Reposted from Dr. Judith Curry’s Climate Etc.
Posted on December 23, 2019 by curryja |
by Judith Curry
Is 3 C warming over the 21st century now the ‘best estimate’? A reframing of how we think about climate change over the 21st century, and my arguments for 1 C.
There has been much discussion over on twitter of the new article by David Wallace-Wells: We’re Getting a Clearer Picture of the Climate Future — and It’s n Not as Bad as it Once Looked. ‘This article is interesting for several reasons, especially since Wallace-Wells has been ‘alarmist in chief.’
Simply put, it is now becoming more widely accepted that RCP8.5 concentration/emissions scenario is highly implausible. See my previous post:
A new article by Zeke Hausfather and Justin Ritchie at the Breakthrough Institute is entitled ‘A 3C World is Now ‘Business as Usual‘. Punchline:
“We find that IEA numbers imply that the most likely outcome of current policies is between 2.9-3.4C warming — which is reduced to around 2.7-3C warming if countries meet their current Paris Agreement commitments.
Uncertainties surround this projection, of course. For one, there are uncertainties in the sensitivity of the climate to rising atmospheric greenhouse gas concentrations that mean emissions expected to produce warming of around 3C could result in warming as little as 1.9C or as much as 4.4C.”
They calculate the amount of warming based on TCRE:
“The amount of warming the world is projected to experience can be pretty closely approximated solely based on cumulative CO2 emissions. This relationship between temperatures and cumulative emissions is referred to as the transient climate response to cumulative carbon emissions, or TCRE. Using the TCRE values developed in the IPCC Special Report on 1.5C (SR15), we can calculate the amount of warming expected over the remainder of the century in our extended IEA scenarios, as well as the uncertainty introduced by the wide range of possible climate sensitivity values.”
“In the figure below we show the amount of warming between the last decade of the 20th century and the temperature of the late 1800s (which is somewhat representative of preindustrial temperatures) for the four RCP scenarios used in the IPCC AR5 and the extended IEA STPS and CPS cases — assuming flat emissions in each after 2040. The width of each bar reflects the 90th percentile range of warming given the uncertainty in climate sensitivity, while the central point represents the average of all the climate models running that scenario.”
This is a nice analysis by Hausfather and Ritchie. Some questions, suggestions and criticisms are outlined below:
Baseline
The 3 C estimates in the paper by Hausfather and Ritchie are based on a baseline period 1880-1900. The canonical rationale is for ‘preindustrial’, which would be mid 18th century, as the Northern Hemisphere was coming out of the Little Ice Age (hardly a climate ‘optimum’). But then, ‘good’ data is available only since the late 19th century.
The rationale for a baseline for manmade global warming in either the 18th or 19th century is that this is when manmade global warming began. There are multiple takes on this, and how much of the early warming was caused by CO2 emissions. Here are some previous blog posts:
- Assessing the causes of early industrial era warming
- Early 20th century global warming
- Modern global warming
The public looks at the 3 C number and thinks it is 3 C more warming from NOW, not since the late 19th century. Warming from NOW is what people care about.
In terms of projecting the amount of warming in 2100, what is the point in going back to 1900, and including all of the 20th century warming as ‘manmade’? It is far simpler to bypass the attribution issues of 20th century warming, and start with an early 21st century baseline period — I suggest 2000-2014, between the two large El Nino events.
In terms of policy, what matters is how much warming we can expect over the 21st century. Yes, the blame game in terms of 20th century warming is useful in terms of motivating people to act on reducing fossil fuel emissions. But at this point, what matters for decision making is how much warming we can expect over the remaining 80 years of the 21st century.
While we complain about the 21st century ‘weather’ and now call them ‘climate disasters’, few of them have plausible arguments for being associated in any way with manmade climate change. Overall the weather in the early 21st century is relatively benign by the standards of the Little Ice Age or even the early 20th century. The slow creep of sea level rise started circa 1860, well before there was significant manmade global warming.
If you start from an early 21st century baseline, you can subtract 1C from the 3C. Simple . . . now we are down to 2C.
TCRE
Nic Lewis wrote a previous post on TCRE: Climate sensitivity to cumulative carbon emissions. Excerpt:
“There are two principal metrics for sensitivity to cumulative carbon emissions. The best known is the transient response to carbon emissions (TCRE). This measures the change in global mean surface temperature (GMST) at the end of a period, typically of the order of a century long, during which CO2 is emitted smoothly. TCRE is stated per 1000 GtC (≡ 1 TtC) emissions, and usually assumes a total of 1000 GtC is emitted. Note that 1000 GtC is the carbon content of 3667 GtCO2.
In CMIP5 earth system models (ESMs), which couple carbon cycle models with atmosphere-ocean global climate models, TCRE ranges from 0.8°C to 2.4°C, with a mean of 1.6°C. The assessment in AR5, which largely mirrors the CMIP5 ESM range, was that the TCRE is likely between 0.8°C to 2.5°C, for cumulative CO2 emissions less than about 2000 GtC, until the time at which temperatures peak. ”
Nic calculated the observationally-based values of TCRE to be 1.05°C.
“The observationally-based TCRE estimate of 1.05°C, although within the AR5 range and the almost identical CMIP5 ESMs model range, is little more than half the level reflected in the central RCP scenario projections in the AR5 SPM.10 chart. Assuming that the 1.05°C estimate is realistic going forward, the IPCC’s chart overstates expected 21st century warming by a factor of approaching two, for all scenarios.”
Yes, there is uncertainty in the observationally-assessed value of TCRE. Similar to the LC18 results, the observationally-based values of climate sensitivity are slightly more than half of the model-derived values.
Lets do math. With a different baseline, we are now down to 2C. Multiply 2C by 0.6 (reduced values of TCRE) to yield a warming of 1.2C.
Natural variability
The IPCC’s 21st century climate change predictions do not include natural variability, they are focused only on manmade climate change. Excerpts from the IPCC AR5:
“With regard to solar forcing, the 1985–2005 solar cycle is repeated. Neither projections of future deviations from this solar cycle, nor future volcanic radiative forcing and their uncertainties are considered.”
“Any climate projection is subject to sampling uncertainties that arise because of internal variability. [P]rediction of the amplitude or phase of some mode of variability that may be important on long time scales is not addressed.”
So . . . does natural climate variability matter for the 21st century climate? Of course it does. The common argument is that natural variability is of small amplitude and we don’t know whether it will contribute to warming or cooling, since we can’t predict it.
Well, is anyone predicting another solar maximum in the 21st century, similar to what we saw in the mid/late 20th century? No . . . rather, there are some predictions for solar cooling in the mid 21st century. Whether there will be a major solar minima in the 21st century is highly uncertain, but the more telling point is that no one is predicting a new maximum. In any event, endlessly repeating the 1985-2005 solar cycle doesn’t seem to be a particularly good bet.
Re volcanoes, the 20th century was quite benign in terms of volcanic eruptions. There were much worse volcanic eruptions in the 18th and 19th centuries. Is there any particular reason to expect the 21st century volcanic eruptions to be as benign as the 20th century. You have to go back to the period 1340-1440 to find another century long period as benign as the 20th century volcanoes.
Now for the multi-decadal and longer ocean oscillations. For the past 25 years, we have been in a regime dominated by the warm phases of AMO. Is anyone predicting that the warm phase will persist through the 21st century? No . . . transition to the cool phase are expected before mid century.
While we can’t predict future solar, volcanic and long term ocean oscillation activity, we can expect multidecadal periods in the 21st century where the external forcing tends towards cooling and also the ocean oscillations support cooling, reduced Greenland ice melt, etc.
Net cooling from natural sources of 0.2C or more is not at all implausible over the 21st century; it is difficult to argue for additional warming from natural sources over the 21st century.
1.2 C minus 0.2 C = 1.0 C
Dangerous?
1.0 C warming for the remainder of the 21st century seems pretty benign. But if you add the ~1.0 C warming since 1890, then we are at 2 C – ‘dangerous’
2C, and then 1.5C, are the touted values of ‘dangerous’ climate change. Some context on ‘dangerous’, and some different perspectives in these previous blog posts:
- What constitutes ‘dangerous’ climate change?
- Did the IPCC AR5 take the ‘dangerous’ out of climate change?
- Redefining ‘dangerous’ climate change
Simply put, in terms of ‘dangerous’ we are looking at extreme weather events, sea level rise and species extinction. I’ve written numerous posts on all of the above, won’t rehash here, other than to point you to the recent IPCC Special Report on Oceans, Cryosphere and Climate, since sea level rise is one issue that is very directly and monotonically linked to warming. Their main conclusion regarding sea level rise:
“Projections of global mean SLR under RCP2.6 result in 0.42 m (0.28–0.57 m; likely range) in 2100. Projections of global mean SLR under RCP4.5 results in0.55 m (0.39–0.71 m, likely range) in 2100. Projections of global mean SLR under RCP8.5 results in 0.97 m (0.55–1.40 m) in 2100.”
If you take out the highly implausible RCP8.5, then we are left with 1-2 feet by 2100, compared to ~7 inch rise in the 20th century. And these values are biased high from climate model simulations that don’t sample the full ‘likely’ range of ECS from the IPCC AR5 – no climate model values between 1.5 and 2.3 C.
The issue of 2 C as ‘dangerous’ is tied to concerns about tipping points, and massive melt of ice sheets that were observed in previous interglacials at comparable temperature. My main response to that concern is a request to paleoclimatologists to sort out what was going in the mid-Holocene ‘climate optimum’, when there is at least anecdotal evidence of much warmer temperatures and higher sea level. (Note re the last 2000 years; I’ve yet see convincing evidence that MBH-style shenanigans have disappeared from PAGES2K, etc.)
Conclusions
1.2 C of additional manmade warming over the remainder of the 21st century isn’t ‘dangerous.’ Yes, there is substantial uncertainty in how the climate of the 21st century will actually play out, and we will undoubtedly be surprised.
But reframing the ‘warming’ with an early 21st century baseline, rejecting RCP8.5 and using more credible values of TCRE goes a long way towards putting manmade global warming into perspective over the course of the 21st century.
I don’t understand all of the technical and science talk included in this article.
I can tell you what I thought I understood after I started following this in the 1990’s. I was lectured that man was polluting the atmosphere with CO2 via his use of fossil fuels and abuse of the land. If the CO2 concentration reached 350 ppm we would reach a tipping point and the earth’s average global temperature would race up uncontrolled. If the average global temperature were to become 2 degree centigrade higher than pre industrial temperatures it would be a catastrophe for humans and the earth as a whole.
We have passed 350 ppm and have not reached or surpassed the catastrophic 2 degrees centigrade increase. Everyone stopped talking about the 350 ppm. Now the talk is about the 2 degree centigrade increase. My understanding is that the average global temperature has already risen 1.5 degrees centigrade from pre industrial times. If that is the case shouldn’t we be three quarters of the way to the end? I some how don’t feel it.
We already know they lied to us about the 350 ppm. I feel pretty confident that the additional .5 degrees centigrade in the coming eight decades is not going to do us in.
Judith Curry’s article seems like an effort to make the hand wavers feel better about their miserable prediction that we are all doomed once we achieve the 2 degree increase, which I am thinking we will. All she is doing is moving the goal post but we will still be 2 degrees warmer than we were in pre industrial times. I can’t see any reason to make the liars feel better about their lies or the mistaken feel better about their mistakes if you prefer.
Having said that I am against wantonly polluting or abusing the earth. The US has made remarkable progress in cleaning up our country, if the rest of the world simply did as much as we have most of our problems would approach insignificance and all our lives would be better.
Long story short we need to force them to fail again.
“My understanding is that the average global temperature has already risen 1.5 degrees centigrade from pre industrial times. If that is the case shouldn’t we be three quarters of the way to the end? I some how don’t feel it. ”
It is my understanding that the “Hottest Year Evah!”, 2016 (which was one-tenth of a degree warmer than 1998, a statistical tie) reached a point that was 1.1C above the 1850-to-present average temperature. The temperatures have currently cooled about 0.4C since the 2016 highpoint, so we are currently 0.7C above the 1850-to-present average.
The year 1934 in the United States was 0.4C warmer than 2016, which would put 1934 right at 1.5C above the 1850-to-present average.
So we have a long way to go even to reach 1.5C above average again, much less 2.0C above average.
After the temperatue highpoint of 1998, the temperatures cooled for many years. My assumption is the same thing will happen after the 2016 highpoint. The temperatures climbed from 1910 to 1940, then they declined from 1940 to 1980, then they climbed again from 1980 to the present where the temperatures did not exceed the levels of the 1930’s, and now we are starting to cool again. President Trump says of the temperatures [paraphrasing], “They go up, and then they go down, and then they go up again”. And that’s what they do All unmodified surface temperature charts show this kind of periodic pattern.
UAH satellite chart:
http://www.drroyspencer.com/wp-content/uploads/UAH_LT_1979_thru_November_2019_v6.jpg
“The temperatures have currently cooled about .4 degrees since the 2016 high point…”. So you are saying that we have cooled .4 degrees in three years yet the CO2 levels are still over 400 ppm. What does that tell you about CO2’s greenhouse effect?
“What does that tell you about CO2’s greenhouse effect?”
Well, it tells me that increased levels of CO2 in the Earth’s atmosphere and atmospheric temperatures are not in sync.
During the time period from 1940 to 1980 the atmospheric temperatures also cooled while CO2 levels increased in the Earth’s atmosphere.
No correlation means . . .
Co2 is not the control knob.
Bob wrote: ” Judith Curry’s article seems like an effort to make the hand wavers feel better about their miserable prediction that we are all doomed once we achieve the 2 degree increase, which I am thinking we will. All she is doing is moving the goal post but we will still be 2 degrees warmer than we were in pre industrial times. ”
From what point is the prediction predicated? 2 degrees from the LIA? 2 degrees since 1850? 1880? 1910? 1979? 2 These are common starting points. Note that these starting points are usually at the end of cooling trend or cool period. What is normal, or is there a normal that isn’t just a statistical construct. All this variation despite co2 concentration. 2 degrees from 280 ppm? 2 degrees from 350 ppm?
My understanding is that the industrial revolution began in the late 1700 or early 1800’s. It is believed that the CO2 concentration was about 280 ppm at that time. I don’t believe we started doing actual real time measurements of CO2 concentrations until 1950 or so. The measurements given for the past were of trapped air bubbles in ice cores from places like Antarctica. Who knows how reliable they are but that is what we have. As for the temperature you must remember they are talking about the average global temperature. We don’t know what the average global temperature is today how could we possibly know what it was over 200 years ago. Today we have very accurate instruments, unlike in the past. The problem is that we have very little coverage of the earth and many land sites are compromised by urban heat island effect. Satellites and balloon measurements are better but we have only been doing them since 1979.
A simple question: What is the optimum global temperature? Come on, you climate scientists, lay your cards on the table.
What is the optimum global temperature?
The optimum for what?
That’s up to the alarmists to define. You are the ones who are proclaiming that any changes are bad.
“emissions expected to produce warming of around 3C could result in warming as little as 1.9C or as much as 4.4C.”
To a non-professional, that looks like a pretty wide range, with the highest value more than twice the lowest. I detect a strong hint of “wild guess” there.
“Wild Guess” is right. There is no evidence CO2 is heating the Earth’s atmosphere. It may be cooling the atmosphere. All these ECS (Estimated Climate Sensitivity) estimates, which are based on how much warmth a doubling of CO2 would cause in the atmosphere, are just wild guesses, and now we are in the process of refining these wild guesses, with no negative feedbacks even considered. They assume CO2 is causing all the warmth based on nothing but assumptions.
Climate Science is a long way from figuring out what CO2 is doing or not doing in the atmosphere. Everything they say is pure, unsubstantiated speculation. The alarmists don’t have one fact to on their side.
Ask any climate scientist to prove CO2 is warming the Earth’s atmosphere. They can’t do it. If they could they would smack down this post of mine in very short order, but they won’t because they can’t. That ought to tell you something. If they had anything other than speculation you can bet they would be rolling it out. I challenge them all the time and every time all we get is crickets from the CAGW promoters. Crickets is all they have. It must really irritate them to be unable to reply to a post like this.
So we are going to get very refined and precise wild guesses?
Yeah, I think the experts have refined it down to close to 1.0C-1.5C for a doubling of atmospheric CO2. A benign number even if you believed in the human-caused climate change speculation.
Current global temperatures cool, and CO2 climate sensitivity numbers are falling. Things are heading “south” for the alarmists! What are they going to do? Why, they will double-down on the wild speculation and scaremongering, is what they will do. It won’t change the numbers, though. The numbers are going against them.
See: Crickets. Alarmists have no answers.
See kids, the guys that are trying to scare you about human-caused climate change can’t answer a simple question about CO2 and the Earth’s atmosphere, yet they want you to be very afraid for your future.
Alarmists are SO predictable. When challenged, they run for the hills! 🙂
That should tell you all you need to know about the sad state of Alarmist climate science.
I think this is the cue for
MERRY CHRISTMAS AND A HAPPY NEW YEAR – and many more of them!
Plus 1 for you.
It has snowed all afternoon here (Christmas day) and right now the storm is lifting, the sun is low in the west, and the iridescence of the low-hanging clouds is red and green. Christmas colors!
Merry Christmas.
Something has been nagging at the back of my mind and It’s taken a while to puzzle it. When I was at school in juniors ’60’ we were taught that the Earth;s core played a part in how warm the planet is. Never see it mentioned, does it play a part? Sorry if it’s a dumb question not my field.
David Hartley, the Earth’s core remains so hot because the heat that is there can only escape very slowly. Extremely slowly. It is effectively self-insulating. The amount of extra “new” heat, which is generated by decay of naturally-occurring radioactive elements, is also very small. Averaged across the whole surface of the planet both of these are very very small compared to the amount of energy received from the sun.
Of course some of the interior heat escapes in “concentrated” form at a few locations like active volcanoes and mid-ocean ridges. Some energy is also dramatically released in earthquakes. While the effect of active volcanoes under some glaciers in places such as the Antarctic Peninsular is possibly significant, the global average effect is still considered tiny. But it is certainly interesting to speculate whether occasional intense bursts of volcanic activity could affect the flow of certain glaciers or maybe trigger ocean currents to change their course or intensity.
Thank you very much for your thoughtful reply reply, very informative.
The usual breathtaking hubris. Current and future policies will have effects remarkably close to zero. Because most of the world is going to continue to use fossil fuels as they see fit, whatever the Hausfathers, graduates from the School of Mosher, or other would-be rulers of the planet, would like to think.
Happy Christmas.
UN water plans from a well known website:
Later:
Having failed to deliver adequate drinking water supplies to the world, UN agencies, hangers-on, and other associated parasites now confine themselves to the modest task of making policies to control the weather and stop humans with inadequate drinking-water supplies from using fossil fuels to improve their lives.
TCR and ECS are the same. Temperature response to a forcing has a lag of about 3 hours, not 3 centuries. Else we would be accumulating heat, day on day, from sun rises 3 centuries ago. We arent.
Ocean heat uptake of warming from CO2 is also impossible, The oceans are 3 C warmer, and longwave cant penetrate water to any real depth and certainly not beyond the cool layer.
Short wave radiation warms the oceans. The temperature of the air regulates how quickly that energy can escape from the oceans.
Yep. The concept of ‘ocean heat uptake’ of IR, heat energy, is a myth, an impossibility. IR can slow the rate at which the sea loses energy, but that energy was from shortwave.
ECS and TCR are three hours apart.
I think the best way to debunk the ‘CO2 acts as a blanket’ fantasy is this:
In the bone dry (no atmospheric humidity) desert areas of the world temperatures can reach 50 dg. C in the daytime.
Shortly after sundown, air temperature falls dramatically, often to subzero levels . Please reply !
The lack of water vapor has a huge temperature effect over deserts, and H2O is the most potent greenhouse gas. At daytime the absence H2O carpet let most of the sun radiation reach the surface. in nighttime the absence of the H2O blanket let more of the heat radiate out. CO2 works the same way, but to much lesser degree.
Thanks,
You say:
CO2 works the same way, but to much lesser degree.
OK, but AFIK it has never been proven that the atmospheres 0,04 pct. CO2 content has any material effect on climate.
You seem to be arguing that unless a blanket is 100% effective, it has no affect.
No, that is evidently not my argument.
But OK, perhaps I should have written : it has never been proven beyond a reasonable, scientific doubt that the atmospheres 0,04 pct. CO2 content has any material effect on climate.
If you think otherwise, perhaps you could provide a link to the proof ?
This climate hysteria is primarily based on 2 things:
1) Climate models based on wildly different assumptions about the earth’s climate, which is basically chaotic, and therefore impossible to model.
2) A model of a fictitious moon-like planet with no oceans. Totally absurd !
Enhanced by the Climate-Industrial-Complex, and the Neo Marxists.
It has been proven that CO2 traps IR energy.
Because of that it has an impact on climate.
As you note, H2O, another greenhouse gas has a big impact.
Likewise, CO2, a weak greenhouse gas also has an impact, a much smaller one.
We can’t pinpoint the impact in the climate record because the impact of CO2 is less than the noise in the system.
Just because we can’t pick a signal out of the noise is not proof that the signal does not and cannot exist.
”It has been proven that CO2 traps IR energy.”
Traps? Where? I would like to see this proof.
CO2 does not trap IR energy. It merely slows the radiation of a small protion of the IR spectrum into outer space.
I read an article last week about solar irradiance measured at various weather stations in the Netherlands and Germany. Since 1980 solar irradiance has increased with 10 to 15 W/m2. This was supposed to be the effect of cleaner air (less aerosols). All data from KNMI climate explorer.
That is far more than the 3.7 W/m2 form doubling CO2 so must have had a considerable effect on the temperature both in the Netherlands and Germany.
More likely because of less clouds. I’ve read some publication that cloud cover went down by some 4-5 percent points during the same period.
We are moving from Climate Pessimum to Climate Optimum conditions, with Greening Sahara, Arab Pensinsula, deserts also greening in Pakistan, India and China…
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Die qualitativ hochwertigen Proxies (etwa Baumgrenzen und pflanzliche oder tierische Spezies) deuten auf deutlich höhere Temperaturen während des Klimaoptimums und vor allem auf weit günstigere Lebensbedingungen als heute.
Der Klima um 1850 (was dumme Menschen aus unerfindlichen Gründen heute als Optimum postulieren) gleicht dagegen eher jenem des Klimapessimums.
Entsprechend war beispielsweise auch die Baumgrenze in den Alpen zeitweise um 200 bis 300 m höher, in Sibirien und Nordamerika lag die Baumgrenze bis zu 300 km weiter nördlich als heute. Gleichzeitig lagen die Wassertemperaturen im nördlichen Indischen Ozean und im tropischen Pazifik .. im Altithermum auf 1 °C über dem heutigen Niveau…
Der bemerkenswerteste Unterschied des Altithermums im Vergleich zu heute war ein deutlich feuchteres Klima in den Wüstengebieten. Es gibt Anzeichen für ganzjährige Flüsse in der Sahara und anderen heutigen Wüsten. Der Tschadsee hatte zu dieser Zeit etwa die Ausdehnung des Kaspischen Meeres. Wie etliche Felszeichnungen aus der Sahara zeigen, gab es zahlreiche Großtierarten wie Giraffen, Elefanten, Nashörner und sogar Flusspferde. Siedlung und Viehhaltung war den Menschen damals in diesen Gebieten möglich. Gleiches wurde durch das feuchte Klima in der Thar (Pakistan) ermöglicht, wo der indische Sommermonsun deutlich stärker ausgeprägt war als heute.[15]
Während des Klimapessimums von 4100 bis 2500 v. Chr., das deutlich niedrigere Temperaturen als das Hauptoptimum 1 aufwies, zog sich die Savannenvegetation abrupt zurück. 3200 bis 3000 v. Chr. wurde das Klima in den Wüstengebieten deutlich trockener, es begann die Desertifikation der Sahara. Die Bewohner der Sahara und anderer werdender Wüstengebiete mussten ihre Lebensräume verlassen und sammelten sich in den Flusstälern des Nils, Nigers, des Huang-Ho (China) und Indus (Pakistan) sowie in Mesopotamien an Euphrat und Tigris.
https://de.wikipedia.org/wiki/Holoz%C3%A4n
Climate Change greening Sahara desert
https://www.mpimet.mpg.de/fileadmin/communication/Max-Planck-Forschung/PDFs/1104_Die_Wueste_gruent.pdf
(hopefully quick enough to counter the next natural Sahel drought caused by AMO cold phase, due in a few years, but with quadrupled population since last famine)
Fooling people into doing anything is actually bad.
A good question to ask is this:
If the predictions are right and there is about 1.5o of warming likely this century, why will that be a bad thing?
What is more likely, based on the track record 9f climate predictions to date, is that the current predictions are useless for policy makers who want to improve the lives of people.
Sleepy quid pro quo Joe Biden says climate change is a big issue. Need we know more about the stupidity of worrying about global warming?
Sea level rise began before 1860. Sustained rise started around AD 1800.
After the Maunder Minimum depths of the LIA in the 1690s, it rose, then fell again during the Dalton Minimum at the end of the 18th century, but never got as low as during the longer, colder Maunder.
I see where Climate etc is still doing its job of keeping skeptics close to the IPCC corral while allowing them some freedom to roam outside. It’s cunningly done, and I’m not surprised to hear that the lady is now happily ensconced with retired military and intel people. When you want to succeed as controlled opposition, best to have plenty of expert spooks around you.
For temps, instead of an extreme number out of the hat like 3 you get a much less alarming 1 (out of the same hat). Yes, you could be that lucky. Sure the seas will rise, but not as much as the “extremists” claim. Or probably not. You see, there’s lots of uncertainty! And uncertainty is such a “wicked problem”. It’s uncertain why I can’t paddle a canoe at Ephesus where the Roman parked whole fleets. It’s uncertain why the cramped battlefield between sea and mountains at Thermopylae is now a wide plain. Everything’s uncertain…but keep soaking up the IPCC message anyway. They have models, and the models can only get better, right?
So long as people keep reducing those fossil fuel emissions and keep glued to the IPCC and its non-Kardashian models, it doesn’t really matter if the Consensus throws us skeptics a bone or two. And because we’re a bit thick we’re given a formula even we can follow: 1.2 C minus 0.2 C = 1.0 C. So that’s 0.2 (out of the hat) for natural cooling and 1.2 (out of the hat) for our naughtiness. It might be a bad thing…but it’s uncertain how bad. Relax, but don’t relax so much that you stop following the IPCC and the main globo agenda. Stay bad…but stay tuned in.
Let me say it without sarcasm. Climate etc is controlled opposition. It has been from the start. It’s slow poison labelled as lemonade, just for skeptics.
Can someone please list some natural feedback variables that are demonstrable positive in value. As I look around nature all I see is negative feedback systems to keep things in balance. Thanks you in advance.
No, that is evidently not my argument.
But OK, perhaps I should have written : it has never been proven beyond a reasonable, scientific doubt that the atmospheres 0,04 pct. CO2 content has any material effect on climate.
If you think otherwise, perhaps you could provide a link to the proof ?
This climate hysteria is primarily based on 2 things:
1) Climate models based on wildly different assumptions about the earth’s climate, which is basically chaotic, and therefore impossible to model.
2) A model of a fictitious moon-like planet with no oceans. Totally absurd !
Enhanced by the Climate-Industrial-Complex, and the Neo Marxists.
Is the link to the David Wallace-Wells paper the correct link?
And we should keep in mind that this global average temperature we are talking about was derived from a bastardized surface temperature record, so the truth is we don’t really know for sure what an optimum/average temperature might be, and we don’t know where we stand today with regard to such a temperature.
The science of the Earth’s climate definitly isn’t settled. Nearly all of it is speculation of one kind or another. And some of it is fraud.
IPCC Intergovernmental Panel On Climate Change
GCM General Circulation Model (many, based on IPCC CO2 assertions)
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These eight links from five authors are all you really need to understand global warming.
My speculation: As the temperature went down into the Little Ice Age, limestone was deposited around the edges of bodies of water. As the temperature has recovered since, the limestone dissolved and added CO2 to the oceans, with a delay of 300-400 years. It was just an accident that this added CO2 coincided with our industrial revolution. Temperature creates CO2, not the other way around. There is proof of that. Read on.
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Pangburn
Shows that temperature change over the last 170 years is due to 3 things: 1) cycling of the ocean temperature, 2) sun variations and 3) moisture in the air. There is no significant dependence of temperature on CO2.
https://globalclimatedrivers2.blogspot.com/
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Connolly father & son
Shows the vertical temperature profile follows the ideal gas laws and is not caused by CO2. Millions of weather balloon scans and trillions of data points have been analyzed to come to these conclusions. One important conclusion is that there is no green house gas effect.
https://globalwarmingsolved.com/2013/11/summary-the-physics-of-the-earths-atmosphere-papers-1-3/
utube:
https://www.youtube.com/watch?v=XfRBr7PEawY
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Pat Frank
Shows that GCM results cannot be extrapolated a few years, let alone 50 or 100.
https://www.frontiersin.org/articles/10.3389/feart.2019.00223/full
and
https://wattsupwiththat.com/2019/10/15/why-roy-spencers-criticism-is-wrong/
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Joe Postma
Shows that the “flat earth model”of the IPCC is too simple. Their real models are built into the GCMs which don’t fit the real data.
https://climateofsophistry.com/2019/10/19/the-thing-without-the-thing/
https://climateofsophistry.com/2019/09/05/real-climate-physics-vs-fake-political-physics/
https://principia-scientific.org/webcast-no-radiative-greenhouse-effect/
Sometimes there’s need for https://www.google.com/search?client=ms-android-huawei&sxsrf=ACYBGNRnveLXZMDYzo59YCrIt2OiFbZWNg%3A1578324177321&ei=0VATXraYE_HjrgTu_43ADQ&q=robert+heinlein+the+door+into+summer&oq=robert+heinlein+the+door+into+summer&gs_l=mobile-gws-wiz-serp.
Q: Why do old farmhouses have a door on the 2ⁿᵈ floor without a balcony – into the snow:
https://www.google.com/search?client=ms-android-huawei&sxsrf=ACYBGNRF6y-ape9Vur8RUFw8XnBULUFILA:1578324674847&q=old+farm+houses+door+2nd+floor+without+balcony+cattle+snow&spell=1&sa=X&ved=2ahUKEwizn9bMpe_mAhVqs4sKHV3iA1AQBSgAegQICRAC&biw=360&bih=518#scso=_y1ITXoyrFsGsrgSKx66oBA19:1240.6666870117188.3333129882812.6666564941406.3333435058594.6666564941406.6666717529297.3333282470703.333333015441895
Someone told the story about Heinlein in winters time having a meeting with his publisher.
He wouldn’t leave alone his cat at home without a door into the summer.
So the white haired dignit senior shone up, as always, with his big briefcase in the bar where he studied his files to prepare for the meeting; ordering bourbon and an extra saucer to his niche.
Pets, dogs and cats weren’t allowed in NY bars. Especially drinking pets.
The bartender never mentioned that Heinlein took the glass while a cat beside him licked from the extra saucer on the bench.