Dr Gray: 2xCO2 up global temp only 10% as much as GCM’s suggest; 0.7C rise from ocean salinity chgs

[GaWx]

 Dr. William Gray believes that the GCM simulation average result of a 3.0 C global sfc temp. increase resuling from doubling the CO2 is about ten times too high due to faulty model assumptions and that it really is only ~0.3 C.

 

 A. Gray says there are two main components assumed by GCM's that erroneously result in that +3.0 C:

 

 1. Direct warming from increased CO2: +1.0 C.

 

 2. Indirect warming from the positive feedback resulting from increased water vapor: +2.0 C

 

 So, +1.0 C + 2.0 C = +3.0 C

 

 

 

B. Gray says it is really as follows:

 

1. Direct warming from increased CO2: +0.5 C. He says that the GCM's incorrectly assume no energy loss due to surface evaporation. The evaporation uses up about half. Otherwise, the direct warming would be 1.0 C. (see section 1 of Gray's linked report)

 

2. Indirect COOLING from NEGATIVE feedback resulting from increased water vapor: -0.2 C. (see figures 8, 9, 16, and 17 of Gray's report).

From section 3 of Gray's report, here is a key paragraph:

 

 "Our observational studies (Gray and Schwartz, 2010 and 2011) of the variations of outward radiation (IR + albedo) energy flux to space (ISCCP data) vs. tropical and global precipitation increase (from NCEP reanalysis data) indicates that there is not a reduction of global net radiation (IR + Albedo) to space which is associated with increased global or tropical-regional rainfall. There is, in fact, a weak tendency to go the opposite way."

 

 Also, from that same section within the caption for figure 8, "The top diagram emphasizes the increasing extra mass flow return subsidence associated with an ever increasing depth and intensity of cumulus convection. Radiation flux to space increases with enhanced deep convection and rainfall due to a lowering of the upper-level emission level and an increase in albedo."

 

So, +0.5 C - 0.2 C = +0.3 C

 

 

C. Gray says that changes in salinity in the upper oceans (more salinity means denser water which means sinking water; ice formation increases salinity of water right below it because the ice formation leaves the salt behind in the liquid water), which have lead to the overall weakening of the global oceans' Meridional Overturning Circulation (MOC), have been the main driver for the 0.7 C global temp. rise since the late 1800's as opposed to AGW having been a major factor. Within that period, mulitidecadal long ups and downs in global temp.'s within the general warming trend have been due to mulitdecadal variations of the general trend. See section 4.

 

 

 Here is a link to Gray's report:

 

http://typhoon.atmos.colostate.edu/Includes/Documents/Publications/gray2012.pdf

 

 

 I'd love to see some comments from all sides of the debate with regard to this interesting paper from a very well respected scientist. IF he's right, AGW is overstated by the GCM average by a factor of about 10!

[Snow_Miser]

As every year goes by without additional warming, it's becoming abundantly clear that Climate Sensitivity has been grossly overestimated by GCMs. We have seen only a small fraction of the warming that was expected in the Tropical Mid Troposphere. Why is it significant? Because that's the signature of a strong negative lapse rate feedback and a strong positive water vapor feedback. If the warming is greatly exaggerated, the lapse rate and water vapor feedbacks are likely much closer to zero than what the models projected. Thus, Climate Sensitivity is likely much lower than what the models suggest it to be.

 

 

So far, the period in 2011-2020 is starting off cooler than in 2001-2010, further confirming the hiatus in recent years.

 

[AvantHiatus]

First of all, is it not a bit outlandish to forecast a 3 degree C rise in such a short period. Warming and cooling events have been slow processes throughout Earth history. Even a rate of 0.3 per decade is still rather unprecedented. 

[Snow_Miser]

First of all, is it not a bit outlandish to forecast a 3 degree C rise in such a short period. Warming and cooling events have been slow processes throughout Earth history. Even a rate of 0.3 per decade is still rather unprecedented. 

 

Dr. Gray isn't talking about 0.3 Degrees C per decade. He's talking about 0.3 Degrees C from an equilibrium doubling of CO2.

 

That seems too low IMO.

[GaWx]

First of all, is it not a bit outlandish to forecast a 3 degree C rise in such a short period. Warming and cooling events have been slow processes throughout Earth history. Even a rate of 0.3 per decade is still rather unprecedented. 

 

 As Snowlover said, Gray is not predicting anything close to 0.3 C/decade. He is predicting 0.3 C from the doubling of CO2 taking multiple decades. Do you think that his estimate of 0.5 C from direct warming and -0.2 from increased water vapor is reasonable from doubling CO2? If not, why not and do you think it is slower or faster?

[csnavywx]

Gray's theory is just Linzden's debunked "Iris" theory with a twist. How do Gray's theories explain the massive, consistent rise in 0-2000m OHC? They can't.

 

The fact is that 90% of the additional trapped energy via CO2+feedbacks is absorbed into the oceans. The IPO (Interdecadal Pacific Oscillation) is one of the dominant factors in helping modulate whether this heat is sequestered into the deeper layers of the ocean or whether it is released into the atmosphere preferentially. The fact that we haven't been cooling at the surface during this phase of strong deep ocean heat sequestration should be a red flag that we're overloading the system via strong external radiative forcing, and when the phase flips, the consequences will be felt at the surface. Most GCM simulations that incorporate the IPO actually show regular 10-15 year periods where little if any warming occurs at the surface (when the IPO is negative). Those same simulations also show equally regular 10-15 year periods (when the IPO is positive) where surface warming is on the order of 0.3 to 0.4C/decade on a low-moderate emissions path. One cannot also forget aerosol loading/forcing trends, which is still an important factor in a world that burns as much coal as we do.

[Snow_Miser]

Gray's theory is just Linzden's debunked "Iris" theory with a twist. How do Gray's theories explain the massive, consistent rise in 0-2000m OHC? They can't.

 

The fact is that 90% of the additional trapped energy via CO2+feedbacks is absorbed into the oceans. The IPO (Interdecadal Pacific Oscillation) is one of the dominant factors in helping modulate whether this heat is sequestered into the deeper layers of the ocean or whether it is released into the atmosphere preferentially. The fact that we haven't been cooling at the surface during this phase of strong deep ocean heat sequestration should be a red flag that we're overloading the system via strong external radiative forcing, and when the phase flips, the consequences will be felt at the surface. Most GCM simulations that incorporate the IPO actually show regular 10-15 year periods where little if any warming occurs at the surface (when the IPO is negative). Those same simulations also show equally regular 10-15 year periods (when the IPO is positive) where surface warming is on the order of 0.3 to 0.4C/decade on a low-moderate emissions path. One cannot also forget aerosol loading/forcing trends, which is still an important factor in a world that burns as much coal as we do.

 

I disagree strongly that Gray's hypothesis is like Lindzen's hypothesis. Lindzen's hypothesis concerns High Clouds decreasing in response to warming, which allows for more heat to be radiated out to space. Gray's hypothesis requires more clouds, so that more sunlight is reflected out to space, providing a negative feedback. OHC measurements are tentative at best, and should not be a dataset in which we should base meaningful conclusions off of.

 

One thing that I posted with GCMs is that they have grossly overestimated the rate at which temperatures have been increasing in the Tropical Mid Troposphere over the last 30-35 years. This is evidence that they have overestimated the water vapor and particularly, the lapse rate feedbacks. If the water vapor and lapse rate feedbacks are close to zero, then climate sensitivity will thus be lower than the 3.1 Degree C equilibrium doubling in GCMs. If the net cloud feedback is negative, then climate sensitivity will be even lower.

 

Should also be noted that we haven't seen a hiatus this long since the early 1970s, so this hiatus period should not be considered to be just another regular 10-15 year hiatus period.

[ben4vols]

Gray's theory is just Linzden's debunked "Iris" theory with a twist. How do Gray's theories explain the massive, consistent rise in 0-2000m OHC? They can't.

 

You are assuming that OHC is correct and that is a big assumption. 

[AvantHiatus]

 As Snowlover said, Gray is not predicting anything close to 0.3 C/decade. He is predicting 0.3 C from the doubling of CO2 taking multiple decades. Do you think that his estimate of 0.5 C from direct warming and -0.2 from increased water vapor is reasonable from doubling CO2? If not, why not and do you think it is slower or faster?

Well, the estimate appears to be a bit conservative because we have not reached equilibrium for current CO2 levels. There was a study on sea levels done that revealed the oceans were as much as 12 feet higher at current CO2 levels in the distant past (sea level follows temperature). I have traditionally focused on ocean temperatures rather than land temperatures when studying global warming and have concluded that a large percentage of global warming is essentially inside the oceans. 

 

Of course, there are negative feedbacks to consider like increased cloud cover which is where I think Grey's insight is valuable. I think we would see at  a 1.0c rise alone without doubling the CO2 by 2050.

 

While this hiatus period is impressive, it's not enough to convince me that global warming is less than advertised. I recognize that there has been a very impressive conjunction of factors such as reduced solar activity and a -PDO La Nina era counter-acting global warming.

[Snow_Miser]

Well, the estimate appears to be a bit conservative because we have not reached equilibrium for current CO2 levels. There was a study on sea levels done that revealed the oceans were as much as 12 feet higher at current CO2 levels in the distant past (sea level follows temperature). I have traditionally focused on ocean temperatures rather than land temperatures when studying global warming and have concluded that a large percentage of global warming is essentially inside the oceans. 

 

Yes, I agree that the 0.3 Degree C number is probably conservative. However, there is likely a significant natural component to the 20th Century Warming. Even if only half is natural, that means that the anthropogenic forcing only caused a 0.35 Degree C response, which would indicate a lower climate sensitivity than 3 Degrees C.

[skierinvermont]

1. The evidence for a climate sensitivity of 3C is not based upon models. An equilibrium sensitivity of 2-4.5C is supported by multiple independent lines of evidence. 

 

http://www.skepticalscience.com/climate-sensitivity-advanced.htm

 

2. Such a low climate sensitivity cannot come come to explaining the large increase in OHC over the last century. OHC estimates are supported by multiple independent lines of evidence, including satellites, tide gauges, and temperature buoys. 

 

3. Strong empirical and theoretical evidence shows that the water vapor feedback is strongly positive, not negative. Atmospheric water vapor has been observed to steadily increase by satellites as the earth warmed. The drop in temperature following the eruption of Pinatubo caused a precipitous drop in atmospheric water vapor. Finally, warm air holds more water and leads to more evaporation. A positive water vapor feedback is strongly supported by the evidence.

 

4. The data in the chart of tropical tropospheric temperature presented by SL is not considered reliable even by the authors of the data themselves. Presenting unreliable experimental data as fact is one of the hallmarks of denial. 

 

5. Finally, SL's selection of the period 2001-2013 to present temperature trends is extremely biased. While that period shows essentially zero warming, if we move the start date just two years earlier, one finds .15C/decade of warming which is exactly what is expected by climate models. SL's chart starts the trend in 2001 because 2001 was the start of the most positive 4 year +ENSO period in history. When selecting trends over short time periods it is important to control for factors such as ENSO. 1999-present is shows little trend in ENSO and is thus not strongly biased by changes in ENSO. Cherry-picking is another hallmark of denial. 

[Snow_Miser]

1. The evidence for a climate sensitivity of 3C is not based upon models. An equilibrium sensitivity of 2-4.5C is supported by multiple independent lines of evidence. 

 

http://www.skepticalscience.com/climate-sensitivity-advanced.htm

 

2. Such a low climate sensitivity cannot come come to explaining the large increase in OHC over the last century. OHC estimates are supported by multiple independent lines of evidence, including satellites, tide gauges, and temperature buoys. 

 

3. Strong empirical and theoretical evidence shows that the water vapor feedback is strongly positive, not negative. Atmospheric water vapor has been observed to steadily increase by satellites as the earth warmed. The drop in temperature following the eruption of Pinatubo caused a precipitous drop in atmospheric water vapor. Finally, warm air holds more water and leads to more evaporation. A positive water vapor feedback is strongly supported by the evidence.

 

4. The data in the chart of tropical tropospheric temperature presented by SL is not considered reliable even by the authors of the data themselves. Presenting unreliable experimental data as fact is one of the hallmarks of denial. 

 

5. Finally, SL's selection of the period 2001-2013 to present temperature trends is extremely biased. While that period shows essentially zero warming, if we move the start date just two years earlier, one finds .15C/decade of warming which is exactly what is expected by climate models. SL's chart starts the trend in 2001 because 2001 was the start of the most positive 4 year +ENSO period in history. When selecting trends over short time periods it is important to control for factors such as ENSO. 1999-present is shows little trend in ENSO and is thus not strongly biased by changes in ENSO. Cherry-picking is another hallmark of denial. 

 

1) If we were to have a Climate Sensitivity of 3 Degrees C, by itself, we should have expected a warming over the 20th Century from Carbon Dioxide to be 1.33 Degrees C. Since we have come no where even close to that, it brings up two possibilities.

 

-Aerosols are significantly masking the warming

-Climate Sensitivity is no where as large as 3 Degrees C.

-Or, it could be a combination of the above two things.

 

The problem is that the aerosol forcing is significantly uncertain. If it's -0.2 w/m^2, then it's not masking that much warming. If it's -2 w/m^2, then it's masking a lot of warming. The only problem is that the aerosol forcing is uncertain, so we don't really know how much warming it's masking.

 

Secondly, a significant natural component to the warming seems likely. After all, solar activity increased dramatically during the 20th Century to levels not seen in 10,000 years, so it seems likely that this would have some impact on climate change during the 20th Century. Solar Activity alone can explain up to 0.5 Degrees C of the warming, leaving for less of a contribution from the anthropogenic forcing.

 

 

2) OHC estimates over the last Century are EXTREMELY tentative. We really did not get a very widespread Global observation network until in 2003 when ARGO floats were deployed to measure OHC. Even so, the ARGO floats have had their share of instrumentation problems as well.

 

In 1985, there were almost no measurements below 1000 meters. Like I said, it's a very sparse dataset that we should not have much confidence in, and concluding that OHC changes are too large to be explained by a lower climate sensitivity is deliberately misleading, and neglects huge uncertainties.

 

 

Note that the above chart shows where measurements were taken for the entire year. They were not all taken at once, making the OHC dataset even more spotty than what is shown above.

 

From here.

 

3) It's basic physics that Boundary Layer Humidification will occur with warming. However, the relative influence from Boundary Layer Humidification is quite small when compared to the Upper Tropospheric changes in Humidity. There are some rough measurements from NVAP that do show a decrease in Water Vapor in the Upper Troposphere. Blizzard was having a discussion with you on this. He mentioned convective overturning as a possible mechanism for this observation.

 

 

While this may not totally cancel out the influence from the Positive Water Vapor Feedback in the boundary layer, it would significantly lessen the influence. Thus, this would be able to explain why the Tropical Middle Troposphere hasn't warmed nearly as much as modeled.

 

4) That's not true. Dr. Spencer and Dr. Christy both worked on that chart, and consider it to be reliable.

 

5) I didn't create that chart. Pierre L. Gosselin created that chart in a bet with Rob Honeycutt and Dana Nuccietelli. Rob and Dana agreed that 2011-2020 would be significantly warmer than 2001-2010. Others said it would be cooler. We shall see who wins in the end, but so far, this decade is starting off cooler than the decade in 2001-2010. Sure ENSO is partially responsible, but other factors like the -PDO and reduced solar activity may certainly play a role as well. Rob and Dana believe that the CO2 forcing can overwhelm any other source of natural variability, so thus, they say that 2011-2020 will be warmer than 2001-2010. The point is that the hiatus period continues, regardless of it's cause, and such a lengthy hiatus period has not been seen in over 40 years.

 

[ORH_wxman]

1. The evidence for a climate sensitivity of 3C is not based upon models. An equilibrium sensitivity of 2-4.5C is supported by multiple independent lines of evidence. 

 

http://www.skepticalscience.com/climate-sensitivity-advanced.htm

 

2. Such a low climate sensitivity cannot come come to explaining the large increase in OHC over the last century. OHC estimates are supported by multiple independent lines of evidence, including satellites, tide gauges, and temperature buoys. 

 

3. Strong empirical and theoretical evidence shows that the water vapor feedback is strongly positive, not negative. Atmospheric water vapor has been observed to steadily increase by satellites as the earth warmed. The drop in temperature following the eruption of Pinatubo caused a precipitous drop in atmospheric water vapor. Finally, warm air holds more water and leads to more evaporation. A positive water vapor feedback is strongly supported by the evidence.

 

4. The data in the chart of tropical tropospheric temperature presented by SL is not considered reliable even by the authors of the data themselves. Presenting unreliable experimental data as fact is one of the hallmarks of denial. 

 

5. Finally, SL's selection of the period 2001-2013 to present temperature trends is extremely biased. While that period shows essentially zero warming, if we move the start date just two years earlier, one finds .15C/decade of warming which is exactly what is expected by climate models. SL's chart starts the trend in 2001 because 2001 was the start of the most positive 4 year +ENSO period in history. When selecting trends over short time periods it is important to control for factors such as ENSO. 1999-present is shows little trend in ENSO and is thus not strongly biased by changes in ENSO. Cherry-picking is another hallmark of denial. 

 

 

I would argue that this range is becoming a more shakey on the higher half of its spectrum as we go through time. A lot of papers since 2009 have been finding more like 1.5-2.8C type sensitivity. The CMIP5 models (to be used for AR5) and also the previous set of GCMs in AR4 are generally too sensitive to the Pinatubo Eruption when it comes to sfc temps and SSTs and are also not robust enough with early 20th century warming. This suggests that either the climate sensitivty to CO2 is too high, or the manifestation of it is much slower than the models show which means warming would be more gradual...but given that the Pinatubo effects in temperature were essentially gone after 3 years in reality, it tends to point more toward a lower sensitivity.

 

Of course, none of this supports a sensitivty as ludicrously low as 0.3C either.

[Snow_Miser]

I would argue that this range is becoming a more shakey on the higher half of its spectrum as we go through time. A lot of papers since 2009 have been finding more like 1.5-2.8C type sensitivity. The CMIP5 models (to be used for AR5) and also the previous set of GCMs in AR4 are generally too sensitive to the Pinatubo Eruption when it comes to sfc temps and SSTs and are also not robust enough with early 20th century warming. This suggests that either the climate sensitivty to CO2 is too high, or the manifestation of it is much slower than the models show which means warming would be more gradual...but given that the Pinatubo effects in temperature were essentially gone after 3 years in reality, it tends to point more toward a lower sensitivity.

 

Of course, none of this supports a sensitivty as ludicrously low as 0.3C either.

 

Without the Cloud Feedback in the GCMs, they would predict an equilibrium doubling of 1.9 Degrees C. It's predominantly the Cloud Feedback that is the final "push" to the 3.2 Degree C equilibrium doubling. Unfortunately, the Cloud Feedback still is pretty uncertain. Of course, if the Cloud Feedback is negative, then it could be much closer to 1 Degree C.

 

From the IPCC section 8.6.2.3:

 

Using feedback parameters from Figure 8.14, it can be estimated that in the presence of water vapour, lapse rate and surface albedo feedbacks, but in the absence of cloud feedbacks, current GCMs would predict a climate sensitivity (±1 standard deviation) of roughly 1.9°C ± 0.15°C (ignoring spread from radiative forcing differences). The mean and standard deviation of climate sensitivity estimates derived from current GCMs are larger (3.2°C ± 0.7°C) essentially because the GCMs all predict a positive cloud feedback (Figure 8.14) but strongly disagree on its magnitude.

[bluewave]

We also have to take slow feedbacks and ESS into account.

 

http://www.nature.com/ngeo/journal/v3/n1/abs/ngeo706.html

 

 

Earth system sensitivity inferred from Pliocene modelling and data

Daniel J. Lunt^1,2, Alan M. Haywood³, Gavin A. Schmidt⁴, Ulrich Salzmann^2,5, Paul J. Valdes¹ & Harry J. Dowsett⁶

 

Abstract

Quantifying the equilibrium response of global temperatures to an increase in atmospheric carbon dioxide concentrations is one of the cornerstones of climate research. Components of the Earth’s climate system that vary over long timescales, such as ice sheets and vegetation, could have an important effect on this temperature sensitivity, but have often been neglected. Here we use a coupled atmosphere–ocean general circulation model to simulate the climate of the mid-Pliocene warm period (about three million years ago), and analyse the forcings and feedbacks that contributed to the relatively warm temperatures. Furthermore, we compare our simulation with proxy records of mid-Pliocene sea surface temperature. Taking these lines of evidence together, we estimate that the response of the Earth system to elevated atmospheric carbon dioxide concentrations is 30–50% greater than the response based on those fast-adjusting components of the climate system that are used traditionally to estimate climate sensitivity. We conclude that targets for the long-term stabilization of atmospheric greenhouse-gas concentrations aimed at preventing a dangerous human interference with the climate system should take into account this higher sensitivity of the Earth system.

 

http://www.skepticalscience.com/hansen-and-sato-2012-climate-sensitivity.html

 

Hansen and Sato examine the longer-term Earth System Sensitivity by adding in slowfeedbacks one-by-one, starting with surface albedo.  Hansen and Sato note the longer-term sensitivity is

"...more dependent on the initial 

climate

 state and the sign of the forcing. The fast-

feedback

 

climate sensitivity

 is a reasonably smooth curve, because the principal fast-

feedback

 mechanisms (water vapor, clouds, 

aerosols

, 

sea ice

) do not have sharp threshold changes. Minor exceptions, such as the fact that Arctic 

sea ice

 may disappear with a relatively small increase of 

climate

 forcing above the 

Holocene

 level, might put a small wave in the fast-

feedback

 curve."

This initial state dependency is illustrated by the more complex shape of the upper curve in Figure 1 above.  For example, during a cooling event to a glacial period like the LGM, the long-term Earth System Sensitivity is approximately 6°C for an equivalent forcing to a doubling (or in this case halving) of CO2.  This is primarily due to the increase in the Earth's reflectivity as large ice sheets form.

During a period like the Holocene while warming to a Pliocene-like climate, slowfeedbacks (such as reduced ice and increased vegetation cover) increase the sensitivity to around 4.5°C for doubled CO2.  However, a climate warm enough to lose the entire Antarctic ice sheet would have a long-term sensitivity of close to 6°C.  Fortunately it would take a very long time to lose the entire Antarctic ice sheet.

Note also that the Earth System Sensitivity is deduced from various past climate changeevents like the Paleocene–Eocene Thermal Maximum (PETM), but the qualitative estimates of longer-term climate sensitivity are less precise than the HS12 fast feedbacksensitivity estimates.  Hence the authors note that Figure 1 above is a schematic.

 

[Snow_Miser]

We would need a ridiculous amount of warming to be "masked" in order to even consider the 4.5 Degree C numbers that Bluewave posted with the Paleoclimate papers to even be plausible. We've warmed 0.7 Degrees C, and with that high of a sensitivity, around 1 degree C should have been masked, assuming all of the warming is anthropogenic (not correct). When we assume that a natural factor has also contributed to the warming, the amount of warming being masked goes up even more.

 

In addition, a bunch of papers have recently come out which shows that the vertical amplification of the warming in the middle troposphere has been significantly exaggerated, suggesting a lapse rate feedback closer to zero, implicitly stating that the Water Vapor Feedback will be closer to zero, since the two are closely linked.

 

From "Plausible reasons for the inconsistencies between the modelled and observed temperatures in the tropical troposphere:"

 

We herewith attempt to detect plausible reasons for the discrepancies between the measured and modeled tropospheric temperature anomalies in the tropics. For this purpose, we calculate the trends of the upper-minus-lower tropospheric temperature anomaly differences (TAD) for both the measured and modeled time series during 1979-2010. The modeled TAD trend is significantly higher than that of the measured ones, confirming that the vertical amplification of warming is exaggerated in models. To investigate the cause of this exaggeration, we compare the intrinsic properties of the measured and modelled TAD by employing detrended fluctuation analysis (DFA). The DFA-exponent obtained for the measured values reveals white noise behaviour, while the exponent for the modelled ones shows that they exhibit long-range power law correlations. We suggest that the vertical amplification of warming derived from modelled simulations is weighted with a persistent signal, which should be removed in order to achieve better agreement with observations.

[PhillipS]

We would need a ridiculous amount of warming to be "masked" in order to even consider the 4.5 Degree C numbers that Bluewave posted with the Paleoclimate papers to even be plausible. We've warmed 0.7 Degrees C, and with that high of a sensitivity, around 1 degree C should have been masked, assuming all of the warming is anthropogenic (not correct). When we assume that a natural factor has also contributed to the warming, the amount of warming being masked goes up even more.

 

In addition, a bunch of papers have recently come out which shows that the vertical amplification of the warming in the middle troposphere has been significantly exaggerated, suggesting a lapse rate feedback closer to zero, implicitly stating that the Water Vapor Feedback will be closer to zero, since the two are closely linked.

 

From "Plausible reasons for the inconsistencies between the modelled and observed temperatures in the tropical troposphere:"

 

We herewith attempt to detect plausible reasons for the discrepancies between the measured and modeled tropospheric temperature anomalies in the tropics. For this purpose, we calculate the trends of the upper-minus-lower tropospheric temperature anomaly differences (TAD) for both the measured and modeled time series during 1979-2010. The modeled TAD trend is significantly higher than that of the measured ones, confirming that the vertical amplification of warming is exaggerated in models. To investigate the cause of this exaggeration, we compare the intrinsic properties of the measured and modelled TAD by employing detrended fluctuation analysis (DFA). The DFA-exponent obtained for the measured values reveals white noise behaviour, while the exponent for the modelled ones shows that they exhibit long-range power law correlations. We suggest that the vertical amplification of warming derived from modelled simulations is weighted with a persistent signal, which should be removed in order to achieve better agreement with observations.

 

Your first claim, that the Earth has only warmed 0.7 C, is demonstrably wrong and, therefore, the remainder of your arguments are very weak.  I'm sure you've seen the global surface temperature record from the BEST project but let's look at it again:

 

 

As anyone can see, from the start of the Industrial Revolution in 1760 to the present the Global Surface Temperature has risen more than 1.5 C.  If one were to cherrypick the starting date one could even show that the temperature has risen 2 C - but cherrypicking is childish, as I'm sure you'll agree.  So for the purposes of this post I'll use the conservative value of 1.5 C.

 

In that same period of time our burning fossil fuels has raised the atmospheric concentration of CO2 from 280 ppm to 400 ppm, an increase of about 40%.  Are we in agreement so far?

 

If all of the observed warming were anthropogenic the fast response sensitivity to a doubling of CO2 would be around 3.75 C  (1.5/0.4).  But I think most of us would agree that the observed warming has been a mix of natural processes and AGW.  So how best to split that 1.5 C warming between natural and anthropogenic?  50-50?  40-60?  20-80?  My opinion, based on the papers I've read, is that the majority of the observed warming is due to AGW - so for this post I'll arbitrarily use a 1/3-2/3 split.  That's 0.5 C of natural warming and 1.0 C of anthropogenic warming.  1.0 C of fast response warming from a 40% increase in CO2 represents an equilibrium sensitivity greater than 2.5C.  Say, 3 C to 3.5 C.

 

Now let's do a reality check by calculating sensitivity using a starting point of 1975.  From the BEST chart the global surface temperature increase since 1975 has been about 0.8 C, and the CO2 concentration has gone from 330 ppm in 1975 to 400 ppm today, an increase of about 20%.  If the 0.8 C was all anthropogenic then the fast response sensitivity would be around 4.0 C.  Using same 1/3-2/3 split as above, the fast response sensitivity works out to around 2.7 C and the equilibrium around 3 to 3.5 C.

 

Those estimates, though admittedly crude, are in reasonably close agreement.  You've presented no plausible evidence that the climate sensitivity is less than the IPCC estimates.  Your ignoring the global temperature record, ignoring radiative physics, and offering only rhetorical handwaving that the observed warming MUST be natural isn't convincing anyone with a brain.

[Snow_Miser]

Your first claim, that the Earth has only warmed 0.7 C, is demonstrably wrong and, therefore, the remainder of your arguments are very weak.  I'm sure you've seen the global surface temperature record from the BEST project but let's look at it again:

 

 

As anyone can see, from the start of the Industrial Revolution in 1760 to the present the Global Surface Temperature has risen more than 1.5 C.  If one were to cherrypick the starting date one could even show that the temperature has risen 2 C - but cherrypicking is childish, as I'm sure you'll agree.  So for the purposes of this post I'll use the conservative value of 1.5 C.

 

In that same period of time our burning fossil fuels has raised the atmospheric concentration of CO2 from 280 ppm to 400 ppm, an increase of about 40%.  Are we in agreement so far?

 

If all of the observed warming were anthropogenic the fast response sensitivity to a doubling of CO2 would be around 3.75 C  (1.5/0.4).  But I think most of us would agree that the observed warming has been a mix of natural processes and AGW.  So how best to split that 1.5 C warming between natural and anthropogenic?  50-50?  40-60?  20-80?  My opinion, based on the papers I've read, is that the majority of the observed warming is due to AGW - so for this post I'll arbitrarily use a 1/3-2/3 split.  That's 0.5 C of natural warming and 1.0 C of anthropogenic warming.  1.0 C of fast response warming from a 40% increase in CO2 represents an equilibrium sensitivity greater than 2.5C.  Say, 3 C to 3.5 C.

 

Now let's do a reality check by calculating sensitivity using a starting point of 1975.  From the BEST chart the global surface temperature increase since 1975 has been about 0.8 C, and the CO2 concentration has gone from 330 ppm in 1975 to 400 ppm today, an increase of about 20%.  If the 0.8 C was all anthropogenic then the fast response sensitivity would be around 4.0 C.  Using same 1/3-2/3 split as above, the fast response sensitivity works out to around 2.7 C and the equilibrium around 3 to 3.5 C.

 

Those estimates, though admittedly crude, are in reasonably close agreement.  You've presented no plausible evidence that the climate sensitivity is less than the IPCC estimates.  Your ignoring the global temperature record, ignoring radiative physics, and offering only rhetorical handwaving that the observed warming MUST be natural isn't convincing anyone with a brain.

 

Not sure why you are using Land Temperature from BEST to refute my claim that Global Temperatures have increased 0.7 Degrees C.

 

From the link:

 

"Expressed as a global average, surface temperatures have increased by about 0.74°C over the past hundred years (between 1906 and 2005; see Figure 1)."

 

That's well established science. A significant portion of the late-20th Century Warming is likely due to the PDO/AMO flipping to their positive state, accelerating the long term warming trend.

 

From Wu et al. 2012.

 

"The Earth has warmed at an unprecedented pace in the decades of the 1980s and 1990s. In Wu et al. (2007) we showed that the rapidity of the warming in the late twentieth century was a result of concurrence of a secular warming trend and the warming phase of a multidecadal (~65-year period) oscillatory variation and we estimated the contribution of the former to be about 0.08°C per decade since ~1980. Here we demonstrate the robustness of those results and discuss their physical links, considering in particular the shape of the secular trend and the spatial patterns associated with the secular trend and the multidecadal variability. The shape of the secular trend and rather globally-uniform spatial pattern associated with it are both suggestive of a response to the buildup of well-mixed greenhouse gases. In contrast, the multidecadal variability tends to be concentrated over the extratropical Northern Hemisphere and particularly over the North Atlantic, suggestive of a possible link to low frequency variations in the strength of the thermohaline circulation. Depending upon the assumed importance of the contributions of ocean dynamics and the time-varying aerosol emissions to the observed trends in global-mean surface temperature, we estimate that up to one third of the late twentieth century warming could have been a consequence of natural variability."

 

 

 

You can see that in the image above, once the data is detrended, a very evident 60 year natural cycle can be seen, and correspond well with the PDO values.

 

 

So one should be careful when interpreting the late-20th Century as somehow an acceleration of Man Made Global Warming. That's why it's better to use the long term trend of 0.7 Degrees C/100 years since the multidecadal variability can early been seen as being superimposed on a long term warming trend.

 

I've posted evidence which shows that the lapse rate feedback is no where as negative as the models had it. Since the Water Vapor Feedback and the Lapse Rate Feedback are closely related in the models, this means that the Water Vapor Feedback is no where as positive as the models had it. Therefore, the total amplification from the Water Vapor Feedback is less than in the GCMs, and thus the Climate Sensitivity is likely less than the 3.2 Degrees C Equilibrium Sensitivity.

[tacoman25]

Almost all of the CO2 increase has come since 1850. The vast majority since 1900. And the point about the +PDO phase at the end of the 20th century enhancing the long term rising temps trend naturally is valid. .7-.8C rise since CO2 started rising appreciably seems reasonable to me. Which would indicate a somewhat lower sensitivity than most GCM projections. If we continue at the same rate, a doubling of the 280ppm level (560ppm) would result in a total warming of about 1.8C.

 

Yes, I know that future projections are counting on more positive feedbacks kicking in.

[Snow_Miser]

Almost all of the CO2 increase has come since 1850. The vast majority since 1900. And the point about the +PDO phase at the end of the 20th century enhancing the long term rising temps trend naturally is valid. .7-.8C rise since CO2 started rising appreciably seems reasonable to me. Which would indicate a somewhat lower sensitivity than most GCM projections. If we continue at the same rate, a doubling of the 280ppm level (560ppm) would result in a total warming of about 1.8C.

 

Yes, I know that future projections are counting on more positive feedbacks kicking in.

 

If we assume that all of the warming is anthropogenic and that nothing is masking the warming (i.e. the aerosol forcing is low) then we could get values between 1-2 Degrees C for the equilibrium doubling of CO2. However, I maintain that there is likely a significant natural contributor to the long term warming trend, thus there is more of a forcing to produce the 0.7 Degree C observed temperature change over the 20th Century. Thus, the actual anthropogenic warming would be closer to 0.35 Degrees C, if we assume that even only half of the warming is natural. The Lapse Rate Feedback being grossly overestimated is just one piece of evidence supporting figures of a lower climate sensitivity. I would also maintain that with Global Brightening since the late-20th Century, aerosols shouldn't be masking as much warming.

[bluewave]

We would need a ridiculous amount of warming to be "masked" in order to even consider the 4.5 Degree C numbers that Bluewave posted with the Paleoclimate papers to even be plausible. We've warmed 0.7 Degrees C, and with that high of a sensitivity, around 1 degree C should have been masked, assuming all of the warming is anthropogenic (not correct). When we assume that a natural factor has also contributed to the warming, the amount of warming being masked goes up even more.

 

In addition, a bunch of papers have recently come out which shows that the vertical amplification of the warming in the middle troposphere has been significantly exaggerated, suggesting a lapse rate feedback closer to zero, implicitly stating that the Water Vapor Feedback will be closer to zero, since the two are closely linked.

 

From "Plausible reasons for the inconsistencies between the modelled and observed temperatures in the tropical troposphere:"

 

We herewith attempt to detect plausible reasons for the discrepancies between the measured and modeled tropospheric temperature anomalies in the tropics. For this purpose, we calculate the trends of the upper-minus-lower tropospheric temperature anomaly differences (TAD) for both the measured and modeled time series during 1979-2010. The modeled TAD trend is significantly higher than that of the measured ones, confirming that the vertical amplification of warming is exaggerated in models. To investigate the cause of this exaggeration, we compare the intrinsic properties of the measured and modelled TAD by employing detrended fluctuation analysis (DFA). The DFA-exponent obtained for the measured values reveals white noise behaviour, while the exponent for the modelled ones shows that they exhibit long-range power law correlations. We suggest that the vertical amplification of warming derived from modelled simulations is weighted with a persistent signal, which should be removed in order to achieve better agreement with observations.

 

We are right on track for around 3C of warming for a doubling of CO2 emissions. CO2 emissions have risen about 40%

since the 1800's with 0.8C of warming  so far. This means that if emissions magically stopped today, there would still 

be 0.6C of warming in the pipeline and we would level off at 1.4C for a 40% increase in CO2. Beyond that 1.4C there

would be slower feedbacks totaling an additional 30%-50% additional warming over a long time scale.

So as of today, we are locked into at least a future temperature rise of 1.8C to 2.0C above pre industrial

revolution levels. With no replacements for the carbon based economy any time soon, expect higher

emissions to continue for a very long time. Who really knows high high emissions will go before we

transition to a post carbon economy.

 

http://www.skepticalscience.com/monckton-myth-10-warming-in-the-pipeline.html

[Snow_Miser]

We are right on track for around 3C of warming for a doubling of CO2 emissions. CO2 emissions have risen about 40%

since the 1800's with 0.8C of warming  so far. This means that if emissions magically stopped today, there would still 

be 0.6C of warming in the pipeline and we would level off at 1.4C for a 40% increase in CO2. Beyond that 1.4C there

would be slower feedbacks totaling an additional 30%-50% additional warming over a long time scale.

So as of today, we are locked into at least a future temperature rise of 1.8C to 2.0C above pre industrial

revolution levels. With no replacements for the carbon based economy any time soon, expect higher

emissions to continue for a very long time. Who really knows high high emissions will go before we

transition to a post carbon economy.

 

http://www.skepticalscience.com/monckton-myth-10-warming-in-the-pipeline.html

 

Not all of the  0.7-0.8 C warming is anthropogenic though. There are plenty of papers in the literature which find a significant solar component to the warming over the 20th Century or since 1850. That means that less of the 0.7 Degree C warming is anthropogenic, and thus, climate sensitivity is less.

[bluewave]

Not all of the  0.7-0.8 C warming is anthropogenic though. There are plenty of papers in the literature which find a significant solar component to the warming over the 20th Century or since 1850. That means that less of the 0.7 Degree C warming is anthropogenic, and thus, climate sensitivity is less.

 

I wouldn't say that is the more likely scenario given past earth history.

 

[Snow_Miser]

I wouldn't say that is the more likely scenario given past earth history.

 

Palaeosens_Fig3a_v2.jpg

 

In recent years a lot of studies have been shifting away from the 2-4.5 Degree C number as a lack of warming in recent years continues to persist, lowering sensitivity estimates.

 

[bluewave]

^^^^^^^

 

There is an obvious red flag with the few recent studies that have lower sensitivity.

The results are most likely influenced by the fact that this is -PDO decade.

But the majority of model studies are clustered around the 3C figure which is agreement with

the paleo data.

 

 

 

http://skepticalscience.com/climate-sensitivity-cicero.html

 

 

There is also a significant red flag in the press release for this study:

Including an extra decade's worth of data into the model should not halve their equilibriumclimate sensitivity value, because the equilibrium sensitivity of the climate system is a relatively constant number, and in reality has not changed radically over the past decade.  This suggests that their model may be overfitting the short-term natural variability.

"When the researchers at CICERO and the Norwegian Computing Center applied their model and statistics to analyse temperature readings from the air and ocean for the period ending in 2000, they found that climate sensitivity to a doubling of atmospheric CO2 concentration will most likely be 3.7°C, which is somewhat higher than the IPCC prognosis.

But the researchers were surprised when they entered temperatures and other data from the decade 2000-2010 into the model; climate sensitivity was greatly reduced to a “mere” 1.9°C."

What changed over the past decade?  Probably the largest single effect is that the 1990s were dominated by El Niño events (which cause short-term surface warming) while the 2000s have been domated by La Niña events (which cause short-term surface cooling).  Thus ending their analysis around the year 2000 may have biased their result high, whereas ending the analysis in 2010 could have biased it low.

Another issue is that the study only includes ocean heat content (OHC) data down to a depth of 700 meters.  Over the past few years, heat accumulation in the upper 700 meters has slowed slightly, but it has been offset by faster heat accumulation between 700 and 2000 meters (according to NOAA data, illustrated in Nuccitelli et al. 2012).  But the heat in that slightly deeper layer will not remain there forever; failing to include it may underestimate the equilibrium warming.

[ORH_wxman]

The biggest issue with climate sensitivity on the IPCC vs other estimates is the timing too...which is what I made my thread last year about. (though it got hijacked for a while with arctic sea ice alarmism).

 

If the climate sensitivity actually is 3C, but the TCR is much less, then their estimates of big warming on the order of 2.8C (using business as usual scenario) by 2100 are going to be wrong.

[Snow_Miser]

^^^^^^^

 

There is an obvious red flag with the few recent studies that have lower sensitivity.

The results are most likely influenced by the fact that this is -PDO decade.

 

 

 

 

We really don't know what the cause of this current hiatus period is. The PDO/ENSO have likely played an important role, but if decreased solar activity is also significantly responsible for the flatline/slight cooling trend, then that means that a significant part of the 20th Century warming is due to the sun, and that requires less of a role for Carbon Dioxide causing the 20th Century Warming, thus a lower climate sensitivity.

[bluewave]

We really don't know what the cause of this current hiatus period is. The PDO/ENSO have likely played an important role, but if decreased solar activity is also significantly responsible for the flatline/slight cooling trend, then that means that a significant part of the 20th Century warming is due to the sun, and that requires less of a role for Carbon Dioxide causing the 20th Century Warming, thus a lower climate sensitivity.

 

Sure we do.

 

http://www.americanwx.com/bb/index.php/topic/39853-the-pdo-and-decadal-global-temperatures-in-climate-change/

[Snow_Miser]

Sure we do.

 

http://www.americanwx.com/bb/index.php/topic/39853-the-pdo-and-decadal-global-temperatures-in-climate-change/

 

Like I said, the PDO has definitely contributed to the stagnation, but many, many scientists disagree on the primary cause.

 

http://pielkeclimatesci.wordpress.com/2011/10/27/candid-comments-from-global-warming-climate-scientists/

 

Roger Pielke puts it very nicely:

 

"These extracts from the Greenwire article illustrate why the climate system is not yet well understood. The science is NOT solved."

[bluewave]

Like I said, the PDO has definitely contributed to the stagnation, but many, many scientists disagree on the primary cause.

 

http://pielkeclimatesci.wordpress.com/2011/10/27/candid-comments-from-global-warming-climate-scientists/

 

Roger Pielke puts it very nicely:

 

"These extracts from the Greenwire article illustrate why the climate system is not yet well understood. The science is NOT solved."

 

Recent papers like the ones that I posted are telling you that this is to be expected for a -PDO period with more

frequent La Nina years. There is no doubt that the Pacific has an important role to play in modulating the

short term rises in global temperature. While over the long term the steady rate of warming will continue.