blizzard1024

Its UHI... see https://www.sciencedirect.com/science/article/abs/pii/S0924271620302082#!

How can we be certain this is related to CO2 levels and not natural variability?  What about the warmth of the 1930s? Did we really know what the ocean heat content was back then? Plus this site in Hawaii that is on this guys twitter only has data back to 1954. This is not long enough to make such sweeping conclusions that manmade greenhouse gases are causing this. 

A recent paper actually is showing continued declines the upper tropospheric absolute humidity even the ERA5 data at 200 mb... see

https://friendsofscience.org/assets/documents/TPW-and-GHE.pdf

This suggests that CO2 is not the driver of the current warming trend. So to blame all this on CO2 levels is a stretch.  

On 9/25/2020 at 9:27 AM, bluewave said:

https://www.disl.edu/about/news/marine-heatwaves-and-hurricanes-study-examines-compounding-impact-of-severe-weather

Several coastal communities are picking up the pieces after being ravaged by hurricanes in the past month. Hurricane Laura, a category 4, and Hurricane Sally, a category 2, seemed to meander their way across the Gulf of Mexico constantly shifting forecasts and keeping meteorologists on their toes. In the hours before these storms struck land, they seemed to explode in intensity. 

Researchers at the Dauphin Island Sea Lab with support from the Jet Propulsion Laboratory can offer insight into why these storms intensified quickly as they moved across the continental shelf. 

“Surprisingly, both Hurricane Laura and Hurricane Sally appeared to have similar setups to Hurricane Michael with both storm events being preceded by smaller storms (i.e. Hurricane Hanna and Marco, respectively),” Dr. Brian Dzwonkowski explained. “This pre-storm setup of the oceanic environment likely contributed to the intensification prior to landfall.  Importantly, this pre-landfall intensification was not well predicted by hurricane models or forecasts, which as you can imagine is critical information for evacuation  and disaster preparation.”

Dzwonkowski and his team’s publication, “Compounding impact of severe weather events fuels marine heatwave in the coastal ocean”, outlines how one storm could impact the intensity of another storm by restructuring the thermal properties of the water column. Nature Communications published the findings in its September issue.

The research focuses on Hurricane Michael which devastated Mexico Beach, Florida, and the surrounding communities, on October 10, 2018. The category 5 storm intensified hours before making landfall. 

Dzwonkowski, a physical oceanographer with the Dauphin Island Sea Lab and Associate Professor at the University of South Alabama in the Department of Marine Sciences, and his team tracked down the key events and processes that pushed the coastal waters in the Gulf of Mexico to an extremely warm state (i.e. a marine heatwave), likely contributing to the intensification of a storm so close to shore. 

Unlike the deep ocean, the continental shelf has a shallow bottom that limits how much cold water can be mixed up to the surface, cooling the sea surface temperature and weakening approaching storms. Dzwonkowski and his team focused on how a strong mixing event pushes surface heat downward and clears the bottom water of its cold water reserve.  If this mixing is followed by a period of rewarming, such as an atmospheric heatwave,  the shelf’s oceanic environment could be primed for the potential generation of extreme storm events, i.e. Hurricane Michael.

This work shows that understanding the preceding weather conditions in a region where a storm is going to make landfall can improve interpretation of hurricane model forecasts  and what the storm is likely to do prior to landfall,” says Dr. Dzwonkowski 

In mapping out heat flux and mixing, the team focused on the Mississippi Bight in late summer and early fall with data gathered by a mooring site off Dauphin Island’s coastline. The mooring site collects data throughout the water column allowing for the full heat content of the shelf to be determined. The period prior to the landfall of Hurricane Michael turned out to be the warmest ocean conditions during this time period in the 13-year record. 

 “Turns out hurricanes and atmospheric heatwaves will be getting stronger in a warming world which would indicate the identified sequence of events that generate these extreme conditions may become more frequent,” Dzwonkowski said.   “The occurrence of extreme heat content events, like marine heatwaves has significant implications for a broad range of scientific management interests beyond hurricane intensity.”Importantly, the mechanisms that generated this marine heatwave are expected to be more frequent and intense in the future due to climate change, increasing the likelihood of such extreme conditions.  

For example, coral reefs and hypoxia-prone shelves are already stressed by long-term warming trends. These temperature-specific benthic communities and habitats are typically of significant societal and economic value. As such, the newly identified sequence of compounding processes is expected to impact a range of coastal interests and should be considered in management and disaster response decisions. 

This research was funded by the NOAA RESTORE Science Program and NOAA NGI NMFS Regional Collaboration network. 

https://www.nature.com/articles/s41467-020-18339-2

 

Abstract

Exposure to extreme events is a major concern in coastal regions where growing human populations and stressed natural ecosystems are at significant risk to such phenomena. However, the complex sequence of processes that transform an event from notable to extreme can be challenging to identify and hence, limit forecast abilities. Here, we show an extreme heat content event (i.e., a marine heatwave) in coastal waters of the northern Gulf of Mexico resulted from compounding effects of a tropical storm followed by an atmospheric heatwave. This newly identified process of generating extreme ocean temperatures occurred prior to landfall of Hurricane Michael during October of 2018 and, as critical contributor to storm intensity, likely contributed to the subsequent extreme hurricane. This pattern of compounding processes will also exacerbate other environmental problems in temperature-sensitive ecosystems (e.g., coral bleaching, hypoxia) and is expected to have expanding impacts under global warming predictions.

Hurricanes have been ravaging the Gulf Coast for eons. How do we know that all of the sudden now they are getting stronger before landfall? How did we measure that 100 years ago?  It's not just ocean heat content that drives Hurricanes. Interaction with the westerlies, wind shear and frictional effects all are important before landfall. You can't say that global warming causes this. The warmer ocean waters can't even be proven to be related to global warming from CO2. This is all hype right before a presidential election. They want voters to believe the weather is getting more severe because of CO2 levels. This is insanity. CO2 levels have little to do with storm severity. Climate scientists want there to be a link so all this research is coming out trying to tie severe weather events to global warming. And Michael Mann is not even an atmospheric scientist. He basically is a climate activist and that is what passes for academia now in atmospheric science departments at major universities. sad. 

5 hours ago, skierinvermont said:

It's a credit to the patience and intelligence of Don, bdwx, and Chubbs that they are willing to take the time to try to reason with some of the gaping errors in what you post.

Climate scientists and their followers are so insistent that they have it all figured out and don't tolerate dissenting scientific opinions. So they need patience? These folks above engage in civil debate. Science generally welcomes debate with the exception of climate science. And yes these folks indeed are intelligent and I enjoy reading their posts. They are also civil which I appreciate. 

5 hours ago, skierinvermont said:

To those of us who have been studying climate science for the last 15 years we know the details of these papers and methods like the backs of our hands 

And you are not open to any debate at all or any uncertainty at all when there is a lot of holes and downright bad science in this climate "crisis" mantra. Almost every major storm or hurricane, wildfires, record heat, record cold, snowstorms etc are now somehow enhanced by CO2?  Okay I will give you the USHCN adjustments are needed but the different way daily average temperatures were calculated I believe before 1922 (correct me if I am wrong) and after, leads to datasets that are measuring two different things. So the error bars are much larger. Comparing apples to oranges. I don't agree with Karl et al 2015 who erased the inconvenient pause between 1998 and 2015 right before the super El Nino of 2016. I don't agree with the RSS who again warmed up 1998-2015 also to erase the pause before the super el nino by retaining the warmer NOAA-14 satellite. Both of these methods are controversial in climate science. 

But let's look at what we agree on.  I agree with the basic physics of the infrared active molecule CO2. It absorbs IR radiation in a small IR band around 15 microns and emits radiation in all directions. All else holding equal, a doubling of concentration of CO2 will lead to around 1.2C of warming. No one debates this. The feedbacks are where the problems begin and disagreements start. You know where I stand on this and other climate scientists on "my side" for lack of a better term. I do agree with you that we should be looking toward other cleaner energy sources for the future. So I am all for that. The disagreement is on how quickly we divest from fossil fuels and its impacts on economies. 

Plus peer review literature is not proof of anything. It is the concepts that are the proof. Many un-peer reviewed blog posts are actually very scientific and in fact a new way to communicate science. Judith Curry is a credit to this. 

Look I will remain civil and on this forum. I question everything it's my nature. I have been studying this problem for 30 years and I too was once a strong believer in dangerous global warming until I dug deeper. I have NO stocks or any funding at all from fossil fuel companies. Ziltch. I have reviewed many papers too in atmospheric science for scientific journals for many years. I have seen a noticeable decline in quality of what is accepted and now passes as peer reviewed literature. Journals have gotten fatter and fatter these days vs 25 years ago. The process was extremely rigorous back in the day. Now it has become much more lax. That is so these journals can publish more and more papers and get more and more money. I also find it interesting that in meteorology two scientists can completely disagree on something and yet maintain a civil and open discussion and actually work together. In the end more is learned by this collaborative approach. Climate science shuts down anyone that doesn't agree with their narrow minded view that CO2 drives the climate. And that is the main reason why I didn't leave this forum. I will not be shut down. Many on "my side" have left this forum and that is a shame. No other science that I know of does this. Why is that? 

Anyway, I am skeptical of a lot of peer reviewed stuff not just climate science but in the broader atmospheric science and meteorological fields. Ok that is enough for now. Have a good day. 

Just now, blizzard1024 said:

Just like you swore you were leaving the forum and came back about 18 hours later. Folks had a good laugh at that.

I decided not to let folks like you chase me off this forum like you did with many others in years past. This should be a climate change forum not a climate activist forum. That is ultimately why I changed my mind. Laugh all you want. But I won't let people that attack others chase me away. Have a nice night 

16 minutes ago, skierinvermont said:

Just like you swore you were leaving the forum and came back about 18 hours later. Folks had a good laugh at that.

Well this statement clearly violates policy and this user is going. And your rudeness should not be tolerated either. This is very classic since you can't back up your claims or are insecure about the science (which is FULL of holes) you resort to attacks.  I don't attack you. You can believe what you want. That is your free choice. My scientific opinions ARE valid and really common sense. But you can see things your way. I won't attack you. Why should I? 

8 hours ago, Bhs1975 said:

Cause he’s a dumb ass.

You're done on this forum. You will get banned now. I will make sure of it. 

5 hours ago, skierinvermont said:

As long as appropriate error bars are used and the author is open and honest about what is happening, there is no problem with stitching.

You can have one graph of proxies, and another totally separate graph of instrumental temp, if you prefer. The conclusion is the same. Warming of the speed and magnitude recorded by instruments over the last 150 years would have been extremely unlikely given the proxy data.

If there was a warming or cooling spike of similar magnitude as today's say in the 1300s would the proxy data be able to detect it given how coarse the dataset is and that it is in fact proxy data?  The proxy data shown in this first paper of this topic shows little change in global average temperature during the Roman Warm Period, Dark age cold period, Medieval Warm period, It does show LIA cooling to some extent. The greenland ice core data clearly shows these temperature fluctuations back for much of the holocene with an overall trend similar to the first paper's results. However as you can see there are a lot of rapid fluctuations. How can we be sure this wasn't global in nature?

9 minutes ago, donsutherland1 said:

If the link between CO2 and global temperatures is “insanity,” even setting aside physics related to CO2’s properties, one should find a large number of research papers making exactly that case.  

You have too much faith is peer reviewed climate literature. There is a lot of bias. The gatekeepers are alarmists.  They have brought the field of climatology to a standstill by focusing on a small portion of the climate system, CO2. This has put back real research in climate at least a generation. 

4 hours ago, donsutherland1 said:

In turn, the increased atmospheric concentration of carbon dioxide promotes additional warming. Given the physical properties of carbon dioxide, it should make no difference how the stored carbon dioxide is released. The impact should be the same if the physical properties of CO2 are understood correctly.

But wait, why doesn't the initial warming lead to increases in water vapor which then amplifies the initial warming? H20 is the primary GHG.  This is the reason by the climate alarmists that doubling CO2 leads to more than 2C of warming. So why does the water vapor feedback do nothing or very little? Why isn't this mentioned. CO2 forcing is relatively weak. So you are relying on two feedbacks really. The warming is kicked off by the amount of solar radiation at 65N due to Milankovitch cycles and then CO2 increases which leads to H20 increases which then warms the Earth and dominates?  But somehow CO2 lags the temperature through the whole Ice core records.  This should have ended this insanity 20 years ago. 

"The observed ongoing warming is consistent with what one would expect when atmospheric carbon dioxide increases."  Correlation does not imply causation. There are dozens of other processes that could cause the ongoing warming which really isn't that extreme. 

3 hours ago, Bhs1975 said:

How many times you gonna rehash this? The SMF ain’t listening.

This is central to the reason why CO2 doesn't drive the climate. As many times as it takes.  The hand waving explanations are not scientific. An objective climate scientist would seriously reconsider the role of CO2 in our climate since its levels follow temperature trends.  CO2 is not the world's thermostat. It leads to a little warming. The whole house of cards upon which  billions and billions of dollars rests on a shaky foundation. That is why people like you, mainstream climate scientists the media and left wingers are so defensive. They know it. They also have the gall to question seasoned sincere atmospheric scientists thinking they know more or ....that these scientists are being "paid off" by big oil. This is not true. It's an excuse.  The mainstream climate scientists need there to be a climate crisis or else their funding will eventually dry up. You know this. Everyone does. 

4 hours ago, donsutherland1 said:

The confidence level will likely be 99%-100% when the IPCC publishes its next assessment (an increase from the current 95% figure).

No person making projections/predictions in atmospheric science more than a 5 days in advance is this confident. For the IPCC to be this confident, shows the political nature of this organization. 

6 hours ago, Bhs1975 said:

This paper shows that SSTs where cooler in the tropics during that time and changes in ocean circulation not CO2 was in the drivers seat like it is now.

 

 

https://web.archive.org/web/20100119135516/http://www.agu.org/pubs/crossref/2002/2001PA000724.shtml

How do you know it is not ocean currents now? Oh yeah I forgot...climate models.  /sarc

4 hours ago, donsutherland1 said:

The “lag” issue has been explained numerous times:

Step 1: Begin the release of CO2 — initial warming kicked off by natural processes was the mechanism

Step 2: Amplify the initial rise in temperatures — increasing atmospheric CO2 amplified the initial rise in temperatures.

And this is not how atmospheric physical processes behave. Something else kicks off warming. Obviously this is more dominant than CO2.  If CO2 was such a dominant factor, then how could the Earth cool while CO2 rises? So some other processes kicks off the warming of the planet, CO2 is passively following the temperature trends with a lag.  So warming occurs while CO2 is falling, then magically the CO2 molecules decide that they have to warm the planet and said feedback begins.  The Earth's atmosphere doesn't behave like a combustion engine either.  Basically when they release the data from the Vostok ice cores in the late 1990s and 2000s and this lag effect was found, objective scientists would have realized that CO2 is not the driver of the climate. It never was before, why now? It is a minor greenhouse gas. I have said this a million times. So you have a minor greenhouse gas CO2 that needs a strong water vapor feedback to really affect the climate system and somehow dominate it?  

What you are saying is that some other mechanism causes warming, then CO2 after several hundred to thousand years or so starts rising, then this kicks off the water vapor feedback? 
It makes more sense if you have warming or cooling from some other process that kicks off the water vapor feedback. Why is it just CO2? That is why the water vapor feedback is probably small because initial warming would have led to increased water vapor which then would warm the Earth. You don't even need CO2 in this argument. The water vapor feedback probably is small and natural mechanisms change the amount of clouds, water vapor, precipitation, and convection and this drives the climate. CO2 is on the sidelines with a small contribution. This is common sense.  The objectivity of mainstream climate scientists is gone because of money, fame, power and egos. 

On 9/25/2020 at 11:09 AM, bdgwx said:

Temperature Reconstruction

Kaufman 2020: Holocene global mean surface temperature, a multi-method reconstruction approach

Kaufman 2020: A global database of Holocene paleotemperature records

Summary: The rate of warming during the contemporary era is likely unprecedented during the Holocene. The global mean temperature is very likely to be much higher than at any point in the last 2000 years and possibly even exceeding the Holocene Climate Optimum 6000+ years ago.

Thank you for the papers. I read both of them. The first paper does show a Holocene warm period in the higher latitudes of the NH of between 2 and 4C which I have read about before. It is also consistent with pollen samples in the northeast U.S which showed a more Oak, hickory, sweet gum like forest north into NY state the lower elevations of New England. The climate in these northern areas was more like Virginia or even north Carolina somewhere 6-8 thousand year ago. Tree line was farther north at least in Canada too. Spruce and fir retreated northward and up the slopes of the Appalachians and New England all based on pollen samples.  But I find it very confusing that the global  temperature anomaly only reached only +.7C globally during this time with such dramatic local climate changes.  Plus neither paper described how they stitched the ERA20C measured data which is much better and higher resolution to this proxy data(it is not perfect due to the various adjustments as discussed before). Apples are being compared to oranges here. These Hockey Stick looking graphs go back to MBH 98. Also they even admit that their proxy data showed  ":This cooling trend occurred while the atmospheric concentrations of greenhouse gases were increasing. Liu et al. (ref. ³) coined the term “Holocene temperature conundrum” to highlight the contradiction between the cooling indicated by proxy evidence versus the warming simulated by global climate models, a trend reinforced in the most recent generation of climate models⁴."  So we had falling temperatures for millenia with rising CO2 levels. This was counter to the global climate models. Hmmm. So was this a time when CO2 didn't drive the climate? Was  it "inactive" like it was the previous 800,000 years in the ice core data as it passively followed the global temperatures and lagging them by 1000s  of years? In fact, the rise in CO2 in the mid to late Holocene probably was related to the rapid warming that occurred prior to 10,000 year ago. The lag effect was present suggesting CO2 had little to do with the climate system.  But in 1900 or so, all that changed and it suddenly became the dominant driver in the global climate system!!  Yeah that makes a lot of sense. / sarc.  And the rapid rise in temperature in the 1900s to early 2000s is superimposed on a very coarse and uncertain PROXY dataset. This is peer reviewed and  I am not impressed or convinced. And it is NOT PROOF just because it is peer reviewed!   People don't understand that. In fact, the lagging CO2 response seen during the mid to late Holocene cooling period just further proves that CO2 is a small component of the climate system.  That is "conveniently" ignored as one of their conclusions is "The GMST of the past decade (2011–2019) averaged 1 °C higher than 1850–1900¹¹. For 80% of the ensemble members, no 200-year interval during the past 12,000 years exceeded the warmth of the most recent decade." If this wasn't a conclusion this paper would have NEVER made it through the peer review gatekeepers who are climate alarmists. 

12 hours ago, donsutherland1 said:

@blizzard1024Tree rings at some locations had seemingly become a less reliable indicator of temperature. More recent research suggests that light (dimming) may have been responsible.

https://phys.org/news/2014-05-arctic-tree-ring-divergence-problem.html

 

interesting. thanks. 

8 hours ago, donsutherland1 said:

If the use of proxy data is the “weakest link,” how would you go about trying to compare today’s temperatures with those during the rest of the Holocene?

Use the proxy data into the 21st century. You are comparing apples to oranges here. Why not look at the proxy data to the 21st century?   I think there is a divergence issue around 1960 though when proxy data shows a fall in temperature. That was Michael Mann's hide the decline "trick".  He wasn't hiding a real temperature decline as is often portrayed on other blogs. For some reason tree ring data diverge from temperatures around this time. I have seen this stitching of 20th century data to proxy data for over 20 years. I will research this by reading those papers again. I didn't get it before back 15-20 years ago. It looks fishy to me. But I will approach it with an open mind. Thanks. 

9 hours ago, bdgwx said:

Kaufman 2020: Holocene global mean surface temperature, a multi-method reconstruction approach

I read this and it looks interesting. But, the adding of the 20th century data statistically is not convincing.  Low resolution proxy data vs better (although not perfect) data from the 20th century. This is the crux of this paper and it is weakest link. But thanks for the paper. 

Abrupt warming?  compared to what?   how do we know how quickly the climate changed in the MWP or LIA? tree rings?  really....

26 minutes ago, SnoSki14 said:

At what point is blizzard just gonna admit he's a climate change denier so we can move on. 

And there's no point arguing with one. You can cite 1000s of examples and debunk every claim they make and they'll still come up with some nonsense.

The fact is that the earth is rapidly warming mostly due to human related activities. Even when factoring in every natural cause, there's still a ton of excess warmth that could only be caused by humans. 

CO2 PPM levels went from 240 to 420+ since the industrial revolution, which is exactly when the long term warming trends began...it's not a coincidence. 

Some 99.7% of the 11K+ scientists agree. The only ones that don't have been proven to have interests in the fossil fuel industry.

If you still reject all this then you're simply a denier who either has some vested interest in the fossil fuel industry or is just some edgy anti-science contrairian, which we def don't need more of. 

Don't you dare call me a denier. I am not denying climate change and even contribution from CO2. I just am not on board with the climate crisis crowd. there is no way that doubling CO2 is going to destroy our climate system. It will warm it by 1-2C. I know the IPCC has set 1.5C as the danger point but I totally disagree with this. During the Holocene climatic warm period it is known that at least the mid and high latitudes were between 2C and 4C warmer than today based on pollen samples and the fact that tree lines were farther north than today or higher up in the Alps.  A warming of 1-2C in the next 50 to 100 years (assuming there is no natural climatic variability) will benefit mankind. of course those who live near the ocean will have problems. But if you build on the beach, mother nature is gonna take it back anyway either from a storm or rising sea levels which have been on-going since the 1800s.  

Another thing, saying that there was no global MWP and LIA is saying the climate system was in almost complete stasis since the year 1000. That is crazy. the climate is always changing. In a sense, those who believe that the climate was stable from 1000-1900 are actually denying climate change! 

12 minutes ago, LibertyBell said:

I'm well familiar with Eisenhower and his great exit speech and it still applies today (Teddy Roosevelt was another very forward thinking conservationist and antitrust conservative, we dont have them these days, sadly, probably because of all the dark money and corporate lobbying in politics.)

Also please check the post, it says I made that response to you, but in actuality it was Skiier.

 

Oh I am so sorry. 

6 minutes ago, LibertyBell said:

Its sort of funny but also quite sad that you think this is brilliant science

It's actually common sense.  A minor greenhouse gas which never dominated the climate system in the past now does.  Lindzen is a brilliant scientist. he would eat you alive in a debate. And no, they are not just siding with common sense to protect the fossil fuel industry. In fact, the mainstream climate scientists are protecting their billions of dollars worth of taxpayer funded research money. You can say the same thing for these climate "activists" who are supposed to be objective scientists. They own the peer review process.  If you don't conform, you either don't get your MS, PhD, or your tenure. President Eisenhower warned about this kind of behavior in his farewell presidential address back in 1961. We are living it today. 

1 hour ago, skierinvermont said:

Funny.. even in the last hundred years there have been changes in circulation patterns. And yet you argue it couldn’t have happened in the past.

Like what for instance....

33 minutes ago, donsutherland1 said:

The authors of the MWP paper did not claim that the NAO was positive throughout the duration of the MWP. When one is dealing with centennial and sub-centennial timeframes, as was the case in the paper, one is dealing with predominant tendencies over those timeframes. A positive or negative tendency does not preclude even significant variability over much shorter timeframes. Weather is day-to-day; climate is longer-term.

The authors found that the western North Atlantic region was generally cold during the MWP unlike the eastern North Atlantic region. Moreover, their study of the glacier record in the Baffin Bay region on which they based their conclusion is supported by additional proxy data. They explained:

Overall, beyond the high-frequency complexity, we interpret these independent proxy records to support our glacier signal, indicating regional cool conditions through the MWP, perhaps interrupted by brief warming episodes. Our glacier record does not rule out periods of decadal warming between ~975 and 1275 CE, but the down-valley persistence of glaciers through this interval indicates that any warming was not of sufficient magnitude or duration to have driven glaciers significantly up-valley.

In contrast to proxy records from the western North Atlantic region, records from the eastern North Atlantic region generally support warm conditions during the MWP. Historical observations and paleo-data indicate that sea ice off the Iceland coast was not common during the MWP, and an SST reconstruction off northern Iceland depicts a sharp rise in temperatures beginning ~1000 through ~1350 CE...

The authors attribute the temperature anomalies to a persistent NAO+ state. This is a persistent tendency over the timeframe they covered.

For example, let's say I was writing a paper on temperatures in the CONUS during the January 2012-2020 period. Among other variables, I could argue that a persistent NAO+ was responsible for the outcome.

January 2012-2020:

The argument againsBut t it would be, 'You can't maintain anomalies for such a period in either direction." But that would never have been my suggestion.

If one went to the daily NAO data for the period in question, one would find:

% days -1.000 or below: 1%
% days negative: 24%
% days positive: 76%
% days +1.000 or above: 20%

Each of the January cases during the period had a positive NAO value. The overall average daily value was just above +0.400.

Now, if one steps back from this example and substitutes the MWP for the January 2012-2020 period and, let's say, year-to-year variability for daily variability in the NAO, one can still wind up with a skewed tendency for positive values over the timeframe considered, even as annual values would be both negative or positive.

Finally, Andrew Dessler was not an author of the MWP paper. His background is in chemistry and physics. The climate system is comprised not just of the atmosphere, but also the hydrosphere, biosphere, and cryosphere. There is no compelling reason that Dr. Dessler is somehow unqualified for climate science.

Also, do you have any papers that refute Dr. Dessler's work?

Thanks.

Overall century time periods, it is very unlikely that climatic features are "regional". There is also a lot of evidence of a MWP and LIA in the SH. I will dig those papers. But we know that Dessler and company are the gatekeepers of peer review which shuts down anything they don't agree with.   

3 hours ago, donsutherland1 said:

The NAO has been suggested as a plausible explanation for the regional temperature variation during the MWP.

So basically the Arctic stayed extremely cold during the MWP because of a +NAO for centuries? Eventually this would break down. Likewise a -NAO for centuries would mean large high pressure systems up there which eventually by radiational cooling would break down. This shows a deep lack of understanding of the NAO and atmospheric fluid dynamics.