The Dryer Gets Wetter

Guest Post by Willis Eschenbach [See Update At The End]

I keep reading that one of the things that we are already seeing (or that is predicted) is that the wet areas of the planet are getting wetter and the dry areas are getting drier, viz:

Expect the Wet to Get Wetter, and the Dry, Drier – Center for Climate …

May 31, 2017 – As the world warms due to human-induced climate change, many scientists have been … summer, wet areas will get wetter and dry areas will get drier. … United States, inner Asia and the Middle East will become even dryer.

Will the Wet Get Wetter and the Dry Drier – Geophysical Fluid …

NOAA GFDL Climate Research Highlights Image Gallery Will the Wet Get Wetter … in precipitation near 20°S and 20°N – latitudes in the subtropical dry zones.

Wet regions getting wetter, dry regions drier as planet warms …

Wet regions getting wetter, dry regions drier as planet warms … simulations of the climate show reductions in rainfall over the drier tropical land regions … that drying of the drier regions continues (right) while wet regions will experience more …

The world’s wet regions are getting wetter and the dry regions are …

Dec 12, 2016 – The world’s wet regions are getting wetter and the dry regions are … warming climate; as the world gets warmer wet regions will continue to get …

Dry lands getting drier, wet getting wetter: Earth’s water cycle …

May 21, 2012 – … get richer’ mechanism, where wet regions get wetter and dry regions drier. … “Salinity shifts in the ocean confirm climate and the global water …

I thought about that while reading a recent study called Rapid Drying of Northeast India in the Last Three Decades: Climate Change or Natural Variability?. (Their conclusion, by the way, was that it was NOT from human actions, but instead that “the recent decreasing trend of NEI summer monsoon rainfall is, rather associated with the strong interdecadal variability of the subtropical Pacific Ocean“.)

So I went to the marvelous KNMI Climate Explorer and got the CRU TS 4.01 gridded precipitation dataset, which covers from 1901 through 2016. I started by looking at the trend of the data since 1901.

Figure 1. Global rainfall, land-only, 1901 – 2016.

Now, there is a trend … but the increase in monthly rainfall is only 2 millimeters per century. This represents an increase of about an inch (25 mm) in the yearly average rainfall. Small.

Next, since the Indian study concerned the recent decades, I looked more closely at the average rainfall over that period. Figure 2 shows the average rainfall around the globe for the period 1980 through 2016.

Figure 2. Average rainfall, 1980 – 2016. Rainfall is shown on a 1° latitude by 1° longitude gridcell basis. All areas with over 2.2 metres/year are shown in darkest blue.

Here you can see the great deserts of the Sahara, the Gobi, the Atacama, and central Australia. You can also see the wet zones of the Amazon, the African rainforests, and Indonesia and Papua New Guinea.

Next, I looked at the individual trends for each 1°x1° gridcell over that same period, from 1980 through 2016.

Figure 3. Precipitation trends, monthly precipitation, millimeters/month per decade. Areas with trends greater than 7 or less than -7 mm/decade are shown in bright blue or bright red. Click to embiggen.

Here we can see the problem indicated in the Indian study, the drying of Northeast India.

Finally, using the combination of precipitation and precipitation trend data, we can see if it is true that the dry areas are getting drier and the wet areas are getting wetter. Figure 4 shows a scatterplot of the two datasets.

Figure 4. Scatterplot, average land-only annual precipitation versus precipitation trend, 1980 – 2017. The black dots with whisker lines show the median and the error range for that precipitation interval.

What this shows is that while the wetter areas are getting wetter, it is not true that the drier areas are getting drier. On average, all areas are getting more rain. Not a lot more rain, of course, but more rain. Once again, the climate models are wrong.

And so one more beautiful climate myth runs aground on a reef of hard facts … the wet is getting wetter, but the dry isn’t getting drier—instead, the dry is getting wetter as well

[UPDATE] I realized that I had another dataset showing rainfall. This is the Tropical Rainfall Measuring Mission satellite rainfall dataset. Here is what that looks like.

Figure 5. Movie loop of the monthly averages of the tropical rainfall, Dec 1997 – Mar 2015. The coverage of the mission only extends from 40°N to 40°S. Note that this covers about two-thirds of the surface of the planet. Units are mm/month.

I ran the same type of scatterplot analysis on this data as in Figure 4, and I got the same results.

Figure 6. Scatterplot, TRMM data, average 40°N to 40°S annual precipitation versus precipitation trend, 1997 – 2015. The black dots with whisker lines show the median and the error range for that precipitation interval.

On average, wet areas are getting wetter, and dry areas are getting wetter as well. Go figure …

Finally, note the wide spread of the data. There are many dry areas getting wetter, and many wet areas getting drier. However, on average they are all either staying the same or getting wetter.

Here, we’re in the “wetter” part of the equation, a rainy Christmas Eve. Well, since it’s 2:03 AM, I guess it’s actually a rainy Christmas morning … so the very best of wet Christmas morning wishes to everyone.


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Kym Smart
December 25, 2018 2:34 pm

” Once again, the climate models are wrong.” “…It is not true that the dryer areas are getting dryer.”

Untrue? Not really. From the third link above:

“Observations and detailed computer simulations of the climate show reductions in rainfall over the drier tropical land regions (including parts of Africa and Australia) over the 20th century…”

Are you are expecting 100% accuracy from a climate model? If not should they be completely abandoned?

Reply to  Kym Smart
December 25, 2018 2:53 pm

If it were just this one, or even if this prediction were one of a minority not coming true, your objection would carry some weight. But when none, not one, zero percent, nary any at all, at all, of the dire predictions ever, ever even hint at coming true, then I would go with the conclusion of the post.

Kym Smart
Reply to  Richard
December 25, 2018 4:57 pm

Models are not predictions.

(All) “climate models are wrong” is just as meaningful as saying they are all right. Some MODELS are accurate enough and so quite useful. But that is just an opinion of course, not “science”.

Reply to  Kym Smart
December 25, 2018 5:33 pm

“Some models are accurate enough”. Engineering ones for example. Climate models not so much.

Kym Smart
Reply to  lee
December 26, 2018 12:53 am

Models are models. If what you are modeling is more chaotic then you might accept output of lower accuracy – that does not eliminate its usefulness.

Reply to  lee
December 26, 2018 5:39 pm

“If what you are modeling is more chaotic then you might accept output of lower accuracy – that does not eliminate its usefulness.”

I don’t think the words”usefulness” and “accuracy” mean what you think they do.

Crispin in Waterloo
Reply to  Kym Smart
December 25, 2018 7:06 pm

Models used by the IPCC made “predictions” until the eventual success of complaints prosecuted against the claims, based on the fact that the word “prediction” is reserved for models that have been validated.

As no climate GCM has ever been validated, the IPCC was forced to change their text to use “projections”. This is a certification that climate models cannot be used to support speculations and vain imaginings such as “if it is wet it will get wetter and if it is dry it will get dryer”. The models have not demonstrated skill at making such predictions.

I am not the least surprised that it is getting wetter everywhere with an increase in temperature. History shows that it it gets warm enough the great desert areas of the Sahara and Gobi turn into grasslands.

How that is a disaster is not clear to me. It seems like a great thing, positive in every way.

Ben Vorlich
Reply to  Crispin in Waterloo
December 26, 2018 9:19 am

Yes indeed, why would increasing desert area be preferred to desert greening. Why would you prefer the LIA to the current warmth. It baffles me.

Reply to  Kym Smart
December 25, 2018 7:31 pm

If the models have no better predictive power than blind guesses, or just the status quo, then they have zero value…or rather negative value.

Clyde Spencer
Reply to  Kym Smart
December 25, 2018 8:19 pm


Saying what is going to happen in the future, is by any other name, a prediction. Just saying “wetter” or “drier” is of little value. There needs to be numbers attached!

What is “accurate enough” to be useful? I’d say that they should be within 5% or 10% of reality to be useful for economic policy planning. Lower levels of accuracy might be acceptable if one is trying to learn more about the dynamics of the climate. But, that isn’t how they are commonly used.

Kym Smart
Reply to  Clyde Spencer
December 26, 2018 12:46 am

The link I refer to above include observations. Another I looked at referred to ‘some’ dryer regions – US South West, parts of the Middle East etc are dryer.

So I think saying its a “myth” is over saucing the goose.

But more importantly, making blanket statements like “climate models are wrong” are inconsequential , unscientific opinions and at best unhelpful. If an alarmist came here claiming climate models are 100% accurate they’d been torn to pieces.

Clyde Spencer
Reply to  Clyde Spencer
December 26, 2018 10:34 am

The link you refer to has a couple temperatures (e.g. 1.5 deg C) and an estimate of a range of land percentage, but is notably missing any quantitative estimate or prediction of just how much more arid the land will supposedly become. Instead, ambiguous and unsupported claims such as “significant” are provided. That is not what I would consider good science.

Kym Smart
Reply to  Clyde Spencer
December 26, 2018 3:28 pm

Did you see the graph that shows obervations of: “declining rainfall over the driest tropical land regions.”?
If you don’t consider that good science could you explain why not?

Clyde Spencer
Reply to  Clyde Spencer
December 26, 2018 4:13 pm

Thinking that I had perhaps overlooked the graph, I went back and looked for it. I still don’t see it.

Kym Smart
Reply to  Clyde Spencer
December 26, 2018 4:26 pm

At this link:

That is the third of Willis’ links above, its titled Dry Tropical Land Regions.

Alan Tomalty
Reply to  Kym Smart
December 25, 2018 9:36 pm

Only the Russian model is in the ballpark of observations. All other models have missed any temperature projection. There would be no physical reason why dry areas would get drier if global warming caused huge forcing of extra evaporation. Sure if that happened the wet areas would indeed get wetter, but for a dry area to get drier, that would mean if the dry area like a desert had no water to evaporate then it must get its water from somewhere else. Whatever caused that water to come from somewhere else (air currents through wind presumably) before CAGW happened, would also be in place after CAGW happened. So after CAGW happened you would expect that the same winds would carry at least the same amount of water to the desert area that they did before CAGW. The wet areas getting wtter and the dry areas getting drier is only computer model simulation projections which have no correspondence to the real world outside the office where the supercomputer is running.

Another Ian
Reply to  Alan Tomalty
December 26, 2018 1:48 am

And IIRC the Russians aren’t sold on the CO2 control knob

old construction worker
Reply to  Kym Smart
December 26, 2018 2:39 am

‘Some MODELS are accurate enough and so quite useful.’ Texas sharp shooter method?

Reply to  Kym Smart
December 26, 2018 5:01 am

So when models fail, please tell us what should be done.

John B
Reply to  Kym Smart
December 26, 2018 6:34 am

Then policy trying to change the society and economy of the entire Planet should not be made based upon them.

In former times ‘models’ were the entrails of sacraficed chickens and blood spatter patterns of doves. These were not 100% accurate either, and that is why they were abandoned, and leaders stopped listening to Shamen and High Priests.

We seem to have regressed.

Reply to  Kym Smart
December 26, 2018 9:43 am

Kym Smart, you’re just stating platitudes — nothing useful. Try again.

Reply to  Kym Smart
December 26, 2018 4:15 pm

I beg thee to present the counter-posit and data! You seem unanimous in your opinion, so show him where he’s wrong!
I tend to lean over here on Willis’ many-year history and presentations here, and his unfailing ability to see through the …Science. Data. Observation. Presentation.
And by God can the man write.

Present thy best to the best!
(Annnnd I just wanna watch…)

Kym Smart
Reply to  Patvann
December 26, 2018 4:40 pm

Willis wrote: “It is not true that the dryer areas are getting dryer.”

1. From the links he posted some obviously are, so perhaps he could have chosen not to be quite so dogmatic.
2. Who says ‘all’ dryer area are getting dryer anyway? Link?

Kym Smart
Reply to  Patvann
December 26, 2018 8:12 pm

Mmm digging deeper it seems some areas may be vulnerable to further drying, not “on average” as you point out.

From the first link above:

The authors, University of Maine glacial geologist Aaron Putnam and climate scientist Wallace Broecker of Columbia University’s Lamont-Doherty Earth Observatory, support their predictions with climate records that chronicle the abrupt warming of earth’s climate after the end of the last ice age, some 15,000 years ago. They predict that during the northern hemisphere’s summer, wet areas will get wetter and dry areas will get drier.

Their prediction pertains to “the northern hemisphere’s summer”, but if that gets omitted then it is no surprise their results could be misinterpreted. In that context their prediction may well be accurate.

Reply to  Patvann
December 26, 2018 9:30 pm

Willis writes

So yes indeed, “some areas may be vulnerable to further drying” …

…as history has shown from archaeology if nothing else. Its obvious that civilizations have come and gone and drought has played a part. Of course many would never have had the technology to store and transport water.

Kym Smart
Reply to  Patvann
December 26, 2018 10:53 pm

In a warming world most places are wetter; including the dryer 50%. That in no way conflicts with the example research cited as you have insinuated.
You’ve picked out a few headlines, but as I pointed out above the researchers are not referring to the driest 50% but to specific areas and time periods “the northern hemisphere’s summer”. So not really apples for apples.

Not so much the reef of hard facts as the swirling, muddy waters of ambiguity.

Kym Smart
Reply to  Patvann
December 27, 2018 12:03 am

Perhap you could test what the researchers are actually predicting: that the driEST places are drying further, say the driest 10%.

Reply to  Patvann
December 27, 2018 1:45 am

Kym writes

That in no way conflicts with the example research cited as you have insinuated.

How much do you want to bet that in a world with no anthropogenic CO2, a similar scatter plot exists?

Everything seems to be “consistent” with AGW.

Matthew R Marler
December 25, 2018 2:47 pm

Thank you.

I rather enjoyed our wet Christmas AM — almost 1 in accumulation since midnight last night.

I hope all of you readers at WUWT are also enjoying your Christmases, and I wish you all a Happy New Year.

Michael in Dublin
December 25, 2018 2:49 pm

Does this not mean that with a little ingenuity we can use some of the water from wetter areas to irrigate the drier areas? This is what has happened for thousand of years till modern alarmists claim we are incapable of finding simple and cost effective solutions – unlike carbon taxes.

steve case
December 25, 2018 2:49 pm

I know this, NOAA’s Climate at a Glance says that Contiguous U.S. Precipitation, January-December 1895-2017 shows a positive trend.

Reply to  steve case
December 25, 2018 3:39 pm

Looking at the time 1895 to current, the slope of the trendline is 0.17 mm per decade. Looking at the time period 1971 to current the trendline is 0.02 MM per decade, and insignificant slope. Although precipitation did increase in the past that was in the early part of the dataset. Precipitation is not currently increasing.

With Iowa data, the data can be split into three time periods. From 1895 to 1928 there was no trend. From 1928 to 1970 there was an increasing trend in precipitation, mostly decrease in the frequency of drought. The third time period is 1970 to current, when there is no trend. The average annual precipitation was less from 1895 to 1928 than from 1970 to current, so including the whole time period from 1895 to current results in and upward slope, though that slope is not continuing.

steve case
Reply to  Chris4692
December 25, 2018 5:21 pm

Chris4692 … 3:39 pm

While you’re busy cherry picking you could point out that Maine, California, Wyoming, Colorado, Montana, Georgia & Idaho all had negative trends since 1895, or at least they did in 2013 when I went through all 48 of the contiguous states.

Alan Tomalty
Reply to  steve case
December 25, 2018 10:09 pm

Steve You arent going to prove that CO2 causes warming by arguing about miniscule precipitation trends. You alarmists are getting very desperate in your claims about the global warming meme where skeptics have shot down the hundreds of fallacies that keep surfacing to try to resurrect this pathetic scam. It surely is a religion to you people.

It reminds me of a thought process about the non existence of God. Some believers in God try to argue that God is in every cell of our bodies either as part of each cell or as an entity within the brain. In the book The Self Illusion by Bruce Hood, he demonstrates by repeatable laboratory experiments that there is NO such thing as a self. You as an identity within your body or brain do not exist. The brain creates an illusion of the self to make you think that you exist as a thinking person with free will. THERE IS NO SUCH THING AS FREE WILL. Laboratory experiments have proved this. However you have to have this illusion or else you would go mad. However you don’t really exist except as a collection of cells. Your brain is not you. It too is only a collection of cells. To quote from his book: “You only exist as a pattern made up of all the other things in your life that shaped you” In other words; your life experiences. So the old saying that when you are young, if you run with wicked or bad people you will become like them ; and the opposite is also true. That fact has been born out in billions of lives. It is your life experiences which make the decision for you at any fork in the road.

So all that is to say, that if you as a separate free will individual doesnt’t exist, then how could God exist inside you either in your cells or as a separate entity? Furthermore iIf he was a separate entity inside you and couldn’t stop you murdering someone, then he is either a mean God or else a helpless God. So then the believer says: Well God exists somewhere out there in the universe. Well, the speed of light would certainly hinder any communication to him or from him.

Believers in a religion believe in it so deeply that they will never admit that they are wrong even if a million facts are shown toprove them wrong. They will always try to resurrect some esoteric reason why their belief should continue. The same thing with climate science and CAGW.

steve case
Reply to  Alan Tomalty
December 26, 2018 1:18 am

Wow! thanks for all the ink – – I guess. Did you just call me an alarmist? Very interesting, I’ll chalk it up to Christmas cheer.

Reply to  Alan Tomalty
December 26, 2018 5:35 am

You should wear the tag “alarmist” with pride. You have worked hard and demonstrated much faith to have earned it.

Clyde Spencer
Reply to  Alan Tomalty
December 26, 2018 10:26 am

If you don’t already do so, you might want to watch the PBS series “Closer To Truth.”

Reply to  steve case
December 25, 2018 7:27 pm

By ‘positive’ do you mean dryer, as in holiday weather, or wetter, as in making sure the crops thrive?

steve case
Reply to  Richard
December 25, 2018 7:50 pm

Positive = more precipitation.

December 25, 2018 2:57 pm

What data are “precipitation trends” based on?

Reply to  Willis Eschenbach
December 25, 2018 4:29 pm

“The data set is gridded to 0.5×0.5 degree resolution, based on analysis of over 4000 individual weather station records. Many of the input records have been homogenized, but the data set itself is not strictly homogeneous.”
In the absence of original data, this is probably the best we can do – but I don’t trust trends of homogenized data.

David S
December 25, 2018 2:58 pm

Sounds like everywhere is getting wetter. That seems like a logical consequence of global warming. Warming causes more water to evaporate from the oceans which means more precipitation worldwide. Although we don’t know necessarily where it will come down, but it sounds like it would be an overall good for agriculture worldwide. More water plus more CO2 would make crops grow well.

Reply to  David S
December 25, 2018 4:39 pm

But the Californian drought was due to ‘Global Warming’. Apparently.

I wouldn’t be surprised if a warming planet caused more rain, but that’s not what the Global Warmers claim.

Reply to  MarkG
December 25, 2018 5:12 pm

Some think California is in a “mega drought”

I really don’t see it.
Reservoir levels are pretty good for this time of year:

Gary Ashe
Reply to  David S
December 25, 2018 8:06 pm

We do know where most of it comes down, at the poles .. heat moves from hot to cold, tropics to poles, to condense out along the way.

Reply to  David S
December 26, 2018 6:23 am

Well said David S: I suspect few if any of the models take into account the Atmospheric Rankine Cycle. Engineers know a lot about how this works; but as radiation is but a small bit player in the process the current scientists tend to ignore it.
However the steam tables tell us that some 680 WattHrs of energy get transported up into the atmosphere and beyond for every Kilogram of water evaporated and returned to earth. The process accelerates when extra energy is supplied but at constant temperature and acts as the opposing force to that of the purported Greenhouse Effect.
Few people realise that the water coming out of their tap could well have originated in the pacific ocean. Winds and differences in pressures ensure a pretty random distribution of returning rain, snow, ice etc. Statistically very difficult to predict.
Meanwhile, as you say, plants are very grateful for the CO2 and water and we grateful for the plants.

December 25, 2018 2:59 pm

Willis just a note about SE Australia. From 1992 to 2009 the IOD was locked into the positive phase and reduced rainfall to a line south of Broome W. Aust to south of Sydney. See IOD link below.

But Australia overall is much wetter after about 1969 see BOM anomaly link 1900 to 2017. But 1895 to 1902 was a very bad drought so that is 1895 to 1969 for much drier Aust conditions.

Here is the study announcing the discovery of the IOD in 2009. This shows up in a SE state like Victoria but is not visible in Aust graph at BOM link below.

Here’s the BOM link for Aust rainfall.

Reply to  Neville
December 26, 2018 3:17 am

Neville, I do not trust BOM with anything. For a start prior to 1900 there were many more stations collecting rain data (mainly at Post Offices around the country. BOM has shut down just about all stations near ( ie within 20m) of Post Offices while they now get data from airports which is not always available continuously. I could give many examples for one is Gayndah Qld PO which had one of the longest records for rain, and temperatures in Qld dating back to at least 1890 but this was closed around 2010 and now data comes from the small Gayndah airport a few Kms outside the town.
The trend deends on the starting date. In my area (SE Qld) average yearly rain from 1893 is 1805 mm. Yes 1902 was the record low of 520mm within a drought period. If one takes that as a start then the rainfall has slightly increase. However the 1890’s were very wet 1893 many think was a record with 3950 mm or 3.95m. However in fact 1898 was wetter with 3996mm or rounded 4.0m. The year close to my place had one day missing in the official BOM record so October was listed as NA which also meant the year was NA. I look at some 6 other sites in the area and 4 of the closest to the official station for the missing day and came up with a monthly and yearly total which was a yearly record (now over 125 years)
If one starts from 1893 there will be a slight decline in rain. This year which will be slightly over the average may lift the trend to zero, offsetting the dryer periods associated with El Ninos around 1998 and 2004. We could now be heading for a wetter period contary to predictions of another El Nino.

Hans Erren
December 25, 2018 3:00 pm

The Netherlands has a clear increasing rainfall trend since 1901, so the dry year 2018 was not expected, and certainly not what “future climate change ” will bring.

Wim Röst
December 25, 2018 3:03 pm

Willis: “All areas are getting more rain. Not a lot more rain, of course, but more rain.”

WR: A bit more of rain in the Sahel but a lot (!) of ‘greening’ is noticed for the Sahel (and for other arid regions). The fertilisation by extra CO2 plays a role: plants need less water because plants can close stomata: not all of them still are needed to inhale enough carbon dioxide, so plants don’t need to lose water vapor by (too much) open stomata as well.

More plant leaves will change local humidity for example during the night. And they will change evaporation and so rainfall. Plant roots will keep more moisture in the soils. Even with a little bit less of rain situations don’t need to change dramatically as long as CO2 rises. Thanks to CO2 greening continues.

But on average rainfall is not diminishing, not even in dry area’s. Thanks for checking, Willis!

Gary Pearse
December 25, 2018 3:05 pm

Merry Christmas to you and family, Willis. Here you are working on an early xmas morn straightening out another flawed climate science proposition. Interesting, that a tiny postage stamp area in NE India turns out to be the foundation for a global dry getting dryer fabrication.

One thing I’ve noted over the past month of your climate articles is you’ve mentioned it raining in your home area in California. It seems at odds with all the hype reporting of mega droughts in the offing, hydroelectricity at risk, and worries about the last days of mountain skiing in the west. Maybe postage stamp foundations are all that’s left of the climate worriers crumbling case.

I was invited to present a paper at the American Exploration and Mining Association annual meeting in Spokane, WA three weeks ago and noted the mountains seemed pretty snow covered. It was also frosty in Spokane in the evenings. I flewback home via Vancouver, BC and passed a very snowy looking Mount Baker where I skied 50 years ago.

John Bell
December 25, 2018 3:27 pm

Great article!
Is there an overall average rise rate, or percent increase per decade per meter of rain/year?
Is this all due to temperature alone one wonders?

December 25, 2018 3:32 pm

Those same words “Simulations of the climate show”.

The warmers want it both ways, if indeed as per their models, its getting warmer then as Earth is in fact a water planet, then we must have more evaporation.

So what happens to all that water vapour ? True a lot comes down in the usual wet areas, but with so much extra water vapour resulting from a warmer Earth, its obvious that some will also fall on previously dryer areas.

The movement of water vapour rising and raining, also means that some parts are in the “Rain shadow area, all perfectly normal. The great deserts of the world have always been there, at least for millions of year They are not recent arrivals , so we know that some parts are wet and some parts are dry.

So what s all the fuss about. ?

Remember that the Greens are not really into “Save the World” That to quote Stalin is in the Useful idiots” category. World government is their true goal, nothing less, and they are good at getting what they want. Lots of Politicians as usual are after that extra vote or two, and the left wing has taken over the Media.


December 25, 2018 4:30 pm

I love this one….Miami gets ~60 inchs a year….that’s another 1/2 inch a month…no one would even notice
…and I’m sure a desert wouldn’t notice

“Although we have found that this process is happening slower than first thought, if global warming exceeds 3°C, wet regions will likely get more than 10 per cent wetter and dry regions more than 10 per cent drier”

Dr Skliris added “The agreement between climate models and observations over the recent past is another important finding of this study because it adds confidence to climate model projections of water cycle amplification under greenhouse gas emission scenarios.”

Reply to  Latitude
December 26, 2018 9:26 pm

I’m always wary of claims of “agreement between climate models and observations over the recent past”, because there is never information about when the model was run and how long there was between then and the observations, and there is rarely if ever information on how well the observations matched the model run. My suspicion is that a model can match some observations quite well over the period that it is tuned to match the observations, ie. it can match observations up to the date of the model run. After the date of the model run, there may be a limited period and/or limited areas where observations continue to match reasonably well, but eventually there will be general divergence. In essence, the models are random number generators within artificial constraints. No better for predicting climate than a clock which runs at variable speed but always shows a time between 0 and 24.

December 25, 2018 5:06 pm

Just a grammar nitpick first on the title and elsewhere in this peice:
“Drier is a comparative adjective meaning more dry. A dryer is one of many types of electrical appliances used to dry things. The words were once interchangeable. The distinction crept into the language through the 20th century and has only recently solidified.”

Moving on:
Willis finds it gets it’s wetter everywhere, which is consistent with a warming planet coming out of the LIA, the coldest period of the last 10,000 years. He highlighted several climateer studies/claims under climate change that predicts the wet areas get wetter, the dry areas get drier, and his results put those claims from the climateers in doubt using their own data.

CTM put this paper and press release up on WUWT about 2 weeks ago:
Record-wet and record-dry months increased in regions worldwide

With the presser (press release) providing this whopper by a study climateer who said:
A central conclusion from our study is that, generally, land regions in the tropics and sub-tropics have seen more dry records, and the northern mid- to high-latitudes more wet records – this largely fits the patterns that scientists expect from human-caused climate change,” according to says co-author Dim Coumou from the Institute for Environmental Studies (IVM) at Vrije Universiteit Amsterdam

Now of course they are talking rainfall extremes in their paper, but monthly rainfall is physically bounded at the low end by zero. So more dry records in the tropics, a place noted for precipitation in general, will have an impact on the rainfall totals. But here these climateers found wet got drier, and dry got wetter (mid- and high latitudes).

Still these Dutch-German climateers who authored the study claim robust statistical analyses results that, “largely fits the patterns that scientists expect from human-caused climate change.”

The essential conclusion I come to is that any result can be found to be “largely consistent with Climate Change” because there have been so many diametrically opposed “results.” Thus the climateers can always post hoc pick the winner. That makes Climate Science as practiced today in peer review journals nothing but Junk Science.

Reply to  Joel O'Bryan
December 25, 2018 5:14 pm

And here I make the “there – their” mistake when I type too fast and don’t proofread. Plus a few other misspellings. Sigh. I miss edit.

Robert MacLellan
Reply to  Joel O'Bryan
December 25, 2018 5:37 pm

“Robust statistical analysis”, that phrase reminds me of a story on CBC back in October…
the gist of which was that too many statisticians report being asked to fudge their results to support a conclusion.

Reply to  Willis Eschenbach
December 25, 2018 9:09 pm

I was about to make a new comment not in reply to another person’s comment about “All areas are getting more rain”. The Figure 4 scatterplot shows that a majority of wet areas, dry areas and in-between areas are getting more rain, and a minority of wet areas, dry areas and in-between areas are getting less rain. The Figure 3 map shows trends – some places have had a trend of rain decreasing after 1980. A majority of them are where I expect rainfall reduction from global warming – around the US West Coast and continental land in the southern part of the tropics, from around 10 degrees S to around the Tropic of Capricorn, due to global warming shifting climate zones northward, due to the Arctic warming more than the Antarctic when the globe warms.

Gary Pearse
Reply to  Joel O'Bryan
December 26, 2018 12:19 pm

Joel, also warming that isnt human-caused would give the same result. They always say at the end that this is what is expected from human-caused CC. Science also requires exactitude in phraseology.

We didnt just crawl out of the LIA. The 80s 90s warm interval was mostly recovery from the 40yr cooling spell after the 1930s-40 hot spell. That means most all of the 0.8C warming of the 20th Century took place before 1940, when CO2 was~280ppm. Little warming can be attributed to the added 40% increase in CO2 since. That is the reason for the egregious adjustments that pushed the 30s-40 peak down more than 0.5C.

Steven Mosher
December 25, 2018 5:34 pm

One reason I tell people not to use KNMI.

they probably did not warn you that CRU TS series are not debiased, an especially thorny problem with precipitation records.

Harris, the author of the series ( 4.02 is the current series BTW) has cautioned users that they should
compare his product with others.

In short, go to the source of the data.
read the papers
Follow the recommendations.

Reply to  Steven Mosher
December 26, 2018 12:17 am

On talk of versions, have you seen a new release of Acorn-Sat from Aust? Geoff.

Reply to  Willis Eschenbach
December 26, 2018 10:46 pm

Glad you have that.
I was about to send it on.
Have not found any new metadata yet.

December 25, 2018 6:23 pm

Our wettest year in recorded history here.

Steven Fraser
Reply to  Jackie Pratt
December 25, 2018 7:43 pm

3rd wettest in the record in DFW, including 3 record setting months. If we get additional .75″ before the 1st, we will finish at #2.

Reply to  Jackie Pratt
December 26, 2018 5:53 am

Where is here?
(In general geography)

Reply to  Jackie Pratt
December 26, 2018 10:35 am

Very wet here in western Maryland, over 70″ this yr so far in many local areas (80+ inches in mountain spots). Surprisingly little flood damage tho, considering the amounts. Local paper mill had to import wood from Wisconsin, tho, because the local forests were too wet/muddy to work in.

December 25, 2018 7:29 pm

My take is simple but shocking. Basically we do not know a thing about 2/3rds of the globe in terms of precipitation.

Yes, water pouring on water is not exciting for some. Yet, wouldn’t it be fun to know if “thermostat hypothesis” has legs?

Merry Christmas

Reply to  Willis Eschenbach
December 26, 2018 6:59 am

Thanks. I am quite surprised to discover the existence of deserts and rainforests on oceans. Profoundly, surprising indeed.

Reply to  Willis Eschenbach
December 26, 2018 7:04 am

Is it possible to merge land and ocean data and create the same movie? Another interesting exercise would be to compute if the rainfall on land would be 1/3 rd of on ocean. Trending the last few decades would be interesting too.

December 25, 2018 7:33 pm

Here is a source of South Indian rainfall data for one small coastal city between 1900 and 2017:
The trend is up, not down at all here.

Richard M
December 25, 2018 7:34 pm

Humans are also putting more water vapor in the air. Several different methods with probably the biggest being irrigation. That water vapor will eventually rain out and find it’s way back to the oceans but it will lead to more precipitation.

Also, more humans are living in and near the deserts so some of our water vapor production is going right to the areas that can use more.

Dr. S. Jeevananda Reddy
December 25, 2018 7:44 pm

Here is a 2nd type of global warmists!!!, destroying the foundations of Science of Climatology and Science of Meteorology. Poor quality reporting.

In Traditional Meteorology/Climatology, World over Meteorological Departments prepared Climate Maps of Meteorological parameters. Rainfall maps represent the isolines of rainfall of station averages/extremes at monthly/annual values. These are acting as guide to water resources and agriculture. These are linked to annual variability in rainfall.

The rainfall is highly variable with orography [Climate System as defined by IPCC] and cyclonic activity. Western Ghats: on the west side (windward side) is the high rainfall zone – humid & sub-humid zone; and east side [leeward side] is the low rainfall-drought prone zone during southwest monsoon and it is reverse pattern during northeast monsoon season. Eastern parts of India get rainfall in southwest monsoon and northeast monsoon, which present a opposite pattern of cycles. Northeast monsoon season presents Cyclonic activity in Bay of Bengal , the rainfall follow this cyclic pattern.

Rain-fed agriculture survives on in-situ rainfall; forests help groundwater aquifers.

Droughts and floods [dry & wet] follow the natural rhythm in rainfall over different parts of the globe. They also vary with latitude and longitude.

Dr. S. Jeevananda Reddy

December 25, 2018 8:36 pm

Thanks Willis for insightful explorations.
Note too that climate variations are not random but show persistence as described by Joseph (Genesis 41:29-31):

There will come seven years of great plenty throughout all the land of Egypt, but after them there will arise seven years of famine

Climate persistence is quantified as Hurst Kolmogorov dynamics. Demetris Koutsoyiannis and his group at ITIA extensivley examined rainfall distributions. They further developed Hurst methodology including for rainfall .
See Koutsoyiannis’ invited prsentation: Hurst-Kolmogorov dynamics and uncertainty
He finds the statistics of Hurst Kolmogorov dynamics are substantially different from Markovian (random) statistics. Almost all climate science publications ignore this.
Further info via ITIA
Other publications on Hurst Kolmogorov

Reply to  Willis Eschenbach
December 26, 2018 6:47 am

Great work and very informative

December 25, 2018 8:54 pm

Please take care when relating rainfall to temperature.
There are many weather stations in Australia whose apparent Tmax is lowered when it rains. Put simply, rain cools – as basic physics would indicate. It is customary to plot temperature against time and rainfall against time. It is interesting to drop time out and plot rainfall against temperature, monthly basis is fine.
You might then start to wonder if there is a need for a ‘rainfall-corrected temperature’ as a more fundamental temperature against which other factors can be compared. Read the work of colleague Dr Bill Johnston. One small sample is here –

Dr. S. Jeevananda Reddy
Reply to  Geoff Sherrington
December 25, 2018 10:40 pm

My Ph.D. Thesis is available in the “The Australian National University”, Canberra — An Agroclimatic Classification of the Semi-Arid Tropics, S.J.Reddy, 1985

In this thesis I analysed the daily rainfall/weekly rainfall data of 82 locations in tropical Australia. This presents maps [spatial distribution] of agroclimatic variables and percent crop failure years. It also included variation of sorghum yields with the effective rainy period at Katherin [1947-67]. Also presented soil water balance simulations results for Pine Creek, Argyl Downs, Derby Atherton, Mt. Surprise, Woodstock, Cl emont, Marlborough, Mitchell.

Thesis also dealt with the data of India and few other West African countries.

This study clearly showed why mechanization failed.

Also, article in a book “Agro-research for the semi-arid tropics: north-west Australia”, Edited by Russell C. Muchow, University of Queensland Press, 1985 — Part Two: Constraints to Agricultural development: 3. Soils and climate by J. Williams, K.J.Day, R.F.Isbel and s.j.Reddy, 31-92

Dr. S. Jeevananda Reddy

Reply to  Dr. S. Jeevananda Reddy
December 26, 2018 12:15 am

Ray Isbel was leader of the Soil Science group CSIRO Townsville when I was a new graduate in Tropical Pastures, same building. Geoff.

Dr. S. Jeevananda Reddy
Reply to  Geoff Sherrington
December 26, 2018 12:53 am


In fact I only met Prof. Williams (soil scientists).

One fine morning My Guide Henry Nix [CSIRO] Leader of the group came to my house along with Prof. Williams.

Prof. Williams asked me to present a paper at the conference. I agreed but expressed that I don’t have daily rainfall data for the norther Australia. He then told me that he will transfer the data through computer. My guide’s group from CSIRO helped me for formetting the data for my programmes [which I wrote in Fortran IV language]. CSIRO computer group helped me running all programmes.

Then I prepared the article and left with my guide and joined IICA/EMBRAPA in northeast Brizil. My guide sent it to Prof Williams and he combined my work with soils [the first three authors are from soils]. Prof. Williams presented at the conference.

Dr. S. Jeevananda Reddy

Dr. S. Jeevananda Reddy
Reply to  Dr. S. Jeevananda Reddy
December 26, 2018 1:01 am

When I was with FAO/UN — agroecological zones project — I along with other expert on pastures [J.R.Timberlake] published a paper:

A simple method for the estimation of potential primary pasture productivity over Mozambique, Agricultural and Forest Meteorology [Elsevier Science Publishers B.V., Amsterdam], 39(1987)335-349.

Dr. S. Jeevananda Reddy

December 25, 2018 9:08 pm

As Willis’ data show, yet another silly CAGW prediction bites the dust…

Logic/physics would suggest the 0.85C (0.05C/decade) of beneficial global warming recovery we’ve enjoyed since 1850 would lead to an increase in global rainfall from increased ocean evaporation, and the empirical evidence support this.

I would have assumed a larger increasing trend of rainfall than just 2mm/century, but, alas…

In addition to a slight increase in rainfall from primarily natural warming recovery, man’s increase in CO2 emissions have increased the CO2 fertilization effect, which have increased global greening by 14%, which, in terms of total expanded greened land area, is equivalent to TWICE the size of the continental US…. Oh, the humanity!… How the hell is increased greening from manmade CO2 emissions a bad thing?

Since it seems likely global cooling may start from the early 2020’s when a 50-year Grand Solar Minimum and 30-year PDO/AMO/NAO cool ocean cycles commence, it’ll be interesting to see what happens to average global rainfall during global cooling.

Logic and physics would suggest global cooling would lead to a decrease in global rainfall, but according to Willis’ graph of global rainfall from 1901~present, during 30-year PDO cool cycles (1880~1913) and (1945~1975), global rainfall seemed to have increased slightly during these global cooling periods, which seems counter intuitive..

If anything, it seems the earth is still too cool. During the Holocene Maximum 8,000 years ago, global temps were about 1.5C~2.0C warmer than now, and archeological data show large areas of the Sahara Desert thrived with wildlife, human settlements, forests, lakes and rivers… Just more evidence CAGW is a hoax… It’s cold that kills, not life-giving warming.

December 26, 2018 12:19 am

Thank you for this post.
In general, do you get the feeling that success with climate data depends on ability to avoid cherry picks, especially with start and end dates of time series data? Geoff

December 26, 2018 12:35 am


Re fig. 1 you say:

… the increase in monthly rainfall is only 2 millimeters per century.

Yes, but that’s for ‘global’ land data (fig. 1), so it doesn’t answer the question you’re asking. If you’re testing the hypothesis that ‘wet areas of the planet are getting wetter and dry areas are getting drier’ then surely ‘wet’ and ‘dry’ land areas need to be sub-divided and separate calculations made for each?

If dry areas really are getting dryer and wet areas really are getting wetter, using global data without differentiating between the two types of area will obscure this.

December 26, 2018 12:49 am

Tim-flim-flam-Flannery could not be reached.

Bob Ernest
December 26, 2018 3:54 am

“Now, there is a trend … but the increase in monthly rainfall is only 2 millimeters per century. This represents an increase of about an inch (25 mm) in the yearly average rainfall. Small“

How does 2 millimeters per century equal 25 mm
Is a yearly average?
Don’t you divide 25 mm by 100 or so?

Sorry for my ignorance. I am 66 and every year out or high school I loose a bit more arithmetic 😂

Thanks for all your hard work. I send it to my friends to try to steer them to the truth.

Reply to  Bob Ernest
December 26, 2018 7:46 am

The chart legends for Figs 2-3 show these as deltas per month. So 2 * 12 = roughly 25mm

Reply to  sciguy54
December 26, 2018 7:49 am

Sorry, now that I scroll up, its Fig 3 only. I blame cold medication.

December 26, 2018 4:41 am

Once again, the climate consensus is shown to be wrong. Their predictions of existential crisis are false.
Once again the climate skeptics are right: nothing dangerous is changing in the climate.
Thank you, Willis.

December 26, 2018 5:06 am

Also ref Bob at 3.54am,
The first para after fig 1 does not make sense. I think you mean trend is 2mm per decade to make an inch over the span of the graph.

Many thanks for all your posts – I appreciate the science and the sea- tales.

December 26, 2018 5:37 am

Very unsurprising to me that as the world has warmed overall since the end of the LIA, precipitation is increasing overall. More evaporation from oceans mean more water in the air and hence more precip.
And also not a bit surprising that warmistas making crap up have been proven wrong again.

December 26, 2018 5:39 am

I live in Jordan.

The past 18 years but, more so, during the past 6 years, the weather has become gradually wetter and cloudier.

This year (2018) we even had clouds in August. In fact, on 30% of the days of August we had 60% cloud cover.

Pop Piasa
Reply to  guidoamm
December 26, 2018 8:15 am

I’m at meridian 90 west and parallel 39 north, observing an increase in high clouds since 2016. We very seldom have clear sky for more than an hour or two before more stratospheric haze dims the sunshine. Really irks my neighbors with solar panels. Consequently, our daytime highs are lower and our nighttime low temps are higher than years like 2012 when we saw weeks without clouds at all.

I wonder if it’s all about where the clouds tend to be on the globe, rather than the total amount of global cloud cover.

Steve O
December 26, 2018 7:46 am

Can rainfall serve as a proxy measure of cloud cover? If you have a tiny bit more rain, you probably also have had a tiny bit more cloud cover. How much additional cloud cover would it take to account for the additional warming seen over the last century, and does that correlate at all with the amount of additional cloud cover estimated from the higher amounts of rainfall?

Pop Piasa
December 26, 2018 7:58 am

This is the dawn of the age of Aquarius. Warmer, wetter, lusher and greener.
Man is in symbiosis with nature, but most fail to recognise it.

Reply to  Pop Piasa
December 26, 2018 12:18 pm

With WV trend having gone flat, sun gone quiet and ocean cycle temperature trend in down slope, I am afraid it is more like the dusk of Aquarius.

December 26, 2018 8:28 am

Wetter poles mean thicker ice core rings. Drier poles mean thinner ice core rings. I am thinking out loud and speculating here. Long periods of thin layers, and long periods of thick layers would be spread apart between more variable layers where thick and thin layers are next to each other with very little trend. Since we are at the top of a warm period, these precipitation ups and downs are not much to bark at (just a pin hole of a window of time) when seen from the 800,000 year wide screen picture window.

Anyone who screams into the night that the climate is weirding out by some places getting wetter while others are getting drier, or some other mix of these signals, appears to be advocating for the jagged downhill slide into killing cold with little water vapor sourced precipitation to support life.

al in kansas
December 26, 2018 10:28 am

Not to be a “wet” blanket, but between the normal measurement error and error due to homogenized data, an annual change of 1 inch per century would seem to me to be well within the error bars that should be included in all statistical studies. It does contradict the “It’s an unprecedented disaster and getting worse” mime.

December 26, 2018 10:38 am

Willis wrote about the scatterplot Figure 4: “What this shows is that while the wetter areas are getting wetter, it is not true that the drier areas are getting drier. All areas are getting more rain. Not a lot more rain, of course, but more rain. Once again, the climate models are wrong.”

This conclusion depends on how you define the terms “wetter and drier”. There is very little precipitation in Antarctica, but most of the continent is covered with thousands of kilometers of frozen water. The scientists who say that wetter regions are going to get wetter and drier regions are going to get drier are using different definitions that you are for wet and dry AND their poorly expressed concepts are being distorted by alarmists to scare us. Their concept of wet and dry sensibly includes both precipitation and evaporation, not just precipitation.

If I understand correctly, in this case, climate scientists are defining wet regions as those that receive more water as precipitation than they lose via evaporation. On land, the excess water runs off. Dry areas are those where evaporation is greater than precipitation, a concept that works for oceans but makes no sense to me for land. Where P-E is negative, it is expected to become more negative. Where P-E is positive, it is expected to become more positive. Sometimes this conclusion is limited to the tropics, where the Hadley circulation determines where rain forests and deserts are located.

There are plenty of points on your scatter plot where precipitation is falling and they could be in regions that are “dry” in terms of P-E. So your plot doesn’t prove they are wrong using their definitions. The data pasted below (if successfully pasted) is consistent with expectations, but our records aren’t good enough to pick out changes that are less than 1% per decade against a background of natural variability and possible systematic error. The magnitude of the change predicted for 2100 is a fall of less that 5% from today for dry areas.

comment image

Since there are two orders of magnitude in precipitation between the wettest and driest locations, climate scientists sensibly report the change in precipitation rate as a percentage, not an amount. And since 1 m of rainfall is average, the slope of the yellow line on your graph is being determined mostly by areas with average rainfall.

December 26, 2018 11:00 am

Willis: There are some powerful constraint on how precipitation (and the convection that produces it) can change on a warming planet, so you are exploring a very interesting topic. If surface evaporation were to rise 7%/K (as saturation vapor pressure does), then an addition 5.6 W/m2/K of latent heat would enter the atmosphere from the bottom. Modtran shows that the net upward radiative flux (OLR-DLR) changes less than 1 W/m2/K with warming. That heat must leave the top of the atmosphere. However, the increase in the amount of heat leaving the top of the atmosphere with warming depends on climate sensitivity: ECS 3.6 K/doubling, 1 W/m2/K; ECS = 1.8 K/doubling, 2 W/m2/K; ECS = 1.2 K/doubling (no feedbacks), 3 W/m2/K; ECS = 0.65 K/doubling, 5.5 W/m2/K. Therefore, a 7%/K increase in evaporation with warming is grossly inconsistent with today’s expectations for ECS. That means the upward convection of moist air (such as the Hadley circulation) must slow. The wet getting wetter and dry getting drier alarmism is associated with the expectation that atmospheric overturning must slow enough to limit the increase in precipitation to about 2%/K.

Steve Fitzpatrick
December 26, 2018 11:40 am

Hello Willis,
Very nice post.
One interesting presentation of the data would be like figure 4, but with the trends normalized by the individual cells’ precipitation rate. It looks like the rate of increase is not far from a constant fraction of the total precipitation, independent of how much precipitation is received.

December 26, 2018 11:55 am

Atmospheric water vapor has been increasing, long term, (graph using NASA/RSS satellite acquired numerical datacomment image) at 1.5% per decade, 8% since 1960. The WV increase (about twice that calculated from increase in vapor pressure due to average global temperature increase of liquid water at planet surface) correlates with irrigation increase.

The WV increase posed the question of whether precipitation increase would be world wide or the hydrologic cycle would become more intense with dry areas becoming dryer. This study supports that precipitation increase is world wide.

If the 2015-2016 el Nino is ignored, WV content looks flat since about 2002 (as does UAH v6.0 TLT (lower troposphere) temperature). It looks like this warming cycle has ended.

How much of recent high precipitation (with incidences reported world wide) has been simply bad luck in the randomness of weather and how much has been because of the ‘thumb on the scale’ of added water vapor?

Reply to  Dan Pangburn
December 26, 2018 12:25 pm

%&#! Make that linkcomment image

Reply to  Willis Eschenbach
December 26, 2018 1:30 pm

Do you still want “Dryer” (the machine) in the title, or “Drier” (the description) for the areas?
Both, iconically, are valid.

Johann Wundersamer
December 26, 2018 2:06 pm

Great! Thanks.

Jan Kjetil Andersen
December 26, 2018 2:08 pm

it is not true that the drier areas are getting drier. On average, all areas are getting more rain.

There is a problem with this statement.

Whether it is dry or not does not only depend on how much it rains, it is also very dependent on the temperature. When it is warmer, more water evaporates so we need more rain to stay on the same “dryness” level.

That means that if the temperature increases it can actually be drier even if the area are getting more rain.

Bill In Oz
Reply to  Jan Kjetil Andersen
December 26, 2018 6:28 pm

No !

Actually if there is more rain this will CAUSE the temperatures to be lower.

Why ? More rain means more moisture available for evaporation from plants and the soil. And that evaporation will lower the temperature in that area.

Now that is physics mate !

This is very very obvious if you examine the temperatures along the line of latitude here in Australia. The 25 degree South line of latitude runs from Maryborough in the East to Shark’s Bay in the West. And this all these areas get roughly the same level of sunlight. However Maryborough has a monsoonal climate with lots of rain from December to March/April. And the temperature pattern reflects this.

Due West is the town of Longreach which is far drier and thus has a much hotter temperature regime.

Further West again is open empty desert… until Shark’s bay which is on the edge of desert.

Jan Kjetil Andersen
Reply to  Bill In Oz
December 26, 2018 10:52 pm

Actually if there is more rain this will CAUSE the temperatures to be lower.
Why ? More rain means more moisture available for evaporation from plants and the soil. And that evaporation will lower the temperature in that area.

This is also correct; however, it does not negate my statement above. Both are true. It is a question of which effect have the largest impact.
We are after all not talking about going from arid to mist areas here. We see in these after all very interesting graphs that the arid areas with annual precipitation less than 1 meter have an increase of less than one mm/ month per decade. It is not trivial to calculate the effect temperature from that, but my intuition says me that 1 mm/month will have negligible effect on temperature.
I think a scatterplot showing annual precipitation against the relative change in monthly precipitation would be useful. Could we see if the arid areas got more or less percentage increase as the wet ones?

Reply to  Jan Kjetil Andersen
December 28, 2018 9:26 am

I agree percent increase would be more informative. IMO it also makes more sense. It would make the assessment even more convincing by raising the dots toward the lower precipitation side of the graph.

Ulric Lyons
December 26, 2018 6:47 pm

It would make sense the regional trends in Figure 3 through 1980 to 2016 are greatly influenced by the AMO shifting phase.

kristi silber
December 27, 2018 11:14 pm

It seems to me it would be very hard to detect a downward trend, on average, in areas that are very dry to begin with. There’s not much more downward to go. You can see this at the far-left hand of the scatterplots. The first one actually does appear to have lowest-precipitation bar very slightly below the 0 line, unless this is just a function of the graphics. And, as others have pointed out, precipitation doesn’t equal how dry or wet a place is. This is not only because of the effect of temperature, but also the timing of the precipitation. Precipitation events are predicted (and observed, in the U.S.) to get more intense, which can lead to greater runoff, leaving proportionally less available for plant growth and aquifer replenishment. One big storm in the Sahara in 2015 could affect the “trend” for that region – likewise, any anomalously rainy year hitting a lot of dry areas toward the end of the period could affect the data. And this is only for land, omitting Antartica. I’m always a little wary of linear trends, though, especially with this kind of data.

It’s interesting data, in any case. Always nice to have more things to think about and explore. Thanks, Willis. (That’s genuine.)

I wasn’t able to find the same page that shows the data Willis has, but I monkeyed around with another page, comparing the difference between averages of various time periods. The period selected has quite an impact. When I compared 1950-1960 with 2008-2018 there were notable differences from the data in the post. For instance, much of Africa north of a line from the horn east has gotten “significantly” drier (on the maps I found, there were hatch marks that denoted a signal less than 1 sd from “natural variability” based on climate models – and a lot of the land was covered in the hatch).

Ronald Chappell
December 29, 2018 2:29 pm

Where do these mental giants come from who can tell us where we get one additional milli-watt of additional power to evaporate 1 thimble full of water. (Hint: It ain’t from CO2 greenhouse, a blanket adds NO additional power to an isolated system.

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