From the EGU:
Heavy rainfall events can be more common in a warmer world (Credit: Annett Junginger, distributed via imaggeo.egu.eu)
Reducing the amount of sunlight reaching the planet’s surface by geoengineering may not undo climate change after all. Two German researchers used a simple energy balance analysis to explain how the Earth’s water cycle responds differently to heating by sunlight than it does to warming due to a stronger atmospheric greenhouse effect. Further, they show that this difference implies that reflecting sunlight to reduce temperatures may have unwanted effects on the Earth’s rainfall patterns. The results are now published in Earth System Dynamics, an open access journal of the European Geosciences Union (EGU).
Global warming alters the Earth’s water cycle since more water evaporates to the air as temperatures increase. Increased evaporation can dry out some regions while, at the same time, result in more rain falling in other areas due to the excess moisture in the atmosphere. The more water evaporates per degree of warming, the stronger the influence of increasing temperature on the water cycle. But the new study shows the water cycle does not react the same way to different types of warming.
Axel Kleidon and Maik Renner of the Max Planck Institute for Biogeochemistry in Jena, Germany, used a simple energy balance model to determine how sensitive the water cycle is to an increase in surface temperature due to a stronger greenhouse effect and to an increase in solar radiation. They predicted the response of the water cycle for the two cases and found that, in the former, evaporation increases by 2% per degree of warming while in the latter this number reaches 3%. This prediction confirmed results of much more complex climate models.
“These different responses to surface heating are easy to explain,” says Kleidon, who uses a pot on the kitchen stove as an analogy. “The temperature in the pot is increased by putting on a lid or by turning up the heat – but these two cases differ by how much energy flows through the pot,” he says. A stronger greenhouse effect puts a thicker ‘lid’ over the Earth’s surface but, if there is no additional sunlight (if we don’t turn up the heat on the stove), extra evaporation takes place solely due to the increase in temperature. Turning up the heat by increasing solar radiation, on the other hand, enhances the energy flow through the Earth’s surface because of the need to balance the greater energy input with stronger cooling fluxes from the surface. As a result, there is more evaporation and a stronger effect on the water cycle.
In the new Earth System Dynamics study the authors also show how these findings can have profound consequences for geoengineering. Many geoengineering approaches aim to reduce global warming by reducing the amount of sunlight reaching the Earth’s surface (or, in the pot analogy, reduce the heat from the stove). But when Kleidon and Renner applied their results to such a geoengineering scenario, they found out that simultaneous changes in the water cycle and the atmosphere cannot be compensated for at the same time. Therefore, reflecting sunlight by geoengineering is unlikely to restore the planet’s original climate.
“It’s like putting a lid on the pot and turning down the heat at the same time,” explains Kleidon. “While in the kitchen you can reduce your energy bill by doing so, in the Earth system this slows down the water cycle with wide-ranging potential consequences,” he says.
Kleidon and Renner’s insight comes from looking at the processes that heat and cool the Earth’s surface and how they change when the surface warms. Evaporation from the surface plays a key role, but the researchers also took into account how the evaporated water is transported into the atmosphere. They combined simple energy balance considerations with a physical assumption for the way water vapour is transported, and separated the contributions of surface heating from solar radiation and from increased greenhouse gases in the atmosphere to obtain the two sensitivities. One of the referees for the paper commented: “it is a stunning result that such a simple analysis yields the same results as the climate models.”
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Please mention the name of the publication (Earth System Dynamics) if reporting on this story and, if reporting online, include a link to the paper (http://www.earth-syst-dynam.net/4/455/2013/esd-4-455-2013.html) or to the journal website (http://www.earth-system-dynamics.net).
More information
This release is based on materials provided by the Max Planck Institute for Biogeochemistry.
This research is presented in the paper ‘A simple explanation for the sensitivity of the hydrologic cycle to surface temperature and solar radiation and its implications for global climate change’ published in the EGU open access journal Earth System Dynamics on 05 December 2013.
Full citation: Kleidon, A. and Renner, M.: A simple explanation for the sensitivity of the hydrologic cycle to surface temperature and solar radiation and its implications for global climate change, Earth Syst. Dynam., 4, 455-465, doi:10.5194/esd-4-455-2013, 2013.
What type of climate are they trying to create?……for instance empirical data from the last six Holocene’s including our own have a variety of temps and climate changes. Do they want the one that was 5C warmer than today?…..or the Maunder Minimum?
Or shall we keep the public guessing with the climate of around 12,000 years ago…when emerging from an Ice Age the temperature rose by 10C in thee years?
Ego-engineering however is what a lot of climate-scientists on the warming side really prefer, and practise with great succes. But pride comes before fall. The current natural cooling will show their true colors.
Right. Let’s put a “sunshade” over Canada/Siberia right now. We could reduce temps from -20F to -30F.
There. Globull warming solved.
It is fascinating to see how the climate hypesters turn, “It may rain more”- a good thing- into “heavy rainfall events may become more common”. It is similar to how every weather event reported is generally framed as a “storm”. Push that fear.
Gene L asks: ” “does CO2 have any effect at all?””
Answer: yes on warm cloudy summer days. No on cold clear winter nights
Re: sailor1031 says @ur momisugly 6:01 am
“does CO2 have any effect at all?””
“Answer: yes on warm cloudy summer days. No on cold clear winter nights”</b?
Shouldn't that be the way around?
IMHO,…their alphabet soup is missing a few letters.
The soup isn’t even stirred it’s “steady state”
Thanks for the interesting articles and comments.
Is it time for all of us, rational people, to shift our attention from failed team of IPCC, Mann, Hansen, and Schmidt to the team of geoengineers? Unlike former, this team has real and large funding and significant academic and political influence.
http://thinkprogress.org/climate/2012/04/15/462803/caldeira-only-ethical-path-is-to-stop-using-the-atmosphere-as-a-waste-dump-for-greenhouse-gas-pollution/
http://www.geoengineeringwatch.org/ken-caldeira-leading-scientist-in-geo-engineering-technology-is-he-willing-to-kill-you/
According to the IPCC they are already Geoengineering, they call it ‘solar radiation management’ and they are warning policymakers not to stop.
“If SRM were terminated for any reason, there is high confidence that global surface temperatures would rise very rapidly to values consistent with the greenhouse gas forcing.”
http://www.globalresearch.ca/solar-radiation-management-geoengineering-and-chemtrails/5356632
[Please do not discuss chemtrails here, per site Policy. — mod.]
@Steve Case: my experience of clear winter nights in Labrador was that there was no detectable CO2 warming (or much other kind of warming). On the other hand on muggy summer days here in Virginia the warming effect of CO2 is quite pronounced. Just anecdotal observation.
“… used a simple energy balance model to determine how sensitive the water cycle is to an increase in surface temperature due to a stronger greenhouse effect and to an increase in solar radiation…”
“A stronger greenhouse effect puts a thicker ‘lid’ over the Earth’s surface but, if there is no additional sunlight (if we don’t turn up the heat on the stove), extra evaporation takes place solely due to the increase in temperature.”
Hmm…. this looks like an introduction to the Thermostat Hypothesis of Willis Eschenbach. They just didn’t follow through with……which leads to the formation of clouds as the opening act of the heat engine heat remover.
It seems to me that there is too little emphasis on some of the fundamental problems with Kleidon & Renner. Kudos to ilearnedthatinhighschool for challenging the assumption of “original climate” and jorgekafkazar for hinting at the use of models. Sorry to others not specifically mentioned that elaborated on those, but I didn’t want to start a huge list.
It should be fundamentally obvious that this paper uses “simple analysis” and “climate models” to “prove” something which is also the fundamental problem with much of the alarmist rhetoric. There can be no real proof of the assertions with simple analysis or climate models. Neither accounts for the real case of real changes that are experienced here on Earth. The only way they could validly prove that one forcing does one thing where a different forcing does another would be to take historical climate data from Earth and control it for other factors not related to the examined forcings (which we should all know is impossible, but they’re the ones claiming they have that level of knowledge to produce their models and make the predictions that they are) and show how each forcing historically changed the climate. That way, the only thing that could be disputed would be the accuracy of the historical data used and the methods of controlling for other factors. I acknowledge that even those elements of dispute yield considerable latitude, but Kleidon & Renner do not even go that far into research and instead just rely on over-simplified guesswork and fantastical models.
If I make a program that counts from two to 200 by twos and then note the lack of odd numbers, I have not discovered anything! I have simply revealed my previous biases. While the analogy is crude, it is reasonably parallel.
I think this is a case of embracing shoddy work because it supports previous bias. Please do not misunderstand. I agree with direction of this blog (which is really too diminutive a label for such a trove of information), but we should, in the interest of fairness and objectivity, be able to identify and indicate to others when a paper is more of the same meaningless hypothetical that is all too common in climate “science” these days even if that means debunking a paper that may buoy a sympathetic argument.
Just as many have indicated in numerous other articles on this blog and in comments how so much of the body of climate research papers is nothing more than dressed-up conjecture, this research paper is likewise. Being that as the case, there is nothing to be gained from any conclusions made from false premises even if it supports our skepticism.
Thanks.
I’m disappointed. I was hoping we could geoengineer by adding CO2 to thermally enrich the Earth and stave off the next ice age.