This press release below from Columbia University shown below suggests that irrigation cools the region undergoing irrigation. However, a study published three years ago of California’s central valley by Dr. John Christy suggests exactly the opposite. See this WUWT post from 2007, then read the Columbia story and decide for yourself.
From UAH: Irrigation most likely to blame for Central California warming
A two-year study of San Joaquin Valley nights found that summer nighttime low temperatures in six counties of California’s Central Valley climbed about 5.5 degrees Fahrenheit (approximately 3.0 C) between 1910 and 2003. The study’s results will be published in the “Journal of Climate.”
===========================================================
From Columbia: Irrigation’s Cooling Effects May Mask Warming–For Now
If Water Runs Short, Some Regions May Suffer Significantly
Expanded irrigation has made it possible to feed the world’s growing billions—and it may also temporarily be counteracting the effects of climate change in some regions, say scientists in a new study. But some major groundwater aquifers, a source of irrigation water, are projected to dry up in coming decades from continuing overuse, and when they do, people may face the double whammy of food shortages and higher temperatures. A new study in the Journal of Geophysical Research pinpoints where the trouble spots may be.
“Irrigation can have a significant cooling effect on regional temperatures, where people live,” said the study’s lead author, Michael Puma, a hydrologist who works jointly with Columbia University’s Earth Institute and its affiliated NASA Goddard Institute for Space Studies. “An important question for the future is what happens to the climate if the water goes dry and the cooling disappears? How much warming is being hidden by irrigation?”
Scientists generally agree that in the last century, humans have warmed the planet about .7 degrees C (about 1.3 degrees F) by pumping vast amounts of carbon dioxide into the air. How much warmer earth will get depends not only on future carbon emissions but an array of other variables. For instance, earth’s oceans and vegetation have been absorbing a growing share of emissions, but recent studies suggest this uptake may be slowing. This could lead to more carbon dioxide in the air, and accelerated warming. On the other hand, humans are also cooling the planet to some degree, by releasing air-polluting particles that lower temperatures by reflecting the sun’s energy back into space. Pumping of vast amounts of heat-absorbing water onto crops is lowering temperatures in some regions as well, say the authors.
Scientists are just beginning to get a handle on irrigation’s impact. In a hundred years, the amount of irrigated farmland has grown four-fold, now covering an area four times the size of Texas. Puma and his coauthor, Benjamin Cook, a climatologist at Goddard and Columbia’s Lamont-Doherty Earth Observatory, are the first to look at the historic effects of mass watering on climate globally by analyzing temperature, precipitation and irrigation trends in a series of model simulations for the last century. They found that irrigation-linked cooling grew noticeably in the 1950s as irrigation rates exploded, and that more rain is now falling downstream of these heavily watered regions.
In warm, dry regions, irrigation increases the amount of water available for plants to release into the air through a process called evapotranspiration. When the soil is wet, part of the sun’s energy is diverted from warming the soil to vaporizing its moisture, creating a cooling effect. The same process explains why drying off in the sun after a swim at the beach can be so refreshing.
Globally, irrigation’s effect on climate is small—one-tenth of one degree C (about 0.2 degree F). But regionally, the cooling can match or exceed the impacts of greenhouse gases, say the scientists. For example, the study found some of the largest effects in India’s arid Indus River Basin, where irrigation may be cooling the climate up to 3 degrees C, (5.4 degrees F) and up to 1-2 degrees C in other heavily irrigated regions such as California’s Central Valley and parts of China. The study also found as much as .5 degree C cooling in heavily watered regions of Europe, Asia and North America during the summer.
The study suggests also that irrigation may be shaping the climate in other ways, by adding up to a millimeter per day of extra rain downwind of irrigated areas in Europe and parts of Asia. It also suggests that irrigation may be altering the pattern of the Asian monsoon, the rains that feed nearly half of the world’s population. These findings are more uncertain, the authors caution, and will require further research.
“Most previous modeling studies were idealized experiments used to explore potential impacts, but this is a much more realistic simulation of the actual impacts,” said David Lobell, a Stanford University scientist who studies climate impacts on agriculture and was not involved in the study. “Their results show some interesting differences by time period and region that will lead to more research and contribute to more accurate simulations of future climate, particularly in agricultural areas.”
Irrigation has increased because it boosts crop yields, supporting many millions of small farmers, said Upmanu Lall, head of the Columbia Water Center at the Earth Institute. But concern is growing that groundwater supplies in India and China may not keep up. “Near term and future climate predictions are essential for anticipating climate shocks and improving food security,” he said. “The study points to the importance of including irrigation in regional and global climate models so that we can anticipate precipitation and temperature impacts, and better manage our land, water and food in stressed environments.”
=====================================================
NOTE: The scientific paper was not provided with the press release.
“But regionally, the cooling can match or exceed the impacts of greenhouse gases, say the scientists.”
What impacts?
Glen, their unlimited budgets. 🙁
Well its obvious that this will occur isn’t it ? Its basically the reverse of the UHI effect. Vegetation / water doesn’t hold heat as well as rocks / dry areas, thus cooling occurs.
Any idiot should be able to tell you that planting trees and irrigating dry areas, will cool them down. It should be obvious logic……..
I’ve got a real problem with the word masking.
As in “warming was masked by cooling”.
“Profits were masked by losses.”
Do they mean negated or countered or lessened?
There has been (according to this) 0.7°C warming in the past century.
The irrigation has “hid” 0.1°C of the warming.
Therefore there should have been 0.8°C of warming.
Thus, we can see what is the solution.
Build many large desalination plants. Use the water to increase the amount of irrigated farmland eight times or more. That will “hide” all of the warming. We’ll go above eight times to cover the CO2 emissions from the coal-fired power plants needed. They’ll be placed along the shores of the neediest areas, Africa etc, where more food, especially locally grown food, will do a lot of good. There will also be a carbon sink effect, at least for awhile, some in the increased foliage compared to what was before, some in proper farming techniques leading to richer, more carbonaceous soil.
The needy will be fed, the warming will be offset, the planet will be saved. Oh, and that pesky “population bomb” -type problem from a projected 9 billion humans needing to fed in the near future will be taken care of.
I now await certain greenies to proclaim this is wrong because we certainly do not need any more of the agri-industrial complex that invariably destroys the environment and sickens the planet, the only cure is to return to the peaceful
hunter-gatherer lifestyle of our ancient ancestors who lived in harmony with Mother Nature consuming only freely-available renewable resources… Whether they honestly word it that way or not.“In a hundred years, the amount of irrigated farmland has grown four-fold, now covering an area four times the size of Texas.”… “Globally, irrigation’s effect on climate is small—one-tenth of one degree C”
If the figures are global and correct, we are talking about an increase from 0.13% to 0.54% of Earth’s surface.
Large areas of wetlands have been drained over the same time period, presumably offsetting the claimed cooling effect. Wetland loss is hard to estimate but over the C20th may be around 10 million square kilometres, or ~0.2% of Earth’s surface.
Whatever the effect then, it is small. Christy’s report was focussing on the effect of irrigation on local temperature stations designated as rural. The effect of those on the temperature records is likely to be a lot larger than the effect of irrigation on actual global temperature.
Wet soil will release water by evaporation and cool the soil due to the heat required for that as latent heat. When this water condenses this latert heat is given up so if this happens near the surface then local air temperatures will increase slightly. It also takes wet air longer to cool than dry air that is why temperatures plummet at night in dry desert regions and your beach side holiday has balmy warm nights.
As a Brit I was telling a visitor from Finland who was complaining at how cold it seemed even though she had felt warmer at temps down to -20 oC at home.I told her that Britain was damp, in the summer it was hot and damp, in the winter it was cold and damp and if it was neither hot or cold it was just damp.
John says:
September 8, 2010 at 5:11 pm
…If you follow the link above back to the 2007 post on Christy’s study, you will see that Anthony did some analysis on Chico’s daily temps, and found — consistent with Christy — that nighttime temps were increasing for the last century. He also found — consistent with the new study — that daytime and daily average temps were decreasing with time, presumably as increased acreage became irrigated between 1900 and 2000…
There are too many other factors involved which make observing the small temperature differences seen as ‘evidence’ by both studies less than meaningful. Understanding micro-climates is very complex, as their interaction with the wider weather regime is dynamic with constant change to boundary conditions.
No firm conclusions can be made about climate impacts of these tiny changes until a better understanding of climate mechanisms is developed and more accurate observational data of much higher granularity is obtained.
More irrigation is a good place to start. Optimizing the total biosphere plant growth potential, is the goal we should be working toward as stewards of the planet, not the growth of wasteful government controls, or the manipulation of stocks and prices of commodities, or creating scare stories to lay the ground work for elitist control, resulting in the detriment of all life forms.
“LIFE forms are able to control the ionic and covalent bounds formed in the process of photosynthesis that binds energy into the making of compounds to build plant structure, that all other life forms digest to extract that energy of these covalent bonds to control all cellular functions.
Plants feed every thing else that lives!
In all cases where active building of compounds, from the basic constituents, are carried out in volume, there is a residual ionic charge carried out of the reaction area by electromagnetic conduction. In small single cell animals, their shapes are designed to most efficiently interface the internal EMF in a controlled way, to the external EMF that would modify or prevent the metabolism process, being conducted as needed by the animal to survive.
In large mammals and people there develops whole tuned structures that interface between organs like the liver that builds and disassembles glycogen for the storage of sugars.
The whole study of acupuncture, and the median lines of conduction woven through out the body is the result the study by those physically able to sense the EMF and coupling points on the skin surface, and at the same time understand the process of maintenance of the balance, phase, and polarity of total flux due to the whole continuum of life.
So that the median lines are the shared pathway of the EMF that is controllably shunted out of the chemical reaction to allow the flexible shifts in efficiency needed to prevent uncontrolled runaway feedback or disease processes that cause death.
Complex cells use semipermeable membranes, pores, vacuoles, and wall structure to do the bulk of the ion transfer related exchanges of the bulk materials. Homeostasis is an ever shifting balance between changing activity levels and internally regulated metabolic processes, and the outside chaos.
Rapid swings in temperature, humidity, Ph balance, gas content of the air, radiation levels that can, through the processes of ionization, inhibit or destroy the covalent bonds needed to maintain optimum health. Maintaining an enclosed dwelling with more environmental balance, so heat / cold related stress, oxidants external and internal and the virus and bacteria that are always trying for optimum cohabitation, are defended against.
All of these relationships are EMF in nature, and one should strive to be aware of their own inner balance and its relationship to the surrounding environment to maintain life energy levels close to optimum health.
Most plants and animals are aware of that and stay in tune with “the balance of nature” stress and other socially generated distractions prevent humans from moving with ease with in this sea of EMF we are constantly awash in. To ignore that this sea exists, and we are able to swim through it at will more easily by going with the shifts in the flows as they happen, only increases the level of disease one encounters.
To as a composite plant / animal biomass striving to maximum our total volume, it behooves us to be aware of how we can regulate our external environment, not just by avoidance of the problem areas, but by making changes in the background parameters that are outside of the optimum ranges for the whole biomass, not just in our dwellings.
If we do not understand how the weather is driven by ions, EMF, tidal effects, solar output, and the relationships between them, we will never learn the difference between what needs to be done, from what can be done to better optimize the global environment to maximize the health of the whole biomass.
So, if this study is right, not only will irrigation help agriculture, but it also cools the planet.
Doesn’t that suggest a rather useful way to counter global warming, if it indeed comes to pass?
Most farmers in all parts of the New World have seen major changes in local climates follow changes in land use and utilisation and understand the implications planting or removing forests, draining swamps and damming rivers, as examples, and have learnt much about the laws of unintended consequences as a result.
But the inhabitants of the old world of Europe and the UK live in landscapes that were modified aeons ago by the industries and farming practices of their forbears, but the changes to their environment are so far in the past that most are unaware of these processes and are highly resistant to any kind of visible change. I believe that this unawareness of historical change in land use is one of the sources of the Utopian silliness that comes from the Green lobby. I was amazed at the Government and Green responses to the serious flooding in the English Midlands a couple of years ago, when increassed rainfall due to alleged Man-made Global Warming was trumpeted as a cause for the flooding; anyone who pointed out that generations of covering flood plains with buildings, concrete and ashphalt was quite a dangerous thing to do was derided as a simpleton or an ignoramus.
I learnt in high school geography classes during the mid 1950s that large urban conurbations create their own warmer and wetter climate; has anything changed, apart from an increase in gullibility?
To tallbloke (1:02 am): Good point about draining of wetlands. A study which says that irrigation has caused 0.1% of warming to be blunted by increasing available moisture isn’t telling the complete story unless it also includes warming increases due to draining of wetlands. Roger Pielke Sr. gave a talk last spring where his group found that central Florida is about 2 degrees warmer than a century ago due to draining of the Everglades.
To Tenuc (2:12 am): I agree with your point that at the micro-climate level, there are too many things going on to draw conclusions based on only one parameter, in this case increasing irrigation.
But I wasn’t addressing whether the temperature trends identified by the two studies, and confirmed by Anthony in Chico, were caused by the one parameter, irrigation.
I was pointing out that there doesn’t actually seem to be a contradiction between the 2007 Christy et al work (which showed increased nighttime warming) and the new study (which shows increased daytime cooling). In fact, as in the 8:22 post above, Christy actually says that the daytime temps cooled, even as the nighttime temps warmed:
“While nighttime temperatures have risen, there has been no change in summer nighttime temperatures in the adjacent Sierra Nevada mountains. Summer daytime temperatures in the six county area have actually cooled slightly since 1910. Those discrepancies, says Christy, might best be explained by looking at the effects of widespread irrigation.”
That is from the 2007 presser you can access from the link above. So both studies agree on more daytime cooling the last century. No disagreement. And that was the only point I was addressing, that I didn’t see where the studies disagreed.
Well, at least we got this out of it:
Scientists generally agree that in the last century, humans have warmed the planet about .7 degrees C (about 1.3 degrees F) by pumping vast amounts of carbon dioxide into the air.
Lat year, before Climategate, that would have been “Scientists overwhelmingly agree…” After all, way back then the science was settled, there was no debate, there was an overwhelming unprecedented peer-reviewed consensus that was historic in magnitude.
And now it’s now.
Here are some basic humid-air physical processes described Follow the link to psychrometrics, etc to see why evaporation occurs and removes heat; and moisture condenses on surfaces.
It’s far from a complete picture of the cyclonic processes because one has to take into account that there are changes in energy due to altitude and that the system is open; able to draw in e.g. less-humid air from around the storm, leading to further surface evaporation.
Processes are non-linear; often constrained by specific boundary conditions that are essentially unknowable. One can try to model them by making lots of assumptions, but other than a blurred picture, precise predictions are impossible. One can gain much more insight by pen on paper, procrastination, argument and watching the skies, seas and the land; than one can by diverting efforts into models that require very expensive computers and ending up naively obsessing about modelling artifacts.
This is all old hat. Irrigation tends to reduce temperature extremes, drainage to increase them, and more vegetation to reduce them. But unless the albedo changes quite a lot there’s not usually much effect on average temperatures.
Douglas DC says:
September 8, 2010 at 6:18 pm
Pamela Gray- exactly, well put…. Now we have “Hay Duke” Kitzhaber D-Retread
runnning for Oregon Governor, who wants to kill that flood control on the Snake, by blowing up the Snake River Dams.
The Grande Ronde and Wallowa Valleys will be covered with wind machines,
no people, or animals, imho, but that is what the appear to want…
________________________________________________________
Yes that is exactly what they want they almost got it through the US Congress in one lump too (now they are implementing it peice by piece, they have not given up, just changed the name and toned down the message. (new improved version: http://www.twp.org/)
In this map from the original version people are allowed free access to the green areas only: http://www.propertyrightsresearch.org/images/wildlands_map.jpg
Map Courtsey of: http://www.propertyrightsresearch.org/articles2/wildlands_project_and_un_convent.htm
Information about the “wild lands/ bio diversity” bill HR 652 – To make the Wildlands Project into official government policy – the politically correct name is National Forest Ecosystem Protection Program. http://www.klamathbucketbrigade.org/YNTKwildlandsproject_table.htm
Hi
Water content in air naturally cools it, as water requires some 4000 times more energy to warm when compared same mass of air. So when water adds mass of air, as result temperature stays lower. On the otherhand water buffers also freezing, because freezing of water requires also more cold when compared to dry air.
Maybe the most important point however is the different nature of forest and swamp land when compared to crop land. As temperature is measured 2 metres above surfce of the earth, forest and swamp land are in nature cooler than cropland. This landscape change definitely must be taken into account when doing this type of research, otherwise it is nul reaserch.
MarkkuP
Anecdotally – I am not sure if it is the irrigation or the fact you have living plants. But traveling along I8 in Imperial valley, there is a marked difference in termperature between the bare desert and the space between the canals.
The only way irrigation can only be a problem is when people first have absolutely gone overboard with drainage to boot. If you drainage too much you need to irrigate too much to saturate the ground enough and keep it saturated, and this is even disregarding the clogging factor. If you instead drainage smart you don’t need to irrigate that much in the first place, but you still have enough drainage to take care of most natural precipitation problems. There’s a whole friggin universe of problems that arise when your ground goes bone dry six feet down.
Well, this is typical of model-induced CAGW. GIGO, it depends upon the model, assumptions and what the researchers want to prove. For example:
Model Diagnosis of Nighttime Minimum Temperature Warming during Summer due to Irrigation in the California Central Valley
Hideki Kanamaru and Masao Kanamitsu
Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California Abstract
This study examines the mechanisms of nighttime minimum temperature warming in the California Central Valley during summer due to irrigation. The Scripps Experimental Climate Prediction Center (ECPC) Regional Spectral Model (RSM) was used to simulate climate under two land surface characteristics: potential natural vegetation and modern land use that includes irrigation and urbanization. In irrigated cropland, soil moisture was prescribed in three different ways: 1) field capacity, 2) half of field capacity, and 3) no addition of water. In the most realistic case of half-field capacity, the July daily minimum temperature in the California Central Valley increased by 3.5°C, in agreement with station observation trends over the past century in the same area. It was found that ground heat flux efficiently keeps the surface warm during nighttime due to increased thermal conductivity of wet soil.
Here’s another paper (I forgot to cut and paste the Title, sorry), and another model output:
As discussed for a very similar model run in Kueppers
et al. (2007), the 1996 model results replicate quite
well many aspects of the Climate Research Unit (CRU)
0.5° × 0.5° gridded observations, which are derived from
surface station data (Mitchell and Jones, 2005). However,
the model has slightly greater, and more variable,
precipitation. The spatial patterns of the model and CRU
winter and summer near surface temperature and specific
humidity are very similar. However, the model has a cold
bias of about −3 °C and also a dry bias of about 15% of
the mean specific humidity. The biases for this domain
are similar in magnitude to those in three other models
(Kueppers et al., 2007). Preliminary investigations suggest
that these biases are related to the fact that the model
has persistent high thin clouds that reduces incoming
solar radiation at the surface forcing an artificially low
land skin temperature.
Colder days, warmer nights, thin clouds, lions, n tigers, n bears, oh my. A non-falsifiable hypothesis with multiple contradictory effects can be so confusing.
I grew up in a small farm town in the SJV and many of the farms that were there in my youth are now developments. UHI should also be taken into consideration when trying to figure out where the heat is coming from. It’s a hell hole in the summer that’s for sure.
Spot on Pamela.
I recall that the Columbia River froze every winter where it flows through Wenatchee, Chelan County, WA. Winter fog in Wenatchee was rare. Then two dams were built, one up river from Wenatchee (Rocky Reach) and the other downriver (Rock Island). Since then the rive no longer freezes and winter fog is common, enough to limit commercial air service to the area.
The dams that supply water irrigation to the Columbia River Basin influence seasonal weather far more the summer irrigation.
This appears to be another justification to shut down irrigation in central CA, as the current assault on farming has been conducted by the feds and greens using the delta smelt as the vehicle.
They continue to throw stuff against the wall while hoping that something – anything sticks. And they are doing it all on our tax dollar. Time to defund the left.
These two studies point to the heart of the global warming debate… real world data analysis versus cyber world theory manipulation. Do note Columbia’s computer analysis is over-generalized. The lead author says, “Irrigation can have a significant cooling effect on regular temperature.” “How much warming is being hidden by irrigation?”
John, I realize this is only an excerpt but irrigation warming is not mentioned.
Christy’s work looks at the world from the bottom up and uncovers two inconsistencies that the models do not see…boundary mountains responding differently from the valley and irrigation producing warming as well as cooling.
Columbia’s top down approach sees warming being hidden by irrigation cooling (well mixed carbon dioxide theory lingers in the background).