Climate change is here — and worse than we thought

[bluewave]

I'm going to respond to this and then back away as I don't want to derail the thread anymore than it has been.

I think most believe AGW is going on. The extent to which man is playing a role is the big question for many.

Regarding any type of funded "disinformation campaign", I believe the pro-AGW/CAGW crowd is not without fault and has more to lose if, in time, their position turns out to be incorrect. Billions and billions of dollars have been poured into research, grants, green initiatives, etc.. Lots of jobs, money, and personal interests are bundled into the pro-AGW position so I don't think those involved would simply say "oh well, I guess we were wrong" and simply walk away without a fight.

The whole world pretty much runs on money and in itself there is nothing wrong with it. You can use money as a tool

to expose truths and make the world a better place to live in. For the most part, that's what I think the motivation is for

many people who choose to make science a career. The difference with the funding against global warming is that

the motivation is for profit at the expense of the well being of the planet. I don't believe that there really is a lot of

money to be made in a field like climate science. Especially these days, there is a great personal sacrifice that

a student makes when entering a scientific career path.

[dabize]

I don't know how history will view the snake oil salesmen who push the AGW agenda.

This oil is from scientific snakes, and actually works.

So its merchants will be vindicated, if there's anyone around to appreciate their efforts

[Vergent]

Is it accurate to say that warming is typically a slower process then cooling?

no, the other way around. Sea level rises much faster than it drops, at least for the last 800,000 years. The oxygen isotopes say the same thing.

[WeatherRusty]

So what is the climate sensitivity exactly? Without knowing that, which you admit you don't know you just give the wide margin given by IPCC, how can you make such a statement?

I don't understand what climate sensitivity has to do with it. Climate sensitivity is the total temperature response to a radiative forcing once temperature has reached full equalibriium with the forcing...ie. warming or cooling to the forcing will have ceased and the forcing will have reached zero.

The current radiative forcing has not yet been equilibrated. The surface temperature must warm further for equilibrium to be reached since at the TOA a positive energy imbalance is determined to be in place.

The warming of the past half century is part of a longer term trend which is still in progress.

The better question would be, how have scientists determined that the radiative forcing by CO2 has grown to outweigh that from all other sources. That requires a long answer. I suggest you take a look at Spencer Weart's The Discovery of Global Warming.

[donsutherland1]

For those who are interested, the Hansen et al., paper can be found at: http://www.pnas.org/content/early/2012/07/30/1205276109.full.pdf

[donsutherland1]

To illustrate the impact of ongoing climate change in the U.S., I ran the numbers for annual mean temperatures from the NCDC dataset. I used the 1895-2011 timeframe. I also used the 20th century climate base (1901-2000) period that is used by NCDC in its climate reports for the reference point ("normal"). The new Hansen paper talks about the dramatic increase in extreme heat in recent years. Here's what I found:

1895-1999:

1σ or more below normal: 13.3% years

2σ or more below normal: 1.9% years

1σ or more above normal: 16.2% years

2σ or more above normal: 3.8% years

Average annual departure: -0.050σ

2000-2011:

1σ or more below normal: 0.0% years

2σ or more below normal: 0.0% years

1σ or more above normal: 83.3% years

2σ or more above normal: 8.3% years

Average annual departure: +1.437σ

The frequency of years with annual mean temperatures of 1σ or more above normal is 5 times what it was during the 1895-1999 timeframe while the frequency of years with annual mean temperatures of 2σ or more above normal is more than 4 times what it was during that earlier timeframe.

The last year with a negative annual mean departure was 1996 (-0.206σ) and the last year with a negative annual mean departure of 1σ or more was 1979. Prior to the 2000s, there had been no decade (or longer) period in the NCDC dataset that saw no years with negative temperature departures. Prior to the current period, which now runs 32 years and counting since a departure of 1σ or more below normal, the longest such period was 21 years (1930 through 1950).

The number of years with negative annual temperature anomalies by decade is as follows:

1900s: 8

1910s: 9

1920s: 7

1930s: 4

1940s: 6

1950s: 4

1960s: 9

1970s: 7

1980s: 5

1990s: 2

2000-2011: 0

The number and percentage of years by 30-year climatic period with negative temperature anomalies are as follows:

1901-30: 24 80.0%

1911-40: 21 70.0%

1921-50: 17 56.7%

1931-60: 14 46.7%

1941-70: 19 63.3%

1951-80: 19 63.3%

1961-90: 20 66.7%

1971-00: 13 43.3%

1981-10: 7 23.3%

I also took the annual average departure (standardized) by decade:

1900s: -0.515σ

1910s: -0.788σ

1920s: -0.262σ

1930s: +0.715σ

1940s: +0.065σ

1950s: +0.210σ

1960s: -0.396σ

1970s: -0.412σ

1980s: +0.336σ

1990s: +0.989σ

2000-2011: +1.437σ

I also took the average departures by climatic period:

1901-30: -0.555σ

1911-40: -0.135σ

1921-50: +0.190σ

1931-60: +0.310σ

1941-70: -0.049σ

1951-80: -0.161σ

1961-90: -0.073σ

1971-00: +0.370σ

1981-10: +0.958σ

In sum, one finds:

1. The current climate is warmer than the 20th century baseline in the U.S.

2. The warming has resulted in rising decadal and climatic base departures.

3. The warming has resulted in increasingly infrequent cool annual anomalies.

4. The warming has led to an increasing frequency of hot (1σ or more above normal) years.

5. The warming has led to recent disappearance of cold (1σ or more below normal) years.

[N. OF PIKE]

I wonder if some of the warming per the 1221 reporting stations could be accounted for by recent urbanization effects close to sites. Ie closer which makes sites error prone. Let me be clear I'm not passionate either way about climate change ...I'm just questioning potential data errors

[TerryM]

cpick79

Google for the BEST studies - they should put your mind to rest.

Terry

[ben4vols]

Hansen is finding some resistance to his recent paper...

From Dr. Martin Hoerling;

Hansen states, “The global warming signal is now louder than the noise of random weather…”

This is patently false. Take temperature over the U.S. as an example. The variability of daily temperature over the U.S. is much larger than the anthropogenic warming signal at the time scales of local weather. Depending on season and location, the disparity is at least a factor of 5 to 10.

I think that a more scientifically justifiable statement, at least for the U.S. and extratropical land areas is that daily weather noise continues to drum out the siren call of climate change on local, weather scales.

Hansen goes on to assert that:

“Extremely hot summers have increased noticeably. We can say with high confidence that the recent heat waves in Texas and Russia, and the one in Europe in 2003, which killed tens of thousands, were not natural events — they were caused by human-induced climate change.”

Published scientific studies on the Russian heat wave indicate this claim to be false. Our own study on the Texas heat wave and drought, submitted this week to the Journal of Climate, likewise shows that that event was not caused by human-induced climate change. These are not de novo events, but upon scientific scrutiny, one finds both the Russian and Texas extreme events to be part of the physics of what has driven variability in those regions over the past century. This is not to say that climate change didn’t contribute to those cases, but their intensity owes to natural, not human, causes.

The closing comment by Hansen is then all the more ironic, though not surprising knowing he often writes from passion and not reason:

Dr. Pat Michaels;

Hansen claims that global warming is associated with increased drought in the US. This is a testable hypothesis which he chose not to test, and, because PNAS isn’t truly peer-reviewed for Members like him, no one tested it for him.

I have [examined] drought data [that] are from NCDC, and the temperature record is Hansen’s own. His hypothesis is a complete and abject failure.

It is hard for me to believe that Hansen did not know this, and yet he went ahead with his paper. This must be true because Hansen has published papers on the Palmer Drought Index and future warming. Administrator Bolden is obligated to investigate the ethics of publishing a paper that the Director of the GISS laboratory knew could not pass the most simple test of hypothesis.

[LocoAko]

I wonder if some of the warming per the 1221 reporting stations could be accounted for by recent urbanization effects close to sites. Ie closer which makes sites error prone. Let me be clear I'm not passionate either way about climate change ...I'm just questioning potential data errors

This has been studied and addressed multiple times by various papers and is thoroughly accounted for.

[donsutherland1]

Hansen is finding some resistance to his recent paper...

From Dr. Martin Hoerling;

Among other things, Hansen was measuring areas of extreme summer heat (3 sigma and above). He observed that such areas previously encompassed 0.1% to 0.2% of the globe. There's no indication that the standard deviation was on the order of +/- 10%. Recently, those areas covered approximately 10% of the globe. Synoptic patterns are not a new variable. The large area of extreme heat is new. The huge increase in such areas of extreme heat far outweigh the noise of natural variability. That part of the paper is very strong.

Dr. Pat Michaels;

Michaels would do well to acquaint or reacquaint himself with PNAS before speculating about its policies. From PNAS's website:

Results from a survey of PNAS authors (347 respondents) indicate that... 86% are satisfied with the peer review process...

At PNAS, we copyedit, format, peer review, and permanently archive all SI.

http://www.pnas.org/...105/8/2755.full

[ben4vols]

Michaels would do well to acquaint or reacquaint himself with PNAS before speculating about its policies. From PNAS's website:

Results from a survey of PNAS authors (347 respondents) indicate that... 86% are satisfied with the peer review process...

At PNAS, we copyedit, format, peer review, and permanently archive all SI.

http://www.pnas.org/...105/8/2755.full

I think you mis-read what Michaels was saying.

[donsutherland1]

Another quick point:

Dr. Hoerling's response may be based on the submitted, not published, paper.

Here's an example of what Hansen wrote when the paper was submitted:

Global wrming since 1951-1980 is about 0.5-0.6°C (about 1°F), which may not seem like much.

Here's the same passage in the published paper:

Global warming since 1951-1980 is about 0.5-0.6°C (about 1°F). This seems small, and indeed it is small compared with weather fluctuations. Yet we will suggest that this level of average warming is already having important effects.

[donsutherland1]

Upon further looking into the matter, Dr. Hoerling was not commenting on Hansen's just-published paper (quoted portion of ben4vols's post). Instead, he was commenting on an op-ed piece written by Dr. Hansen: http://dotearth.blog...arming-climate/

Dr. Hansen's op-ed in question could be found at: http://www.nytimes.c...he-climate.html

Dr. Hansen's paper, which provides greater clarity on the magnitude of climate change vs. weather fluctuations, was published in August 2012. Dr. Hoerling's response to the op-ed was published in May 2012. In short, Dr. Hoerling's critique did not concern the just-published Hansen paper.

[donsutherland1]

More regarding Dr. Hoerling and Dr. Hansen:

1. Dr. Hoerling has concluded that the 2011 Texas drought (recent research) and 2010 Russian heat wave (published paper: http://www.esrl.noaa.gov/psd/csi/pubs/docs/RussianHeatWave_revisedGRLmerged_version.pdf) were mainly the result of natural factors. There is published literature (http://www.pik-potsdam.de/~stefan/Publications/Nature/rahmstorf_coumou_2011.pdf and http://journals.ametsoc.org/doi/pdf/10.1175/BAMS-D-12-00021.1) that suggests that both events were, at least, made more likely on account of climate change, even if one cannot conclude that they were highly unlikely in the absence of climate change. Dr. Hansen weighed in on the opposite side of Dr. Hoerling on those events. With that context, Dr. Hoerling's response may both be a critique of Hansen's paper and a defense of his own research.

2. Dr. Hoerling's main objection to the Hansen paper is the lack of clear demarcation between drought and heat waves (largely the Texas drought and heat of 2011).

http://www.nytimes.com/2012/08/07/science/earth/extreme-heat-is-covering-more-of-the-earth-a-study-says.html?_r=4&smid=tw-share

3. The common ground between Dr. Hoerling and Dr. Hansen is probably larger than their specific area of disagreement (attribution). Both men believe AGW is under way.

[bobbutts]

Does anyone else have an opinion on this? Are skeptics/deniers not permitted to question the science here. What about lukewarmers who accept the physical basis for AGW, yet believe climate sensitivity to be very low? For instance, should someone like ORH_wxman (Will) be ignored because he believes natural variability is largely responsible for the warming we have experienced to date, in defiance of the peer-reviewed literature?

I believe Will adds significantly to the conversation. IMO he's one of the more honest posters in this forum. I'm not saying everything he says is correct, but rather he's not posting it for the lolz or some agenda.

I'd ignore Qvectorman

[dabize]

Does anyone else have an opinion on this? Are skeptics/deniers not permitted to question the science here. What about lukewarmers who accept the physical basis for AGW, yet believe climate sensitivity to be very low? For instance, should someone like ORH_wxman (Will) be ignored because he believes natural variability is largely responsible for the warming we have experienced to date, in defiance of the peer-reviewed literature?

ORHWx (Will) in particular bothers me because I know that he is a very good met from his NE forum posts and quite gracious to boot, even to rank amateurs like me, and I always respected him a lot and learned a lot about NE weather from his posts. However, here he constantly seems to be fighting the implications of climatological data, selectively distrusting data that support AGW. He has a tendency to argue that changes in mechanism caused by AGW should never be invoked (or even explored) in explaining current SI-related events if they conflict in any way with the concepts that explained past patterns of SI melt. This seems to me clearly misguided, and I find it very surprising. I have seen things like this in my own area of scientific expertise.

His manner also seems to me to be more defensive, arrogant and dismissive of alternative viewpoints here. I admit that this impression might be because I am personally alarmed (not too a strong a word) at both the course of events, and our failure as a society to ward off what could be a manageable problem if we start managing it now. My alarm at AGW and Will's unwillingness to consider the current changes as disturbing indicators that require action put us on opposite sides politically and put a barrier between us. I really regret that this is so.

However, I think that anyone who brings a reasonably informed viewpoint to the table and argues from evidence ought to be accorded respect, whatever their opinions. The disagreements that we see on this topic are rooted in cognitive neuroscience (which I DO know something about) and are inevitable. We cannot root them out and must live with them.

I apologize for the wordiness of this post - I needed to get this off my chest.

[dabize]

I believe Will adds significantly to the conversation. IMO he's one of the more honest posters in this forum. I'm not saying everything he says is correct, but rather he's not posting it for the lolz or some agenda.

Agreed.

[ORH_wxman]

ORHWx (Will) in particular bothers me because I know that he is a very good met from his NE forum posts and quite gracious to boot, even to rank amateurs like me, and I always respected him a lot and learned a lot about NE weather from his posts. However, here he constantly seems to be fighting the implications of climatological data, selectively distrusting data that support AGW. He has a tendency to argue that changes in mechanism caused by AGW should never be invoked (or even explored) in explaining current SI-related events if they conflict in any way with the concepts that explained past patterns of SI melt. This seems to me clearly misguided, and I find it very surprising. I have seen things like this in my own area of scientific expertise.

His manner also seems to me to be more defensive, arrogant and dismissive of alternative viewpoints here. I admit that this impression might be because I am personally alarmed (not too a strong a word) at both the course of events, and our failure as a society to ward off what could be a manageable problem if we start managing it now. My alarm at AGW and Will's unwillingness to consider the current changes as disturbing indicators that require action put us on opposite sides politically and put a barrier between us. I really regret that this is so.

However, I think that anyone who brings a reasonably informed viewpoint to the table and argues from evidence ought to be accorded respect, whatever their opinions. The disagreements that we see on this topic are rooted in cognitive neuroscience (which I DO know something about) and are inevitable. We cannot root them out and must live with them.

I apologize for the wordiness of this post - I needed to get this off my chest.

I think you have a misguided perception of my views on AGW.

Considering or exploring is a lot different than denying any connection at all. No, I am not "alarmed" at AGW. I am aware of its existence, but choose to read as much available data as possible before jumping to drastic conclusions.

If there is one thing that is very commonly true in science (and especially in atmospheric science), its that extreme views are often not the correct ones. Usually the truth tends to lie between somewhere.

[dabize]

I think you have a misguided perception of my views on AGW.

Considering or exploring is a lot different than denying any connection at all. No, I am not "alarmed" at AGW. I am aware of its existence, but choose to read as much available data as possible before jumping to drastic conclusions.

If there is one thing that is very commonly true in science (and especially in atmospheric science), its that extreme views are often not the correct ones. Usually the truth tends to lie between somewhere.

Quite.

I think the problem is more one of "What is extreme?". In all of us, this attribution is made by the limbic system - a part of the brain that doesn't read papers much!

I spent years trying to get people to listen to my "extreme" view on the etiology of Alzheimers and the metabolism of tau protein. Today, my view is conventional wisdom. I can prove this - its in the published (peer reviewed) literature. So I know of what I speak.

[DoctorMu]

I really haven't participated in the CC discussion, but from a biologist's viewpoint, the deductive nature of this science means discussions within published articles are rife with speculation. Still, the ultimate question to ask is "would the Earth be cooler if CO2 in the atmosphere were 280 ppm instead of 390 pm?" Back in the 80s, we measured CO2 in the atmosphere using a Scholander analyzer (quite an arduous task) for calculations in metabolic measures. The method was the Gold Standard for direct measurement. We consistently measured 330 ppm then, to the elevation is quite extraordinary within my adult life.

I think the answer to the question posed in that manner is quite clear, although the complexities in attributing CC to individual weather events is highly challenging, although patterns can be predicted.

CO2 distributes well in the atmosphere - the readings in Antarctica are similar to Mauna Loa, Hawaii.

We KNOW the extra CO2 has been produced by burning fossil fuels, since 500 million year old hydrocarbons lost any trace of C14 eons ago. therefore there is a decreasing amount of C14 in the atmosphere.

CO2 retains heat in part of the infrared (heat) range of radiation. The increases in CO2 in the atmosphere predicts pretty well the increase in ground temp of 1.5°F. Whether increased water vapor content (reasonable if temp increases) will exacerbate this effect is still unclear. The discussion is fascinating and look forward to reading and learning more.

[WeatherRusty]

I think you have a misguided perception of my views on AGW.

Considering or exploring is a lot different than denying any connection at all. No, I am not "alarmed" at AGW. I am aware of its existence, but choose to read as much available data as possible before jumping to drastic conclusions.

If there is one thing that is very commonly true in science (and especially in atmospheric science), its that extreme views are often not the correct ones. Usually the truth tends to lie between somewhere.

Will,

I used you as an example of one end on the rather wide spectrum ranging from honest skepticism to denial. I was informed that we would do well to ignore certain intransigent posters, as not doing so only distracts from what could otherwise be productive discussion. I could have mentioned skier also.

You tend to argue strongly against the likelihood of serious climate change, while skier argues strongly for the validity of the underlying scientific basis for AGW. He and I think alike in that regard.

What you two have in common is that you look to current observations as evidence that climate sensitivity is on the low side. This makes the two of you what we call lukewarmers.

I will argue with you till i'm blue in the face that we can not determine climate sensitivity in situ, if it that easily determined we wouldn't require the many intricate studies looking at the problem from so many angles. Still, despite all those studies climate sensitivity is still not well confined at 2c - 4.5C for a radiative forcing the equal of 3.7W/m^2. ...

Am I to put you on ignore when you argue 'natural cycles' play a larger part than the science permits? I don't think so.

The other end of the spectrum would be easily ignored, but where do we draw the line?

[CoastalWx]

Will,

I used you as an example of one end on the rather wide spectrum ranging from honest skepticism to denial. I was informed that we would do well to ignore certain intransigent posters, as not doing so only distracts from what could otherwise be productive discussion. I could have mentioned skier also.

You tend to argue strongly against the likelihood of serious climate change, while skier argues strongly for the validity of the underlying scientific basis for AGW. He and I think alike in that regard.

What you two have in common is that you look to current observations as evidence that climate sensitivity is on the low side. This makes the two of you what we call lukewarmers.

I will argue with you till i'm blue in the face that we can not determine climate sensitivity in situ, if it that easily determined we wouldn't require the many intricate studies looking at the problem from so many angles. Still, despite all those studies climate sensitivity is still not well confined at 2c - 4.5C for a radiative forcing the equal of 3.7W/m^2. ...

Am I to put you on ignore when you argue 'natural cycles' play a larger part than the science permits? I don't think so.

The other end of the spectrum would be easily ignored, but where do we draw the line?

I think many mets out there are in the same spectrum as Will. I put myself right with his thoughts. We know about AGW and we know it exists. We are all about finding the answers, but we understand there are many volatile and intricate cycles that the Earth goes through. It's just difficult to figure out how or why something happened and perhaps we are slower to jump to conclusion like some are. There is no right or wrong answer...but Will is knowledgeable with this and I hope people actually listen to what he says. I hope people listen to some other differing thoughts and not view them in a defensive manner...but perhaps question them why they feel that way. Same goes from people who are total deniers.....I hope they listen to the other side as well.

[QVectorman]

I think many mets out there are in the same spectrum as Will. I put myself right with his thoughts. We know about AGW and we know it exists. We are all about finding the answers, but we understand there are many volatile and intricate cycles that the Earth goes through. It's just difficult to figure out how or why something happened and perhaps we are slower to jump to conclusion like some are. There is no right or wrong answer...but Will is knowledgeable with this and I hope people actually listen to what he says. I hope people listen to some other differing thoughts and not view them in a defensive manner...but perhaps question them why they feel that way. Same goes from people who are total deniers.....I hope they listen to the other side as well.

I agree with both of the above and I believe many of us have stated multiple times we don't deny there has been warming or it's taking place. Just that many believe there are a lot of loose ends and every piece of research on both sides can be picked to pieces and errors found in them. I will be the first to admitted I have learned some new things from links Terry has provided. I don't think any of us are close minded to info and papers posted from either side. I'm going to assume that most of us believe the answer is some where in the middle.

[LakeEffectKing]

^^^^ These^^^^

[ben4vols]

Dr. Christy has a pretty good read and response to the wild claims made by Hansen's cherry picking.

LINK TO FULL ARTICLE

A quick look at the time series of the US record of high T_Max’s (Fig.1.1 in Part 1) indicates that the period 1951-1980 was one of especially low variability in the relatively brief 110-year climate record. Thus, it is an unrepresentative sample of the climate’s natural variability. So, for a major portion of the observed NH land area, the selection of 1951-80 as the reference-base immediately convicts the anomalies for those decades outside of that period as criminal outliers.

This brings up an important question. How many decades of accurate climate observations are required to establish a climatology from which departures from that climatology may be declared as outside the realm of natural variability? Since the climate is a non-linear, dynamical system, the answer is unknown, but certainly the ideal base-period would be much longer than 30 years thanks to the natural variability of the background climate on all time scales.

We can test the choice of 1951-1980 as capable of defining an accurate pre-greenhouse warming climatology. I shall simply add 20 years to the beginning of the reference period. Certainly Hansen et al. would consider 1931-1950 as “pre-greenhouse” since they considered their own later reference period of 1951-1980 as such. Will this change the outcome?

The result is the third curve from the top (open circles) in Fig. 2.1 above, showing values mostly in the low single digits (6-year average of 2.9 percent) being generally a quarter of Hansen et al.’s results. In other words, the results change quite a bit simply by widening the window back into a period with even less greenhouse forcing for an acceptable base-climate. (Please note that the only grids used to calculate the percentage of area were those with at least 90 percent of the data during the reference period – I couldn’t tell from Hansen et al. whether they had applied such a consistency test.)

The lowest curve in Fig. 2.1 (squares) uses a base reference period of 80 years (1931-2010) in which a lot of variability occurred. The recent decade doesn’t show much at all with a 1.3 percent average. Now, one may legitimately complain that since I included the most recent 30 years of greenhouse warming in the statistics, that the reference period is not pure enough for testing the effect. I understand fully. My response is, can anyone prove that decades with even higher temperatures and variations have not occurred in the last 1,000 or even 10,000 pre-greenhouse, post-glacial years?

That question takes us back to our nemesis. What is an accurate expression of the statistics of the interglacial, non-greenhouse-enhanced climate? Or, what is the extent of anomalies that Mother Nature can achieve on her own for the “natural” climate system from one 30-year period to the next? I’ll bet the variations are much greater than depicted by 1951-1980 alone, so this choice by Hansen as the base climate is not broad enough. In the least, there should be no objection to using 1931-1980 as a reference-base for a non-enhanced-greenhouse climate.

What was that Dr. Hansen? Your predictions turned out to be what? Mostly true but worse than you thought? No your predictions were worse than most thought and worsening by the year.

[easternsnowman]

Dr. Christy has a pretty good read and response to the wild claims made by Hansen's cherry picking.

Excellant, it shows how the left picks out stats and data to verify their radical extreme views to use as an excuse to have big goverment telling us how to live and what is good and bad for us!

LINK TO FULL ARTICLE

What was that Dr. Hansen? Your predictions turned out to be what? Mostly true but worse than you thought? No your predictions were worse than most thought and worsening by the year.

[donsutherland1]

Dr. Christy has a pretty good read and response to the wild claims made by Hansen's cherry picking.

Dr. Hansen was referring to the global incidence of summertime 3σ deviations, not solely the U.S. basis. Had Dr. Christy examined GISS, he would find that both the 1951-80 and his recommended 1931-80 periods yield remarkably similar results on a global basis.

1951-80 (June-August):

Mean anomaly: -0.0003°C

Standard Deviation: 0.0987°C

1931-80 (June-August):

Mean anomaly: -0.0058°C

Standard Deviation: 0.0930°C

In short, Dr. Christy's argument that the 1951-80 baseline is not representative does not hold merit in the global context against which Dr. Hansen is examining areas of extreme summer heat.

[donsutherland1]

Using the NCDC's base reference period (1901-2000), there is a higher incidence of hot summers (1σ or more above normal) than in the past. For descriptive purposes, I describe a "hot summer" as having a departure of +1σ, "very hot summer" as having a departure of +2σ, and "extremely hot summer" as having a departure of +3σ.

The frequency data is as follows:

1990-2011 vs. 1895-1989:

+1σ: 6.2 times as common

+2σ: 7.2 times as common

+3σ: 4.3 times as common

2000-2011 vs. 1895-1989:

+1σ: 10.2 times as common

+2σ: 13.2 times as common

+3σ: 7.9 times as common

2002-2011 vs. 1930s:

+1σ: 1.4 times as common

+2σ: 2.5 times as common

+3σ: Same frequency

In terms of average summer temperature departures, they are as follows:

1895-1989: -0.050σ

1930-1939: +1.249σ

1990-2011: +0.869σ

2000-2011: +1.353σ (hotter than the 1930s on average)

2002-2011: +1.368σ (hotter than the 1930s on average)

In short, even if one changes reference periods, the reality is that the incidence of hot, very hot, and extremely hot summers since 1990 has been higher than it was during the past. Moreover, the last 10 years (2002-11) has also had a higher frequency of hot and very hot summers and same frequency of extremely hot summers as the 1930s. The same pattern of greater recent warmth shows up in the average departures from normal.

The source of temperature data is the National Climatic Data Center (NCDC).

[PhillipS]

Using the NCDC's base reference period (1901-2000), there is a higher incidence of hot summers (1σ or more above normal) than in the past. For descriptive purposes, I describe a "hot summer" as having a departure of +1σ, "very hot summer" as having a departure of +2σ, and "extremely hot summer" as having a departure of +3σ.

The frequency data is as follows:

1990-2011 vs. 1895-1989:

+1σ: 6.2 times as common

+2σ: 7.2 times as common

+3σ: 4.3 times as common

2000-2011 vs. 1895-1989:

+1σ: 10.2 times as common

+2σ: 13.2 times as common

+3σ: 7.9 times as common

2002-2011 vs. 1930s:

+1σ: 1.4 times as common

+2σ: 2.5 times as common

+3σ: Same frequency

In short, even if one changes reference periods, the reality is that the incidence of hot, very hot, and extremely hot summers since 1990 has been higher than it was during the past. Moreover, the last 10 years (2002-11) has also had a higher frequency of hot and very hot summers and same frequency of extremely hot summers as the 1930s.

The source of temperature data is the National Climatic Data Center (NCDC).

Thank you, Don. That is a clear and compelling analysis.