Guest Post by Willis Eschenbach [Updated, see end of article]
One of the claimed dangers of a few degrees warming of the Earth is increasing drought. Drought is a very difficult thing to fight, because it is hard to manufacture water. So this is a frightening possibility.
I have long claimed that “a warmer world is a wetter world”. I have said this without any actual data, based solely on the following logic.:
Increased temperature —> increased evaporation —> increased precipitation.
Today I graphed the numbers for the US precipitation. I used the USHCN state-by-state precipitation database, which also includes area-averaged values for regions of the US, and for the US itself.
First, here is the change in precipitation in the US since 1895:
Figure 1. Annual precipitation in the US. PHOTO SOURCE
Since the both the US and the globe have warmed since 1895 it seems that a warmer US is a wetter US. However, precipitation is spotty and unevenly distributed. One area can be very wet while a nearby area is dry, so what about the precipitation in each of the states?
The USHCN database contains state data. Since there are drier states and wetter states, I looked at the percentage increase in precipitation rather than the absolute change in precipitation. Here are the state-by-state results:
Figure 2. State by state changes in precipitation, 1895-2009. Values are change per century divided by average annual rainfall.
One of the things that AGW supporters have been saying would result from warming is that the desert belts would move poleward. These are the great belts that circle the earth at about 30° North and 30° South latitude. The North American belt encompasses the Southwestern US (Southern California, Arizona, New Mexico, and Texas) and Northern Mexico. If these belts were actually moving poleward as the globe warmed over the last century, we should see decreased precipitation in the Southwestern US.
Instead, all of the southwestern states have increased rainfall. The main area with decreased rainfall encompasses the Rocky Mountain states in the central Northwestern US.
My conclusions? Precipitation is indeed spotty. A warmer US is indeed a wetter US. And there is no decrease in the Southwestern US data which would show that the great northern desert belt is moving polewards. So either the desert belt is not moving poleward, or the movement is offset by the overall increase in precipitation.
[UPDATE] Some commenters have correctly pointed out that I have only shown the precipitation, which doesn’t show the change in droughts. This is because droughts are a combination of soil moisture, temperature, rain, and other factors. This is measured by the Palmer Drought Severity Index (PDSI). The PDSI index values have the following meaning:
-4.0 to less (Extreme Drought)
-3.0 to -3.9 (Severe Drought)
-2.0 to -2.9 (Moderate Drought)
-1.9 to +1.9 (Near Normal)
+2.0 to +2.9 (Unusual Moist Spell)
+3.0 to +3.9 (Very Moist Spell)
+4.0 to above (Extremely Moist)
I used the USHCN database cited above to look at the state-by-state trends per century in the PDSI. Note that these are not the average PDSI values by state, which are without exception in the range -1.9 to +1.9 (near normal). Figure 3 is a histogram of the trends per century. A “histogram” shows the number of states (left scale) that have a certain trend range (bottom scale).
Figure 3. Histogram of state trends per century of the PDSI
The trend in most of the states (39 out of 48) is toward less drought (increasing PDSI). However, most of the trends (32 of 48) are between 0 and +2.0, which is not a large change. As a result, most of the trends are not statistically significant. Figure 4 shows the significant state trends:
Figure 4. Significant trends in the PDSI in the US states.
As you can see, despite the warming of the last 115 years shown in the USHCN dataset, while some of the PDSI trends have decreased, almost all of the statistically significant changes in the PDSI are positive (less drought). And few of the changes are statistically significant.
The IPCC models say that increasing warmth will lead to increasing drought, particularly in the mid-latitudes:
In a warmer future climate, most Atmosphere-Ocean General Circulation Models project increased summer dryness and winter wetness in most parts of the northern middle and high latitudes. Summer dryness indicates a greater risk of drought.
Despite these model prediction, we have seen no such increase in drought in the US. For most of the US, there has been so statistically significant change in the PDSI index showing the number and strength of droughts in most US states. And where there has been a statistically significant change, it is in the direction of reduced drought.
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Also, did you look at the percentages of what falls as rain and what falls as snow? That would be an interesting exercise to accompany this one. Unica una sugerencia.
“mikael pihlström (11:47:28) :
Interesting as your map of USA precipitation 1895-2009 is can you tell
your readers please, that it does not disprove IPCC projections showing a South West USA dustbowl towards the end of 21th century.
It doesn’t disprove my prediction that the South West USA will not be a dustbowl towards the end of the 21st century, either. But since the ipcc has not got any projection right so far, including a couple of eventualilties involving the the real occurrence of conditions opposite to what the ipcc projected as critical, and now the “lost” heat, I’m feeling very confident in my prediction. How about you, yours?
But I guess they’re bound to get one right sometime, perhaps the exception which proves the real rule, and we’ll probably have to wait at least that long, so maybe you’re onto something.
Yet on the other hand, China and India, and apparently Russia, are betting against CO2CAGW at least in regard to their little areas of the world, so there’s that, too……
There you see MattB… if you actually bother to put in the effort you can put forth an argument worth debating. Shame you didn’t bother the first time, eh?
As for inciting the masses, this web site certainly doesn’t do that, but I would bet the proverbial farm that some of the web sites you frequent do exactly that. I have seen your abuse of others at other sites mate. You have form.
But keep digging your hole here… it will be amusing to see you dismantled argument by argument… much like Keating taking apart Hewson.
BTW My word what is this in an IPCC report?!? An executive summary even?!?
“Increased precipitation intensity and variability are
projected to increase the risks of flooding and drought
in many areas. The frequency of heavy precipitation events
(or proportion of total rainfall from heavy falls) will be very
likely to increase over most areas during the 21st century, with consequences for the risk of rain-generated floods. At the same
time, the proportion of land surface in extreme drought at any
one time is projected to increase (likely), in addition to a tendency
for drying in continental interiors during summer, especially in
the sub-tropics, low and mid-latitudes.”
Source: http://www.ipcc.ch/pdf/technical-papers/ccw/executive-summary.pdf
Increased drought… not decreased. The logic in incredible… I mean really. I call this the “have my cake and eat it” approach to logical reasoning.
Willis Eschenbach (21:27:32) :
You are right: I am off my meds, I’ll try to be more coherent. But then, I thought this was the internet. My apologies to Briffa too; upon reflection the paper I was mentally blaming him for was by someone else.
A moving weighted average seems more appropriate to me.
Use of a filter seems appropriate where there there is an underlying signal and high-frequency noise. I fail to see how a 17-year filter reveals any underlying signal.
The only difference I see is that using the filter could give a trend line centered on the middle of the data with small blank areas at the left and right margins, compared to the moving average which would show the lack of data to make a trend line all on the right edge.
As to end point smoothing, yes that is my real objection. Why smooth the end points? Why not just end the smoothed line where you have full data to smooth the line?
I look at stock charts all day long. If I add a moving average to my stock charts, I don’t expect the line to go to the last data point. I can’t even remember a stock analyst trying to hype a stock with a moving average smoothed to the end of the data, so I’d bet the SEC has rules about that kind of thing.
I read the paper you linked and I am impressed with the effort you put into finding a “best” smoothing algorithm. I don’t understand why the best method is better than no method. Fundamentally, it seems to me like an effort to fill in data where you don’t have enough data. When Mann did it with temperature data in the GRL paper you reference, it obscured important information: that the line was so heavily smoothed it should not be used to infer anything about current trends.
In your rainfall graph above, it wouldn’t have hurt anything to just end the smoothed line a couple years before the end of the graph. Would have set a good example, imo.
mikael pihlström (14:07:49): … we now have to make a risk assessment and decide on action/inaction.
Here’s my risk assessment: WARMER IS BETTER. More rain, longer growing seasons, more productivity, more biodiversity, more food, more fiber, etc. etc.
It is a stone cold fact that humanity prefers warmer climes. Canada is not crowded; Bangladesh is. Which is warmer? Siberia is not crowded, Rwanda is. Which one is cold, which one is warm? See:
http://en.wikipedia.org/wiki/File:Countries_by_population_density.svg
In fact, Life Itself prefers it warmer. The most bio-diverse places in the world are on the Equator. The least are in polar regions.
Regarding action/inaction, my advice is the combined governments of the world should pursue policies that do not cool the globe but instead make the globe warmer. The reasoning is that WARMER IS BETTER.
I think the AGW argument is that water vapour is a GHG so increased evaporation will warm the atmosphere, which will not be able to dissipate the heat and so it will reduce precipitation. This is, of course, wrong. If it were correct then increased evaporation would increase warming, which would increase evaporation, etc. The equator would be a boiling fog!
It appears the equation for water vapour forcing was just made up, probably by Hansen, as a fudge factor :
http://climaterealists.com/index.php?id=5563
In fact research has shown that water vapour has a negative feedback on temperature, cooling warmer regions and warming cooler regions, essentially acting as a thermostat. For example, the temperature difference between the poles and the equator is small compared to the difference in energy received. Also consider an area with little or no water, such as the Sahara. The sand will be incredibly hot during the day and freezing overnight. We intuitively ‘know’ water has a moderating effect on climate.
These ideas are covered in detail in this very readable article :
http://www.landshape.org/dokuwiki/doku.php?id=introduction
Although covering a lot of ideas, it is based around an explanation of Miskolczi’s theory where he tries to put the effects of water vapour on to a precise scientific footing. I would certainly recommend a read. [Actually, probably a few reads. It has a lot of detail!]
I am particularly attuned to rainfall because I own a company that does whitewater rafting photography and video production (Click the website for a vid), and am an old river runner. It has been a rough decade, with only a couple of good years for rain.
Here in Northeast Wisconsin we are in mid-summer drought conditions when we should be in spring run off. The last two summers featured stretches of 6 weeks at a time with no rain. The last few winters featured no storms of a foot or more of snow, two medium sized storms all winter, and we have only had a small fraction of our spring rain. We have had about 2 good wet years since Y2K.
It seems that every time a storm threatens to get north of Green Bay, high pressure comes from the north and blocks it. It is uncanny the excuses and strange patterns that keep it from raining here. It has been going on long enough that it is heading from weather to trend status. We are seeing a lot of stress on the plant kingdom, and are seeing record low levels in lakes and rivers. We are not at desertification yet, but there are changes like trees sprouting in dry lake beds.
My home rivers (~45N) are at record low levels, or just above record lows. The 11 year mean flow on the one river is 887cfs, and today we are at 204(record low). The second river has a 17yr mean flow today of 4360cfs, today it runs at 998(record low). It can run 20k cfs in spring. River three has a 43 year mean of 907cfs, and is at 254 today. That one is also 20cfs off of the record low set in 2002. Area lakes are almost 2′ lower than usual. My little pond should have 3-6 feet of water, and you could walk across it without getting your ankles wet.
The point is we are seeing some real moderate to long term drought in NE WI. At the same time southern Wisconsin has been seeing a lot of rain and show, and even severe flooding. As Dr Becker and others pointed out, state lines are a bad delineation for this. Maybe NWS zones would be more accurate.
[youtube=http://www.youtube.com/watch?v=bdrGS__yg6Q&hl=en_US&fs=1&rel=0]
A couple of clarifications, if I may.
The sand deserts of Australia are extensive. Goat herders are, for all reasonable study, negligible, and always have been. The carrying capacity of much land is about one wombat a square mile.
The far S-E of Australia (non-desert) had drought from 2000 to 2009. However, this decade was the second wettest since 1900-1909 for the whole of Australia.
For agricultural purposes, there is vast movement of underground water (e.g. the Great Artesian Basin) which is often overlain by desert.
Desert can be relieved at the mouth of the Murray River, by rainfall some months beforehand in Queensland, some 1,400 km away. This can upset correlations at a fixed location.
David Stockwell has written on Niche Modeling that there has been no increase in drought incidence in Australia since recording began. A recent paper asserting the opposite is alleged to have inadequate statistics.
Evaporimeter measurements are not always reliable. One cause of errror was from birds bathing in the pans, now covered by mesh.
“Desert”, loosely defined, covers some 2,800 x 2,000 km in area. While much of it is loosely bound by vegetation, there are extensive areas of shifting sand dunes. The desrt extens to the Indian Ocean for about half of its N-S extent.
The N-S extent of desert is about from 17 to 34 degrees south latitude. A movement to or from the Pole would not be easy to measure.
Only a small percentage of the desert was affected by land clearing by man, so far as can be reconstructed. Most present desert was desert shown by early expeditions (Burke & Wills 1860 confirming this along their central N-S path, Eyre in 1839-41 for E-W along the Southern edge).
At Alice Springs, in the centre, the annual temperature range is about 17 deg C from summer to winter. The highest daily temperature temperature was about 45 deg C, the lowest about -5 deg, since the WWII move to the airport weather station.
Mattb (21:59:59)
Mattb (22:02:13)
My line “is actually the IPCC line”? My graphs “concur with the IPCC”? Say what?
Mattb, perhaps you should actually read the IPCC reports. Others have, including myself. From the IPCC Fourth Assessment Report Summary for Policymakers (FAR SPM), Table SPM.2:
So yes, the IPCC very clearly states that it is “likely” that there will be increasing droughts. I didn’t have to get past the SPM to prove my point. You sure you are up to date with the IPCC report?
If you are, surely you have gone beyond the SPM to read Chapter 10, “Global Climate Projections”. In it I find:
and
and
The models project droughts going from 1% of the planet to 30% of the planet, and you are talking about how I agree with the IPCC? My friend, you’ve lost the plot. Chapter 10 continues:
The US warmed by 0.8°C from 1895 to 1909. If warmth brings “increased summer dryness” and a “greater risk of drought”, why haven’t we seen it?
You say of my article, “It is an incitement to frenzied climate ignorance” … seen a mirror lately? Look at the update to the head post above, there is very little change to the US Palmer Drought Severity Index (PDSI). Overall, the trend in the US is towards less drought, not more.
NOTE: HEAD POST HAS BEEN UPDATED
w.
Oh sorry Willis – silly me for thinking we were discussing the rainfall trends over the USA as per your article above. I also think you are confusing what has happened in the past with what is predicted for the future.
Regarding Willis Eschenbach (02:04:42) :
Quote from the IPCC…
“This is shown in Figure 10.12, and has been documented in the more recent generation of models.”
It is quite astounding how a computer model is treated as an observation and then “documented”. The advocates feel they have the basic global view long settled, now they are narrowing the field to local effects.
Let it never be said about you that your arrogance exceeded your ignorance. Unfortunately it is to late for some in the field of climate science.
The distribution of precipitation is even more uneven than temperatures. A cooling planet could spell more draughts for some areas due to the interactions of different oscillations. Take for instance the severe, long term drought that hit the Tidewater States during the coldest decades of the LIA. But, in the subtropics and tropics, severe long term drought occured during some of the warmest decades of the MWP (See Central America and the West Sahara). In both cases, oscillations like ENSO and the AMO had a direct impact on precipitation patterns.
***************
Mattb (02:16:22) :
Oh sorry Willis – silly me for thinking we were discussing the rainfall trends over the USA as per your article above. I also think you are confusing what has happened in the past with what is predicted for the future.
*******************
The climate models are no doubt in worse shape than Toyota’s computer models for their car computer. Do you REALLY BELIEVE the computer model projections??? REALLY???
Geoff Sherrington (01:34:13) :
“The far S-E of Australia (non-desert) had drought from 2000 to 2009. However, this decade was the second wettest since 1900-1909 for the whole of Australia.”
This and other things you say is good information for sure. But,
if we go back to IPCC projections for end of 21th: a pronounced
drying is projected for SE USA, but only slightly or not at all for Australia.
BTW. I think someone said here, that the SW of Western Australia has
some drought?
If you had quoted my entire statement, it would be clear to everyone that I was referring to past events, not future events, viz:
If these belts were actually moving poleward as the globe warmed over the last century, we should see decreased precipitation in the Southwestern US.
——
Partly true: if I would have quoted the entire statement, I would
have understood better your argument. But, I think your interpretation
is wrong. Poleward movements cited by IPCC seem to be individual
species and e.g. treelines, most of them in arctic/alpine environments.
In fact I don’t think a prairie/semidesert/desert example is given.
My point is that a shift of whole vegetation zones poleward would come
after significant warming, the one we see right now could not do that.
Poleward movements of species: it is not a closed case yet, but yes
there is movement. I remind you that a catastrophic escalation in the
worst IPCC scenarios could trigger mass extinction.
Sorry
mikael pihlström (06:21:15)
was a reply to Willis
Re: Willis Eschenbach (Apr 18 21:32),
Understood, Willis – thanks.
Technically, if the desert belt movement was occurring quickly enough it could result in a signature like the one shown in the map (since the lower edge of the desert belt could have already passed by the SW US), but practically I doubt even the most alarmed of the alarmists would say that’s predicted!
Glad to see this article today. Last night (Sun 4/18), The Weather Channel had an apocalyptic program on at 10pm EDT, “The Future Earth”, which was predicting terrible drought, major dust storms damaging Las Vegas, huge locust swarms invading Europe, etc. By around 2025, if I recall correctly.
Exciting cinema but bad science, it seems.
Thanks all.
—
David
David Smith (09:31:58) :
willis, your main point about the lack of a drying trend in the US is a good one.
As an exercise, though, I do wonder, though, whether “increased temperature = increased evaporation = increased precipitation” is necessarily correct. Evaporation is a function of temperature and of the humidity of the air into which it evaporates. The humidity of the air is a function of how well the precipitation cycle (mostly the Hadley-Walker aspect) works.
The precipitation cycle depends on how well each leg works. If the cooling/sinking leg does not work so well with increased CO2 then perhaps the upper troposphere becomes “clogged” with relatively warm air, which inhibits the formation/size of rain clouds.
Something to ponder.
David
REPLY:
I think the formation of rain clouds is more closely linked to particulate (aerosols) acting as nuclei for rain drop formation.
“…Secondly, rain drops cannot form without aerosols. They start the clouds off by providing the moisture with points around which to collect, called condensation nuclei. Every single raindrop needs one of these tiny particles, which have diameters of less than one thousandth of a millimetre, as a starting point. The moisture from the rising air condenses on the aerosol particles. This releases the heat that was originally needed to evaporate the water.
If there are only few particles in the air, the drops grow so quickly that they fall before all the water can condense….”
Aerosol particles can consist of sea salt, sand grains, soot particles, sulfates and other materials of organic and inorganic origin….” http://www.sciencedaily.com/releases/2008/09/080909111026.htm
I don’t know how many times I have posted this. Willis observes:-
“”” Increased temperature —> increased evaporation —> increased precipitation. “””
So check out SCIENCE for July-7, 2007. Authors Frank Wentz (RSS Santa Rosa cA.) et al; “How Much more Rain will Global Warming Bring ?”
They provide the how much; from actual real observations; not Playstation Game playing.
Specifically:- A one deg C (1 C) increase in global mean surface Temperature, results in a 7% increase in total global Evaporation, and in Total Global Precipitation; and also in total Atmospheric Water Content.
This strongly disagrees with the Playstatyion GCMs. Now the first part Evap = Precip is well understood and the modellers agree; if it wasn’t true then we would end up with the oceans up in the sky. But the modellers say that the amount of evap/Precip, is only 1% to 3% per deg C, not the 7% that Gaia says it is; as observed by Wentz et al. (there’s that obligatory 3:1 climatology fudge factor) The GCMs do agree with the 7% increase in total Atmospheric Water Content.
So this supports the warming = drought^-1 rather than drought.
Left unsaid; but obvious to any 8th grade high school science student, is that a 7% increase in precipitation might be expected to be accompanied by something in the range of a 7% increase in total global precipitable cloud cover; as in dark rain clouds. That increase might be a combination of increased cloud area, increased cloud water content, and hence optical density, and increase in cloud persistence time.
All of which would imply a strong negative feedback surface cooling due to extra blocking of ground level solar insolation (increased albedo, and increased optical density).
So I wish people would download a copy of the Wentz et al Paper so that this subject doesn’t have to come up all the time. Along with the John Christy et al paper from Jan 2001 (I think in Geophysical Research Letters) that reported on about 20 years of ocean buoy data of simultaneous water Temperature (-1 metre depth) and near surface Air Temperature (+3 metres height) that showed that water temperature increases exaggerated the warming of the near surface atmosphere (izzat lower Troposphere) by something like 40%, over that near 20 year period (starting presumably about 1980).
The more important result was that those two temperatures are not correlated (why on earth would anyone expect them to be); which means that prior to 1980, near surface air temperatures canot be recovered from the 150 years of the bucket of water ocean surface temperature data.
To me that means we don’t have any idea what global air temperatures were prior to 1980.
Those two papers, are to me the biggest stumbling blocks of the whole AGW mantra.
As I have said many times; “It’s the Water, Stupid !”
mikael pihlström (14:07:49) :
“….Then, the sceptic side retorts that the models are not good, or,
also frequently that models are not science.
But that is not enough, the temptation to come in and disprove ‘too
early’ is so strong. Willis Eschenbach: “We should see decreased
precipitation in the Southwestern US. Instead, all of the southwestern
states have increased rainfall.”
Is that not an attempt to disprove something ?”
If you do not understand that is a basic in science, then I suggest you read
CARGO CULT SCIENCE by Richard Feynman
” ….But there is one
feature I notice that is generally missing in cargo cult science.
That is the idea that we all hope you have learned in studying
science in school–we never explicitly say what this is, but just
hope that you catch on by all the examples of scientific
investigation. It is interesting, therefore, to bring it out now
and speak of it explicitly. It’s a kind of scientific integrity,
a principle of scientific thought that corresponds to a kind of
utter honesty–a kind of leaning over backwards. For example, if
you’re doing an experiment, you should report everything that you
think might make it invalid–not only what you think is right about
it: other causes that could possibly explain your results; and
things you thought of that you’ve eliminated by some other
experiment, and how they worked–to make sure the other fellow can
tell they have been eliminated.
Details that could throw doubt on your interpretation must be
given, if you know them. You must do the best you can–if you know
anything at all wrong, or possibly wrong–to explain it. If you
make a theory, for example, and advertise it, or put it out, then
you must also put down all the facts that disagree with it, as well
as those that agree with it. There is also a more subtle problem.
When you have put a lot of ideas together to make an elaborate
theory, you want to make sure, when explaining what it fits, that
those things it fits are not just the things that gave you the idea
for the theory; but that the finished theory makes something else
come out right, in addition.
In summary, the idea is to try to give all of the information to
help others to judge the value of your contribution; not just the
information that leads to judgment in one particular direction or
another…..”
Adapted from the Caltech commencement address given in 1974
http://www.lhup.edu/~DSIMANEK/cargocul.htm
mikael pihlström (06:21:15)
I love the “could”, “might”, “may” school of doomsday catastrophism. You are 100% right. It could trigger mass extinction. And a pickle could jump out of a jar and squirt juice in my eye … but I doubt both greatly.
See my post, “Where Are The Corpses”, for facts rather than “mights” and “coulds” about extinction.
Willis Eschenbach (11:01:39) :
I love the “could”, “might”, “may” school of doomsday catastrophism. You are 100% right. It could trigger mass extinction. And a pickle could jump out of a jar and squirt juice in my eye … but I doubt both greatly.
The pickle jumping is now or within hours. When I say ‘could’ I have the
100 year perspective inside my head and I see a myriad of pathways, which
range from likely to improbale, hence …
I could stop saying could, but then I would use ‘risk’ and I don’t suppose
it would change a thing.