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Global Warming / Climate Changes Pt. 19

Re: Global Warming / Climate Changes Pt. 19

Unread postby rockdoc123 » Mon 03 Jul 2017, 10:10:57

LOL! Please explain exactly how I can be "wrong" about this!


I was referencing this statement

If I am not mistaken, it is the most recent study (Yale - Tan 2016) that is the high end outlier.

Am I interpreting this correctly?


which was obviously intended to suggest the most recent work was pointing to high ECS, to which I posted more recent examples that were lower.
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Re: Global Warming / Climate Changes Pt. 19

Unread postby Tanada » Mon 03 Jul 2017, 11:13:27

Fundamentally if you take all the catastrophic headline grabbing projections out of the picture and just look at the data a couple things become clear.
First the climate is certainly warmer than it was in the 19th and 18th centuries.
Second humans have added billions of tons of CO2 and other greenhouse gasses to the atmosphere.

When you go from those basic facts to proclaiming humans will keep increasing greenhouse effect until mass extinction does us all in you cross over IMO from what the data says to what some advocate wants you to believe for some reason. That advocate may be a Luddite that hates all technology, or they could be a high tech 'renewable' believer, or any of a whole spectrum of other reasons. Many of them proclaim they are just using the Precautionary Principal. But every single one of them I have talked too when you get them to be honest is advocating against fossil fuels for some reason other than climate change.

The ones I find most amusing are the catastrophists who believe humanity is evil simply because of the instinctive way we behave. We know certain behaviors are instinctive because they were used by our most distant ancestors back 250,000 years and still we do them today. Yet while they decry their disgust with humans and human behavior they demand we stop acting like humans while also claiming we deserve the extinction they are hoping we are inflicting upon ourselves.

Well everyone let me point out that the laws of physics don't give two hoots in hell what your politics or advocacy are. Under the laws of physics we know about the band saturation effect, each chemical has a signature of frequencies of light it absorbs and re-radiates in a random direction.
Image
If you simply look at the graph and start with the blue band that represents water you can see with your own eyes why good scientists say water vapor is the most significant GHG and because of the way the water cycle works there is very little we can do about it. The planet is 70 percent covered by water and we are not going to change that in any meaningful way.

The next band is red for Carbon Dioxide and it has three significant peaks and a small one. However half of the small peak and all of the left most tall peak are swamped by the water vapor absorption band, in essence they have no effect because anything they would absorb would be absorbed by water vapor even if they were not present. The two right end spikes of CO2 absorption are partially covered by the water band and in effect they broaden the range of frequencies being captured and re-emitted slightly.

The green band is Oxygen including Ozone. Like water vapor Oxygen is a massive part of our natural planet making up 21% of our atmosphere. There isn't a darn thing we can do to increase or decrease it on a human timespan nor should we because without it we all suffocate pretty darn quick. The bread absorption covering the whole left end of the graph is the ozone layer in the upper Stratosphere. It is formed by sunlight hitting the upper air and ionizing it, and the process saves our behinds from that ionizing UV radiation which is so good at causing skin cancer and cataracts. The narrow tall spike is the stuff we breathe so again it is something we can do nothing about.

The orange band is nitrous oxides. These gasses form a couple different ways, one is from lighting through the air which is the main natural source. The other is high temperature combustion where air is used as the oxidizer, like high temperature fires inside the cylinders of internal combustion engines. We try to reduce our man made output with things like catalytic converters on gasoline engines. However if you look carefully at the graph you will see the lower tall spike is completely swamped by other gasses so it has little if any impact, and the upper spike is partly covered by a broad spike in the water band and serves to broaden it slightly. The most impactful effect is in the lower middle of the spectrum it is a weak absorber of some frequencies and adds that weak absorption to the total cumulative picture.

Lastly we get the pink Methane band. This gas has two spikes with a small hump in between. Fortunately the hump in the middle is swamped by the Water frequencies so we can ignore that completely. The rightward spike is swamped by the NOx band and also partially covered by the water band so even absent the NOx it would simply provide a slight broadening of the water frequencies. For the leftward spike the lower end of it is swamped by three other bands, Nitrous, CO2 and H2O. The narrow upper spike does slightly broaden the water absorption band in the 3 micron range.

If you overlay the water and oxygen bands that are completely beyond our control and then overlay each of the other three individually anyone with eyes can see CO2 is by far the most significant of the three main man made GHG components. Having said that the CO2 band already extends the whole height of its strip in the spikes. This means CO2 already absorbs all it can absorb in the center of those frequency spikes, and the only way for it to absorb more is by broadening the spikes. Spikes grow broader as more of the specific component is added to the mix, but the effect is VERY GRADUAL. Twice as much CO2 does not make the spike twice as broad. Twice as much CO2 causes an inverse geometric increase in absorption, in other words it is the doubling effect where each doubling has less and less cumulative effect.

While it matters whether that doubling effect is 2 C or 6 C it does not matter quite as much as some folks seem to think. Because of human population growth over the last two centuries we have been burning fossil fuels at an ever growing rate of consumption. Everyone knows this at least if they are honest. However this is the PEAK OIL website dedicated to the fact that finite resources run out at some point. We are at or near the peak in world oil supply. Like it or lump it oil is a finite resource and we are expending it at a prodigious rate of combustion. 95 MILLION barrels of crude oil a day, more or less. It by some miracle there are 3 Trillion barrels remaining today AND we can keep burning at the same rate of consumption that is 31,789 days of consumption, aka 4511 weeks aka 86 years 6 months. How many here believe we have 3 Trillion barrels left? That is not the main point however, the main point is OIL IS FINITE. Once we burn it all up it is gone, fini, no longer an additional factor.

We have a lot more Methane in the form of natural gas than we do oil for the blunt reason that fracked shale gas is simply a very abundant resource. However as we start down the back slope of peak oil there will be greater and greater incentive to substitute methane for petroleum everywhere possible. This means as the oil starts dropping off natural gas consumption will be required to expand rapidly to help offset the energy requirements of our civilization. Some places like Cincinnati and Los Angeles have already converted municipal fleets of public transit and refuse removal to run on cheap natural gas. As we go over the hump and down the peak oil slide the number of cities doing that will change overnight until almost all of them have switched over.

I am a historian by nature and training. You do not find overnight collapse scenarios in history. On rare occasions like the end of the Maya pyramid building culture there is a sudden end to written records. However even in those cases the population did not drop dead, the most likely answer based on archeological evidence is the lower poor revolted and killed or chased off the educated literate class. After that the civilization reverted into village size population centers instead of city size population centers and it stayed around that level until the Spanish arrived with disease vectors. Something people miss a LOT when talking about civilizations like the Maya is they had been civilized as in agriculture communities for a very long time. Because of this they were more resistant to European diseases than the first peoples further north that were more recent adopters of agriculture. While about 90-95% of Mississippian peoples that lived in the broad center of North America were killed off by disease in the Maya/Aztec and Inca regions of central and south America the death toll was closer to 65-70% This is why you can find a large minority of cohesive first peoples in southern Mexico where they make up 30% of the national total population. It is also the reason the majority of the Mexican population is of mixed ancestry instead of majority European ancestry like the USA/Canada are even today. Even in the Mississippian civilization also known as the Mound Builder culture the devastation caused by European diseases didn't end everything. The survivors went right along a year later planting the same crops they had been planting before and maintaining their languages and traditions. They lost a lot of inherited knowledge because they had no system of writing and knowledge was passed from one generation to the next orally. When so many died their knowledge died with them, but the culture persisted in a smaller form right up until the Europeans swamped them with a double whammy, forcing eastern tribes to move west into their territory early on, and then invading that territory themselves a few generations later. By the time Europeans got around to asking the survivors about the mounds 200+ years after the diseases killed off so many none of them knew. In many cases the survivors by that point were formerly eastern tribes who had migrated into the territory and defeated the Remanent who had known a few generations earlier.

Anyway back on the topic. Human instinct drives us to use fire, thus it has been for close to a quarter of a million years. Fossil fuels burn. Ergo humans instinctively burn fossil fuels. This was a limited extent until the invention of functional low pressure steam engines in the 1700's. Once we learned how to harness steam to do mechanical work we discovered a massive new reason besides heat/light/cooking for burning fossil fuels. Compared to the same mechanical effort done via muscle power burning fossil fuel is a huge advantage with even the most primitive low pressure steam engine. Believing that humans are going to give up burning fossil fuels before they are too difficult to extract is IMO a form of magical thinking. Even the ancient Roman Empire did some coal mining where seams broke the surface, and all they used it for was heating baths and in some instances blacksmith forging. Have a massive nuclear holocaust right after you finish reading this and kill half the world population within the first year. The survivors are still instinctive burners and by and large they have heard of coal and oil and natural gas. Some of them live near open pit coal mines. Even if there are no functional machines left the coal mines are still there and people can still get the coal out with pick and shovel if they have to. Instinctive burners are not going to stop burning no matter how hard you wish they would. In order of precedence humans want to eat, mate and burn. Fighting is actually further down the list as most people do not want to fight, but everyone wants to stay warm when it is cold and most of us prefer cooked food over raw.

Admit it to yourself, if we can access a flammable material sooner or later we will burn it for reasons that seem sound on the individual scale at that moment in time. Once you accept that you can forget all the fantasies about 'renewable' energy putting an end to the age of fossil fuels and think about the long term consequences. We will burn it all. What does that mean?

Short term it means somewhere around two more Trillion barrels of oil converted into CO2 and H2O. The water vapor rains out but the CO2 persists at least a few thousand years which on the life scale is effectively permanent. Add in the equivalent of about another two Trillion barrels of oil in the form of Methane. Then pile in about 5 Trillion barrels of oil equivalent of coal. All together that means CO2 is going to keep going up for another century more or less until we physically run out. Forget fantasies about governments ending fossil fuel combustion because what doesn't get burned in one place is offset by burning somewhere else. Even if the socialist utopia one world government suddenly appeared they would still burn everything because people want energy and burning stuff is an easy way to supply that energy and avoid revolts by the lower classes. Anyone who things socialist utopias are classless is fooling themselves, it is also a human instinct to for hierarchies. Someone is always on top and they employ middle management to keep the lowest layer from easily accessing them.

So we SHALL burn all the oil/gas/coal that can be accessed. We are even so clever we have developed techniques to burn very deep coal seams in situ and extract the gasses to use on the surface. Once you accept that reality the next fundamental fact is, how much fossil fuel does the whole world have for use to burn? Depending on your source it works out to around enough to increase CO2 up to between 7,000 ppmv and 9,500 ppmv depending on what source you believe.

So how many doubling's is that? 280_560_1120_2240_4480_8960 aka 5 doubling's on the high estimate 4.5 on the low estimate. So if the optimists are correct we get 2 C a doubling and
from 9 C to 10 C increase in global average. If the pessimists are correct we get 6 C a doubling and 27 C to 30 C global average increase. But wait! The Earth has not managed to get over 23 C in the last 100 Million years, so even though levels already exceeded 3 doubling's in the era of the Dinosaurs with levels around the 2300 ppmv mark the average temperature was very stable around 22 C global average ice free to both poles. The massive suspected methane burst at the PETM only managed to bump the Earth average up to 23 C.

This raises the obvious question, if three doubling's from pre-industrial levels resulted in a world with a global average of 22 C compared to the 13 C of the 18th Century what does that mean for us? Well the difference between 22-13 = 9. This is extremely strong evidence that each doubling results in a 3 C average increase in global temperature until you hit a limit where negative feedback's make additional warming more and more difficult. If we accept the preponderance of scientific evidence we will acknowledge that 3 C per doubling is the most likely answer.

This does not mean there is a smooth transition all the way from 280 ppmv to 2300 ppmv. The climate of the planet clearly demonstrates a bifurcated hysteresis, a threshold behavior where temperatures hold in a narrow range then suddenly step up or down and hold in a different but still narrow range. I am convinced by many papers read over a lifetime than the Earth has three quasi stable steps between full hothouse to full icehouse with our current continental configuration. Below about 320 ppmv the planet exibits cyclic icehouse conditions where major glaciation from both poles extends down to about 40 degrees latitude away from the Equator. This is the climate we evolved in and many are afraid if we leave it we will suffer severely. Bad news, we left that climate in the early 1970's. The second 'step' on the climate staircase is between 320 and 560 ppmv where the Northern Hemisphere was relatively ice free and the subtropics extended as far as 60 degrees north with temperate climate extending to 75 degrees north. We are well inside this step and one day now the climate will show this by Greenland melting much more quickly every summer until relatively ice free and the Arctic ocean becomes ice free every summer. The third step is somewhere between 560-780 ppmv and that step puts us in the greenhouse where Antarctica also melts every summer until the continent is relatively ice free. This begs the question, if the threshold is 780ish ppmv for a 22 C global average how did the Earth maintain that temperature up to 2300 ppmv and even higher? The real answer is negative feedback mechanisms kick in somewhere around 800 ppmv and the global average stops going up even with a doubling from 800 to 1600 or a 1.5 doubling's to 2400 ppmv. In effect this means the world average temperature becomes relatively insensitive to CO2 increases above 800 ppmv. This also means that math of 3 C per doubling to 2400 ppmv is invalid because all of the increases take place between 280 and 800, not 280 and 2400. So recalculating that 9C of increase takes place between 280_800 which is a doubling plus 220 more or less. IOW with this knowledge the idea of doubling being the metric is seen as no longer valid. The threshold is the significant number, not the relationship between that number and the base value. We don't know precisely what the threshold number is for the first step, however the behavior of the Arctic Sea Ice since 2005 presents evidence we are close to or might have already passed that threshold. The only thing that has prevented us from returning to the climate of 20 million years ago when the Arctic was relatively ice free including all of Greenland outside of mountain peaks is inertia. The remaining sea ice and the Greenland ice cap are effective albedo reducers reflecting most sunlight without absorbing it and changing the frequency when emitting it back out to space. However every time more of the sea ice melts than the summer before we get closer and closer to the blue ocean event at which point the albedo effect significantly decreases and heating rates substantially increase. Ice acts as a giant heat sink absorbing the energy not reflected away in huge quantities before it transitions from ice to water. Once we get a blue ocean event that enthalpy of transition ceases to be a factor and the quantities of energy absorbed by the ocean surface skyrocket. This is once again simple physics, nothing new or mysterious. IMO when we hit the blue ocean event we have made that first step and Greenland will all melt over the following few decades. The main cause of this rapid melting will be weather events, namely summer rainfall. Put a number of ice cubes in a strainer in your sink and time how long it takes for them to melt. Then take a similar number in the same strainer and sink and sprits them with room temperature water from a spray bottle every five minutes until they all melt. The second set of ice cubes will absorb most of the energy in the light spray of room temperature water and will melt an order of magnitude faster.

Greenland is doomed, possibly ice free as soon as the 22nd Century. Accept that fact and plan accordingly. Mostly that means if you don't like subtropical weather and plan to live more than a couple decades into the future you should either move south of the Equator or much closer to the North Pole.

Also keep in mind that at the current rate of population and fossil fuel use growth we are likely to meet that 750-800 ppmv level where Antarctica will melt too before we run out of fossil fuel to burn. If we are building up 3 ppmv a year now we shall likely exceed 4 ppmv a year by 2030 as more and more combustion based fossil fuel use gets added to our civilization. It was not that long ago that we were only building 2 ppmv a year, and it is well within a human lifespan that we were build 1 ppmv a year or less. Factor in substitution of coal for oil as we peak out and those numbers will inevitably grow faster. Also sea surface sinks appear to be slowing down in capacity to absorb though whether this is saturation or simply the speed of emissions is not totally clear. Even if we managed to hold at 3 ppmv a year that would be another 245 by the end of the century putting us at 660ish ppmv CO2 and on the threshold of hothouse earth. If sinks are at capacity and we hit 5 ppmv by 2030 that would be about a doubling from where we are today or over 800 ppmv at the turn of the next century which would almost guarantee an ice free Antarctica not long after.

The question is not IF we will burn it all, simply WHEN.
The question is not IF we will recreate the Hothouse Earth of the dinosaurs, simply HOW SOON.
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Re: Global Warming / Climate Changes Pt. 19

Unread postby baha » Mon 03 Jul 2017, 11:45:48

Wow Tanada, That is an impressive analysis. I would add some of those relationships are exponential. Change starts out slow and builds. 3C per doubling is probably an average, but your point is valid.

And reduce the population by 90% and you increase the time required to burn it all by 90%. Maybe at that rate natural processes will have a chance to limit the damage.
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Re: Global Warming / Climate Changes Pt. 19

Unread postby dohboi » Mon 03 Jul 2017, 15:29:40

Yes, many nice points there, T, some of which I have made repeatedly over the years.

But as to blame (and let me know if this draws us too far off topic and we should start another thread), I do wonder if you think that there is anything any human or collection of humans could do that could not be excused by saying 'he/she/they were just following their instincts.'

I breathlessly await your response (oops, breathing is instinctual.. :-D ). :)
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Re: Global Warming / Climate Changes Pt. 19

Unread postby dohboi » Mon 03 Jul 2017, 18:33:35

http://www.airspacemag.com/daily-planet ... 180963910/

Most Mass Extinctions Have Been Due to Global Warming
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Re: Global Warming / Climate Changes Pt. 19

Unread postby jedrider » Mon 03 Jul 2017, 20:35:08

I'm getting my tank tops and shorts ready for such an event. Maybe, an umbrella, too. It's not going to catch me by surprise ;-)
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Re: Global Warming / Climate Changes Pt. 19

Unread postby dohboi » Mon 03 Jul 2017, 21:53:11

Good idea! :) :(

This Map Shows How Badly Climate Change Will Impact Each County In The US

As temperatures go up, the US economy will suffer, according to a new study. And the warmer it gets, the worse the damages will be.
US counties face steep economic damages tied to future global warming, with the poorest counties to be hit hardest, according to a county-by-county analysis published on Thursday.

The warmer it gets, the worse that farms, businesses, and people will fare.

“As temperatures goes up, the economy gets damaged,” study author Amir Jina of the University of Chicago told BuzzFeed News, adding that “for each additional degree, there’s increasing damages done.”...


https://www.buzzfeed.com/zahrahirji/cli ... tudy-shows

Interactive map at the above link.

"Stephen Hawking: Trump Pushing Earth's Climate 'Over The Brink'"

http://www.npr.org/sections/thetwo-way/ ... -the-brink
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Re: Global Warming / Climate Changes Pt. 19

Unread postby Tanada » Mon 03 Jul 2017, 23:55:07

dohboi wrote:Yes, many nice points there, T, some of which I have made repeatedly over the years.

But as to blame (and let me know if this draws us too far off topic and we should start another thread), I do wonder if you think that there is anything any human or collection of humans could do that could not be excused by saying 'he/she/they were just following their instincts.'

I breathlessly await your response (oops, breathing is instinctual.. :-D ). :)


Excuses are like anuses, everyone has one and all of them stink.

It is instinctive to burn things, but that doesn't mean you burn down your own barn or the neighbors house. It is instinctive to try and procreate, not to mention most people find the practice rather enjoyable. That doesn't mean everyone goes out of their way to have a child every two years from onset of fertility until loss of fertility.

Those things being said just because people moderate instinctive behavior doesn't mean they will cease to preform instinctive behavior either. Perhaps we will moderate our behavior and spend three centuries consuming all the remaining fossil fuels instead of 150 years. I don't see any evidence of that but I accept the possibility.
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Re: Global Warming / Climate Changes Pt. 19

Unread postby dohboi » Tue 04 Jul 2017, 06:45:51

Excuses are like anuses, everyone has one and all of them stink.

It is instinctive to burn things, but that doesn't mean you burn down your own barn or the neighbors house


Nicely put. Thanks.
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Re: Global Warming / Climate Changes Pt. 19

Unread postby kiwichick » Wed 05 Jul 2017, 16:49:31

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Re: Global Warming / Climate Changes Pt. 19

Unread postby dohboi » Thu 06 Jul 2017, 13:46:08

Thanks, kc. More here:

Why the climate is more sensitive to carbon dioxide than weather records suggest


https://phys.org/news/2017-07-climate-s ... ather.html

According to their statistical analysis, historical weather observations reveal only a portion of the planet's full response to rising CO₂ levels. The true climate sensitivity will only become manifest on a time scale of centuries, due to effects that researchers call "slow climate feedbacks".

To understand this, it is important to know precisely what we mean when we talk about climate sensitivity. So-called "equilibrium climate sensitivity", or slow climate feedbacks, refers to the ultimate consequence of climate response – in other words, the final effects and environmental consequences that a given greenhouse gas concentration will deliver.

These can include long-term climate feedback processes such as ice sheet disintegration with consequent changes in Earth's surface reflection (albedo), changes to vegetation patterns, and the release of greenhouse gases such as methane from soils, tundra or ocean sediments. These processes can take place on time scales of centuries or more. As such they can only be predicted using climate models based on prehistoric data and paleoclimate evidence.

On the other hand, when greenhouse gas forcing rises at a rate as high as 2–3 parts per million (ppm) of CO₂ per year, as is the case during the past decade or so, the rate of slow feedback processes may be accelerated.

Measurements of atmosphere and marine changes made since the Industrial Revolution (when humans first began the mass release of greenhouse gases) capture mainly the direct warming effects of CO₂, as well as short-term feedbacks such as changes to water vapour and clouds.
A study led by climatologist James Hansen concluded that climate sensitivity is about 3℃ for a doubling of CO₂ when considering only short-term feedbacks.

However, it's potentially as high as 6℃ when considering a final equilibrium involving much of the West and East Antarctic ice melting, if and when global greenhouse levels transcend the 500-700ppm CO₂ range.
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Re: Global Warming / Climate Changes Pt. 19

Unread postby rockdoc123 » Thu 06 Jul 2017, 14:42:54

https://www.theguardian.com/environment ... w-research

https://phys.org/news/2017-07-climate-s ... ather.html


The paper referenced by this bit of journalism:

Proistosecu, C and Huybers, P. 2017. Science Advances. Vol. 3, no. 7, e1602821
DOI: 10.1126/sciadv.1602821


Does not suggest ECS at 6.0 but rather a range of values for ECS with median of 3.4 and a range of values for what they call ICS (instantaneous climate sensitivity which is more or less the same as Transient climate sensitivity) of 2.5. The distribution of each is lognormal and highly skewed with 6.0 in the case of ECS sitting out at the <5% chance of occurrence and 4.5 in the case of ICS sitting out at the <5% chance of occurrence. When you look at the chart I posted up thread this is not inconsistent with Masters (2013) which showed a most likely case of 2.1 and a highly skewed range from 1.5 to 5. The authors point to their view of ICS being a better fit with historical data and in that distribution there is as great a chance ICS is less than 1.5 as there is it is greater than 4.5.

This is not the same as calculating a median ECS of 6.0 or larger, completely different from a probability standpoint.
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Re: Global Warming / Climate Changes Pt. 19

Unread postby dohboi » Thu 06 Jul 2017, 18:58:56

Or you can just go by what the actual lead author says:

“The hope was that climate sensitivity was lower and the Earth is not going to warm as much,” said Cristian Proistosescu, at Harvard University in the US, who led the new research. “There was this wave of optimism.”

The new research, published in the journal Science Advances, has ended that. “The worrisome part is that all the models show there is an amplification of the amount of warming in the future..."
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Re: Global Warming / Climate Changes Pt. 19

Unread postby rockdoc123 » Thu 06 Jul 2017, 19:12:28

Or you can just go by what the actual lead author says:


or you can ignore potential misquotes in grey journalism and actually read the frigging paper moron.
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Re: Global Warming / Climate Changes Pt. 19

Unread postby dissident » Thu 06 Jul 2017, 20:00:39

dohboi wrote:Thanks, kc. More here:

Why the climate is more sensitive to carbon dioxide than weather records suggest


https://phys.org/news/2017-07-climate-s ... ather.html

According to their statistical analysis, historical weather observations reveal only a portion of the planet's full response to rising CO₂ levels. The true climate sensitivity will only become manifest on a time scale of centuries, due to effects that researchers call "slow climate feedbacks".

To understand this, it is important to know precisely what we mean when we talk about climate sensitivity. So-called "equilibrium climate sensitivity", or slow climate feedbacks, refers to the ultimate consequence of climate response – in other words, the final effects and environmental consequences that a given greenhouse gas concentration will deliver.

These can include long-term climate feedback processes such as ice sheet disintegration with consequent changes in Earth's surface reflection (albedo), changes to vegetation patterns, and the release of greenhouse gases such as methane from soils, tundra or ocean sediments. These processes can take place on time scales of centuries or more. As such they can only be predicted using climate models based on prehistoric data and paleoclimate evidence.

On the other hand, when greenhouse gas forcing rises at a rate as high as 2–3 parts per million (ppm) of CO₂ per year, as is the case during the past decade or so, the rate of slow feedback processes may be accelerated.

Measurements of atmosphere and marine changes made since the Industrial Revolution (when humans first began the mass release of greenhouse gases) capture mainly the direct warming effects of CO₂, as well as short-term feedbacks such as changes to water vapour and clouds.
A study led by climatologist James Hansen concluded that climate sensitivity is about 3℃ for a doubling of CO₂ when considering only short-term feedbacks.

However, it's potentially as high as 6℃ when considering a final equilibrium involving much of the West and East Antarctic ice melting, if and when global greenhouse levels transcend the 500-700ppm CO₂ range.


As is typical, the authors are not fully aware of the ocean response. It is rather clear that the surface ocean layer is warming very fast and it will not take centuries for the transition to quasi-isolation from deeper waters (together with an anoxic biochemical regime) to occur. An isolated surface ocean layer by definition implies a sharp transition in the warming of the atmosphere. So it is simply absurd to talk about one temperature for the CO2 doubling response. The current metric applies to atmospheric warming so there will be a jump in this warming when the oceans stop being effective heat sinks. Hence, the climate sensitivity will jump as well.

Now if they used a metric that integrated heat in the full ocean-atmosphere system, then there would not be a large jump in the accumulation rate in the total system.

It looks to me like 3 C is too small for a CO2 doubling. We are currently at over 1.5 C with less than a CO2 doubling. And the system is not equlibrated yet (ignoring the ocean surface stagnation effect and any epic clathrate melting). It is likely that the relevant figure for humanity is > 6 C per CO2 doubling.
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Re: Global Warming / Climate Changes Pt. 19

Unread postby Ibon » Thu 06 Jul 2017, 20:21:28

Tanada wrote:
The question is not IF we will burn it all, simply WHEN.
The question is not IF we will recreate the Hothouse Earth of the dinosaurs, simply HOW SOON.


Great effort Tanada. I read your post during middle of the night insomnia....

Long term there is another question. At what rate could we continue to burn fossil fuels whereby the sequestration rate matched or exceeded what we consume.

A lot of this is speculation but we should consider that on this path moving forward of when we burn all the fossil fuels there will most likely be a correction to human population which could conceivably take us down to a population level that consumes fossil fuels at the rate they can be sequestered by a biosphere already burdened by elevated levels of CO2 after a couple of centuries of industrial civilization. It will be at that point that we see CO2 levels flat lining probably for a long period before we start to see the levels decrease.

Again, a whole lot of speculation and I do not hold too much credibility to the models the longer forward they extend into the future. Simply an acknowledgement of the complexity of the feedbacks and tipping points. Acknowledging also the inevitability that we will burn all the fossil fuels results in a certain resignation and acceptance of this pathway. At least until we see credible alternative scenarios or game changing consequences.

I rarely speculate on this anymore due to the inevitability of where we are going.
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Re: Global Warming / Climate Changes Pt. 19

Unread postby Subjectivist » Fri 07 Jul 2017, 04:09:17

Tanada wrote:This does not mean there is a smooth transition all the way from 280 ppmv to 2300 ppmv. The climate of the planet clearly demonstrates a bifurcated hysteresis, a threshold behavior where temperatures hold in a narrow range then suddenly step up or down and hold in a different but still narrow range. I am convinced by many papers read over a lifetime than the Earth has three quasi stable steps between full hothouse to full icehouse with our current continental configuration. Below about 320 ppmv the planet exibits cyclic icehouse conditions where major glaciation from both poles extends down to about 40 degrees latitude away from the Equator. This is the climate we evolved in and many are afraid if we leave it we will suffer severely. Bad news, we left that climate in the early 1970's. The second 'step' on the climate staircase is between 320 and 560 ppmv where the Northern Hemisphere was relatively ice free and the subtropics extended as far as 60 degrees north with temperate climate extending to 75 degrees north. We are well inside this step and one day now the climate will show this by Greenland melting much more quickly every summer until relatively ice free and the Arctic ocean becomes ice free every summer.


I hadn't really thought of it this way much, mostly because the media constantly talks about average climate sensativity. From looking over such pages as google spit out it is clear the Earth has been a hothouse in the past any time the atmosphere was above 800 ppm CO2. The difference between todays world average and 800 ppmv average temperature is 8 C. Anyone who googles for a few minutes can confirm these facts. It is also evident the Earth exhibits thee conditions, at least since the end of the dinosaurs. Hothouse where everything melts over 800 ppm, icehouse where everything freezes under 200 ppm, and the middle state where the north is melted but Antarctica still frozen.

So if the difference between all frozen and all thawed is between 200 and 800 ppm that means each is a threshold sets a crucial zone limit of 600 ppm. Below the zone climate is icehouse, above the zone the climate is hothouse. Temperature wise the difference between icehouse and hothouse is only 12 C world average. 200-400-800 is only TWO doublings of CO2 for that 12 C temperature change, and the middle zone where the entire north is ice free is between about 350 and 550 ppm, roughly speaking. I write roughly speaking because the lectures I have seen on threshold behavior are pretty clear. While we are in the icehouse zone with periodic ice ages like now the world temperature is very elastic and doesn't easily pass a peak before falling back down towards the middle of the range. But if the temperature is forced beyond the top of the elastic range it snaps into another range, a step change.
Somewhere in the middle of that range, where we are right now CO2 wise anyhow, the world sits in that half and half condition with warm north but frozen Antarctica. The whole Miocene epoch fits in that description, and at those times most of Florida and Louisiana were under the sea, not dry land. Compensating for that a bit northern Canada and Alaska had forest growing all the way to the Arctic coast.

Right now we have CO2 levels like those that existed from 18 million years ago up until about 5 million years ago. To think this will have a small impact when the world of that Miocene was half warm and only Antarctica had permanent ice is fooling yourself. However threshold behavior and climate sensitivity strike me as theories at odds with each other. Threshold behavior is by definition elastic over a set range, then snaps to a new range. Climate sensitivity on the other hand is based on the idea of a smooth integrated change.

We know the climate is a step change function, everything about paleoclimate makes that crystal clear. If the climate sensitivity model worked then things would be constantly changing a thousandth of a degree at a time. We know that doesn't work out in practice because weather effects change temperature averages over a dozen degrees change from summer to winter. I have come to see all these climate sensitivity arguments as not just a distraction, but a bad way of describing things that causes people to form a false picture of how the climate works.
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Re: Global Warming / Climate Changes Pt. 19

Unread postby rockdoc123 » Fri 07 Jul 2017, 09:56:55

As is typical, the authors are not fully aware of the ocean response.


Not sure how you get this from the paper as there is little discussion about individual forcings and feedbacks. They indicate their analysis is based on 24 General Circulation Models from CMIP5. Are you suggesting that none of the current models handles ocean responses correctly?

As well there are a host of paleo ECS studies over millions of year intervals that end up with ECS values similar to that derived from models which still sit in the range outlined in the 2013 AR5. Are you suggesting there is something going to happen with the oceans that has never happened before?
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Re: Global Warming / Climate Changes Pt. 19

Unread postby kiwichick » Sat 08 Jul 2017, 07:20:35

@ rd.....you would have to be a complete idiot to think that what is happening now is anything like any previous climate change in this planet's history.......its happening 10? times faster than ever before with the amount of GHG's we are pouring into the system.
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Re: Global Warming / Climate Changes Pt. 19

Unread postby rockdoc123 » Sat 08 Jul 2017, 10:10:35

its happening 10? times faster than ever before with the amount of GHG's we are pouring into the system.


and you would definitely be a complete idiot if you actually believed that nonsense. Measurement of time scales is important. Comparing change measured in years or decades against change where the accuracy of time measured is in the thousands of years at best is not easily done and takes a bit more than parroting standard climate change memes.

But don't believe me:

Kemp, D. B. et al, 2015. Maximum rates of climate change are systematically underestimated in the geological record. Nature Communications, 6, doi:10.1038/ncomms9890

Abstract
Recently observed rates of environmental change are typically much higher than those inferred for the geological past. At the same time, the magnitudes of ancient changes were often substantially greater than those established in recent history. The most pertinent disparity, however, between recent and geological rates is the timespan over which the rates are measured, which typically differ by several orders of magnitude. Here we show that rates of marked temperature changes inferred from proxy data in Earth history scale with measurement timespan as an approximate power law across nearly six orders of magnitude (102 to >107 years). This scaling reveals how climate signals measured in the geological record alias transient variability, even during the most pronounced climatic perturbations of the Phanerozoic. Our findings indicate that the true attainable pace of climate change on timescales of greatest societal relevance is underestimated in geological archives


from the discussion:

Geological temperature changes defined at typically centennial to multimillennial timespans cannot capture the full variance of the climate system operative at shorter timescales; aliasing variability that is readily apparent from higher resolution and more recent records


Taking into account timespan-dependent scaling, warming rates through intervals such as the Permian–Triassic boundary and the PETM likely exceeded current rates on decadal timescales, at least intermittently


notwithstanding all of that.....speed or the rate of change doesn't have much to do with either TCS or ECS so I am not sure what you are on about.
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