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gerontocrat

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #150 on: September 18, 2020, 12:33:37 PM »
Is Central Arctic a combination of the blue seas or a separate entry?
I'm pretty sure it's only the Central Arctic Sea - as in the NSIDC definition of 3.2 million km2 which is MAISIE Area 11.

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kassy

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #151 on: September 18, 2020, 05:55:44 PM »
Thanks. I found the percentages oddly similar but looking at graphs it is a seasonal effect for most of the time.
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Re: The Climatic Effects of a Blue Ocean Event
« Reply #152 on: September 18, 2020, 07:57:38 PM »
As with ESAS methane, nobody wants to hear about albedo, better to err on the side of least drama, hundreds of examples documented by AbruptSLR on that forum.

Thanks.

People are also not that into real simple climate science.

Paris agreement. We keep under some ´safe´ 2C level.
Safe is not actually defined so lets substitute the usual climate tipping points. Keeping the permafrost a sink has failed. Saving the arctic ice has failed. Not triggering Antarctica too etc.
And that is with current temps.

The Arctic ices ´old ice skeleton´ is clearly failing so next year might be even worse in the Central Arctic. I think this region is more vulnerable then people usually argue so we might see unprecedented losses there soon (this decade) and then we will see what Earth calculates for the budget and what the actual knock on effects are.
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Archimid

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #153 on: September 19, 2020, 08:59:12 AM »
This is a huge deal in itself, calculated below as a trillion tons of CO2 emission equivalent. (No one gives a hoot about local DMI 80N graphics.)

The last sentence of the abtract in "Radiative Heating of an Ice-Free Arctic Ocean" seems to agree with the above sentence.

Quote
This is equivalent to the effect of one trillion tons of CO2 emissions. These results suggest
 that the additional heating due to complete Arctic sea ice loss would hasten global warming by an estimated 25 years.

IMHO, this is the wrong way to understand the consequences of a BOE.  Annualizing and globalizing the local impact of the loss of sea ice minimizes its impact.  A BOE is more impactful for the magnitude of the local change than for the potential increase in global temperatures.
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gerontocrat

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #154 on: September 19, 2020, 10:00:02 AM »
This is a huge deal in itself, calculated below as a trillion tons of CO2 emission equivalent. (No one gives a hoot about local DMI 80N graphics.)

The last sentence of the abtract in "Radiative Heating of an Ice-Free Arctic Ocean" seems to agree with the above sentence.

Quote
This is equivalent to the effect of one trillion tons of CO2 emissions. These results suggest
 that the additional heating due to complete Arctic sea ice loss would hasten global warming by an estimated 25 years.

IMHO, this is the wrong way to understand the consequences of a BOE.  Annualizing and globalizing the local impact of the loss of sea ice minimizes its impact.  A BOE is more impactful for the magnitude of the local change than for the potential increase in global temperatures.
I would go even further, and suggest a future BOE is somewhat of a distraction - by just looking at the climatic effects of a BOE we can end up ignoring the here and now.
And by concentrating on Albedo we can end up ignoring the climatic effect of open water in winter.

There is a study that links a very cold winter in North America with low winter sea ice in the Bering Sea. As I write this, it looks like some real weather will hit the central Arctic from Siberia by mid-week. Insolation will be minimal, but that weather will be travelling over large areas of open water where a few years ago it would have been ice. there are climatic effects in the here and now.

A BOE will likely be just another marginal addition to climatic effects accumulated over the years.
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Archimid

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #155 on: September 19, 2020, 02:58:18 PM »
Before I continue I want to make it clear. I think that paper is great in its own merits and I understand the tremendous usefulness of casting the problem in terms of CO2 and global temps. We need more papers like that.

That said, I think the spectrum of changes that will happen due to a BOE started already. We are seeing the beginings of a BOE.  I think BOE induced climate change will exponentially increase  from here until surface Temperatures N80 depart their historic temperature variability ( or lack thereof)  during summer.  At that point climate change will already be the stuff of our worst nighmares.

However, that point will mark a further acceleration of change that would make an outside observer take the year of a BOE as a tipping point for Earth's climate. To an observer inside the planet, it will be a continuum of SHTF.

I think the lack of variability of Summer N80 temperatures, even after decades of global warming, is what makes it such a great marker.



This is air temperatures, but taken so close to the surface that surface conditions mostly dictate the temperatures. When this number departs its long term variability the planet will enter a distinctly different climate regime in the NH.
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El Cid

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #156 on: September 19, 2020, 07:12:53 PM »
When talking about BOE one should never forget that Greenland (2,1 M sqkm) is basically constantly ice covered and will be so for hundreds of years. The total ice covered area is therefore Arctic Ice+ 2,1 M sq km. Even during a BOE (which is defined by some as ice below 1 M sqkm in the Arctic Ocean), there will still be a grand total of 3 M sqkm of ice - with all its effects on NH climate.

So a BOE is NOT a qualitative change, it is part of a trend. It is going from last summers' cca 6 M sqkm of ice (4+2) to 3 or 2,5. It will have effects but not qualitatively different from the trends we already see. And this is what we see:

A-Team

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #157 on: September 19, 2020, 07:30:44 PM »
Quote
My effect is so much more important than your effect.
Please keep comments appropriate to the "Climatic Effects of a Blue Ocean Event" forum. This is not a catch-all forum for climate change or climate policy discussion. 'Climatic' means inappropriate for local Arctic-only seasonal impacts as these have their own forums.

Consider discussing and developing your favorite BOE climatic effect based on other recent scientific journal articles. Just making bald assertions or intuiting is not going to work quantitatively given the complexity of planetary climate systems. Try https://scholar.google.com/ to see where a given subject is at. Full text can always be located at https://sci-hub.se/.

Rightly or wrongly, the vast majority of climate science focuses on long-term build-up of greenhouse gases and their effects at NH mid-latitudes where most white people live and most of their food is grown. Rightly or wrongly, messaging is currently centered on CO2 levels and what can be done to reduce it (more trees, less beef consumption, fossil fuels, consumerism). All this is incredibly important but unacceptably off-topic given this forum's restricted remit.

The authors here framed their result in the above context, the trillion extra tons. Their calculated effect on annual heat retention alone is enough by itself to seriously undercut current global policy planning on climate change and to significantly offset benefits from planting trees, going vegan and riding wind-powered electric bicycles. Yes, lots of other feedbacks like ESAS methane could pile on but there are forums for those too.

My subsequent posts will be looking into the calculation itself and its reliability. Science does not arrive written on clay tablets. Already, an alternative method has been published. Those authors find less of an effect but actually their results still call for a massive effect (which they call 'modest'). Still, both calculations could be wrong or have too high a level of uncertainty to deserve concern priority.

To repeat, the loss of the planet's primary climate-buffering refrigerator (seasonal high latitude albedo) is only one aspect of downstream consequences of fractional loss of Arctic sea ice increasingly matching the insolation season.

BOE events do not happen overnight on Sept 14th but instead will have a long lead-up of increasing areas of low albedo open water, a much better match to peak insolation than mid-Sep dates which don't match at all. More sunlight absorbed means less reflected up and, after cloud and atmospheric processes, less incident sunlight escaping out to space.

The papers under consideration look only at this: heat retained = TOE input - TOE output above 60ºN and attributable to massive sea ice loss.

The three articles do not aspire to represent all downstream aspects nor to compare its impacts to all others; they merely assert it is large and real. If you find scientific errors missed by peer reviewers -- and that happens -- please document specifics. Alternatively, write a separate post based on different articles about your pet effect.
 
The first graphic is taken from a pair of easy-read classics by Perovich, Stroeve and others. They follow the solar insolation distribution during seasonal evolution of the surface, the complement of the Pistone 2019 independent top of atmosphere observations and projections.

Solar partitioning in a changing Arctic sea-ice cover
DK Perovich et al
Annals of Glaciology 52(57) 2011

"The daily values of albedo depend on the local onset dates of melt and freeze-up. The albedo sequence includes melt ponds, assuming they follow an evolution similar to that observed by Perovich and others (2002). Using the method of Markus and others (2009), daily averaged satellite passive microwave temperatures are used to map four onset dates for each grid cell for each year: early melt, full melt, early freeze-up and full freeze-up.

"Briefly, the melt season is determined using temporal changes in brightness temperatures at 37 GHz and temporal changes in the gradient ratio between 19 and 37 GHz

1. Before melt onset the snow albedo is 0.85.
2. At early melt the albedo decreases to 0.81.
3. Starting with full melt, there is a linear decrease to 0.71 in 15 days.
4. For the next 6 days, decrease from 0.70 to 0.50.
5. Albedo decreases by 0.0029 d–1 (but to no less than 0.2).
6. At early freeze-up set albedo to 0.46, representing some ponds freezing.
7. At full freeze-up, albedo increases by 0.026 per day to 0.85."

Increasing solar heating of the Arctic Ocean and adjacent seas, 1979–2005:
DK Perovich et al
Geophys. Res. Lett., 34(19), L19505. (10.1029/2007GL031480.)

The graphical time series will look at incipient fractional BOE: open water in the Arctic Basin at the time of maximum insolation (summer solstice, June 21). There is a surprising amount of open water already on that date and has been for years. However the AMSR2 record used is not long enough to distinguish trend from natural variability. That is a fool's errand anyway if the New Arctic is qualitatively different. However the unweighted locational average is still instructive.

The animation will show open water for the years 2013-20 (since 2012 data starts later). The second graphic will provide the average geographic distribution for open water for eight years on the solstice and later dates. A preliminary version gives the idea.

This average is calculated graphically to sidestep the flawed netCDF. Select open water blue in each year and color it 240 white (out of 256 pure white). If every year has open water at a given pixel location, then all the pixels will be 240 and the average atoo in the output graphic. If 7 years are open water, then 7/8 or 210 is the output, and so on down to 1/8 yielding 30, not quite black. 

Thus the average-graphic is strongly but accurately binned into a 8-10 colors (allowing a few extra for land and and pole markers. The image can then be recolored with any discrete palette without disturbing quantitative accuracy.

To weight recent years more heavily, their layer simply needs to be duplicated by the chosen weighting number.
« Last Edit: September 20, 2020, 11:01:22 AM by A-Team »

The Walrus

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #158 on: September 19, 2020, 07:47:13 PM »

I think the lack of variability of Summer N80 temperatures, even after decades of global warming, is what makes it such a great marker.



This is air temperatures, but taken so close to the surface that surface conditions mostly dictate the temperatures. When this number departs its long term variability the planet will enter a distinctly different climate regime in the NH.

I believe that the lack of summer warming north of 80 is more than just a result of the ice cover.  The entire Arctic ocean covers 14 million km2.  At minimum, the ice covers ~4 million km2.  That means that over 70% of the ocean is ice free.  That should have some effect on the overall temperature.  But according to the graph, it does not.  Therefore, it must be more an effect of rising concentrations of CO2 and other gases than ice cover.  While the trapping effect of CO2 can be seen easily during the winter months in the graph, there is little trapping effect during the summer months.  The long hours of darkness mean that much heat is lost to the atmosphere, and subsequently, space.  The added CO2 in the atmosphere decreases that loss, and the result is an increase in temperature.  During summer, there are no hours of darkness, so consequently, no heat loss.  The incoming solar radiation is decreased just slightly by the increased concentration of CO2, such that the difference is unapparent in the graph (it may balance the added heat from ocean circulation also).  Further ice loss is not likely to change summer temperatures significantly.

oren

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #159 on: September 20, 2020, 12:26:24 AM »
Walrus, please don't spread nonsense pet theories bordering on denial. Heat is radiated to space in the daytime too, and CO2 does contribute to warming in summer. Temps N of 80 do not cover 14 million km2, and the DMI weighting is further skewed towards the pole. So the region is still refrigerated by sea ice, the loss of which will surely lead to increased summer temperatures.

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #160 on: September 20, 2020, 12:27:30 AM »
A-Team, thank you for the educational posts in this thread.

The Walrus

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #161 on: September 20, 2020, 02:48:52 AM »
Walrus, please don't spread nonsense pet theories bordering on denial. Heat is radiated to space in the daytime too, and CO2 does contribute to warming in summer. Temps N of 80 do not cover 14 million km2, and the DMI weighting is further skewed towards the pole. So the region is still refrigerated by sea ice, the loss of which will surely lead to increased summer temperatures.

Since when is the concept that sunlight warms the earth and it cooks at night a “nonsense pet theory?”  The arctic is covered by more ice in winter, but that does not prevent temperatures from increasing.  You cannot possibly be implying that stating that increased atmospheric concentrations of CO2 have a greater impact on nighttime heat loss than daytime heating is somehow denialism!  Perhaps you need to read more about how the atmosphere warns the planet and arctic amplification.

kassy

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #162 on: September 20, 2020, 10:55:43 AM »
Temps N of 80 do not cover 14 million km2, and the DMI weighting is further skewed towards the pole.

That is the relevant part. So for now the ice is still there.
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The Walrus

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #163 on: September 20, 2020, 02:45:32 PM »
Temps N of 80 do not cover 14 million km2, and the DMI weighting is further skewed towards the pole.

That is the relevant part. So for now the ice is still there.

Yet, temperature changes in Greenland do not support this theory.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5258655/

"The marked warming during February deserves attention and a more detailed investigation of its origin should be made. Since it is observed over large parts of the West coast, it is unlikely that changing sea ice conditions are the main trigger as we assume that the warming would then predominantly affect the stations where the sea ice change occurs. Since both regions with and without seasonal sea ice show this warming signal, we rather assume it is connected to changed atmospheric patterns, asymmetric changes in the north Atlantic oscillation or the Greenland blocking index"

kassy

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #164 on: September 20, 2020, 10:28:01 PM »
It´s not a theory since we can see the ice there even if it is in bits.

A significant air pressure decrease in September is evident for the 1996–2014 period, which may be linked to delayed sea ice formation.

Which is mainly happening outside the core region of the graph.
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metalreflectslime

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #165 on: September 21, 2020, 07:56:47 AM »
How would a BOE cause famines?

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #166 on: September 21, 2020, 12:09:11 PM »
How would a BOE cause famines?
By changing the wind patterns of the NH and hence the precipitation patterns, thus causing drought and flooding in diverse places and lowering crop production.
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El Cid

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #167 on: September 21, 2020, 12:44:21 PM »
How would a BOE cause famines?
By changing the wind patterns of the NH and hence the precipitation patterns, thus causing drought and flooding in diverse places and lowering crop production.

That is the biggest question. Warmth in NH midlatitudes is usually not harmful. Actually, in most places it is beneficial because of a a longer growing season. Huge areas of Canada, Russia and the US will be better for agriculture IF the rains come.
We know that globally there will be more rain with warming, we just don't know where and how much will fall.

I think our best indication for future rain patterns is studying Pliocene climate/biomes/climate conditions. For example here:

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2002GC000358

Table 2 lists 72 places, where we have temperature and/or precipitation estimates for the Pliocene warm period, when temperatures were cca 3-5 C higher and there was no Arctic Ice cap. Generally, Europe and North America saw more precipitation, eg. Arizona had savannas , Nevada ponds, marshes, Utah at least 600 mm rain, Europe had more rain than now, etc.

josh-j

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #168 on: September 21, 2020, 10:31:31 PM »
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2002GC000358

Table 2 lists 72 places, where we have temperature and/or precipitation estimates for the Pliocene warm period, when temperatures were cca 3-5 C higher and there was no Arctic Ice cap. Generally, Europe and North America saw more precipitation, eg. Arizona had savannas , Nevada ponds, marshes, Utah at least 600 mm rain, Europe had more rain than now, etc.

While I certainly don't have the knowledge to disagree on this point, I would guess there might be a difference between rainfall within the stable warm period and rainfall during a rapid transition into a warm period.

Its the potential year-to-year unpredictability I'm worried about.

El Cid

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #169 on: September 22, 2020, 07:27:21 AM »
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2002GC000358

Table 2 lists 72 places, where we have temperature and/or precipitation estimates for the Pliocene warm period, when temperatures were cca 3-5 C higher and there was no Arctic Ice cap. Generally, Europe and North America saw more precipitation, eg. Arizona had savannas , Nevada ponds, marshes, Utah at least 600 mm rain, Europe had more rain than now, etc.

While I certainly don't have the knowledge to disagree on this point, I would guess there might be a difference between rainfall within the stable warm period and rainfall during a rapid transition into a warm period.

Its the potential year-to-year unpredictability I'm worried about.

That is an absolutely valid argument

KiwiGriff

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #170 on: September 22, 2020, 07:41:41 AM »
I am of course in the south
How  ever we seem to be getting wild swings in rain fall
Record wet things die we lost trees due to soggy soil three years ago.
Record dry things die I lost many ten year old tree ferns last year.
You can not plan for a future with such unpredictable weather.
The local ecology can not hope to cope with such swings and neither can human infrastructure.

Animals can be driven crazy by placing too many in too small a pen. Homo sapiens is the only animal that voluntarily does this to himself.
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Re: The Climatic Effects of a Blue Ocean Event
« Reply #171 on: September 22, 2020, 09:26:43 AM »
Quote
Warmth in NH midlatitudes is usually not harmful. Actually, in most places it is beneficial because of a a longer growing season.

The growing season will not grow longer. It will grow more irregular. More early/late frosts. More early/late heatwaves. More heavy rains and droughts.  More heavy snows and droughts. Less regularity. That is what is happening now, I expect it to increase as we approach a BOE.
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Re: The Climatic Effects of a Blue Ocean Event
« Reply #172 on: September 22, 2020, 09:51:51 AM »
Quote
Warmth in NH midlatitudes is usually not harmful. Actually, in most places it is beneficial because of a a longer growing season.

The growing season will not grow longer. It will grow more irregular. More early/late frosts. More early/late heatwaves. More heavy rains and droughts.  More heavy snows and droughts. Less regularity. That is what is happening now, I expect it to increase as we approach a BOE.

That is not the experience of the past 10 years, at least not in Europe. There seems to be no growth in the standard deviation of temperature. Both monthly high and low temperatures are higher. The growing season IS longer. There is a marked change since 2007 for sure but that is a change of general warming.
For example in my country the average last frost date is now earlier by 13 days (2010s vs 1960-1990), the average first frost date is later by 13 days and both monthly minimum and maximum temperatures are higher by 1-3 C. This is true for most of Europe. Not based on anecdotal evidence but on hard data measurements.

Shared Humanity

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #173 on: September 22, 2020, 03:36:39 PM »
There is a marked change since 2007 for sure but that is a change of general warming.



Hmmmm...I seem to recall some big event happened in 2007 regarding Arctic Sea ice. Can't quite put my finger on it.

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #174 on: September 22, 2020, 03:51:40 PM »
There is a marked change since 2007 for sure but that is a change of general warming.



Hmmmm...I seem to recall some big event happened in 2007 regarding Arctic Sea ice. Can't quite put my finger on it.

Just one roadmark on a long road.
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The Walrus

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #175 on: September 22, 2020, 03:51:54 PM »
Quote
Warmth in NH midlatitudes is usually not harmful. Actually, in most places it is beneficial because of a a longer growing season.

The growing season will not grow longer. It will grow more irregular. More early/late frosts. More early/late heatwaves. More heavy rains and droughts.  More heavy snows and droughts. Less regularity. That is what is happening now, I expect it to increase as we approach a BOE.

That is not the experience of the past 10 years, at least not in Europe. There seems to be no growth in the standard deviation of temperature. Both monthly high and low temperatures are higher. The growing season IS longer. There is a marked change since 2007 for sure but that is a change of general warming.
For example in my country the average last frost date is now earlier by 13 days (2010s vs 1960-1990), the average first frost date is later by 13 days and both monthly minimum and maximum temperatures are higher by 1-3 C. This is true for most of Europe. Not based on anecdotal evidence but on hard data measurements.

A similar observation can be made for the U.S.  While, rainfall has generally increased, the standard deviation has remained constant.

https://19january2017snapshot.epa.gov/climate-indicators/climate-change-indicators-us-and-global-precipitation_.html

A study focusing on just the Midwestern U.S. showed an "increase in the number of heavy precipitation events as well as overall increase in the number of wet days and multiple wet day events."  This trend is exemplified in both the "increased flood risk" and "decreased incidence of drought" as well as "reduced numbers of extreme and exceptional droughts."

http://glisa.umich.edu/media/files/NCA/MTIT_Historical.pdf

The increased precipitation has not been accompanied by an increase in variability.

El Cid

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #176 on: September 22, 2020, 07:36:59 PM »
There is a marked change since 2007 for sure but that is a change of general warming.



Hmmmm...I seem to recall some big event happened in 2007 regarding Arctic Sea ice. Can't quite put my finger on it.

Yes, It is not a coincidence. Europe's weather changed very much after 2007. If you compare before 2007 and after 2007 there is a significant difference. And that difference in temperatures is a higher average but not a higher standard deviation. The weather has gotten warmer but not more volatile. That was my point.

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #177 on: September 22, 2020, 09:55:27 PM »
There is a marked change since 2007 for sure but that is a change of general warming.



Hmmmm...I seem to recall some big event happened in 2007 regarding Arctic Sea ice. Can't quite put my finger on it.

Yes, It is not a coincidence. Europe's weather changed very much after 2007. If you compare before 2007 and after 2007 there is a significant difference. And that difference in temperatures is a higher average but not a higher standard deviation. The weather has gotten warmer but not more volatile. That was my point.

As I read it, your statement suggests that the marked change after 2007 was not due to far more ice free Arctic Ocean but rather simply general warming. I would argue the marked change is directly related to less ice.

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #178 on: September 22, 2020, 10:23:21 PM »
Here is a clearly written August 2020 scientific BOE paper from the modeling community that makes for interesting reading. The focus is paleo, not on the little understood Pliocene but rather the last inter-glacial, as analyzed in HadGEM3 (HadGEM3-GC3.1-N96ORCA1 CMIP6 PMIP4) which is said much improved for its Arctic melt pond treatment (so timely, given the Polarstern's pole photos!). After validation, HadGEM3 is run forward to predict a 2035 BOE with a million sq km threshold for ice free.

The latest Hadley model (with its higher equilibrium climate sensitivity of 5.5K) concludes that the Arctic Ocean was ice-free during much of 130,000–116,000 years before present. Sediment cores (isotopes, Beaufort shelf microfauna, planktonic foraminifera in Arctic cores, ostracodes from the Lomonosov and Morris Jesup Rise) established  long ago that temperatures were 4–5 °C warmer than pre-industrial and sea ice a lot less but previous simulations were missing something and could not reproduce the higher temperatures. That missing something was earlier melt pond albedo loss according to this paper.

The authors duly note a conflict with a new sea-ice proxy IP25 (a branched isoprenoid of 25 carbons) interpreted as evidence of perennial ice cover in the central part of the Arctic Ocean but the applicability here is unclear.

They also write that HadGEM3 mid-latitude temperatures are higher than some proxy records but that the "validation of LIG temperatures outside the Arctic is beyond the scope of this study and suffers from sparse data records'.

The sea-ice loss in August and September is robust and persistent with (non-BOE) sea ice being present in just 2% of the model runs by Aug/Sept. This is due to an oddity of how the earth's orbit affects insolation reaching various latitudes in various months, see attached figure.

"The interglacial top-of-atmosphere radiative flux north of 70°N is 60–75 w/m2 higher than during the pre-industrial 1850in early summer. This increase in incoming radiation is well known and has been applied in previous LIG climate-model simulations. The crucial aspect is to what extent this increase causes additional melt of sea ice. Snow-covered sea ice has a high albedo, so only a small fraction of the additional incoming short-wave radiation flux causes more melting.

"The substantial increase of surface net short-wave flux (with maximum value of around 70 w/m2 in July) is caused by a decrease of surface albedo. In contrast to previous simulations, HadGEM3 includes a physically based melt-pond model, which substantially modifies the ice-albedo feedback. Sea ice melts because of the direct absorption of sunlight and transmission of short-wave radiation through ponded and bare ice to the ocean, which in turn warms. Melt ponds forming in summer months thus contribute to melting sea ice as more radiation reaches the ocean.

"We find that clouds over sea ice play little role in determining LIG − PI anomalies in the surface energy balance of the Arctic region. The contribution from the long-wave radiation to the total energy balance anomalies (computed between 70 and 90°N) is almost zero. Indeed, north of 70°N, the Arctic cloud area fraction is almost identical in the LIG and PI HadGEM3 simulations. Fewer clouds during these summer months allow more solar radiation to reach the ocean.

"In contrast to previous simulations, HadGEM3 includes a physically based melt-pond model, which substantially modifies the albedo feedback. Sea ice melts because of the direct absorption of sunlight and transmission of short-wave radiation through ponded and bare ice to the ocean, which in turn warms. Melt ponds forming in summer months thus contribute to melting sea ice as more radiation reaches the ocean. This relationship is implicated in a faster rate of summer sea-ice melt in HadGEM3 in the LIG than in the PI. In July, most of the LIG sea ice is already melted or has a concentration smaller than 50% . By September, all the LIG sea ice is melted.

"In previous work, the persistence of summer sea ice in the cen- tral Arctic during the LIG was linked to a slowdown of the Atlantic Meridional Overturning Circulation (AMOC). However, over the 200 years of our simulations, the AMOC is almost unchanged between the LIG and PI. Thus, the hypothesized compensating mechanism, by which a reduction in northward oceanic heat transport (owing to a weakening of the AMOC) prevents sea-ice loss in the central Arctic during the LIG13, does not occur.

"the Arctic sea ice in HadGEM3 historical simulations is too thick compared with present-day observations. However, this bias towards thick sea ice in HadGEM3 does not provide protection from complete Arctic summer sea-ice loss during the LIG. Indeed, the transition under LIG insolation into a summer sea-ice-free (zero multiyear ice) state in HadGEM3 takes around five model-years to complete. Once the multiyear sea ice has disappeared in our simulations, it does not return. Over 200 years of simulation, the August and September sea-ice extent exceeds the ice-free threshold of 1 million km2 only in four and five years for September and August resp.

"The ability of the HadGEM3 model to realistically simulate the very warm LIG Arctic climate provides independent support for predictions of ice-free conditions by summer 2035. This should be of huge concern to Arctic communities and climate scientists."

I wanted to look at text annotations of the melt pond code component. However this requires multiple registrations and even license applications. The authors declare all other data is available in the paper and its voluminous Supplementary Information.

Data availability
The CMIP3-6 model data used in this study to compute ECS and ice-free years are available from the Earth System Grid Federation (https://esgf-node.llnl.gov/). The HadCM3 and HadGEM3 model outputs used to support the findings of this study are available from http://gws-access.ceda.ac.uk/public/pmip4/vittoria/CMIP6LIG_ HadGEM3_CMIP3_HadCM3/. The HadGEM3 model outputs prepared for CMIP6 can be found at https://doi.org/10.22033/ESGF/CMIP6.419 

Code availability
The source code of the HadCM3 model and the HadGEM3 model’s atmospheric component (Unified Model) is available under licence. To apply for a licence, go to http://www.metoffice.gov.uk/research/modelling-systems/unified-model. JULES is available under licence free of charge; see https://jules-lsm.github.io/. The NEMO model code is available from http://www.nemo-ocean.eu. The model code for CICE can be downloaded from https://code.metoffice.gov.uk/trac/cice/browser.

Sea-ice-free Arctic during the Last Interglacial supports fast future loss  [2035 BOE]
MV Guarino ... J Stroeve D Schroeder D Feltham et al  complementary pdf attached
https://www.nature.com/articles/s41558-020-0865-2  August 2020

Past evidence supports complete loss of Arctic sea-ice by 2035
British Antarctic Survey August 2020
https://www.sciencedaily.com/releases/2020/08/200810113216.htm
« Last Edit: September 23, 2020, 01:06:26 AM by A-Team »

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #179 on: September 23, 2020, 06:58:26 AM »
Their has been an increase in extreme events. High temperatures extreme rainfall storms etc.

El Cid

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #180 on: September 23, 2020, 07:55:45 AM »
As I read it, your statement suggests that the marked change after 2007 was not due to far more ice free Arctic Ocean but rather simply general warming. I would argue the marked change is directly related to less ice.

We have no argument here SH. Arctic sea ice loss seems to have a very direct effect on NH midlatitudes climate. My argument (based on European data) was only that temperature-variability has not become bigger so far.

***

Modelling results: Great article quoted by A-team but I have little faith in (regional effects based on) climate models since they can not even replicate known Holocene Optimum Europe precipitation patterns and temperatures and can not replicate the Green Sahara - only with very unreal tweaks. Maybe these new models are better than previously, don't know.

***

LIG Arctic sea ice cover: I read studies that (based on paleo data) claimed that the Arctic was mostly ice-free and some that claimed the opposite. Anyway, during the Eemian thermal optimum, studies show warmer temperatures than today in Europe, a treeline moving north by a lot and more precipitation. Europe was covered by forests much further to the north than now possible.

***

intestitial,

I know the popular narrative of growing variability. However, claiming that there will be more extreme  heat days does not mean that variability is higher. Variability is growing if there are more extreme hot AND cold days. That does not seem to be the case. There are more very hot days and less very cold days. That is a significant difference.

As for rain, it is likely that with more energy in the system there will be more extreme rain events but that hasnt happened yet either

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #181 on: September 23, 2020, 10:11:35 AM »
Thanks for the link A-team.

Quote
Once the multiyear sea ice has disappeared in our simulations, it does not return.

Yup. Winter ice returns, but Arctic sea ice becomes seasonal all the way to the North Pole. This will change the Northern Hemisphere climate in a geological instant.
 

To El Cid and others:

The "growing season" does not equal summer or "not winter". Growing anything requiere many more variables than just temperatures or the variability of temperatures. All these variables are changing faster as the world warms ( entropy increases) AND as the arctic melts these variables change even faster in the NH.

Even then, global or country temperature variability say nothing about extreme events, in fact the overly broad variables you are using hides extreme events.

Quote
LIG Arctic sea ice cover: I read studies that (based on paleo data) claimed that the Arctic was mostly ice-free and some that claimed the opposite.

A-team's link probably explains it.

Quote
"In previous work, the persistence of summer sea ice in the cen- tral Arctic during the LIG was linked to a slowdown of the Atlantic Meridional Overturning Circulation (AMOC). However, over the 200 years of our simulations, the AMOC is almost unchanged between the LIG and PI. Thus, the hypothesized compensating mechanism, by which a reduction in northward oceanic heat transport (owing to a weakening of the AMOC) prevents sea-ice loss in the central Arctic during the LIG13, does not occur.
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El Cid

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #182 on: September 23, 2020, 01:43:16 PM »
The "growing season" does not equal summer or "not winter". Growing anything requiere many more variables than just temperatures or the variability of temperatures. All these variables are changing faster as the world warms ( entropy increases) AND as the arctic melts these variables change even faster in the NH.

That sounds like religion to me ("temperature and precipitation volatility does not matter, a longer growing season does not matter, because there MUST be some variables that portend tragedy for agriculture, although I don't know what"). 

Last time I checked the Eemian probably did have only seasonal ice (BOE!), yet Europe was heavily forested even in Northern Scandinavia where we currently have tundra, and the Sahara was green, so somehow this must have been beneficial for life there. If trees grew very well, it must not have been that terrible I guess.

And no, this is not denialism, this is science. Let's see what happened the last (few times) when we had BOE. Then we can have an idea about the climatic effects of BOE, the title of this thread.

A BOE by itself will not destroy mankind. A hothouse Earth might. That's why we must stop AGW as fast as we can, because we are not just going towards BOE, we are actually rushing towards hothouse Earth. There is a huge difference between the two!

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #183 on: September 23, 2020, 09:43:25 PM »
The average is getting warmer but more extreme events are occurring. Recently Colorado went from record heat to snow in a short time. Plants don't survive things like that very well. If you have drought conditions for months or even a few years than it is followed by a years worth of precipitation in one day. We are used to a planet that slowly transitions through seasons now we get whiplash. On reflection variability may not be the right word for what I mean but it is a huge problem.

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #184 on: September 23, 2020, 11:23:10 PM »
The average is getting warmer but more extreme events are occurring. Recently Colorado went from record heat to snow in a short time. Plants don't survive things like that very well. If you have drought conditions for months or even a few years than it is followed by a years worth of precipitation in one day. We are used to a planet that slowly transitions through seasons now we get whiplash. On reflection variability may not be the right word for what I mean but it is a huge problem.

We may be used to slow transitions, but nature is anything but.  Warming is occurring more strongly at night and during winter, such that diurnal and seasonal changes have been less extreme.  Rainfall has increased also, but it has been accompanied by a decrease in drought, so that farmers have been better able to adjust.  By the way, Colorado is known for its sudden changes.  That was not even a record breaking change.  I think variability is the correct word, and the weather is getting less variable.

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #185 on: September 24, 2020, 08:04:51 AM »
The average is getting warmer but more extreme events are occurring. ...
... If you have drought conditions for months or even a few years than it is followed by a years worth of precipitation in one day.

Once again, you would need to prove this. Current data that I have seen has not shown a significant increase in extreme rain events in Europe, has not shown significantly longer drought periods and has not shown  extreme intramonth temperature swings either. I studied data from many European cities.

If we remain scientific, we need to  examine the available data, not anecdotal evidence. I do not see even theoretically why temperature swings would be bigger with a BOE (and I do not see that in data from the 2010s vs the historical average either), although I understand that storm strength and extreme rain events could (and likely will) increase - in theory.

prove me wrong, give us the data, eg on the change of first and last frost dates in the USA, average monthly minima and maxima, number of precipitation days. If I see later first frosts, earlier last frosts, lower minima and at the same time higher maxima for each month and a significant fall in precipitation days for most of the US, then you are right.

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #186 on: September 24, 2020, 09:03:55 AM »
Frequency of extreme precipitation increases extensively with event rareness under global warming
G. Myhre, K. Alterskjær, C. W. Stjern, Ø. Hodnebrog, L. Marelle, B. H. Samset, J. Sillmann, N. Schaller, E. Fischer, M. Schulz & A. Stohl
Scientific Reports volume 9, Article number: 16063 (2019)

Abstract
Quote
The intensity of the heaviest extreme precipitation events is known to increase with global warming. How often such events occur in a warmer world is however less well established, and the combined effect of changes in frequency and intensity on the total amount of rain falling as extreme precipitation is much less explored, in spite of potentially large societal impacts. Here, we employ observations and climate model simulations to document strong increases in the frequencies of extreme precipitation events occurring on decadal timescales. Based on observations we find that the total precipitation from these intense events almost doubles per degree of warming, mainly due to changes in frequency, while the intensity changes are relatively weak, in accordance to previous studies. This shift towards stronger total precipitation from extreme events is seen in observations and climate models, and increases with the strength – and hence the rareness – of the event. Based on these results, we project that if historical trends continue, the most intense precipitation events observed today are likely to almost double in occurrence for each degree of further global warming. Changes to extreme precipitation of this magnitude are dramatically stronger than the more widely communicated changes to global mean precipitation.

The increase in the frequency of extreme precipitation, i.e. the number of events per unit time with intensity above a given threshold, has generally received much less attention18,19,20,21. Unlike for intensity changes, the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5) gave no quantitative estimates of frequency changes22. Recent analyses of observations over Europe4,23 and over the US23,24,25,26 however show a substantial frequency increase. Here, we analyse a comprehensive data set of changes in the total amount of water falling as extreme precipitation, quantifying the contributions from changes in the intensity and the frequency, and including both observed and simulated precipitation. We investigate events that are rarer than those used in earlier studies, and find larger changes in the total amount of extreme precipitation than has been previously quantified.

To illustrate how changes to the total extreme precipitation are affected by both frequency and intensity, Fig. 1a shows a conceptualized probability density function (PDF) of daily precipitation corresponding to a reference surface air temperature (purple line), compared to one with a higher surface air temperature (orange). The increase in the intensity of heavy precipitation is illustrated by the horizontal blue arrow; the increase in frequency as the vertical green arrow. If we define “extreme” precipitation to be any event above a certain percentile, as illustrated by the dotted vertical line, Fig. 1a demonstrates that the total change in extreme precipitation amounts depends on changes to both intensity and frequency.



Further.
Heavy precipitation in Europe.
Not a file format that i can link to directly here please go to website.
https://www.eea.europa.eu/data-and-maps/indicators/precipitation-extremes-in-europe-3/assessment#:~:text=The%20intensity%20of%20heavy%20precipitation,eastern%20Europe%20since%20the%201960s.&text=Heavy%20precipitation%20events%20are%20likely,and%20eastern%20Europe%20in%20winter.
Observed trends in maximum annual five-day consecutive precipitation in winter and summer.




 

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Archimid

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #187 on: September 24, 2020, 09:45:48 AM »
That sounds like religion to me ("temperature and precipitation volatility does not matter, a longer growing season does not matter, because there MUST be some variables that portend tragedy for agriculture, although I don't know what").

No. It is merely a matter of precise words. The "growing season" requieres a host of elements other than temperature.

Global warming is much worse for its climate change than for its warming.

Quote
Last time I checked the Eemian probably did have only seasonal ice (BOE!), yet Europe was heavily forested even in Northern Scandinavia where we currently have tundra, and the Sahara was green, so somehow this must have been beneficial for life there. If trees grew very well, it must not have been that terrible I guess.

Your understanding of the time frames involved and the order of events is terribly mixed up.

The eemian warming happenned over centuries and the cooling happenned over millenia.

They were heavy forests in scandinavia AFTER hundreds of years after the warming happenned. It takes centuries to grow  thick forests but they can burn in an instant. So to an outside observer observing the woods that formed over millenia and applying them to human timescales it would look as if "it must not have been that terrible".

Quote
And no, this is not denialism, this is science. Let's see what happened the last (few times) when we had BOE. Then we can have an idea about the climatic effects of BOE, the title of this thread.

No you are talking nonsense by using events that took place over millenia and applying it to a BOE, an event that happens over decades.

Quote
A BOE by itself will not destroy mankind. A hothouse Earth might. That's why we must stop AGW as fast as we can, because we are not just going towards BOE, we are actually rushing towards hothouse Earth. There is a huge difference between the two!

Absolutely wrong. Climate change is worse for its changes in climate than for the rise in temperatures. One of those changes that will mark a change in climatic regime is a BOE.

Before a hothouse get us, the changes in weather, hydrology, fauna, flora and microbial life will.
« Last Edit: September 24, 2020, 09:51:47 AM by Archimid »
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El Cid

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #188 on: September 24, 2020, 10:15:40 AM »
Further.
Heavy precipitation in Europe.
Not a file format that i can link to directly here please go to website.
https://www.eea.europa.eu/data-and-maps/indicators/precipitation-extremes-in-europe-3/assessment#:~:text=The%20intensity%20of%20heavy%20precipitation,eastern%20Europe%20since%20the%201960s.&text=Heavy%20precipitation%20events%20are%20likely,and%20eastern%20Europe%20in%20winter.
Observed trends in maximum annual five-day consecutive precipitation in winter and summer.

This is not bad Kiwi but all this shows is the maximum five-day consecutive precipitation. Lots of rain is not necessarily a problem. There is plenty of rain in rainforests as well and plants grow well (I bet that NZ five-day cons.precipitation is at least double of Europe). That by itself is no problem. Besides. The EEA charts show basically no change in concentrated winter precipitation and only small growth in summer. This won't stop us from growing food.

Mind you, in the 80s no corn was grown in Poland and Russia because it was too cold (they grew wheat and rye back then). Now Poland and Ukraine are major corn producers. Russian grain production went across the roof. Summer rains probably help too.  Grain yields increased in the 2010s globally as well:

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #189 on: September 24, 2020, 10:55:34 AM »
Quote
here is plenty of rain in rainforests as well and plants grow well

  Can we talk about the diversity of plant life and the type of plant that grow in each region? Or how about the time it takes to grow a tree vs  the time it takes to burn a tree?

Or forget about plants. Lets talk about how long it takes to create a forest vs how fast it can burn.

Maybe let's forget about the natural world and focus exclusively on the plants we grow. Why are there "zones" for growing? Why is wheat not grown in the the tropics? Why are mangoes not grown in the Arctic?

How do managed crops react to large changes in the flow of rivers?

Nah. You are glazing over the meat and bones of the problem with a blanket generalization that "the growing season " grows. That generalization is wrong.
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Re: The Climatic Effects of a Blue Ocean Event
« Reply #190 on: September 24, 2020, 11:24:29 AM »
Intuitively I would think daily temperature swings in the Arctic would decrease if it is sea as opposed to ice, from the thermal inertia of water. Of course, intuition is seldom accurate in complex science like climate.
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Re: The Climatic Effects of a Blue Ocean Event
« Reply #191 on: September 24, 2020, 01:28:45 PM »
That sounds like religion to me ("temperature and precipitation volatility does not matter, a longer growing season does not matter, because there MUST be some variables that portend tragedy for agriculture, although I don't know what").

No. It is merely a matter of precise words. The "growing season" requieres a host of elements other than temperature.


But it is the main driver. If it´s above 6 or 8 C for a while the plants start waking up for spring.
Of course if you live further south where it does not freeze there might be different definitions in use.
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Re: The Climatic Effects of a Blue Ocean Event
« Reply #192 on: September 24, 2020, 01:37:08 PM »
Intuitively I would think daily temperature swings in the Arctic would decrease if it is sea as opposed to ice, from the thermal inertia of water. Of course, intuition is seldom accurate in complex science like climate.

Polar day and polar night work a bit differently...it´s not diurnal.

Also the DMI 80N chart shows that ice keeps temps pegged so that means the ice keeps temperatures stable.

We´ll know more in a decade.  ;)
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Re: The Climatic Effects of a Blue Ocean Event
« Reply #193 on: September 24, 2020, 04:34:24 PM »
Intuitively I would think daily temperature swings in the Arctic would decrease if it is sea as opposed to ice, from the thermal inertia of water. Of course, intuition is seldom accurate in complex science like climate.

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. 

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #194 on: September 24, 2020, 09:58:46 PM »

But it is the main driver. If it´s above 6 or 8 C for a while the plants start waking up for spring.
Of course if you live further south where it does not freeze there might be different definitions in use.

Down at 18N the growing season begins now. It is hot outside, but it rains almost every afternoon, dousing the heat and preparing the soil for next morning growth spurt. If it doesn't rain it is so hot that many plants wilt, even if watered. They recover, but you can tell they are hurting.

Over the next few months temperatures will become very nice and humidity will drop to something similar to what you call "growing season". The plants will get less sunlight but still get a solid 10 hours with comfortable 25C weather and occasional ocean driven showers.

Believe it or not, my exposure to the consequances of a BOE will likely be less than people living much further North.

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #195 on: September 25, 2020, 06:32:00 AM »
Intuitively I would think daily temperature swings in the Arctic would decrease if it is sea as opposed to ice, from the thermal inertia of water. Of course, intuition is seldom accurate in complex science like climate.

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.
That has nothing to do with the thermal inertia of water, its about melting ice. Where there is still ice to melt there will be little temperature rise above 0C.

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #196 on: September 25, 2020, 08:15:31 AM »

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:

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #197 on: September 25, 2020, 09:19:22 AM »
How is DMI N80 heavily skewed?
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Re: The Climatic Effects of a Blue Ocean Event
« Reply #198 on: September 25, 2020, 09:47:29 AM »
Down at 18N the growing season begins now. It is hot outside, but it rains almost every afternoon, dousing the heat and preparing the soil for next morning growth spurt. If it doesn't rain it is so hot that many plants wilt, even if watered. They recover, but you can tell they are hurting.

Over the next few months temperatures will become very nice and humidity will drop to something similar to what you call "growing season". The plants will get less sunlight but still get a solid 10 hours with comfortable 25C weather and occasional ocean driven showers.

Believe it or not, my exposure to the consequances of a BOE will likely be less than people living much further North.

At your location main bottleneck for growth is water.  At high latitudes it is temperature and (lack of) sunlight. This means temperature increase will extend the growing season.

SteveMDFP

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Re: The Climatic Effects of a Blue Ocean Event
« Reply #199 on: September 25, 2020, 01:29:50 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.