From Master Resource, by Chip Knappenberger
Yesteryear’s climate extremes are today’s climate normals. Yet we are largely oblivious and better off. A hundred years from now the same will be true. Ho hum….
But not everyone thinks this way. Take NASA’s James Hansen for example.
Hansen has recently published a prominent paper (in the Proceedings of the National Academy of Sciences, PNAS) and placed a prominent op-ed (in the Washington Post) that are aimed at raising the public’s awareness of the impacts of climate change, both now and in the future. In a rather candid admission for a scientific paper (and one which in most cases would have resulted in an immediate rejection), Hansen (and co-authors) proclaim that “…we were motivated in this research by an objective to expose effects of human-made global warming as soon as possible…” To drive the point home further, Hansen’s op-ed was headlined “Climate change is here — and worse than we thought.”
What Hansen wants us to know, is that as temperatures increase, temperatures at the high end of the scale that were once statistically very rare (i.e., extreme) will become considerably less rare.
I agree completely.
However, Hansen is of the opinion that once this knowledge becomes widely known and associated with human greenhouse gas emissions (one of the many ways that human activity can alter the climate), that the majority of people will hasten to support actions (legislative, regulative) aimed at curtailing such emissions.
I completely disagree.
For one thing, it is not clear to me that warmer (and higher atmospheric CO2 levels) isn’t in many ways better. Robert Murphy pointed to recent economic analyses that found this to be the case, at least for some additional warming. And there are plenty of other potential benefits.
For another, as Roger Pielke Jr. points out, there is a lot of evidence that folks who already accept that human activities are impacting the climate still don’t clamor for actions to mitigate that influence—at least very expensive ones.
And thirdly, a changing climate is quickly and thoroughly absorbed in everyday life such that no one really cares about how it used to be and simply adjusts to how it is.
…
“Extreme” Temperatures
In his PNAS paper, Hansen defines “extreme” high temperatures as being at least three standard deviations above the average—an event which should only occur about 0.13% of the time based on a normal (bell-shaped) distribution. Hansen points out that as the average temperature increases, the distribution of observed temperatures will shift to the right (toward higher temperatures), with the consequence that the occurrence of extremes will increase dramatically when judged by the old distribution. Figure 1 shows this.
Fig. 1 The left hand (blue) bell curve represents the distribution of a set of temperature observations from some period in time. The average (or “mean”) temperature is indicated by the red vertical line. The standard deviation (and its multiples) are indicated on the x-axis. Only 0.13% of the data points exceed (lie to the right) a value of three standard deviations from the mean. The right hand (red) bell curve represents the distribution of a set of temperature observations from a warmer climate. The shape of the distribution is the same, but the average temperature (red vertical line) is higher (by a value of one standard deviation) from the original climate. In the warmer climate, the number of observations that exceed three standard deviations from the original climate (region filled in dark red) has greatly increased (to a value of 2.28% of the observations).
Let’s look at the numbers in Figure 1 a bit more closely. I’ll use an example of climate change where the average temperature increases by an amount equal to the value of one standard deviation (a standard deviation is a measure of variability such that two-thirds of all observations fall within one standard deviation of the average of all observations). In this new, warmer climate (with a variability the same as the old, cooler climate) the occurrence of events exceeding three standard deviations above the old average increases by about 17.5 times. Specifically, a high temperature event that used to occur only about 0.13% of the time, now occurs about 2.28% of the time. Or, if you wanted to add a more attention-getting spin, you could say that the occurrence of extreme events has increased by over an order of magnitude.
Temperatures in the real world over the past 50 years or so have behaved somewhat like my example.
In his paper, Hansen notes that globally, since the 1950s, the average temperature has increased by about a standard deviation, and as expected, the occurrence of extreme (greater than 3 standard deviations above the old mean) temperatures has increased considerably.
Here is how Hansen et al. describe their findings:
The most important change…is the appearance of a new category of extremely hot summer anomalies, with mean temperature at least three standard deviations greater than climatology. These extreme temperatures were practically absent in the period of climatology, covering only a few tenths of one percent of the land area, but they are occurring over about 10% of global land area in recent years. The increase of these extreme anomalies, by more than an order of magnitude, implies that we can say with a high degree of confidence that events such as the extreme summer heat in the Moscow region in 2010 and Texas in 2011 were a consequence of global warming.
Several commentators around the web have taken umbrage to the final sentence above, arguing that the role of global warming in those specific weather events has been overstated, and/or improperly calculated. Others are fully supportive. But rendering an opinion about this is not the subject of my commentary.
Instead, I want to show that it really doesn’t matter. While these events may be noteworthy now, if temperatures continue to rise into the future, they will eventually become status quo and ho hum. And while that that may sound frightful now, by then, we’ll not even notice.
So, don’t worry.
Case and Point: Temperatures in Washington DC.
Over the past 142 years (from official records starting in 1871), the average summer temperature in our nation’s capital has increased by about 4.5°F from a variety of causes (Figure 2).
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Very true. What’s more is that people live all around this planet from very low temperatures to very high temperatures. Folks living in Ahwaz and Kuwait deal with average highs of 46.7oC (116.1oF). DC has a long way to go before they reach that still-liveable-level. And thanks to cheap electricity, everyone spends most of their day in comfortable climate controlled environments.
But where Hansen and his ilk will take this argument is that it’s all about the rate of change…the so-called fact that temperatures are going up and they aren’t coming back down unless we take action, while positive climate feedbacks will accelerate this temperature increase to a tipping point from where there is no return from becoming a climate like Venus.
And that requires a crystal ball, or a couple climate models, or both. And like the soothsayers of the past, there is big money in making predictions and scaring people.
To be honest, you are describing the frog in a pot of slowly heating water. The frog, unaware of the ultimate end game, sits quietly and croaks.
The greater metropolitan District of Comedy is a massive Urban Heat Island, as are most major metropolitan areas. While Hansen attributes the changes to CO2, it is likely that UHI has had a greater impact, particularly on Tmin, as noted by Dr, John Christy in two posts on Dr. Spenser’s blog.
It appears that Dr. Hansen is having increasing difficulties discerning the difference between “what he knows”, “what he thinks he knows” and “what he believes”.
Even taking figure 1 as scientifically supportable, it’s zohneristic to highlight the increase in extreme warmth without highlighting the decrease in extreme cold.
When the world was passing in and out of MWP/LIA/stable climate periods people were subject to these statistical artifacts multiple times. People with no education, kings, and paupers, survived. Since the last true climate change we have learned to fear what those people adapted easily to. We have also learned to exploit the information, promulgate fear, and grow powerful from controlling that fear. Not unlike the old Chicago mobs.
Someone should plot the growth of scientific corruption in the field of climate and the growth of fear mongering over time. Toss in government money spent on this over the same time frame.
I take umbrage with this article because it relies on a statistics to arrive at frequency of extremes in a warmer world while ignoring the laws of physics which dictate changes in the variability that the statistics are trying to predict.
The laws of physics require that low temperatures (night time, winter, high latitude) will see MOST of the change and high temps (day time, summer, low latitude) will see the LEAST change. So on that basis alone it does NOT follow that an “average” temperature increase will drive high temperature extremes commensurate with the statistical analysis shown.
FURTHER, if we’re talking extremes in terms of temperature, we must consider both ends of the scale, which means that we must also ask; What happens to extreme lows? The answer is that since the physics requires that temperature increases be heavily weighted toward low temps, that means fewer extreme lows. Going back to the same statistical analysis and applying it to both ends of the spectrum with the physics in mind, we’d see more extreme highs, but no nearly so many as predicted, and we’d see fewer extreme lows by several times that amount. By looking at both ends of the spectrum we would expect to see FEWER extremes as a total, not to mention that extreme heat kills a tiny fraction of the number of people that extreme cold kills every year.
But let’s not stop there, let’s consider OTHER forms of extreme weather. Temperature differentials are what drive the wind and all the extreme weather associated with it. The daily heating and nightly cooling due to the planet’s rotation is part of the story, the other part being that heating in the tropics is much higher than heating in the high latitudes. This creates energy imbalances that try to even themselves out by moving energy from high concentrations to low via air and ocean currents. Going back to the physics, since the least warming happens in the tropics and day time highs, while the most happens in the high latitudes and at night time lows, the temperature of the planet becomes more uniform. The more uniform the temperature, the fewer extreme events we see that are driven by temperature differential. Indeed, we’ve been measuring Total Cyclone Energy for about 30 years now and it has been steadily dropping.
So while I understand the author’s premise that yesterday’s extremes are today’s normal, it simply doesn’t follow that we’ll see more extremes in a warmer world. Will see marginally more extremes of some specific types, but for the majority of the extremes that matter, extreme lows and extreme storms, the physics says we will see less.
The problem with people like Hansen is and always has been that they assume that linear projection they are plotting will continue on its present course forever. Tain’t so.
As long as the temperatures remain in the range we now enjoy, food production will support this rather large human population. The bad part is going to be when the temperatures begin to drop again. Then humanity — and all life — will be facing a challenge. Only the most adaptable and durable will survive.
dp (# August 23, 2012 at 8:56 am),
Except that we are not croaking, but thriving.
-Chip
davidmhoffer (# August 23, 2012 at 9:15 am),
I my article I am talking about seasonal (summer) average temperatures. So an extreme event, in my analysis, is an unusually warm summer. Which will (without a shrinking of the variance) become more frequent as the average temperature increases.
I am making no comment here as to the impacts of a changing climate on other types of extremes, although I have discussed them on other occasions in the back issues of both at Master Resource and World Climate Report.
-Chip
And only the warmists say we’re in a cooking-pot (a closed system).
“Cheere up Brian. You come from nothing, you end up as nothing. So what’ve you got to loose? Nothing!”
From “Always look on the bright side of life – Eric Idle”
“To be honest, you are describing the frog in a pot of slowly heating water. The frog, unaware of the ultimate end game, sits quietly and croaks.”
Even frogs are smarter than whoever thought up this silliness…
Perhaps it should be noted that Hansen’s “climatology”, only includes 30 years, if it had included 60 years, i.e., an earlier positive phase of the PDO, the increased frequency of extreme events might also have been closer to the real normal and warming might have been more realistically seen in the perspective of natural variation.
We’re not in the end game yet. But there may not be one. The end game in this context means the temperature continues in one direction until it annihilates humanity as Hansen suggests. Neither of us thinks that is going to happen, but your depiction doesn’t make a case for that. You’ve best described the frog in the pot by suggesting we’ll quietly adapt, giving no thought to the change or the consequences.
I suggested in my second post that this has been going on for a long time and agree it is part of the natural adaptability of many species, but to describe it as an idyllic unnoticed byproduct of climate evolution seems to me a poor argument. It is the path of the uninformed and I think more than ever skeptics need to present an informed perspective.
It is true that nobody I’m aware of anyway craves the temperatures common during the LIA, and the subsequent warming is now ho hum. For how long will this be true? It cannot be forever, obviously, because life is not compatible when the temperature rises above a certain level. We will certainly notice. Why introduce this unsupportable position?
“dp says:
August 23, 2012 at 8:56 am
To be honest, you are describing the frog in a pot of slowly heating water. The frog, unaware of the ultimate end game, sits quietly and croaks.”
Like many analogies, this steaming, overheated one comes from the anal region.
How about a frog in a pot of cool water? As the water warms to room temperature, the frog will likely find a mate, reproduce and soon tadpoles will be swimming around in the pot.
That’s the last 20,000 years in a nutshell.
Figure 1 caption confuses the vertical mean lines being compared, calling them both “red vertical lines”, one in parentheses and the other not.
It seems to me that the assumption of a Gaussian distribution for temperatures isn’t necessarily valid. I think a Levy distribution (long tailed) is most likely the case. In other words, year after year the climate doesn’t change much but the climate can change in large amounts, and we really can’t say it’s changing infrequently, at least in the last 500K years.
pcknappenberger says:
August 23, 2012 at 9:36 am
davidmhoffer (# August 23, 2012 at 9:15 am),
I my article I am talking about seasonal (summer) average temperatures. So an extreme event, in my analysis, is an unusually warm summer
>>>>>>>>>>>>>>>>>
Yes, I get that. But your statistical model is linear and so results in a frequency of unusual summer temps that is too high, and focusing on summer events alone is misleading. In fact, it is a fallacy.
If you surveyed people in the temperate zones (where the physics requires that the bulk of these effects be their most pronounced) and asked them if they thought that 5% more extreme high summer temps per year was a bad thing, you would get one result. If instead you asked if 40% fewer extreme lows in winter but the price is 5% more extreme highs in summer was a bad thing, you would get a completely different answer. If you broke the results down by latitude, they’s be increasingly skewed toward “are you kidding me? that’s a GOOD thing” at higher latitudes.
Per Einstein, every problem should be made as simple as possible, but no simpler. I understand and even agree with your sentiment, but I think it over simplifies the issue and leads to a perspective that excludes the MOST important aspects of warming that the public in general needs to understand.
Doug Huffman (#August 23, 2012 at 10:16 am ),
Thanks. I fixed it in my original post over at Master Resource.
-Chip
I’m not so sure that bell curves apply in this case. And I’m absolutely sure that global warming will NOT shift the curve in the simplistic manner shown. The right hand side of the curve would move a tiny bit to the right; the left hand side could move a little farther to the right. The putative mechanism for global warming is via radiation, which is driven by T^4. The high temperature hand side of the curve therefore resists moving to the right, the low temperature side, not as much.
pcknappenberger,
Allow me an analogy to go along with my earlier comment.
If you were told that there would be an extra $1,000 in tax deductions on your next pay check, I’m guessing you would think that is a bad thing.
If you were told that your next pay check would be an extra $4,000, less $1,000 for taxes, I’m guessing you would think that is a good thing.
Your article focuses on the extra tax, and that is my problem with it.
Record extremes are so full of artifacts the results are meaningless. The only way to determine high-max and high-min record increase is with long standing well maintained sensors, with filters added to remove El Nino and La Nina immediate affects and echoes. The timing and location of station drop-out and new station add-on, not to mention poor station quality control will muddy the results and produce spurious statements like Hansen’s.
davidmhoffer (# August 23, 2012 at 10:37 am ),
I don’t think we are in disagreement. Recall, from my article that I stated:
“For one thing, it is not clear to me that warmer (and higher atmospheric CO2 levels) isn’t in many ways better.”
You’re discussing detals that I just didn’t go into for the purposes of my article…although you clearly thought that I should have :^)
-Chip
Hansen thinks that:
Supposing global warming does start up again (unlikely in my opinion), the most important change will be the disappearance of an old category of extremely cold winter anomalies. It is very clear that in terms of human impact, cold extremes do more harm than hot extremes at current tempertures.
When dealing with extremes, one should be using an extreme value distribution (rather than normal) in their statistical analysis. Record temperatures are extreme values. The time between an old record and a new one follows an extreme value distribution rather than the shifting of the tail of a normal distribution. The length of the period that records are kept is another factor to consider.