Monthly Archives: November 2007

Climate Metric Reality Check #1 – The Sum Of Climate Forcings and Feedbacks Is Less Than The 2007 IPCC Best Estimate Of Human Climate Forcing Of Global Warming

Climate Science is going to present observational data and other information in coming web postings that raises questions about the validity of claims in the 2007 IPCC report. One of the issues is whether climate feedbacks amplify or mute radiative forcings caused by human activities. The IPCC asserts that climate feedbacks in fact amplify the human effect. We can test this assertion using observational data.

If the magnitude of the IPCC estimates of radiative forcings from human causes are greater than or equal to the sum of the total observed radiative forcings and feedbacks (i.e. the total climate system radiative imbalance), then the feedbacks have actually reduced the effect of radiative forcings caused by human activities. By contrast, if the magnitude of radiative forcing caused by humans is less than the sum of the total observed radiative forcings and feedbacks than the feedbacks have amplified the human radiative forcings.

In this first reality check, the information that is used is

1. Total Radiative Forcing from Human Causes

The radiative forcings from human causes are provided by the 2007 IPCC Report [see page 4 of the Statement for Policymakers; Fig. SPM.2].

Their value is +1.6 [with a range of +0.6 to +2.4 Watts per meter squared]

This value, as reported in a footnote in the IPCC report, is supposed to be a difference with between current and pre-industrial values (but note that that this is not what is stated in the figure caption).

2. Total Observed Radiative Forcings and Feedbacks

Ocean heat content data can be used to diagnose the actual observed climate forcings and feedbacks [Pielke Sr., R.A., 2003: Heat storage within the Earth system]. Here I will use Jim Hansen’s value for the end of the 1990s of

+0.85 Watts per meter squared

(even though this is probably an overstatement (see)).

Thus, the total observed radiative forcing and feedback of 0.85 W/m^2 lies below the IPCC central estimate of 1.6 W/m^2 for just the human contribution to radiative forcing. This suggests that the climate feedbacks most likely act to diminish the effects of human contributions to radiative forcing, though it is important to recognize that a small part of the IPCC range (0.6 to 0.85) falls under the observed value from the work of Hansen.

This suggests that, at least up to the present, the effect of human climate forcings on global warming has been more muted than predicted by the global climate models.

This issue was inadequately discussed by the 2007 IPCC report. Climate Science has weblogged on this in the past (e.g. see), but so far this rather obvious issue has been ignored.

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Filed under Climate Change Metrics

Loss Of Herb Saffir – A Pioneer In Communicating Hurricane Risk To The Public and Policymakers

As many of you have read in the news, Herb Saffir has died (see). Herb Saffir, along with Robert H. Simpson, is a developer of the famous categories 1 through 5 of hurricane intensity.

As a tribute to his continual contribution to engineering and science throughout a long lifetime, I am posting below a guest weblog that he permitted us to post earlier this year. He will be missed.

Comments by Herbert S. Saffir on Hurricane Katrina [originally posted February 13 2007]

Herbert S. Saffir is recognized internationally as one of the most outstanding experts on the relationship of property damage due to hurricanes. His expertise was used to create the well-known Saffir-Simpson scale of hurricane intensity.

With his permission, I have reproduced a summary of his conclusions on the intensity of Hurricane Katrina in New Orleans.

“Discussion by Herbert S. Saffir, P.E., Hon. M.ASCE of ‘Performance of Glass/Cladding of High Rise-Buildings in Hurricane Katrina’ by Ahsan Kareem and Rachel Bashor, University of Notre Dame.

The ‘Performance of Glass/Cladding of High Rise-Buildings in Hurricane Katrina’, Wind Engineering, December 2006, is a valuable commentary on the destruction of glass and cladding on high-rise buildings in New Orleans during the hurricane.

In the opinion of this writer, Hurricane Katrina was not a major hurricane event for New Orleans. The central eye of Katrina made landfall in Mississippi, approximately 30 miles east of the center of the New Orleans business district. New Orleans was in the weak quadrant of the storm. It is interesting to note that the paper confirms that wind speeds were only about 90 miles per hour, in 3 second gusts, in Katrina, in New Orleans; these speeds are well below the design speeds of 118 mph given in ANSI A58.1 (1982) and the design speeds of 130 mph, 3 second gust, given in ASCE 7-05 (2005).

The writer believes that much of the damage in New Orleans was similar to high-rise building damage in Hurricane Alicia in Houston (1983), where winds were probable not over 90 mph.

The writer also believes there was insufficient attention to design and installation of cladding and glass, and poor code enforcement, in New Orleans. Unfortunately, this paper does not review the building code requirements in force for glass and cladding; it does not review and analyze the individual design plans for those structures in New Orleans damaged by Katrina.�

This summary is valuable and sobering as it further reinforces the view that New Orleans, despite all of the damage that occurred with the failure of the levees, has not yet seen its worst case hurricane landfall.

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Filed under Guest Weblogs

Upcoming Climate Science Papers

In the coming weeks and months, Climate Science will post information on several new papers from our research group. We have been busy with research studies while Climate Science was not actively updated. Among the research findings of our papers are:

1. We have used observational data of long term temperature trends at 2 heights near the surface to show that these trends are different at night under light winds. This raises serious questions regarding David Parker’s papers that light and stronger wind temperature trend data were found to be the same. Parker’s conclusions were a major finding in the 2007 IPCC report that is used to claim there are no differences in trends between urban and rural sites.

2. We have used the North American Regional Reanalysis to document that while tropospheric temperature trends have been positive over the last several decades, the water vapor content of the troposphere has been essentially constant. This raises questions on the model simulations which predict a constant relative humidity with increases in tropospheric temperatures.

3. In a preliminary poll of climate scientists, we have found that a significant minority disagree with the 2007 IPCC conclusions, either concluding that is it too conservative with respect to the risk of human-CO2 caused climate change, or overstates the relative role of this specific climate forcing.

4. We have shown in several studies that the downscaling of multi-year global model predictions by regional climate models is very strongly dependent on the lateral boundary conditions of the parent model. That the regional model is not substantially independent from the parent model means that claims of added regional predictive skill in coming decades using dynamic downscaling needs to be examined further before this approach is considered robust.

5. We have identified a wide range of issues with using the near-surface global average temperatures to assess the radiative imbalance of the Earth’s climate system. The implication from several of the problems with this data set is that the warming in recent years has been overstated. Indeed, for a global average near surface temperature to be used to diagnose the Earth’s radiative imbalance, this temperature must be a thermodynamic proxy for the thermodynamic state of the earth system. As such, it must be tightly coupled to that thermodynamic state. We show that, particularly for nighttime and high latitude winter land temperatures (which are used in the construction of a global average surface temperature), it is not closely coupled.

6. The European heat wave of 2003 is further shown to be a shallow atmospheric event, in terms of its extreme anomaly, and cannot be directly attributed to the radiative forcing of added CO2. Dry soils in Europe during this event seem to be a major reason for its extreme heat near the surface.

Climate Science will provide details on these and other results, as the papers are published, or we otherwise decide to disseminate.

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Filed under Climate Science Reporting

Arctic Tundra Shrub Invasion And Soot Deposition: Consequences For Spring Snowmelt And Near-surface Air Temperatures

This paper has already been discussed on Watts Up With That but I want to further emphasize that this research demonstrates not only the role of shrubs on spring snow melt in the Arctic, but also the significant role of black carbon deposition. This issue was identified in the 2005 National Research Council report as being a major climate forcing, but its importance was not adequately discussed in the 2007 IPCC report. As a result, policymakers are attributing a larger fraction of recent near-surface arctic warming to the radiative effect of added CO2, rather than from soot.

Strack, J., R.A. Pielke Sr., and G. Liston, 2007: Arctic tundra shrub invasion and soot deposition: Consequences for spring snowmelt and near-surface air temperatures. J. Geophys. Res., 112, G04S44, doi:10.1029/2006JG000297.

The abstract reads

“Invasive shrubs and soot pollution both have the potential to alter the surface energy balance and timing of snow melt in the Arctic. Shrubs reduce the amount of snow lost
to sublimation on the tundra during the winter leading to a deeper end-of-winter snowpack. The shrubs also enhance the absorption of energy by the snowpack during the melt season by converting incoming solar radiation to longwave radiation and sensible heat. Soot deposition lowers the albedo of the snow, allowing it to more effectively absorb incoming solar radiation and thus melt faster. This study uses the Colorado State
University Regional Atmospheric Modeling System version 4.4 (CSU-RAMS 4.4), equipped with an enhanced snow model, to investigate the effects of shrub encroachment and soot deposition on the atmosphere and snowpack in the Kuparuk Basin of Alaska during the May–June melt period. The results of the simulations suggest that a complete invasion of the tundra by shrubs leads to a 2.2C warming of 3 m air temperatures and a
108 m increase in boundary layer depth during the melt period. The snow-free date also occurred 11 d earlier despite having a larger initial snowpack. The results also show that a decrease in the snow albedo of 0.1, owing to soot pollution, caused the snow-free date to occur 5 d earlier. The soot pollution caused a 1.0C warming of 3 m air temperatures and a 25 m average deepening of the boundary layer.”

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Filed under Climate Change Forcings & Feedbacks

November 27, 2007: Climate Science Is Relaunching As An Information Source

As a result of very positive encouragement from many Climate Science readers, I have decided to relaunch the website. The format will be different than in the past, however, in that comments will not be permitted. The posting of information will not be on a schedule, but when new information on a climate science issue is available that is otherwise not very visible, or has been misrepresented in the media.

The presentation of climate science in the media, unfortunately, remains biased, as has been documented numerous times on Climate Science. Thus, I have decided to reenter this mechanism of providing information. While comments will not be permitted on the website, guest presentations will be invited when there is value in providing this source of information.

Climate Science will thus provide a source of information on climate that, hopefully, will be useful to others, as part of a much needed effort to provide a balanced view of climate science.

Thanks to those who have found my website of value and take the time to read it!

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Filed under Climate Science Reporting