problematic.

A BOE will bring much of the things Oren lists but all these are already in play. After a BOE much will be worse because it is a step away from current climate towards a much hotter earth. It should kick up global temps by a bit.

PS: Texas should not be in that list because that is just a human failure.
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Re: The Climatic Effects of a Blue Ocean Event
« Reply #234 on: March 09, 2021, 02:40:57 PM »
Quote
PS: Texas should not be in that list because that is just a human failure.

But human failures exacerbate almost any weather event. Even with the failures Texas would have been fine without the freeze. And you always have human failure.
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Re: The Climatic Effects of a Blue Ocean Event
« Reply #235 on: March 09, 2021, 02:54:14 PM »
Depends on how you read it.

While it is understood that changes happening
within the Arctic do not stay there, it is less certain
whether current Arctic warming is already driving an
increase in storm frequency and extreme weather
events across the mid-latitude


So this is about the current changes and attribution is always problematic with these things.
It does not discuss BOE conditions when attribution will be much less problematic.

A BOE will bring much of the things Oren lists but all these are already in play. After a BOE much will be worse because it is a step away from current climate towards a much hotter earth. It should kick up global temps by a bit.

PS: Texas should not be in that list because that is just a human failure.

While you seem to be certain, the authors of the paper are not. 

"Part of the difficulty in assessing the contribution of Arctic sea ice loss to changes in weather conditions derives from the fact that different modeling studies give divergent results depending on the specific model set-up.  Another key aspect is our still poor understanding on the two-way interactions between the tropospheric and stratospheric polar vortex."

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #236 on: March 09, 2021, 03:02:16 PM »
i don't think a BOE does anything by itself. 2012 was a sort-of-BOE (in some seas) and not much was changed. I think it is more of a process than a one-off event. Our climate is already changing.

Also, BOE means more water vapour = more rain/snow in mid to high latitudes. Also, more warmth = longer growing season. 

So, BOE will likely be good at some places and bad for other regions.
I think Canada and Russia are winners.

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #237 on: March 09, 2021, 04:09:12 PM »
i don't think a BOE does anything by itself. 2012 was a sort-of-BOE (in some seas) and not much was changed. I think it is more of a process than a one-off event. Our climate is already changing.

Also, BOE means more water vapour = more rain/snow in mid to high latitudes. Also, more warmth = longer growing season. 

So, BOE will likely be good at some places and bad for other regions.
I think Canada and Russia are winners.

I would add the Sahel region of Africa, which was greener during prior warmer eras.

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #238 on: March 09, 2021, 04:21:16 PM »
Quote
Even with the failures Texas would have been fine without the freeze.

You cannot control the freeze, you could plan not to fail.

Modelling results are one thing but if you assume BOE (which this thread does) you are looking at a different climate state or a huge step towards it. I think next decade will teach us a lot about that but we will see.

Quote
i don't think a BOE does anything by itself. 2012 was a sort-of-BOE (in some seas)


It is just the record worst year in some metrics and that is not the same as a BOE.
Last years ice ruble around the pole looked really bad but it was still quite a lot of ice just all broken up.

A BOE is when there is only water/ when we lose everything over 1 million square km.
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Re: The Climatic Effects of a Blue Ocean Event
« Reply #239 on: March 09, 2021, 04:38:12 PM »
i don't think a BOE does anything by itself. 2012 was a sort-of-BOE (in some seas) and not much was changed. I think it is more of a process than a one-off event. Our climate is already changing.

Also, BOE means more water vapour = more rain/snow in mid to high latitudes. Also, more warmth = longer growing season. 

So, BOE will likely be good at some places and bad for other regions.
I think Canada and Russia are winners.

I would add the Sahel region of Africa, which was greener during prior warmer eras.

On a real practical note:
Much of Russia will be melting slush emitting carbon so how is that winning?
Canada also has very little soil to start from if you want to go farming and a whole bunch of forests that would die so good?
Sahel. Well if it got more rain then it would green slowly.

None of this will be helpful on a time scale useful for us.
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Re: The Climatic Effects of a Blue Ocean Event
« Reply #240 on: March 09, 2021, 05:49:52 PM »
Russia: Russia is already emerging as a major agri-exporter. Warming means higher yields. Warming means some areas swithcing from wheat to corn which is more productive (because of the C4 pathway of photosythesis).

Canada: same. Warming = longer growing season= more calories

Texas: the majority of Texas DID NOT experience record cold. There were major, even colder Arctic outbreaks during the 20th century. Texas was a loser because of human stupidity (no interconnector to other states and stupid regulation), same as those Californian fires: people build in the middle of extremely dry forests which routinely burn down (natural process) and are amazed that they lode their homes...

So far, we have not seen any growth in the volatility of NH weather due to Arctic melting. I studied numerous data from various countries and have yet to see any proof of growing volatility. What I see is warming during almost all seasons.

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #241 on: March 09, 2021, 06:37:53 PM »
Northern Hemisphere Summers May Last Nearly Half the Year by 2100
https://phys.org/news/2021-03-northern-hemisphere-summers-year.html



Without efforts to mitigate climate change, summers spanning nearly six months may become the new normal by 2100 in the Northern Hemisphere, according to a new study. The change would likely have far-reaching impacts on agriculture, human health and the environment, according to the study authors

In the 1950s in the Northern Hemisphere, the four seasons arrived in a predictable and fairly even pattern. But climate change is now driving dramatic and irregular changes to the length and start dates of the seasons, which may become more extreme in the future under a business-as-usual climate scenario.

"Summers are getting longer and hotter while winters shorter and warmer due to global warming," said Yuping Guan, a physical oceanographer at the State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, and lead author of the new study in Geophysical Research Letters.

The new study found that, on average, summer grew from 78 to 95 days between 1952 to 2011, while winter shrank from 76 to 73 days. Spring and autumn also contracted from 124 to 115 days, and 87 to 82 days, respectively. Accordingly, spring and summer began earlier, while autumn and winter started later. The Mediterranean region and the Tibetan Plateau experienced the greatest changes to their seasonal cycles.

If these trends continue without any effort to mitigate climate change, the researchers predict that by 2100, winter will last less than two months, and the transitional spring and autumn seasons will shrink further as well.

"A hotter and longer summer will suffer more frequent and intensified high-temperature events—heatwaves and wildfires," Zhu said. Additionally, warmer, shorter winters may cause instability that leads to cold surges and winter storms, much like the recent snowstorms in Texas and Israel, he said.

Seasonal changes can also wreak havoc on agriculture, especially when false springs or late snowstorms damage budding plants. And with longer growing seasons, humans will breathe in more allergy-causing pollen, and disease-carrying mosquitoes can expand their range northward.

Jiamin Wang et al, Changing Lengths of the Four Seasons by Global Warming, Geophysical Research Letters (2021).
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020GL091753
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Sciguy

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #242 on: March 10, 2021, 12:16:22 AM »
Evidence for recent abrupt climate change and its implications. A BOE should have a similar impact.

A global environmental crisis 42,000 years ago

https://www.researchgate.net/publication/349448597_A_global_environmental_crisis_42000_years_ago

Quote
Abstract
Geological archives record multiple reversals of Earth’s magnetic poles, but the global impacts of these events, if any, remain unclear. Uncertain radiocarbon calibration has limited investigation of the potential effects of the last major magnetic inversion, known as the Laschamps Excursion [41 to 42 thousand years ago (ka)]. We use ancient New Zealand kauri trees (Agathis australis) to develop a detailed record of atmospheric radiocarbon levels across the Laschamps Excursion. We precisely characterize the geomagnetic reversal and perform global chemistry-climate modeling and detailed radiocarbon dating of paleoenvironmental records to investigate impacts. We find that geomagnetic field minima ~42 ka, in combination with Grand Solar Minima, caused substantial changes in atmospheric ozone concentration and circulation, driving synchronous global climate shifts that caused major environmental changes, extinction events, and transformations in the archaeological record.

According to the ice cores, the temperatures changed a lot 42,000 years ago in Greenland and were pretty stable in Antarctica during the magnetic field weakening.  Its hard to tell if the temperature changes were different from the normal temperature changes when the the field was stable during the past 100,000 years.



And increasing the time going back, the changes during the magnetic field weakening don't seem too extreme compared to interglacials.


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Re: The Climatic Effects of a Blue Ocean Event
« Reply #243 on: March 10, 2021, 06:26:50 AM »
How many years after a BOE would it take for famines to start happening?

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #244 on: March 10, 2021, 07:38:05 AM »
How many years after a BOE would it take for famines to start happening?

Most posters here would answer that immediately (or that it already should be happening except that despite AGW agri-yields and harvests are ever bigger).
I see our local climate models unable to correctly hindcast conditions from a few thousand years ago (especially precipitation-wise) and draw the conclusion that you should not trust them, because they can't tell you what will happen.

 My answer is that famines won't happen. Famines will only happen IF major agricultural regions will see very much reduced rainfall OR extreme cold. During known history, it was almost always extreme cold or lack of rain that brought food shortages, not warmth

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #245 on: March 10, 2021, 10:41:22 AM »
Most posters here would answer that immediately
I disagree with this assessment, and think it best to avoid making such generalizations. Just state your opinion.

As for the original question by m.r.s, it is not a given that famines are a result of a BOE. The best is to wait and see, take about a decade for the first BOE (my personal estimate), then a decade of observations.

The problem is famines could also be a result of civilizational collapse and of the human population having exceeded its carrying capacity a while ago, and ongoing destruction of the environment as a result. So your observations might suffer from interference when it comes to assigning reasons.

Or famines might not happen at all, and technology will have saved us, or the planet's carrying capacity is in reality much higher. I doubt both of these hopes, but they are not impossible.

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #246 on: March 10, 2021, 12:31:37 PM »
How many years after a BOE would it take for famines to start happening?

Most posters here would answer that immediately (or that it already should be happening except that despite AGW agri-yields and harvests are ever bigger).
I see our local climate models unable to correctly hindcast conditions from a few thousand years ago (especially precipitation-wise) and draw the conclusion that you should not trust them, because they can't tell you what will happen.

 My answer is that famines won't happen. Famines will only happen IF major agricultural regions will see very much reduced rainfall OR extreme cold. During known history, it was almost always extreme cold or lack of rain that brought food shortages, not warmth

Historically, this is true.  Whatever the cause of the warmth, they did not result in famines.

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #247 on: March 10, 2021, 02:05:05 PM »
But all historic warming we know happened during ice age earth so for most areas during most time cooling was more of a problem then warming because plants were growing well within their tolerance zone.

We already have these pressures.
https://www.sciencedaily.com/releases/2021/03/210308111954.htm

In fact we do not really need a BOE event for famines although they themselves are mostly a result of a distribution problem (we have enough food for everyone, we just are not interested in getting everyone fed).
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Re: The Climatic Effects of a Blue Ocean Event
« Reply #248 on: March 10, 2021, 02:49:12 PM »
How many years after a BOE would it take for famines to start happening?

Most posters here would answer that immediately (or that it already should be happening except that despite AGW agri-yields and harvests are ever bigger).

I would. Humanity is already feeling the effects of climate change. Agricultural losses that result directly from climate change can already be quantified. Technology and our current wealth allow us to adapt and repair agriculture faster than it can be destroyed by the increasingly destructive weather.

The earth is very giving. Humans are very resourceful. The combination of the two makes the human food chain a formidably redundant system. As long as we can repair and improve our systems faster than climate change can destroy or degrade them, we are good to go. That has been the case up until today.


 Neanderthals were not so resourceful 42,000 years ago.


According to the ice cores, the temperatures changed a lot 42,000 years ago in Greenland and were pretty stable in Antarctica during the magnetic field weakening.  Its hard to tell if the temperature changes were different from the normal temperature changes when the the field was stable during the past 100,000 years.



I think that the most significant part of this research is the extremely detailed timeframe of about 1000 years obtained from trees.  When looking into the consequences of abrupt climate change one can't look at the time frame of thousands of years. One must look at the time frame of decades. Attached, Figure 4 from the referenced paper.
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Re: The Climatic Effects of a Blue Ocean Event
« Reply #249 on: March 10, 2021, 03:17:17 PM »
It is a totally different thing to a BOE and thus off topic here.

Quote
The earth is very giving. Humans are very resourceful. The combination of the two makes the human food chain a formidably redundant system. As long as we can repair and improve our systems faster than climate change can destroy or degrade them, we are good to go. That has been the case up until today.

But do check out soil degradation, changes in water tables, chemical pollution etc.
None related to BOE effects btw...
Þetta minnismerki er til vitnis um að við vitum hvað er að gerast og hvað þarf að gera. Aðeins þú veist hvort við gerðum eitthvað.