From a new paper by Dr. Greg Kopp and Dr. Judith Lean, new finding on the solar minimum TSI in 2008:
The most probable value of total solar irradiance representative of solar minimum is 1360.8 ± 0.5 W m−2, lower than the canonical value of 1365.4 ± 1.3 W m−2 recommended a decade ago. This new value, measured by SORCE/TIM, is validated by irradiance comparisons to a NIST‐calibrated cryogenic radiometer in the new TSI Radiometer Facility. Uncorrected scattering and diffraction are shown to cause erroneously high readings in non‐TIM instruments.
That’s lower by 4.6 watts per square meter. This may mean that many climate models will have to be reinitialized if it is decided that this value they derive from SORCE is more accurate than the value established previously.
By way of a forcing comparison to this suggested revision, according to NOAA ESRL:
The total effective climate forcing for all GHGs including CO2 and ozone (O3) from the beginning of the industrial revolution in 1750 to the year 2000 is 2.63 watts per square meter.
So a change of 4.6 watts per square meter to the old baseline TSI is more than double the total GHG forcings. (Averaged over the earth’s curvature, it works out to about 0.85 watts per meter*) That’s still not chump change. It will be interesting to see how this shakes out in models. It is important to note this caveat from their abstract:
TIM’s lower solar irradiance value is not a change in the Sun’s output, whose variations it detects with stability comparable or superior to prior measurements; instead, its significance is in advancing the capability of monitoring solar irradiance variations.
Improved measurements of sun to advance understanding of climate change
From Eurekalert: WASHINGTON—Scientists have taken a major step toward accurately determining the amount of energy that the sun provides to Earth, and how variations in that energy may contribute to climate change.
In a new study of laboratory and satellite data, researchers report a lower value of that energy, known as total solar irradiance, than previously measured and demonstrate that the satellite instrument that made the measurement—which has a new optical design and was calibrated in a new way—has significantly improved the accuracy and consistency of such measurements.
The new findings give confidence, the researchers say, that other, newer satellites expected to launch starting early this year will measure total solar irradiance with adequate repeatability – and with little enough uncertainty – to help resolve the long-standing question of how significant a contributor solar fluctuations are to the rising average global temperature of the planet.
“Improved accuracies and stabilities in the long-term total solar irradiance record mean improved estimates of the sun’s influence on Earth’s climate,” said Greg Kopp of the Laboratory for Atmospheric and Space Physics (LASP) of the University of Colorado Boulder.
Kopp, who led the study, and Judith Lean of the Naval Research Laboratory, in Washington, D.C., published their findings today in Geophysical Research Letters, a journal of the American Geophysical Union.
The new work will help advance scientists’ ability to understand the contribution of natural versus anthropogenic causes of climate change, the scientists said. That’s because the research improves the accuracy of the continuous, 32-year record of total solar irradiance, or TSI. Energy from the sun is the primary energy input driving Earth’s climate, which scientific consensus indicates has been warming since the Industrial Revolution.
Lean specializes in the effects of the sun on climate and space weather. She said, “Scientists estimating Earth’s climate sensitivities need accurate and stable solar irradiance records to know exactly how much warming to attribute to changes in the sun’s output, versus anthropogenic or other natural forcings.”
The new, lower TSI value was measured by the LASP-built Total Irradiance Monitor (TIM) instrument on the NASA Solar Radiation and Climate Experiment (SORCE) spacecraft. Tests at a new calibration facility at LASP verify the lower TSI value. The ground-based calibration facility enables scientists to validate their instruments under on-orbit conditions against a reference standard calibrated by the National Institute of Standards and Technology (NIST). Before the development of the calibration facility, solar irradiance instruments would frequently return different measurements from each other, depending on their calibration. To maintain a long-term record of the sun’s output through time, scientists had to rely on overlapping measurements that allowed them to intercalibrate among instruments.
Kopp said, “The calibration facility indicates that the TIM is producing the most accurate total solar irradiance results to date, providing a baseline value that allows us to make the entire 32-year record more accurate. This baseline value will also help ensure that we can maintain this important climate data record for years into the future, reducing the risks from a potential gap in spacecraft measurements.”
Lean said, “We are eager to see how this lower irradiance value affects global climate models, which use various parameters to reproduce current climate: incoming solar radiation is a decisive factor. An improved and extended solar data record will make it easier for us to understand how fluctuations in the sun’s energy output over time affect temperatures, and how Earth’s climate responds to radiative forcing.”
Lean’s model, which is now adjusted to the new lower absolute TSI values, reproduces with high fidelity the TSI variations that TIM observes and indicates that solar irradiance levels during the recent prolonged solar minimum period were likely comparable to levels in past solar minima. Using this model, Lean estimates that solar variability produces about 0.1o Celsius (0.18o Fahrenheit) global warming during the 11-year solar cycle, but is likely not the main cause of global warming in the past three decades.
GEOPHYSICAL RESEARCH LETTERS, VOL. 38, L01706, 7 PP., 2011
doi:10.1029/2010GL045777
A new, lower value of total solar irradiance: Evidence and climate significance
Greg Kopp
Laboratory for Atmospheric and Space Physics, Boulder, Colorado, USA
Judith L. Lean
Space Science Division, Naval Research Laboratory, Washington, D. C., USA
The most accurate value of total solar irradiance during the 2008 solar minimum period is 1360.8 ± 0.5 W m-2 according to measurements from the Total Irradiance Monitor (TIM) on NASA’s Solar Radiation and Climate Experiment (SORCE) and a series of new radiometric laboratory tests. This value is significantly lower than the canonical value of
1365.4 ± 1.3 W m-2 established in the 1990s, which energy balance calculations and climate models currently use. Scattered light is a primary cause of the higher irradiance values measured by the earlier generation of solar radiometers in which the precision aperture defining the measured solar beam is located behind a larger, view-limiting aperture. In the TIM, the opposite order of these apertures precludes this spurious signal by limiting the light entering the instrument. We assess the accuracy and stability of irradiance measurements made since 1978 and the implications of instrument uncertainties and instabilities for climate research in comparison with the new TIM data. TIM’s lower solar irradiance value is not a change in the Sun’s output, whose variations it detects with stability comparable or superior to prior measurements; instead, its
significance is in advancing the capability of monitoring solar irradiance variations on climate-relevant time scales and in improving estimates of Earth energy balance, which the Sun initiates.
Received 7 October 2010; accepted 30 November 2010; published 14 January 2011.
Citation: Kopp, G., and J. L. Lean (2011), A new, lower value of total
solar irradiance: Evidence and climate significance, Geophys. Res.
Lett., 38, L01706, doi:10.1029/2010GL045777.
See the paper here (PDF)
big h/t to Dr. Leif Svalgaard
* UPDATE: from ClimateWatcher in comments:
The TSI averaged over the earth’s surface area and the amount not reflected to space:
1/4 ( 1 – a ) * S
1/4 – the ratio of circle through which radiation passes to the surface are of sphere.
a – albedo ( let’s use 0.3 even though nobody knows for sure)
So the comparison should be
0.25 * 0.7 * 4.6 W/m^2
or about 0.85 W/m^2
That’s still not negligible but not a doubler.
Interesting to note that 0.85 W/m^2 was the amount the earth was supposedly
out of balance by per Hansen and Trenberth.
Given the uncertainty in Solar constant, albedo and mostly thermal emission,
there’s no way anyone really knows if the earth is out of balance or not.
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Hmmm, lower TSI, yet global temperatures keep increasing…hmmmm
REPLY: Wrong conclusion, see the caveat. This is a baseline recalibration, though TSI was lower during solar minimum as it always is. – Anthony
Hooray! Some real science on a measurement regime that feeds into global warming calculations. This is the first such work in the last thirty years. Now, if only the same could be done for the measurement regimes used on sea, land, and in the atmosphere. Then maybe we could get some trustworthy data. Climate science is hardly more than a newborn and the so-called scientists baying like wolves about the disaster of AGW should weaken their outrageous claims to bring them in line with actual evidence. Climate science as practiced by Hansen and friends is the apotheosis of hubris.
Strange, I have not seen a solar irradiance anomaly graph yet. Those are so trendy these days. But the best part is that you get to choose your average.
Excellent!
Science advances with improved data. This new instrument seems a real step forward.
It would be helpful to place comparable emphasis on the in orbit stability of the instrument, which is not mentioned much in the report.
Given the controversies that have arisen from adjustments to both terrestrial as well as orbital instrument readings relevant to monitoring the earth and the atmosphere, a stable TSI measurement is very much needed.
Separately, the difference from prior measures of TSI is about 4x the stated error range for the prior estimate. It would be useful to do a postmortem to analyze why the error was underestimated so substantially.
This sounds encouraging. Some real empirical science. Once we have another 30 years or so of data then maybe we can draw some real conclusions.
Re: rushmike
Hmmm, increased CO2 yet global temperatures remain stable…hmmmm
CAGW folks claim that a 3.7 watt/m2 forcing causes a 3-4deg C rise in temp.
The graph above shows that a forcing of about 1W/m2 over a solar cycle causes a temp increase of only 0.1deg C, or a sensitivity 10 times smaller than CAGW.
The main driver is cloud cover, as determined by the ERBE data.
I think it is time to stop taking paper recommendations from Leif,
“Using this model, Lean estimates that solar variability produces about 0.1o Celsius (0.18o Fahrenheit) global warming during the 11-year solar cycle, but is likely not the main cause of global warming in the past three decades.”
So a change of 4.6 watts per square meter to the old baseline TSI is more than double the total GHG forcings.
Not so.
The TSI averaged over the earth’s surface area and the amount not reflected to space:
1/4 ( 1 – a ) * S
1/4 – the ratio of circle through which radiation passes to the surface are of sphere.
a – albedo ( let’s use 0.3 even though nobody knows for sure)
So the comparison should be
0.25 * 0.7 * 4.6 W/m^2
or about 0.85 W/m^2
That’s still not negligible but not a doubler.
Interesting to note that 0.85 W/m^2 was the amount the earth was supposedly
out of balance by per Hansen and Trenberth.
Given the uncertainty in Solar constant, albedo and mostly thermal emission,
there’s no way anyone really knows if the earth is out of balance or not.
REPLY: Ah, excellent point if that calc is accurate. I’ll be happy to add this as a caveat. – Anthony
Does this mean they’ve found the missing heat?
The comparisons of forcing elements are not equal of course.
IPCC likes to throw everything into one pot
solar, CO2, O3, Sulfates, Black Carbon.
But they are not strictly comparable, even though we pretend so.
While we average solar over a sphere, many processes,
snowmelt for example, are more effected by the peak insolation,
not the diurnal or seasonal average.
CO2 emits to space in the stratosphere, while H2O emits from the troposphere.
Not all forcings are created equally in the mythical forcing calculation.
Amazing!! This is really breaking news.
Interesting, but not surprising, that there is a clear correlation between TSI and sunspot activity, which varies in the range of 1-2 W/m2 between minima and maxima.
The next question is whether there is a negative feedback caused by increased cloud formation owing to more Cosmic Gamma Rays interacting with condensation nucleii during periods of low solar activity…..
If, as is beginning to look likely, we are entering a period of prolonged minimum solar activity, then the next 20-30 years promise to be very instructive indeed.
Let’s hope their are enough climate scientists prepared to remove their heads from the sand and attend the “lecture”.
Its been dark so long that when you see a pin prick of light at the end of a tunnel it can be blinding.
Long live the scientific method gone missing these past 10 years. Hopefully the sums add for either side of the debate.
It is in error to only use TSI to evaluate the sun’s influence on earth’s climate.
rushmike says:
January 14, 2011 at 3:28 pm
Hmmm, lower TSI, yet global temperatures keep increasing…hmmmm
No. Wrong. Earth’s temperature does not continue to increase. It is in error to determine what is happening in global temperature trend at this moment. Global mean temperature is now biased by the El Nino that ended in May 2010. One needs to wait until the current La Nina has bottomed out to get a nore accurate guage on trend.
In any case, we can all conclude that there has been no statistically significant warming for 16 years. It was 15 years but you can add 1 year on since nothing statistically significant happened since it was 15 years 1 year ago.
If the new TSI data is correct it now aligns with the EUV values recorded over the past minimum showing a decline in the base level. The plot thickens.
“Using this model, Lean estimates that solar variability produces about 0.1o Celsius (0.18o Fahrenheit) global warming during the 11-year solar cycle, but is likely not the main cause of global warming in the past three decades.”
==========
O.K., but brings a transistor to mind. ??
It is a recalibration that changes the number for the insolation for the models and energy balance equations?
Does this mean that Trenberth’s energy never made it to the earth?
If not, please include a dummies guide for this dummy.
The earth has no energy balance. The sun is the only forcing and obviously the k&t diagram is a load of nonsense since the numbers are meaningless! Science is lost.
Geoff Sharp says:
January 14, 2011 at 4:34 pm
If the new TSI data is correct it now aligns with the EUV values recorded over the past minimum showing a decline in the base level. The plot thickens.
The data does not allow this conclusion.
Quote: “Disagreement among overlapping observations, as apparent in Figure 3, indicates undetected drifts that suggest the TSI record is not sufficiently stable to discern solar changes on decadal time scales.“
“So a change of 4.6 watts per square meter to the old baseline TSI is more than double the total GHG forcings”
Good try, but no. 2.63*2=5.26. 5.26 is more than 4.6, not less. You also seem not to know that to calculate the solar forcing, you need to divide the change in TSI by 4, because solar radiation falls on half of a rotating planet, and then multiply by 0.7 to account for the fact that 30% is reflected. So now we have not 4.6 but 0.805W/m². That’s quite a lot less than the greenhouse gas forcings. And finally you seem not to have understand that this is not even a forcing, even though you manage to quote the bit about “TIM’s lower solar irradiance value is not a change in the Sun’s output”.
I think you have to really want to be wrong to get that much wrong in such a short article.
This new baseline value of 1360.8 Watt/m2 solar intensity was seen since long in all SORCE data. The question was, where is the calibration problem, with the old satellite data which give 1365 W/m2 or the new ones, delivered by SORCE. Or are there real shifts in solar intensities from minimum to minimum? Only then this would have consequences for the climate. I guess, Leif would insist that there are no such solar intensity changes from one solar minimum to the next.
It is interesting to note that Old Abbot’s terrestrial data, taken between 1923 and 1954, give the baseline value of 1357 W/m2. Not bad for those guys from Smithsonian Astrophysical Observatory. Maybe Abbot’s data are trustworthy, after all?
See http://www.ngdc.noaa.gov/stp/solar/solarirrad.html#abbot
Werner Weber says:
January 14, 2011 at 5:35 pm
I guess, Leif would insist that there are no such solar intensity changes from one solar minimum to the next.
What I would say [a bit more conservatively] is that such changes have not been demonstrated. Accepting that SORCE/TIM has the best calibration one can intercalibrate with the other instruments. E.g. with PMOD that was the one showing a decrease this past minimum. Greg Kopp and I looked at this early last year and with this result:
http://www.leif.org/research/PMOD%20TSI-SOHO%20keyhole%20effect-degradation%20over%20time.pdf
Climate Watcher’s formula above is correct for the solar forcing in watts/m2.
And then if one calculated the temperature impact using the Stefan-Boltzmann equations, it would only be about a 0.15C difference.
So the Earth’s average surface temperature is 14.35C instead of 14.50C. Noone really knows what this number is anyway so it doesn’t matter particularly.
It will not result in the climate models having to make major adjustments since there is already a very wide margin in what the models simulate the Earth’s average temperature to be. The range is literally from 16.0C to 13.0C according to some data that lucia put together.
http://rankexploits.com/musings/wp-content/uploads/2009/03/temperatures_absolute.jpg