SOLAR SURPRISE: In the most recent solar cycle, the sun put out more visible light than anticipated by scientists, exacerbating global warming.
Image: Courtesy of NASA / Solar Dynamics Observatory
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The sun controls Earth's climate, bathing us in light ranging from ultraviolet to visible that warms the planet and drives the heat engines we know as weather systems and ocean currents. The sun is changeable, cycling from maximum to minimum outputs over a roughly 11-year cycle, increasing or decreasing the amount of light that reaches Earth as a result of the poorly understood aspects of the sun's seething nuclear fusion. Now new satellite measurements reveal that from 2004 to 2007—the declining phase of an unusually low and prolonged solar minimum—the sun put out even less ultraviolet light than expected but compensated by putting out more visible light.
"The amount of visible radiation entering the lower atmosphere was increasing, which implies warming at the surface," says atmospheric physicist Joanna Haigh of Imperial College London, who led the research, published in Nature on October 7. (Scientific American is part of Nature Publishing Group.) "The solar radiative forcing of climate increased by 0.1 [watt per square meter]." That means the sun, at least for those three years, played a larger role in ongoing climate change than previously thought.
Global climate change—average temperatures have risen by roughly 0.6 degree Celsius since the beginning of the 20th century—is caused by greenhouse gases in the atmosphere. These gases, chief among them carbon dioxide (CO2), act as a blanket, trapping the sun's heat that would otherwise be radiated back into space. Rising greenhouse gas levels in the atmosphere means rising average temperatures for the planet, causing climate change.
But the change from 2004 to 2007 in the sun's output of visible light, and the attendant warming at Earth's surface of 0.1 watt per square meter, is roughly equivalent to the overall forcing of the sun on the climate over the past 25 years—estimated by the U.N. Intergovernmental Panel on Climate Change to be an additional 0.12 watt per square meter. That suggests scientists may have overestimated the sun's role in climate change.
Regardless, the solar change is dwarfed by the impact from the extra heat trapped by CO2 alone since 1750: an additional 1.66 watts per square meter, an effect that other greenhouse gases, such as methane, strengthen further. In other words, whereas the new satellite measurements call into question computer models of solar output, it does not change the fundamental physics of human-induced global warming.
Still, the finding suggests that scientists' understanding of solar cycles and their impact on climate needs more work. "The result reverses understanding of solar cycle climate effects," which had been that the sun generally warms the climate on the way up from minimum to maximum and generally cools the climate on the way down from maximum to minimum, explains atmospheric scientist Piers Forster of the University of Leeds in England. "But the opposite seems to have been true of the last solar cycle."
In addition, the larger than expected loss of UV light meant less stratospheric ozone up to 45 kilometers above the surface, but more above that line. That distinguishes this solar cycle from the preceding two and "suggests that the declining phase of solar cycle 23 is behaving differently to previous solar cycles," the team wrote.
Of course, solar irradiance measurements from just three years of one solar cycle cannot be applied to any other period than the one measured by the Spectral Irradiance Monitor on NASA's Solar Radiation and Climate Experiment (SORCE) satellite. "We cannot extrapolate to a 250-year period," Haigh says. "While this increase is similar to that produced by greenhouse gases, it may well turn round with the 11-year cycle so it can't be used to imply any long-term forcing."
In fact, the solar minimum for the last cycle was reached in 2009, and the sun's activity has picked up in the intervening months. It remains to be seen if that will bring a decline in the sun's output of visible light—and therefore a decline in the sun's contribution to a warming climate during this upward part of the present solar cycle. The sun "was thought to be having a cooling effect over the last few years," Forster notes, a thought now shown likely to be mistaken. "Perhaps the sun has been trying to warm the Earth after all."
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31 Comments
Add CommentThis article's analysis seems to presume that the effects of Solar activity should be immediately imparted on the Earth, producing immediately corresponding climate change. It seems to me that the Earth contains a great deal of material mass that may take some time to respond to varying heating conditions.
Reply | Report Abuse | Link to thisAt least some analysis should be performed to determine if reduced thermal energy from the Sun produces climatic cooling at some later (lag) time.
I'm sure these brilliant scientists already considered this simple possibility and know all about it and who am I to make such a stupid suggestion to these experts who know all about it, but it wouldn't hurt to ask them, would it? I'm sure I just don't understand, but thanks in advance for the expert consideration.
Science is based on reason and facts. It is frustrating to have emotional text with out content or reason. Please keep politics in another venue. Thanks gibby.
Reply | Report Abuse | Link to thisFor my part, the study is excellent, and well reported. It puts solar climate effect in good perspective.
I've been telling my friends for ten years or more that the sun feels hotter than when I was young. Am I the canary in the coal mine? Maybe it's just that I'm older and more sensitive now. Those red bumps on my arms might indicate that. More sunblock please!
Reply | Report Abuse | Link to thisWhat stupid science.
Reply | Report Abuse | Link to thisSo now less solar energy is causing more global warming.
The prolem with this study is the first line. It assumes that the solar insolation is te only sources of energy into the planet.
What about gravity? Doesn't gravity cause the Earth rotation? How about Gravity causing tidal effect?
Then there is garavitational potential energy. When the Earth gets further away fro the Sun or Jupiter doesn't it build up potential energy, which then gets released back as kinetic energy as the Earth "falls" back closer to the gravity source.
See Gravity cause CLimate Change" at www.scribd.com for more info.
If you read this article you probably decided to fill in a questionnaire asking about your point of view regarding carbon sequestration.
Reply | Report Abuse | Link to thisIf you didn't noticed, the questionnaire was 'surprisingly' sponsored by shell!
Carbon sequestration is an unproved, dangerous idea that has been defended by oil and carbon companies to make governments invest in research instead of in green proven technologies just so they can keep on doing what they've always had.
Please get informed and when you get to answer questions, know who is asking them and with which purpose!
Shell is probably more capable and, sorry to say, less prejudicial than our own government in taking such a survey. Those who disagree with the results choose to attack the surveyor rather than accept the fact that Americans still question the human effect on global warming and the government solution.
Reply | Report Abuse | Link to thisThe questions were asked and answered.
not one cogent comment on the article , the article states that dureing a solar minumum earth receved more energy than was expected and that no one is sure why , this has nothing to do with politics or human caused warming ,which is real by the way .
Reply | Report Abuse | Link to thisThe sun must play a role in global warming. We played no part in the interglacial warming period we are now in, nor did we play a role in the past ice ages. The Pleistocene Epoch started about 1.6 million years ago and is the most recent global ice age. There has been 4 or 5 interglacial periods during this time each lasting about 20 to 30 thousand years. We are about 18,000 years into this one and it stalled a time or two after it started. The mini ice age was just a hiccough in this interglacial period.
Reply | Report Abuse | Link to thisI suspect the sun goes through periods of "helium digestion" following tens of thousands of years consumption of hydrogen. Helium probably accumulates in the core until it interferes with the solar furnace, then has to be re-distributed resulting in "turbulent" times for the sun causing the interglacial periods. Once it is re-distributed, the sun quiets down resulting in another ice age.
Right - I don't think the Sun's role in determining the highly variable climate of the Earth even in the absence of humanity can be argued.
Reply | Report Abuse | Link to thisThe Nature Letter describing this research at least contains a free abstract:
"The thermal structure and composition of the atmosphere is determined fundamentally by the incoming solar irradiance. Radiation at ultraviolet wavelengths dissociates atmospheric molecules, initiating chains of chemical reactions—specifically those producing stratospheric ozone—and providing the major source of heating for the middle atmosphere, while radiation at visible and near-infrared wavelengths mainly reaches and warms the lower atmosphere and the Earth’s surface1. Thus the spectral composition of solar radiation is crucial in determining atmospheric structure, as well as surface temperature, and it follows that the response of the atmosphere to variations in solar irradiance depends on the spectrum2. Daily measurements of the solar spectrum between 0.2 µm and 2.4 µm, made by the Spectral Irradiance Monitor (SIM) instrument on the Solar Radiation and Climate Experiment (SORCE) satellite3 since April 2004, have revealed4 that over this declining phase of the solar cycle there was a four to six times larger decline in ultraviolet than would have been predicted on the basis of our previous understanding. This reduction was partially compensated in the total solar output by an increase in radiation at visible wavelengths. Here we show that these spectral changes appear to have led to a significant decline from 2004 to 2007 in stratospheric ozone below an altitude of 45 km, with an increase above this altitude. Our results, simulated with a radiative-photochemical model, are consistent with contemporaneous measurements of ozone from the Aura-MLS satellite, although the short time period makes precise attribution to solar effects difficult. We also show, using the SIM data, that solar radiative forcing of surface climate is out of phase with solar activity. Currently there is insufficient observational evidence to validate the spectral variations observed by SIM, or to fully characterize other solar cycles, but our findings raise the possibility that the effects of solar variability on temperature throughout the atmosphere may be contrary to current expectations."
I think that what can be said is that, in the short 3 year mid-cycle data sampled, the spectrum of light produced by the Sun has varied in unexpected ways, producing unexpected effects on the atmosphere and atmospheric and surface warming.
IMO, the rest is speculative conjecture.
Reply | Report Abuse | Link to thisHowever, as I understand, it is considered that the current cycle of ice ages began when the land bridge between North and South America formed, rerouting ocean currents and dramatically changing the flow distribution of heat around the globe.
Reply | Report Abuse | Link to thisSimilarly, changes in the distribution of land masses have produced dramatic climatic effects in the even more distant past.
In the "snowball Earth" scenario, it is thought that it was ended by the internal heat of nuclear decay and thermal mass that eventually produced volcanic eruptions that filled the atmosphere with GHGs, increasing temperature.
It seems pretty clear that the apparent recent dramatic increase in global temperatures coincides with and is most likely produced by humanity's increasing combustion of most of the Earth's stored hydrocarbons over the past couple of centuries.
There are complex factors involved: I doubt anyone has developed an analytical climatic model that can accurately predict future conditions, since dramatic changes in critical factors are a certainty as the stored hydrocarbons are depleted.
Chicken Little and politcal opportunists have driven these same stupid climate arguments since the 60's when I first heard speculations about climate disasters. It was impending doom then and it's impending doom now. It was vanity then and it's vanity now. It was absurd then and it's absurd now.
Reply | Report Abuse | Link to thisAs a Tennesseean, I can spot a charlitan a long way off, say the distance to Carthage. Al Gore makes Bernie Madoff look like an amateur.
@docspot, "I can spot a charlitan a long way off" so can I. He's generally some idiot with a very strong opinion but without any facts to support them. We are all tired of the pathological liars who believe if you repeat some disinformation long enough and vehemently enough it will turn into a fact. Please save your comments for fox news where opinionated B.S. is welcome.
Reply | Report Abuse | Link to thisWarming is caused by infrared radiation and not by visible light as stated in this article.
Reply | Report Abuse | Link to thisThe Nature Letter's abstract more correctly states:
Reply | Report Abuse | Link to this"Radiation at ultraviolet wavelengths dissociates atmospheric molecules, initiating chains of chemical reactions - specifically those producing stratospheric ozone - and providing the major source of heating for the middle atmosphere, while radiation at visible and near-infrared wavelengths mainly reaches and warms the lower atmosphere and the Earth's surface. Thus the spectral composition of solar radiation is crucial in determining atmospheric structure, as well as surface temperature, and it follows that the response of the atmosphere to variations in solar irradiance depends on the spectrum"
IMO, the SA article is unclear in this regard.
From the early we have to build up our concern and respect to save our beloved earth. We'll waiting for the advance discovery..:)
Reply | Report Abuse | Link to thisIf climate changes were the result of variance in the relation positions of the masses in the solar system; wouldn't that be pretty obvious since it would occur periodically?
Reply | Report Abuse | Link to thisEveryone---read comment #15. It is well reasoned
Reply | Report Abuse | Link to thisRobert Schmidt- LOL---you did exactly what you complained about others doing.
Reply | Report Abuse | Link to thisGood point. I think it is misleading to say that they overestimated the effect of Solar effects and immediately conclude that Global Warming is going to be worse. It is just as likely if not more so that their estimation of the effects of CO2 are equally flawed. What this article says to me is that we really don't know where all the energy comes from nor where it goes. Which has been my argument to Climate Alarmists all along: you're asking an unanswerable question. Can CO2 trap heat? Yes, in a closed system. But unlike Greenhouses, the Earth is a dynamic system and has many geophysical processes that contribute to the process of blocking energy (sending more back into space), trapping energy, and releasing energy. All three of these take place, and CO2 is simply a very small part of it. Water vapor, storms, erosion, wave action, the Earth's magnetic field, and thousands of other things effect the Earth's energy balance. Anyone who claims that the "Science is settled" on this matter does not have a sufficient understanding of Science or History.
Reply | Report Abuse | Link to thisOne of the most basic laws of physics states that energy and matter cannot be destroyed and it be transformed from one state to another. Our understanding of the sun's energy output on the Earth IS incomplete. Some forms of particles and energy can be reflected, while others can be absorbed. When particles (usually ions) and/or energy is absorbed, it can be converted to heat. Every time you step on the brakes in your car, your forward motion is converted to heat by the brakes. You can see some of them glow red to white hot. The auroras are rather beautiful and is VISIBLE ABSORPTION.
Reply | Report Abuse | Link to thisI never said in my original comment, that man does not pollute or convert the Earth. We are very guilty of a major crime against nature. Our actions ARE exacerbating the suns effects on global warming.
The interglacial period we are in has been very good for mankind. It has enabled us to proliferate out of control. With billions of us on the Earth, we are having a major impact on its surface (oceans included), the atmosphere and are extending our influence to the space above. We are not angels. We are more like a virus. We adapt to the onslaught and continue to proliferate. Regardless of what is responsible for global warming, we have to clean up our act or drown in our own filth.
I generally agreed with your line of reasoning and was inspired to expand on it. Sorry if I seemed to be picking on you - Thanks.
Reply | Report Abuse | Link to thisIn reply to jtdwyer, I think we see eye to eye on this matter.
Reply | Report Abuse | Link to thisNo matter what the speculations are, they are just that, speculations. Scientists see a thread of evidence and publish a speculation based on the evidence, for all to see, so we can add it to the pool of data. Sometimes it's a blind ally, sometimes they are right on. The few "dead ringers" make history, such as Charles Darwin and Issac Newton just to name a couple, the list is rather long.
What I have seen in many cases is the inability to see the forest for the trees. Dwelling on tiny shreds of evidence or just one aspect can be very misleading. Sometimes you have to step back and look at the whole picture. You just might find what you are calling a cause, is in reality an effect.
look how long it took to realize the Earths core is heated by fission driving plate tectonics. My speculation on the sun is based on a collection of physics and astronomical data. For example: we say the sun cannot fuse helium because it doesn't have the mass to create the required conditions. Nowhere on Earth do we have the conditions for fusion, but we have the hydrogen bomb, a fusion bomb. I speculate the sun can temporarily create the conditions and pop off an accumulation of helium. I am not a scientist, but I can see how such an occurrence could create solar phenomena such as sun spots and solar flares, generating powerful magnetic fields in the process. The current theory is the magnetic fields are the cause, not the effect.
Right or wrong, it's fun to speculate. I was right about the fission in the Earths core. I speculated on that one decades before it came to be accepted. If I am right, maybe someone who is qualified and equipped may take a lead and be able to prove it. The newest solar satellite will be able to "see" into the suns interior. I can't wait to see what they find.
This article is rubbish. Just look at the original work to see why.....
Reply | Report Abuse | Link to thisThe Shell advertisement is an example of push-polling because none of the allowed responses were acceptable. They all assumed ongoing fossil fuel dependence (which suits Shell (and BP and Exon) despite their clean-tech advertising campaigns)
Reply | Report Abuse | Link to thisWhat was really reassuring was that of the people who responded, more than 99% chose "Other" - which must encompass all the options Shell did not present - like renewable energy, energy efficiency, local production, lifestyle changes.
It is refreshing to see that 99% of people can see through Shell's propaganda - and by extension, some of the weird political views about climate change being put about.
Despite rigging the questions, credit to Shell for at least not rigging the results.
Anything to deny that CO2 is causing global warming. I thought we settled this like 20 years ago. Its just so much easier on corporations to blame the sun.
Reply | Report Abuse | Link to thisCO2 isnt a direct pollutant but the way it heats up the earth can definitely cause complications for the survival of the human race. I guess you people need this explained to you the way I'd tell a toddler.
Reply | Report Abuse | Link to thisFocus on REAL pollution such as particulates, ground-level ozone created by adding ethanol to the fuel supply, sulfides, and NOx. CO2 is a GOOD gas that increases plant growth. The more we have, the more life on Earth is created. More CO2 means more food for us and everything else.
Reply | Report Abuse | Link to thisIf our idiot politicians were in charge of determining CO2 levels I'll bet many would say zero, not realizing that when it drops to 150 ppm, nearly all plants on Earth DIE.
CO2 is certainly a greenhouse gas. However, the big question is whether its influence at present is the major driving force of the current global warming or merely a tiny influence easily overwhelmed by other climate drivers, such as the sun?
Reply | Report Abuse | Link to thisPersonally, I think all climate factors are so complex that basically climate does a random walk most of the time, until really big events like a supervolcano or extinction-level asteroid strike pop up. My thesis will be confirmed if the coming years seem to return to a cooling pattern (or maybe even a sudden onset little ice age) as all "global warming can cause global cooling" just-so stories are ridiculous and the political public will treat them as such.
If the computer models are good then they should be able to explain past climate swings. Until they do I'll withhold judgement.
Reply | Report Abuse | Link to thisThanks for the info. I have heard that vinegar is a great <a href="http://www.rapidmedicalresearch.com/study-24-Irritable-Bowel-Syndrome">diarrhea remedy</a> if you live in Cleveland, OH. Not really. Don't drink vinegar. It's gross.
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