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Solar Cycle Linked to Global Climate
18 July 2009
Establishing a key link between the solar cycle and global climate, research led by scientists at the National Science Foundation (NSF)-funded National Center for Atmospheric Research (NCAR) in Boulder, Colo., shows that maximum solar activity and its aftermath have impacts on Earth that resemble La Niña and El Niño events in the tropical Pacific Ocean.
The research may pave the way toward predictions of temperature and precipitation patterns at certain times during the approximately 11-year solar cycle.
These results are striking in that they point to a scientifically feasible series of events that link the 11-year solar cycle with ENSO, the tropical Pacific phenomenon that so strongly influences climate variability around the world. The next step is to confirm or dispute these intriguing model results with observational data analyses and targeted new observations.
—Jay Fein, program director in NSF’s Division of Atmospheric Sciences
The total energy reaching Earth from the sun varies by only 0.1% across the solar cycle. Scientists have sought for decades to link these ups and downs to natural weather and climate variations and distinguish their subtle effects from the larger pattern of human-caused global warming.
Building on previous work, the NCAR researchers used computer models of global climate and more than a century of ocean temperature to answer longstanding questions about the connection between solar activity and global climate.
The research, published this month in a paper in the Journal of Climate, was funded by NSF, NCAR’s sponsor, and by the US Department of Energy.
We have fleshed out the effects of a new mechanism to understand what happens in the tropical Pacific when there is a maximum of solar activity. When the sun’s output peaks, it has far-ranging and often subtle impacts on tropical precipitation and on weather systems around much of the world.
—NCAR scientist Gerald Meehl, lead author
The new paper, along with an earlier one by Meehl and colleagues, shows that as the sun reaches maximum activity, it heats cloud-free parts of the Pacific Ocean enough to increase evaporation, intensify tropical rainfall and the trade winds, and cool the eastern tropical Pacific.
The result of this chain of events is similar to a La Niña event, although the cooling of about 1-2 degrees Fahrenheit is focused further east and is only about half as strong as for a typical La Niña.
Over the following year or two, the La Niña-like pattern triggered by the solar maximum tends to evolve into an El Niño-like pattern, as slow-moving currents replace the cool water over the eastern tropical Pacific with warmer-than-usual water. Again, the ocean response is only about half as strong as with El Niño.
True La Niña and El Niño events are associated with changes in the temperatures of surface waters of the eastern Pacific Ocean. They can affect weather patterns worldwide.
The paper does not analyze the weather impacts of the solar-driven events. But Meehl and his co-author, Julie Arblaster of both NCAR and the Australian Bureau of Meteorology, found that the solar-driven La Niña tends to cause relatively warm and dry conditions across parts of western North America.
More research will be needed to determine the additional impacts of these events on weather across the world.
Building on our understanding of the solar cycle, we may be able to connect its influences with weather probabilities in a way that can feed into longer-term predictions, a decade at a time.
—Gerald Meehl
Scientists have known for years that long-term solar variations affect certain weather patterns, including droughts and regional temperatures. However, establishing a physical connection between the decadal solar cycle and global climate patterns has proven elusive.
One reason is that only in recent years have computer models been able to realistically simulate the processes associated with tropical Pacific warming and cooling associated with El Niño and La Niña. With those models now in hand, scientists can reproduce the last century’s solar behavior and see how it affects the Pacific.
To tease out these sometimes subtle connections between the sun and Earth, Meehl and his colleagues analyzed sea surface temperatures from 1890 to 2006. They then used two computer models based at NCAR to simulate the response of the oceans to changes in solar output.
They found that, as the sun’s output reaches a peak, the small amount of extra sunshine over several years causes a slight increase in local atmospheric heating, especially across parts of the tropical and subtropical Pacific where Sun-blocking clouds are normally scarce.
That small amount of extra heat leads to more evaporation, producing extra water vapor. In turn, the moisture is carried by trade winds to the normally rainy areas of the western tropical Pacific, fueling heavier rains.
As this climatic loop intensifies, the trade winds strengthen. That keeps the eastern Pacific even cooler and drier than usual, producing La Niña-like conditions.
Although this Pacific pattern is produced by the solar maximum, the authors found that its switch to an El Niño-like state is likely triggered by the same kind of processes that normally lead from La Niña to El Niño.
The transition starts when the changes of the strength of the trade winds produce slow-moving off-equatorial pulses known as Rossby waves in the upper ocean, which take about a year to travel back west across the Pacific. The energy then reflects from the western boundary of the tropical Pacific and ricochets eastward along the equator, deepening the upper layer of water and warming the ocean surface.
As a result, the Pacific experiences an El Niño-like event about two years after solar maximum. The event settles down after about a year, and the system returns to a neutral state.
El Niño and La Niña seem to have their own separate mechanisms, but the solar maximum can come along and tilt the probabilities toward a weak La Niña. If the system was heading toward a La Niña anyway, it would presumably be a larger one.
—Gerald Meehl
Resources
Gerald A. Meehl and Julie M. Arblaster (2009) A Lagged Warm Event–Like Response to Peaks in Solar Forcing in the Pacific Region. Journal of Climate 22 (13) doi: 10.1175/2009JCLI2619.1
July 18, 2009 in Brief | Permalink | Comments (10) | TrackBack (0)
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Presumably as more blinders fall away we will see more studies of this nature describing the influence of the sun on Earth's climate cycles. This is not to mention what may lay ahead with Svensmark's work and the CLOUD09 experiments getting underway at CERN.
http://cdsweb.cern.ch/record/1181073/
This study, the recent PETM study, the Danish National Space Center cosmoclimatology publications, and the CERN efforts all indicate a growing acceptance of climate forcings other than GHG.
http://spacecenter.dk/research/sun-climate/cosmoclimatology/a-brief-summary-on-cosmoclimatology
Posted by: sulleny | July 18, 2009 at 09:19 AM
Yes, some of the worst summers have been linked to peak solar activities such as solar storm, sunspot, etc.. I
Increase in solar output can also lead to earth warming and vice versa...But, there ain't nothing that we earthlings can do about the sun! It's a million times the size of the earth! It is so unfair, isn't it?
All that we can collectively do now is to drastically reduce GHG in order to prevent run-away global warming. That is within our collective power to change. The GHG effect is very powerful and can do a lot to manipulate earth's temperature. That's the thermostat that we can use to regulate our climate and to prevent catastrophe.
Posted by: Roger Pham | July 18, 2009 at 05:55 PM
I must have missed something. In a massively complex and interacting system like the climate, no one sensible has been saying the sun doesn't matter. No one says it doesn't force climate. There was, and is, no conspiracy.
As Roger Pham points out, given you get massive climate effects from small changes in solar insolation (like El Nino) then large amounts of carbon dioxide induced forcing can't be good. Oh, and for good measure,CO2 from our 50,000 coal fired power stations is rapidly acidifying the oceans and changing conditions for life on 70% of the planet.
Posted by: SVW | July 18, 2009 at 07:29 PM
"CO2 from our 50,000 coal fired power stations is rapidly acidifying the oceans and changing conditions for life on 70% of the planet."
Your reference for this is?
Posted by: sulleny | July 18, 2009 at 11:09 PM
Unhappy Day! Where once the character known to GCC readers was "Roger Pham" - we now have a poor imitation. Dare we say fake? You see, in the old days Roger used to make informed comments about engineering matters, including arguments why an H2 economy was not unreasonable.
Alas. Today we have a mere shell of the character. What with statements such as: "the sun! It's a million times the size of the earth! It is so unfair, isn't it?"
While this sounds daunting and might cause some to tremble - grade school astronomers know that the sun's diameter is only 109 times the Earth's diameter. Even on a mass scale the Sun is 330,000 times Earth's mass. But hey, when it comes to global warming, hyperbole is the descriptor of choice.
Roger, quit the circus and come back to reason!
Posted by: Reel$$ | July 19, 2009 at 09:46 AM
Hi, Reel$$
109 x the linear dimension of the earth. 109^3 (cubed) equals to: 1,295,209 times the volume of the earth. Of course, since the sun is mostly hydrogen and helium, it has much lower density than the earth, the latter having a core of iron and nickel, therefore, the density of the sun is, as you mentioned, 330,000 times the earth's mass (as if that is not big enough!).
I hope that dealing astronomical dimensions will help keep us humble...how fragile and insignificant we are in this whole universe...and that we must be careful in what we do to the Earth, for it is our only life-supporting system in the inhospitable harshness of space, with extremes of temperatures, cosmic radiation, and lack of Oxygen...In the last 4.5 billion years history of the Earth, human lives have been but a blink of an eye in geological time frame...too complex to be probable...whereas simple bacteria have been around for billions of years...If we are not careful, our very complexity will be the seed of our destruction...whereas the bacteria have much faster reproduction rates and mutation rates, are infinitely more adaptable than we are.
While the rate of human evolution will be far slower than that of the bacterium, what keep human adaptable is our brain function, which models after natural evolutionary pattern of natural selection...in that...good ideas got selected and propagated while bad ideas will get discarded...gradually, our inventions and our concept of nature and our understanding of nature get perfected, just like the ICE got perfected over the last 100 years.
Let's remain humble and open our mind to new ideas and concepts...and continue to learn and reject inconsistent thought processes.
Posted by: Roger Pham | July 19, 2009 at 10:05 AM
He's back! Thank you (reel) Roger for once again illuminating these pages with cogent remarks that edify. Your comment on humility noted. Thank you.
Back to engineering: what is your reaction to distributed energy in the form of methane (NG) driven CHP in residences? In particular comparison of electromechanical devices (ICE, Stirling) vs. solid state SOFC or PEM as the generating source?
Posted by: Reel$$ | July 19, 2009 at 12:13 PM
Thank you, Reel$$.
T
he theoretical efficiency of CHP is around 80%-90%, which is great. Practically, however, there are several problems that prevent mass adoption of CHP in residences (personal homes).
Proper maintenance of these small units is an additional burden that a typical consumer may not be able to keep up with. Even with proper maintenance, the replacement cost of components and overhaul cost will negate much of the savings from utility bill.
Fuel cells have advantages over ICE in that these units usually requires less maintenance, quieter and without emission, but FC are more expensive at the present.
Then, we will have the problem of what to do with waste heat of these CHP units in seasons that space heating is not needed. In the summer, arguably, an adsorptive chiller using waste heat at ~90 degrees C can be used for space cooling. These adsorptive chillers have COP of about .7 to .9, not particularly efficient for single stage, so, a rather large CHP with a lot of electricity to sell will be need to cool a decent house. The overall cost-effectiveness and durability of these adsorptive chillers are not well known since they are produced in such small numbers at the present. Warmer regions do not need much heat in the winter, but a lot of cooling in the summer, whereas cold climates needs a lot of heat in the winter but little cooling in the summer...so balancing these can also be issues.
The best bet now is investment in "Negawatts", or energy efficiency...keep your home real energy efficient...learn to adapt yourself to the weather (set house temp cooler in the winter and warmer in the summer), better insulation...planting trees around the house...etc. will pay off great dividend.
Posted by: Roger Pham | July 19, 2009 at 02:40 PM
sulleny, happy reading:
http://www.ipcc.ch/publications_and_data/publications_ipcc_fourth_assessment_report_synthesis_report.htm
Posted by: Anne | July 20, 2009 at 04:08 AM
It makes no sense to use domestic cogen systems for cooling. If you have a cogenerator with a thermal efficiency of 20% and an absorption system with a CoP of 0.6 and a compression-cycle A/C at a CoP of 4, your net CoP is (0.2*4+0.8*0.6)=1.28. If you fed the same fuel to a combined-cycle powerplant at 60% and ran the compression A/C with it, your total CoP is 2.4: nearly twice as great.
It does make sense to use absorption systems if you are starting with heat instead of fuel, e.g. the output of evacuated-tube solar collectors. Such a system could provide space heat in winter, absorption A/C in summer and DHW year round.
Posted by: Engineer-Poet | July 22, 2009 at 09:22 PM