The sun and global warming?

But if the climate is so sensitive to a tenth of a watt/m^2 change in the solar forcing, why wouldn't it be as sensitive to a change in the radiative forcing from greenhouse gases ten times that amount? If you want to claim that there are feedbacks that are specific to solar forcing, you need to postulate a mechanism by which that would occur. Otherwise, you've crossed the line from rational objection to conjecture and idle speculation.

Climate physicists who know this stuff inside and out can't think of feedbacks that make physical sense that are specific to solar forcing. It's all about photons, and last time I checked photons didn't have little labels on them so that a feedback knew only to use the longwave photons coming only from changes in the solar output.

edit: So you don't have specific mechanisms. All you have are speculative hypotheses that don't have much in the way of empirical validation.

Before skeptics will make any headway with climate physicists, they would all do well to come up with plausible mechanisms that agree with the available data. For example, if clouds are causing the warming, show an increase in clouds commensurate with the warming. The ISCCP data show no such increase that I am aware of, yet skeptics trundle out clouds ad nauseum as though nobody modeling climate has ever even considered clouds. Similarly, when people went out to look at correlations between cosmic rays and clouds that they found nothing significant, and given the subtle changes in cosmic rays and solar output, for there to be a real connection any such correlation would stand out like a searchlight. Yet every third post here is some skeptic concluding that it *must* be cosmic rays, or niggling over some trivial detail that means nothing in the larger picture.

CO2 is affecting the radiative balance of the planet and that is changing climate. You can argue, as Lindzen does, that the effects won't be severe, but arguing CO2 isn't important is, at this point, purely emotional denial, not rational skepticism. (I should also point out that you might not believe me, I'm a nobody, but you're saying Lindzen, a chaired professor of atmospheric science at the world's 1st or 2nd ranked technical university, doesn't understand radiative forcing as well as you do and he, not you, is wrong? That proposition, to me, is delusional.)

I understand that skeptics hate the notion their lifestyle is a problem. I hate the idea as well, and furthermore, I don't see any rational solutions to the problem, but you won't find me accepting irrational, ill-considered nonsense masquerading as honest objections just to quell my guilt or justify inaction.

How about this ... The Sun is responsible for ALL warming on the planet . That may be over simplistic to say but if the planet warms , that energy comes from THE SUN ! So , what on Earth regulates that energy ? Well , the big culprit of late is of-coarse Co2 . If you took the politics out of the discussion , then historically , we would never suspect Co2 as a major temperature driver , nor should we today . It is no coincidence that the largest by-product of capitalism is also the bad guy in the GW debate . Current Science tells us this , if the earth had a thermostat , it would be the clouds . Cloud cover seems to be the most influential factor in regulating the Suns energy and far more powerful than the greenhouse signature , which we can't even find . The Sun also influences cloud cover , making the Sun the number one factor in the warming of our planet , not Co2 , not Man . If anyone can PROVE otherwise then you have my FULL attention . BTW , a statement from NAS isn't PROOF !

I'm sorry gcnp ... can you show where Co2 forcing (man made at that) is any more plausible than cloud cover for most warming of the last 100 years . No , you cant . Here's the thing , we can look at Co2 activity far far into the past . However , we can only look at cloud activity over the last 40 years or so . Big difference ! Like I said before , WE WOULD NEVER SUSPECT C02 AS A MAJOR TEMPERATURE DRIVER IN THE PAST . It just doesn't fit into the big picture . Where is this greenhouse warming of our planet ? We haven't found it . We have been looking for the greenhouse signature but..... hmmmmm..... it's just not their . Why a cooling trend for the past 7 years ? Oh , let me guess , natural forcing ? So when it cools it is nature but when it warms it's man , how convenient . Just to set the record straight about Lindzen who you speak so highly of and rightfully so . He doesn't believe that most of the warming over the last 100 years is due to man , not a good name to bring to the discussion if you are an AGW believer .

This is a popular myth that is doing the rounds and is losely based on NASA reports but has been grossly distorted and exaggerated by some global warming skeptics. It would be a good idea to read the original NASA reports so you can put things into context. In short - there is evidence to suggest that the south polar ice cap is melting, there is also evidence to suggest the north polar ice cap is expanding. Therefore whatever warming is happening on Mars is only affecting parts of it. The probable reason for any warming on Mars are the global duststorms that sweep across the planet for days on end, such an event on earth (were it possible) would also lead to significant changes in our climate. Further, Mars is very, very different to our own planet thus making any comparisons very unreliable. It has no breathable atmosphere, is not largely vegetated, isn't predominantly water, experiences extreme temperature changes, is so cold that the ice caps aren't frozen water but frozen gas (carbon dioxide) and it's not inhabited by humans. It would be a very conveneint solution to say that the Sun is to blame for warming on Mars and on Earth, if that were the case then the other planets and moons in our solar system would also be warming - they're not. There's 172 of them all told and on 165 of them no warming has been observed. We have extremely accurate instruments for measuring changes in the output from the sun and we know that the difrerence between the highest and lowest outputs (insolation maxima and insolation minima) is very small - enough to cause global warming or cooling over thousands and millions of years but nowhere near enough to bring about the changes we've witnessed in the last few decades. The actual difference between maximum and minimum output is a variation of a little less than one thousandth (a variation of 1.3 Watts per square metre per year against a mean of 1366 W/m2/yr). Again, please refer to the original NASA reports, the skeptics are trying to fool you by concealing facts and distorting others.

Yes, we can be sure the Sun is not responsible for the recent increase in temperature.

The warming effect of CO2 is a basic physical property of CO2. A simple physics model of CO2 gives temperature increases in the ballpark of what we're seeing. More complicated models are used simply because they more accurately describe the temperature increase.

Against that you're trying to say there are unknown effects of solar irradiance on ocean currents, etc. Why pick an unknown effect over a known one?

A final refutation of the idea is that solar irradiance was going down, while temperatures were going up. The mechanism for that effect would be a doozy.

Lockwood, Frohlich, Recent oppositely directed trends in solar climate forcings and the global mean surface air temperature, Proc. R. Soc. doi:10.1098/rspa.2007.1880

Note that this is simply one of many papers refuting this idea. A scientist has said "The problem with putting another nail into the coffin of the theory of "solar warming" is finding a place to put it."

EDIT - Of course solar changes need to be included in modeling. But the data shows that solar changes CANNOT be a major factor in the warming of the last 30 years. and that, in fact, they have had a small negative effect on warming recently. Lockwood and Frohlich are one of a number of papers that have demonstrated that.

Could the Sun have a slightly greater importance than the IPCC has quantitatively estimated? Of course. Could it be the MAJOR reason for recent warming? No way.

And this is also true.

"can we/you be so sure that GHG aren't playing a larger role than the IPCC assigns them? After all, there are many scientists that claim the IPCC is underestimating the problem as well."

Well said.

EDIT2 - "even with PMOD's negative trend, the sun could still cause warming."

How?

The temperature jumped over 0.6 degrees Farenheit from 1910 to 1940 and had nothing to do with CO2 emissions. We had no satellites in orbit to measure TSI during that time period. The current warming period is not any more substantial than the last and is just as likely to be caused by multi-decadal ocean cirrculation patterns. Which are not even considered in climate models. If it is true that ocean surface temperature are the driving force behind the recent global warming, civilization is in for a shock over the next few decades, and the AGW crowd will be responsible for lulling humanity into a false sense of security, as predicted cooling phases in both Atlantic and Pacific sea surface temperatures in phase with continued decline in solar activity will more than likely cause a dangerous episode of global cooling.

This chalk board physics lesson just awe's me. It's the uneven distribution of heat that should be question. From there it becomes even more complicated. The atmosphere distributes the heat from the pole to the equator to the oceans. For those that read the IPCC reports in dimly lighted rooms. I would reread about the uncertainties involved, along with some reassessments. They can't agree on emissions, much less speculate on coronal projections or come to grips that the sun has unpredictable flares. It doesn't mean studies on natural variations are useless, it's the one thing they can't model successfully....for now.

I think gcnp and Bob already answered the question well. Certainly it's possible that the solar role in the recent warming is somewhat understated. For example, as Tomcat noted, Scafetta&West managed to assign 25-35% of the recent warming to solar effects (though I think their study had some significant flaws).

However, I think it's highly unlikely that solar effects can account for any significant fraction of the recent warming. I think the effects are reasonably well understood, and the radiative forcing is more than an order of magnitude smaller than that from CO2 alone, so you would need a major unknown effect to account for a significant amount of recent warming. I just don't see it.

*edit* Tomcat - the claim that the 1910-1940 warming had zero anthropogenic effect is just plain false, and you know it. During that period TSI and volcanic forcings also increased, which is not the case now. You should also know this.

I don't know if you have selective amnesia or are in denial, but pretending we're completely ignorant of climate changes less than a century ago is just ridiculous. Get your head out of the sand.

"So, given our level of understanding, can we be so sure that the sun isn't playing a larger role than the IPCC assigns it?"

Maybe not, but given our/your level of understanding regarding GHG, can we/you be so sure that GHG isn't playing a larger role than the IPCC assigns is? After all, there are many scientists that claims IPCC is underestimating the problem as well. For example, we're already on the way to exceed their worst case scenario regarding GHG emissions.

Climate is complex and nobody knows it all. But from the GHG-theory which IS understood, I think it would be wise to not just "wait and see", considering the possible consequences.

Photons are not behind the model Svensmark published, gamma radiation from outside our solar system is, which excludes our sun as the direct culprit. But a weakened magnetic field from the Sun allows the gamma rays which are normally swept away before they reach us to enter the atmosphere and interact with it. Svensmark's theory is that the rays impact water vapor molecules and cause additional cloud formation. If the current solar cycle remains dormant we may well see dramatic cooling such as we had during the Little Ice Age.

It would be nice to put this issue to bed since most of us agree we ought to move away from fossil fuels and develop alternative and renewable energy sources. The sticking point is that one side insists we do that now, before any alternative is available, meaning a large cutback in industry for part of the world, while China and India can continue as usual. The other side would like to take action to not only find and develop alternatives but actively reduce CO2 and other greenhouse gases in the atmosphere, or find another way to moderate global temp. Some of us remain suspicious that the IPCC insists this must be done according to a plan which seems to only serve to centralize political power in that body and transferring wealth and production from developed nations to those that are called developing nations.