Posted on 04/19/2008 5:34:50 AM PDT by Delacon
More thoughts on AGW ... I gave here:
http://climateprogress.org/2008/03/31/is-450-ppm-carbon-dioxide-politically-possible-1/#comment-11344
If you read the post correctly there is one firm conclusion: The only way to address Global Warming via post-fossil fuel power generation ie ” zero carbon supply side”, is through Nuclear Energy.
The key issues are SCALABILITY and COST PER WEDGE. We didnt get that number, but some thoughts:
1. Wind - great, but its well-known reliability issue that precludes wind from being more than 10-20% of the grid. In Texas they are finding out the truth, wind exists and people exist but they arent close to eachother. A lot of cost to build the grid. More cost to keep the grid stable with variable wind power. You need peaker plants (nat gas?) and/or capacitive power (hydro?) to buffer it.
2. A single solar wedge costs $14 *trillion* ?!? Cant afford it. (Paul K)
Solar PV will come down in price, but even then, solar simply will never be cost-competitive for large scale. Useful for off-grid, remote, some rooftops (maybe) maybe even 3rd world.
This leaves aside the obvious issues of siting for solar and the fact that it will work in some locales (AZ) fine but not others (British Columbia) so well.
3. Nuclear - any wind or solar subsidy would go 10 to 50 times farther in CO2 reductions if applied to nuclear, as the level of subsidy / GW rated is much less and the generation / rated GW is higher than any alternative.
4. the “10 Yucca Mountains” is silly. We can have recycling of used nuclear fuel. Arent we for recycling in other areas, why not used fuel, which is 95% reusable? Do that and you still need only one small repository, and it doesnt even need to geological long-term safe. In other words, disposal is a non-issue, and if you think its enough to derail an AGW solution, then AGW must not be a serious problem to you.
As of right now, today, nuclear is 20% of generation in the US, and 70% in France and close to that in South Korea. In short, there are countries where nuclear is a viable 70% baseload generation solution. There are no countries where any other non-fossil and non-hydro solution gets close to that. Points #1 and #2 tell you that wind and solar wont cut it to even get to 1 wedge, but even if they do, they wont scale beyond it.
Yet when nuclear is raise, we get the scaremongering like this: “(3 nuclear plants built each week for 50 years)” … well, guess what … ANY wedge has those huge scale issues. How many thousands and thousands of wind turbines is a mere 13GW rated? well, that is only a dozen large nuclear plants, but is 13,000 or so wind turbines, consuming thousands of acres and requiring billions in transmission infrastructure to be useful. (For Texas, about $6 billion in such infrastructure on top of the turbine cost).
400 nuclear power plants, or 20/year for 40 years is doable for the US, and they would pay for themselves as with current costs nuclear is actually the cheapest form of energy to generate. Siting is easy - just let any existing site quadruple capacity. BTW the blog earlier states “And the power isn’t cheap: 8.3 to 11.1 cents per kilo-watt hour.” This is clearly false. The actual costs are much lower in the 4-5 cents/KWh range.
Double nuclear again, to about 800 GW rated for the US, and you will have made electricity fossil-fuel free (almost - 75% nuclear 10% wind 10% hydro+solar, 5% nat gas), and displaced most of the transportation energy (with plug-in hybrids) - All it requires is 800 nuclear power plants of 1GW+ each, at a US subsidy cost of under $100 billion *total* (over 40 years, so it is tiny really!), and a move towards wind/solar for 20% of generation.
End result is a reduction of US emissions by 80%, reduction in oil fuel use by 2/3rds.
If a single wedge does this … “requiring one-sixth of the world cropland.” … one has to notice that nuclear energy, with small land footprint, no emissions, is a more benign and less intrusive answer.
It may be that environmentalists will pose the greatest threat to the environment by opposing the one real solution to Global Warming - nuclear power.
“The problem with convincing people that global warming heating is going to make things FUBAR is that it is extremely nuanced ”
The real problem is that the hype is wrong. The models that predicted ‘worst case’ scenarios have been proven wrong by latest satellite measurements and studies of precipation systems. Sea level rise is not accelerating. Temperature rises are not matching models. And the models that use water vapor feedback are gradually getting disproven by data. Just one example:
http://www.uah.edu/News/newsread.php?newsID=875
Tropical cloud cover is a negative feedback in the climate system:
“All leading climate models forecast that as the atmosphere warms there should be an increase in high altitude cirrus clouds, which would amplify any warming caused by manmade greenhouse gases,” he said. “That amplification is a positive feedback. What we found in month-to-month fluctuations of the tropical climate system was a strongly negative feedback. As the tropical atmosphere warms, cirrus clouds decrease. That allows more infrared heat to escape from the atmosphere to outer space.”
Recent cooling trends dont disprove global warming, but they should at least make those hyping Global Warming to take notice: Natural climate change is real and the truth is almost surely not as bad as the hype pretends. Dont assume every weather event is due to man. Dont believe the lie that the ’science is done’, its still learning. In the end, things are not even close to FUBAR, unless we destroy the environment or economy in a chimerical quest to end global warming.
“Contrary to what Jeffery Sachs thinks, solar power towers and corn based ethanol share something in common: they are both very expensive and have significant adverse environmental effects.”
Correct.
“The majority of people won’t understand the implications of sustained drought ” Models that show global warming show overall increases in precipitation. Higher CO2 levels allow plants to grow with less water requirements, ie they are more drought tolerant.
“The carbon sinks — the oceans, forests, soils, and tundra — are saturating, even as the carbon sources — the burning of fossil fuels plus deforestation — are growing.”
There is no reason nor evidence to support this.
As CO2 concentration increases, the gas diffusion law states that ocean CO2 capacity increases. Further, the biosphere is a more productive absorber due to “CO2 fertilization” effect. The sinks will pull more CO2 as CO2 concentrations rise.
The trendlines of CO2 concentrations are not accelerating, so that even if man is outputting more CO2, the levels are not rising any faster.
Thus, the carbon sinks are *not* saturating.
From part XX - Gore’s Guru Disagreed:
Although Dr. Revelle recognized potential harm from global warming, he also saw potential benefits and was by no means alarmed, as seen in this 1984 interview in Omni magazine: Omni: A problem that has occupied your attention for many years is the increasing levels of CO2 in the atmosphere, which could cause the earth’s climate to become warmer. Is this actually happening? Revelle I estimate that the total increase [in CO2] over the past hundred years has been about 21%. But whether the increase will lead to a significant rise in global temperature, we can’t absolutely say. Omni: What will the warming of the earth mean to us? Revelle There may be lots of effects. Increased CO2 in the air acts like a fertilizer for plants ... you get more plant growth. Increasing CO2 levels also affect water transpiration, causing plants to close their pores and sweat less. That means plants will be able to grow in drier climates. Omni: Does the increase in CO2 have anything to do with people saying the weather is getting worse? Revelle People are always saying the weather’s getting worse. Actually, the CO2 increase is predicted to temper weather extremes .
Wegman:
You may not have heard of Mann or read Mann’s study but you have often heard its famous conclusion: that the temperature increases that we have been experiencing are “likely to have been the largest of any century during the past 1,000 years” and that the “1990s was the warmest decade and 1998 the warmest year” of the millennium. You may have also heard of Mann’s hockey-stick shaped graph, which showed relatively stable temperatures over most of the last millennium (the hockey stick’s long handle), followed by a sharp increase (the hockey stick’s blade) this century.
Mann’s findings were arguably the single most influential study in swaying the public debate, and in 2001 they became the official view of the International Panel for Climate Change, the UN body that is organizing the worldwide effort to combat global warming. But Mann’s work also had its critics, particularly two Canadians, Steve McIntyre and Ross McKitrick, who published peer-reviewed critiques of their own.
Wegman accepted the energy and commerce committee’s assignment, and agreed to assess the Mann controversy pro bono. He conducted his third-party review by assembling an expert panel of statisticians, who also agreed to work pro bono. Wegman also consulted outside statisticians, including the Board of the American Statistical Association. At its conclusion, the Wegman review entirely vindicated the Canadian critics and repudiated Mann’s work.
“Our committee believes that the assessments that the decade of the 1990s was the hottest decade in a millennium and that 1998 was the hottest year in a millennium cannot be supported,” Wegman stated, adding that “The paucity of data in the more remote past makes the hottest-in-a-millennium claims essentially unverifiable.” When Wegman corrected Mann’s statistical mistakes, the hockey stick disappeared.
Wegman found that Mann made a basic error that “may be easily overlooked by someone not trained in statistical methodology.
Richard Tol vs Stern Report
Because of his immense reputation, the Stern report itself relied on Tol’s work in coming to its conclusions. But Sir Nicholas twisted Tol’s work out of shape to arrive at unsupportable conclusions.
As one example, Sir Nicholas plucked a figure ($29 per ton of carbon dioxide) from a range that Tol prepared describing the possible costs of CO2 emissions, without divulging that in the very same study Tol concluded that the actual costs “are likely to be substantially smaller” than $14 per ton of CO2. Likewise, in an assessment of the potential consequences of rising sea levels, Sir Nicholas quoted a study co-authored by Tol that referred to the “millions at risk,” ignoring that the same study then suggested greatly reduced consequences for those millions due to the ability of humans to adapt to change.
Throughout his report, in fact, Sir Nicholas not only assumed worst possible cases, he also assumed that humans are passive creatures, devoid of ingenuity, who would be helpless victims to changes in the world around them. Such assumptions underpinned Sir Nicholas’s claim that “the overall costs and risks of climate change will be equivalent to losing at least 5% of global GDP each year, now and forever,” and led Tol to view Sir Nicholas’s conclusions as “preposterous.” Tol’s conclusion: “The Stern review can therefore be dismissed as alarmist and incompetent.”
Tol and Sir Nicholas are worlds apart, and not just because of Sir Nicholas’s recklessness with the facts. Where Sir Nicholas paints an altogether bleak picture, Tol’s is far more nuanced: Global warming creates benefits as well as harms, he explains, and in the short term, the benefits are especially pronounced.
Yes, global warming is real, he believes, and yes, measures to mitigate it should be taken. But unlike the advocates who believe that the science is settled, and the global warning debate is over, Tol thinks that much research needs to be done before we know how best to respond.
“There is no risk of damage [from global warming] that would force us to act injudiciously,” he explains. “We’ve got enough time to look for the economically most effective options, rather than dash into ‘actionism,’ which then becomes very expensive.”
AGW LINKS:
CO2 (and some other gases) absorb IR radiation over about 8% of the spectral range of black body radiation emitted by the surface. These bands a very nearly saturated by CO2 and H2O. In principle increasing CO2 levels could lower the rate at which the Earth cools by radiation into space, causing warming of the planet. There are signatures e.g. expected warming of the atmosphere at a rate faster than surface warming. This has been modeled by global circulation models. However to get surface heating of more than about 1 K for a doubling of CO2 (280 - 560 ppm) there needs to be purely positive H2O feed back. There has also not been as much warming as would be expected from the logarithmic nature of absorption due to a change in concentration of CO2.
There are problems with this theory. The first is that purely positive feedbacks imply an unstable system and this doesn’t seem to be the case. There are also many possible negative feedback that exist which haven’t been included in the models. Secondly, there seems to be a large difference between the model output and what is actually happening with regards to the temperature changes in the various ‘spheres. [Douglass, Christy et. al. IJC 2007] There also appears to be some evidence that there has been a cooling trend in the last ten year that was not predicted by modeling, even after removal of ENSO effects.
http://www.climateaudit.org/phpBB3/viewtopic.php?f=4&t=237
LINKS:
http://rankexploits.com/musings/2008/what-are-the-ipcc-projections-and-how-not-to-cherry-pick/
http://www.climateaudit.org/phpBB3/viewtopic.php?f=4&t=236
JohnV “The 11-year solar cycle averages out so does not need to be considered in a multi-decade trend. That is, it has little effect on the *mean* trend just as ENSO has little effect on the *mean* trend. It only affects the trend over short time scales. I doubt there is any discussion of the solar cycle in SRES.”
This suggests 2 things:
1. the dangers for short time scales period in trend estimation.
Why do we have a start-point of 1980 for trendlines and not 1950, for example? the longer time-period, the less chance for
mistaking trendless noise for trendline forcing.
2. Any temperature estimation needs both a CO2 ‘signal’ and have a ‘natural variability’ trendless ‘noise’ component to be non-falsifiable. Whether or not you can predict PDO/ENSO variability, it needs to be modeled as a component of variation in the
Any IPCC estimate needs to incorporate and quantify it.
“A net trend of 0.05 degC/decade over 20 years would invalidate many of the predictions made by the IPCC.”
The estimation needs to be of this form:
- X degC/century AGW CO2 warming ‘signal’ + Y degC/year ‘noise’
there can be multiple ‘noise’ / non-trend natural variability components, such as:
Y0 degC/year ‘yearly noise’ + Y1 degC/decade ‘decadal oscillations’ (11-year cycle) + Y2 degC/century ‘multi-decadal osciallations’ ‘long cycle variability’
You could even go to a Y3 ‘1500 year cycle’ of the unstoppable global warming theory.
With that as a model, you could ask a different question:
FOR WHAT VALUES OF X, Y0, Y1, etc. DO THE TEMPERATURE VALUES MATCH (or do not get falsified)?
One thing wholly unclear is how much of 0.6C temp rise since 1950 is due to AGW and how much is due to something else.
Yet if X from a *timescale* perspective is a long-trend variation, then one can pair it up with long-trend Y3 oscillations, do an FFT on the data or other form of variational analysis, to break out the short trends from the long trends.
It’s apparent that all the IPCC models have Yi=0, and thus dont even fit this framework.
http://i30.tinypic.com/34pzzuc.jpg
http://i26.tinypic.com/20t2b2o.jpg
“No-one is arguing that the current climate changes are outside of “planetary variation”. “
Huh? That is exactly what IPCC and Al Gore have claimed. Even further, they have claimed that most-to-all of the warming is due to AGW, with high probability. We have Mann, based on the flawed hockey stick, claiming that recent temperatures are highest in 1000 years (range of data error doesnt support that). None are provable statements, neither are supported by the data, but they are out there.
I agree with the view that climate is complex. Such complexity and the reality of the complex and ongoing natural variability in climate has been a pillar in the ‘skeptics’ case: Because we have so many variables, it is impossible to justly claim that we *know* previous warming is due to man. Until we have fully and accurately accounted for all sources of natural variability, such statements are hubristic speculation.
“However before we even reach this point we have a graph that stops at 1998.” While alarmists find it convenient to stop at that high note of 1998, Carter’s chart goes to 2008 (today). It is merely mislabelled.
It does show that 1998 was hotter than any year since, and as such is a PROOF POINT to disprove the phony claim that warming is due to man. It cannot be, since CO2 has risen while temperatures fell. Conclusion: Natural variability exists and is large enough to outweigh AGW over a decade-long period.
http://www.sciencealert.com.au/opinions/20082204-17218.html
lucia,
If I understand your question, then my answer is yes. Allow me to clarify that I’m answering the right question:
The trend from Jan2001 to Mar2008 can be written as:
(1)
T = A + E + S + O + W
where
A is the AGW trend,
E is the ENSO trend,
S is the solar-cycle trend,
O is the trend from other sources (AMO, PDO, etc)
W is weather noise
The IPCC trend is basically just A. You have shown that E is fairly small and have attempted to correct for it. Your ENSO-corrected trend can be written as:
(2)
Te = A + S + O + W
W is the remaining error bars, which you have estimated as plus or minus 1.7K/century.
That leaves S and O (plus the W noise). I can’t say anything intelligent about O, but S has been estimated. If the solar cycle temperature amplitude is between 0.06K and 0.16K (references that I found from a quick search), then S is between -0.9K/century and -2.3K/century for the last 7 years. To keep it simple, I’ll define S = -1.5K/century (a little less than the average of the range).
Re-writing (2) to solve for A:
(3)
A = Te - S - O - W
Substituting your computed trend of 0.1K/century:
(4)
A = 0.1 + 1.5 - O - W
Neglecting O and expanding W as error bars at plus or minus 1.7K/century:
(5)
-0.1 K/century < A < 3.3K/century
or,
(6)
A = 1.6 K/century plus or minus 1.7K/century
This is very close to the IPCC trend of 2.0K/century. The results are similar using the temperature trends without ENSO correction.
All of these effects are included in all the standard methodology and when you do the full calculation - using all the spectral lines, using full atmospheric profiles, using all the spatial information you end up with the the standard number - i.e. 2xCO2 gives ~4 W/m2 forcing. You can continue to point to special cases that don’t use all the lines, that don’t use full profiles and that don’t integrate over the surface of the planet, but they won’t change the numbers you’d get if you did. There are real uncertainties in climate science - the role of aerosols, clouds, ice sheet response etc., I would advise focussing on them, and not on physics that has been known and properly calculated for decades. - gAVIN
t is not that anthropogenic CO2 emissions are a physically impossible explanation for the recent warming, it is just that the model evidence that is dismissive of a reasonable size solar contribution strains credulity. Even if the poorly understood level of solar activity were to fall back from one of the highest levels in the last 8000 years, to the still elevated levels reached in the earliest part of the 20th century, they will still be responsible for some of the current energy imbalance. Climate commitment studies and physical reasoning about the thermal capacity of the oceans tell us that the climate system takes centuries to adjust to a new level of forcing. A short intervening period of higher forcing won’t magically accelerate the adjustment of the deep levels of the ocean, and a mid-century aerosol cooling would only delay the adjustment.
The question is still open. The current models don’t have the credibility to reject the hypothesis that a significant part and perhaps even most of the recent warming can be explained by the plateau in poorly understood solar activity. Both the AGW and solar hypotheses require a signficant mid to late 20th century variation in aerosol forcing to explain the temperature signal. AGW may eventually explain most of the recent warming, but the coincidence of an unusually high plateau in solar activity, that is unlikely to continue, and a climate that is arguably within the range of natural variability, justifies some skepticism and humility.
During the past ~120 years, Earth’s surface temperature is correlated with both decadal averages and solar cycle minimum values of the geomagnetic aa index. The correlation with aa minimum values suggests the existence of a long-term (low-frequency) component of solar irradiance that underlies the 11-year cyclic component. Extrapolating the aa-temperature correlations to Maunder Minimum geomagnetic conditions implies that solar forcing can account for ~50% or more of the estimated ~0.7-1.5°C increase in global surface temperature since the second half of the 17th century. Our analysis is admittedly crude and ignores known contributors to climate change such as warming by anthropogenic greenhouse-gases or cooling by volcanic aerosols. Nevertheless, the general similarity in the time-variation of Earth’s surface temperature and the low-frequency or secular component of the aa index over the last ~120 years supports other studies that indicate a more significant role for solar variability in climate change on decadal and century time-scales than has previously been supposed. The most recent aa data for the current solar minimum suggest that the long-term component of solar forcing will level off or decline during the coming solar cycle.
http://adsabs.harvard.edu/abs/1998GeoRL..25.1035C
http://www-ssc.igpp.ucla.edu/personnel/russell/papers/731/fig1.gif
CO2 forcing is 1.5W
http://www.ipcc.ch/ipccreports/tar/vol4/english/wg1figts-9.htm
http://www.weatherquestions.com/Roy-Spencer-on-global-warming.htm
I want to make it clear that the average effects of precipitation systems are indeed contained in today’s computerized climate models. But for global warming, a model mimicking their average behavior isn’t sufficient, for it is too easy to get the right answer for the wrong reason. Instead, we need to answer the question: How do precipitation systems change in response to mankind’s small addition of greenhouse gases to the atmosphere? This is where I believe the models are wrong. Models tend to amplify the Earth’s natural greenhouse effect in response to mankind’s small addition of greenhouse gases; but I believe that real precipitation systems do just the opposite...they slightly reduce the total greenhouse effect by adjusting water vapor and cloud amounts, to keep it in proportion to the amount of available sunlight.
But the influence of precipitation systems on the global climate doesn’t end there. They also indirectly control cloud amounts in remote regions, even thousands of miles away from any precipitation system. This is because the convective (vertical) overturning of the global atmosphere being forced by precipitation processes largely determines the vertical temperature profile of the atmosphere. That temperature profile, in turn, exerts a strong influence on cloud systems.
What we really need to know is how the efficiency of precipitation systems changes with temperature. Unfortunately, this critical understanding is still lacking. Most of the emphasis has been on getting the models to behave realistically in how they reproduce average rainfall amounts and their geographic distribution — not in how the model handles changes in rainfall efficiency with warming.
Fortunately, we now have new satellite evidence which sheds light on this question. Our recently published, peer-reviewed research shows that when the middle and upper tropical troposphere temporarily warms from enhanced rainfall activity, the precipitation systems there produce less high-altitude cirroform (ice) clouds. This, in turn, reduces the natural greenhouse effect of the atmosphere, allowing enhanced infrared cooling to outer space, which in turn causes falling temperatures. (Our news release describing the study is here.)
This is a natural, negative feedback process that is counter-intuitive for climate scientists, most of whom believe that more tropical rainfall activity would cause more high-level cloudiness, not less. Whether this process also operates on the long time scale involved with global warming is not yet known for sure. Nevertheless, climate models are supposedly built based upon observed atmospheric behavior, and so I challenge the modelers to include this natural cooling process in their models, and then see how much global warming those models produce.
Solar variability graph - with pro-AGW commentary;
http://www.metoffice.gov.uk/corporate/pressoffice/myths/4.html
“No matter how suggestive the GHG concentration curves are to the naked eye relative to the plateau in solar activity, without positive feedbacks, anthropogenic GHGs can only account for less than a third of the recent warming. Credible attribution of the rest of the less than 1W/m^2 energy imbalance requires models that can reproduce the observed solar response, and have a much better “match” to the climate than current models.”
Solar output varies significantly over 11-14 year cycles, has generally increased over the past century (the increase stopping about 30 years ago) and has declined since about mid 1990s. While the output peaked about 30 years, the minimum of the cycle was still higher than the previous one. It is also important to note, during that 30 years solar output was still higher than the previous century (and first half this one). Shortly after there is a significant decline in CRF in the 90s, warming did, in fact, stop.
Also of interest, the high energy cosmic rays that are known to affect low cloud cover are less affected solar activity, and when looked at independently rather lumped together with all cosmic ray flux (see Nir Shaviv’s sciencebits.com website), the relationship is quite striking. There are lags and feedbacks that dampen temperature signal too. The theory is entirely consistent with recent observations.
precitipation cycle will have a cooling effect:
vapor - rain - cooler at surface via evaporation.
What is the negative forcing of higher precipitation?
What about convection?
Wow, great post!!!
You are welcome... I was just collefcting notes to help understand this issue, and thought I’d share key data points.
Here is another piece of the puzzle that helps:
http://www.climate-skeptic.com/2007/11/single-best-rea.html
Great chart shows the observe warming against the model of CO2 sensitivity on a log curve ... the result of that
is simple 0.6C increase for 36% rise in CO2.
that ratio, based on the Delta-T = alpha*ln(C/C0) model, gives you alpha=1.95
this means that at 550ppm we will have a further rise of:
0.72C
and at 750ppm we will have a further rise of:
1.32C
Why arent we using those as the sensitivity numbers?
The modellers add in feedback effects and justify it by saying that the warming is ‘in the pipeline’. The problem with that argument is that if there is a heat sink, the ability of that heat sink to cool surface is limited by the conductive ability to transmit heat. If it can transmit heat effectively, there would be no time lag.
1. Global warming is real.
- CO2 is up from 280ppm to 380ppm
- temperature record shows about 0.6C warming since 1950
- solar variability does not account for it
2. Global warming is not a crisis.
- the warming amounts in temp data are less than worst-case models
- there is natural variability that is not accounted for in models
- estimates/claims of sea-level rise and extreme weather events are unsupported by data
- CO2 increases fertilize plants and increase precipitation, both positive impacts
3. The positive feedbacks in the models are wrong/unsupported
4. Actual temperature record supports a lower sensitivity number
- see above link
5. The reason the models are wrong is due to how they treat water vapor and clouds. They treat them as positive feedbacks when they are really negative feedbacks.
(See the works of Prof Roy Spencer)
QED. Global warming is a real effect that is about 1/3 the impact that Al Gore/Hansen are estimating.
Supporting data on this.
The climate sensitivity number that arises from my back of envelope calculation is 1.95C.
This number is not much lower than the average climate model sensitivity number since 1999 (average of 2.65C):
http://members.aol.com/bpl1960/ClimateSensitivity.html
No it must be a more recent article or paper. Sorry I misplaced the link. Soden as a leading climate modeller continues to narrow his band. But here is something by Soden with - in my opinion - a statement of similar significance.
Large discrepancy between observed and simulated precipitation
trends in the ascending and descending branches of the tropical circulation:
http://www.nerc-essc.ac.uk/~rpa/PAPERS/allan_and_soden_2007.pdf
An increase in global mean precipitation with temperature
of around 6%K1 [Wentz et al., 2007] requires an
increase in the atmospheric net radiative cooling that is
larger than expected [Allen and Ingram, 2002]. It is possible
that the models do not capture decadal variability in
precipitation and radiative cooling adequately, possibly
relating to changes in cloud and aerosol radiative effects
[e.g., Wielicki et al., 2002; Mishchenko et al., 2007].
Continued monitoring of tropical precipitation and further
improvements in satellite calibration and retrieval algorithms
are required to explain the large discrepancy between
observed and model predicted changes in the atmospheric
hydrological cycle.
ARCO does cleanup:
Re #72 and others: The Coal Oil Point seep has been going on for years. In the early 1980s I was part of a team that measured the volume of gas; it amounted to about 6 tons per day. It was mostly methane, but there were significant amounts of higher order alkanes (ethane, propane,etc.). Quite a bit of H2S as well (it smelled REALLY bad!). Our study was sufficient to convince ARCO to build an underwater “umbrella” that captured most of the gas and sent it ashore via pipleline to a processing plant. ARCO received emission credits from the local air pollution control district for doing so.
The bonus was that the beaches of Santa Barbara (my home town) became much less covered with tar!
overlooked this discussion, as it was started during my trip to Iceland… But there are a few recent studies about cloud behaviour which challenge the positive cloud feedback included in (near all) current climate models.
Chen and Wielicki (2002) observed satellite based cloud changes in the period 1985-2000, where an increasing SST (+0.085 C/decade) was accompanied with higher insolation (2-3 W/m2), but also higher escape of heat to space (~5 W/m2), with as net result 2-3 W/m2 TOA loss to space for the 30N-30S band. This was caused by faster Walker/Hadley cell circulation, drying up of the upper troposphere and less cirrus clouds.
In 2005, these findings were expanded by J. Norris with surface based cloud observations in time (from 1952 on for clouds over the oceans, from 1971 on over land) and latitudes. There is a negative trend for upper-level clouds over these periods of 1.3-1.5%. As upper-level clouds have a warming effect, this seems to be an important negative feedback.
J. Norris has a paper in preparation about cloud cover trends and global climate change.
On page 58, there is a calculation of cloud feedback, assuming that the observed change in cloud cover is solely a response to increased forcing. The net response is -0.8, which is a very strong negative feedback… Of course this is the response, if nothing else is influencing cloud properties/cover, but important enough for further investigation.
Even internal oscillations, like an El Nino (1998) leads to several extra W/m2 more net loss of energy to space, due to higher sea surface temperatures. Thus IMHO, if models include a (zero, small or large) positive feedback by clouds, they are not reflecting reality.
CO2 WITHOUT FEEDBACK IS A 1.2C NUMBER:
“Converting the 4 W/m^2 absorbed to a 1 K difference can be done by a slightly modified version of the Arrhenius equation. Arrhenius figured out the temperature of a blackbody at a given distance from the sun by equating the incoming energy, bouncing energy off using albedo, and assuming that the round body acts as a black-body emitter with emissivity 1. The zeroth-order approximation of climate comes from adding in a factor to this equation accounting for heat trapping; i.e. accounting for long-wave radiation emissivity. The final equation looks like this: Temperature = ((1-albedo) * solar_luminosity / (16 * sigma * emissivity * pi * solar_distance^2))^0.25. If you use SI units, the solar luminosity of the sun is 3.844E26 watts, the solar distance is 1 AU = 1.496E11 meters and sigma is the Stefan-Boltzmann constant = 5.6704e-8 W/m^2/K^4. The bond albedo of Earth is around .29 (the authors above are using .3), and you have to run the equation backwards to get the long-wave emissivity of the Earth in pre-industrial times. If you take the mean preindustrial temperature as 288.0 K (= 14.85 degrees Celsius), sub it in the equation, the time-averaged long-wave emissivity comes out to .6220. You can then compute the average intensity of the Earth’s outgoing radiation using Intensity = sigma * emissivity * Temperature^4. This comes out to 242.6 W/m^2 for preindustrial Earth. You then suck back 4 W/m^2 from that number for the doubled CO2, dropping it to 238.6 W/m^2, and recompute the emissivity for the new Earth. This gives .6117. Plug that back in the temperature equation, and voila, new Earth has a balanced temperature of 289.2 K. Subtract the two temperatures to get 1.2 K per 4 W/m^2 extra absorbance, as required. Or you could use calculus and get essentially the same number, which is what they are doing.”
The solar irradiance is 1367 W/m^2 with the 11-year solar cycle varying by +/- 0.6 W/m^2 and longer-term changes varying as much +/- 3.0 W/m^2 over the past 1,000 years.
If these changes are not reflected in the climate record, why would we expect 4 W/m^2 to make such a diference?
[Response: To compare like with like you need to divide the solar irradiance changes by 4 and multiply by 0.7 to account for the geometry and albedo effects. So even with your (rather high) estimate of what the long term solar changes are only about 0.5 W/m2 - significantly smaller than the ~1.6 W/m2 net estimate of all anthropogenic forcings since the pre-industrial. That’s why it has been such a challenge to tease out a consistent solar response in the paleo-record. - gavin]
I took the 4 W/m^2 from doubling CO2 giving a 1 K rise in the absence of feedbacks noted in the original post, and added the 1.5 W/m^2/K feedback rise on top of that, using the same 4:1 conversion ratio. This raises the temperature another 0.375 K. That temperature rise, in turn, must get amplified by the same feedback effects as well, adding 0.56 W/m^2 more input. That raises the temperature another 0.141 K. This continues until the terms get so small that they don’t count any more. To three decimal places, this gives a 1.600 K temperature rise at equilibrium.
Effective sensitivities in the models:
Soden:
“The last column in the figure represent the effective sensitivity. They range in value from 0.88 W/m2/K to 1.64 W/m2/K. If you assume a canonical value for the radiative forcing from doubling CO2 of 4W/m2, you can estimate the corresponding surface temperature change as dT=dQ/eff_sens. The low end of the range for these models is 4/1.64 = 2.4 K. The high end of the range is 4/0.88=4.5. So the estimated range for this set of models (2.4-4.5 K) is slightly larger than that referred to at the top of the article.”
Standard estimate is:
5.3 ln(C/C0) = 3.4C for doubling of CO2.
NASA Langley’s ERBE team, who made the report by Wielicki et al. (2002) in “Science”, has revised their calibration. The increasing decadal trend of outgoing longwave radiation in the tropics still exists, but is much reduced in magnitude. Combined with the decreasing trend of reflected solar radiation (which has changed little by the revision), the net trend is now increase of gain by the earth (~ 1 W/m2 per decade). Analysis of ISCCP data at NASA GISS, though indirect as evaluation of radiation budgets, resulted in similar trend as the revised ERBE trend. See
http://eosweb.larc.nasa.gov/PRODOCS/erbe/quality_summaries/s10n_wfov/erbe_s10n_wfov_nf_sf_erbs_edition3.html
and a preprint of a paper by Wong et al. to be published in J. Climate at
http://asd-www.larc.nasa.gov/~tak/wong/f20m.pdf .
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