Monthly Archives: May 2006

A Fox News Channel Documentary aired last evening May 21st entitled “Global Warming: The Debate Continues.â€? The Documentary was very informative in communicating the need to assess the risk to society of global warming relative to other natural- and human-caused risks. This “vulnerability” framework is a theme that has been emphasized on the Climate Science weblog (e.g. see and see). The use of the vulnerability perspective would allow policymakers the ability to quantify risk from the spectrum of environmental and social risks, rather then replying on hyperbole in the media (e.g. see) to drive the policy agenda.

I would like to see a Part II of the Fox News Documentary, where the diversity of climate forcings, beyond global warming are discussed, as well as what are the effective climate metrics to assess climate variability and change. These topics have been discussed frequently on Climate Science, as they are inadequately covered in the existing international and national assessments of climate change.

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What Level of Skill of Multi-Decadal Global Climate Prediction Can Be Concluded From The CCSP Report “Temperature Trends in the Lower Atmosphere: Steps for Understanding and Reconciling Differences”?

The Climate Science website has discussed the lack of skill in multi-decadal climate predictions (e.g. see). This weblog extracts information from the CCSP Report “Temperature Trends in the Lower Atmosphere: Steps for Understanding and Reconciling Differencesâ€?, and an associated news report, which further confirms the level of ability of the multi-decadal global climate models in providing skillful reconstructions of the surface and tropospheric temperature trends over the last few decades using the global models forced by prescribed climate forcings (which, of course, is a time period when we have observed data).

A necessary, although not a sufficient, test of potential skill for the future decades is that the least several decades be accurately predicted.

As given in a summary of the CCSP Report, the news report by Richard Kerr in the May 12, 2006 issue of Science, entitled, “No Doubt About It, the World is Warmingâ€? (subscription required) includes the text,

“The report authors found that over the 25-year satellite record, the surface and the midtroposphere each warmed roughly 0.15°C per decade averaged over the globe, give or take 0.05°C or so per decade. The tropics proved to be an exception: The models called for more warming aloft than at the surface lately, whereas most observations showed the reverse. Reconciling that discrepancy will have to wait for the next round of synthesis and assessment.â€?

The CCSP claims that the global models can skillfully predict global average surface and tropospheric temperature trends, yet they cannot skillfully predict tropical zonally averaged surface and tropospheric temperature trends. The significance of this admission is, unfortunately, not pursued. A skillful global average cannot be achieved if a significant portion of the globe (the tropics) is not skillfully predicted!

Second, from page 145 of the 2006 Response to the Public Comment of the CCSP Report “Synthesis and Assessment Product 1.1 “Temperature Trends in the Lower Atmosphere: Steps for Understanding and Reconciling Differencesâ€?,

“Owing to natural internal variability, models cannot be expected to reproduce regional patterns of trend over a period as short as 20 years from changes of radiative forcings alone.â€?

Thus, even the CCSP Committee accepted that regional predictive skill can not be attained for periods of two decades. The Report is silent on what time period skillful regional predictions of surface and tropospheric trends can be achieved, but it is clearly longer than 20 year time frames.

A very significant conclusion from the CCSP Report, therefore, is that the multi-decadal global climate predictions have demonstrated NO skill at predicting regional surface and tropospheric temperature trends. This is a major conclusion from the Report, even if the Committee chose not to mention it. Thus the application of the multi-decadal global climate models to regional projections in the 21st century for surface and tropospheric temperatures are not scientifically sound. Moreover, if the models cannot skillfully predict temperature, the much more difficult climate variables such as precipitation certainly should not be provided to the impact community or to policymakers as skillful projections.

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The Final Meeting Information on “The Earth’s Radiative Energy Budget Related to SORCE” Conference Has Been Posted

The final list of invited talks at the 2006 SORCE Science Meeting, motivated by the NASA/EOS Solar Radiation and Climate Experiment (SORCE), has been posted. An earlier post on this meeting was given on April 4, 2006.

The meeting, entitled “Earth’s Radiative Energy Budget Related to SORCE” will be held in September 2006 in Washington state. Contributed papers for this meeting can be submitted until July 14, 2006.

I have reordered the list of invited speakers below to emphasize the diverse range of climate forcings, beyond the radiative effect of CO2, which will be discussed at the meeting. This meeting framework builds on the perspective provided in the 2005 National Research Council report entitled “Radiative Forcing of Climate Change: Expanding the Concept and Addressing Uncertainties”. and in the 2003 National Research Council report entitled “Understanding Climate Change Feedbacks”.

1. Aerosol Direct Effect

Brian Cairns, NASA GISS, Columbia University, New York, New York : The aerosol direct effect

2. Aerosol Indirect Effects

Jim Coakley, Oregon State University, Corvallis: The aerosol indirect effect

3. Land Use/Land Cover Change

Roni Avissar, Duke University, Durham, North Carolina: Land use/land change

4. Vegetation and other Surface Dynamics

Jay Herman, GSFC, NASA, Greenbelt, Maryland : Ozone variability and the biosphere

Al Arking, Johns Hopkins University, Baltimore, Maryland: Differential effects of SW and LW radiation on the surface energy budget and climate implications

Ellsworth Dutton, NOAA Earth System Research Laboratory, Boulder, Colorado: The surface radiative energy budgets

5. Solar forcing

Judith Lean, Naval Research Laboratory, Washington, DC: Solar radiative forcing

6. Climate feedback effects will also be presented. These include

Robert Cahalan, GSFC, NASA, Greenbelt, Maryland: Clouds and radiation

Graeme Stephens, Colorado State University, Fort Collins: The cloud-climate feedback

Judy Curry, Georgia Institute of Technology, Atlanta: Hurricane response in the climate system

Ken Jezek, Byrd Polar Research Center at Ohio State University, Columbus: The ice feedback

The presentation of the climate forcing of the well-mixed greenhouse gases will also be presented, in order to provide a perspective on the other climate forcings;

Bill Collins, National Center for Atmospheric Research (NCAR), Boulder, Colorado: Radiative forcing by greenhouse gases

Overviews of climate as a system will also be presented;

V. Ramanathan, Scripps Inst. of Oceanography, Univ. of California, San Diego : The regulation of Earth’s albedo

Ka-Kit (KK) Tung, University of Washington, Seattle: Climate responses to forcing

Peter Pilewskie, LASP, University of Colorado, Boulder: Overview of the radiation budget in the lower atmosphere

Roger Pielke Sr., University of Colorado, Boulder: Regional and global climate forcings

7. Observations of components within the Climate System

Jerry Harder, LASP, University of Colorado, Boulder: The role of VIS-IR / SIM in climate science

Greg Kopp, LASP, University of Colorado, Boulder: The role of TSI / TIM in climate science

Norm Loeb, NASA Langley Research Center, Hampton, Virginia: The accuracy of TSI / SSI in climate models

Bill McClintock, LASP, University of Colorado, Boulder: The role of UV / SOLSTICE in climate science

Xuemin Shen, Shanghai Institute of Technical Physics, China: China Earth Radiation Budget Experiment (CERBE)

Tony Slingo, University of Reading, United Kingdom: Observations of the Earth’s radiation budget from geostationary orbit and from the surface

Marty Snow, LASP, University of Colorado, Boulder: Mg II C/W index time series

Bruce Wielicki, NASA Langley Research Center, Hampton, Virginia: Earth’s radiation budget from space

Tom Woods, LASP, University of Colorado, Boulder: SORCE mission update

A major question that will be raised at this meeting is the need to better quantify the relative role of the radiative effect of CO2 on climate system heat changes (“global warming”), and the role of this climate forcing more broadly in climate variability and change. As discussed on the Climate Science weblog, the role of carbon dioxide as a fraction of the radiative heating has been overstated, based on new estimates of other radiative forcings (see). Also, the evaluation of the role of the human- and natural climate forcings and feedbacks requires a regional focus, not the use of a global average surface temperature as the climate metric to communicate to policymakers (see). The role of solar forcing will be a major topic addressed at this meeting, and the latest information on this climate forcing will be a significant contribution that results.

The September meeting (along with the Santa Fe meeting in July 2006) promise to broaden the issues in climate science that can then be communicated to other scientific colleagues and, more generally, to the public and policymakers.

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Further Documentation of the Drought Threat in the Western United States

Another paper has appeared which further emphasizes why we need a vulnerability perspective on environmental risk, including climate. The paper also provides additional documentation to refute the claim in the Wall Street Journal article (see) that the last 100 years were so unusual in terms of climate.

The paper is in Water Resources Research and is entitled “Updated streamflow reconstructions for the Upper Colorado River Basin” (subscription required) by Connie A. Woodhouse, Stephen T. Gray, and David M. Meko (thanks to Willie Soon for alerting me to it).

The abstract of the paper reads,

“Updated proxy reconstructions of water year (October–September) streamflow for four key gauges in the Upper Colorado River Basin were generated using an expanded tree ring network and longer calibration records than in previous efforts. Reconstructed gauges include the Green River at Green River, Utah; Colorado near Cisco, Utah; San Juan near Bluff, Utah; and Colorado at Lees Ferry, Arizona. The reconstructions
explain 72–81% of the variance in the gauge records, and results are robust across several reconstruction approaches. Time series plots as well as results of cross-spectral analysis indicate strong spatial coherence in runoff variations across the subbasins. The Lees Ferry reconstruction suggests a higher long-term mean than previous reconstructions but strongly supports earlier findings that Colorado River allocations were based on one of the wettest periods in the past 5 centuries and that droughts more severe than any 20th to 21st century event occurred in the past.”

The paper includes the text,

” ……longer duration droughts have occurred in the past. The Lees Ferry reconstruction contains one sequence each of six, eight, and eleven consecutive years with flows below the 1906–1995 average (1663– 1668, 1776–1783, and 1873–1883). Overall, these analyses demonstrate that severe, sustained droughts are a defining feature of Upper Colorado River hydroclimate. Flows in the Upper Colorado are also shown to be nonstationary over decadal and longer timescales, making short term records inappropriate for most planning and forecast applications.”

Further that,

“The long-term perspective provided by tree ring reconstructions points to looming conflict between water demand and supply in the upper Colorado River basin. This suggestion has even greater relevance today. Demands on the Colorado River over the pastdecades have risen to meet or exceed average water availability.”

This is a sobering conclusion, and one that we also reached in our paper ” Drought 2002 in Colorado – An unprecedented drought or a routine drought?“.

Regardless of human- and natural- climate variability and change in the future, even with the repetition of past drought conditions, the consequences to the western United States will be huge. The time to prepare for these inevitable events is now.

The study also shows why a focus on regional climate is essential. The use of a global average surface temperature trend is a useless climate metric to assist policymakers in dealing with the drought threat. The appropriate temperature metric is the monitoring of regional tropospheric temperature variability and trends, and to determine the limits of skillful seasonal and longer term forecasts of the regional pattern.

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Fox News Channel Documentary on Global Warming to Air

A Fox News Channel Documentary will air this Sunday night May 21st at 10pm ET: “Global Warming: The Debate Continues.” We will discuss on Monday on the Climate Science weblog.

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Policymakers Need to Move Beyond the Global Average Surface Temperature Trend as the Primary Climate Change Metric

The focus on a specific increase of the global average surface temperature has become the climate change icon that is reported on frequently in the media (e.g., see “Global warming worst in 20 000 years – report“), in government assessments and in a range of scientific papers (e.g., Jones and Moberg 2002).

The question as to what is meant by a global average surface temperature has been raised previously on the Climate Science weblog (e.g., see). As reported in the 2005 National Research Council Report (see and see ); (slightly edited for the weblog)

“According to the radiative-convective equilibrium concept, the equation for determining global average surface temperature of the planet is

dH/dt = f – T’/lamba

and

H = the integral of the density of air times the specific heat of the air times temperature through the depth of the heating within the climate system.

H is, therefore, the heat content of the land-ocean-atmosphere system. The variable f is the radiative forcing at the tropopause, T′ is the change in surface temperature in response to a change in heat content, and λ is the climate feedback parameter, also known as the climate sensitivity parameter, which denotes the rate at which the climate system returns the added forcing to space as infrared radiation or as reflected solar radiation (by changes in clouds, ice and snow, etc.). In essence, λ accounts for how feedbacks modify the surface temperature response to the forcing. In principle, T′ should account for changes in the temperature of the surface and the troposphere, and since the lapse rate is assumed to be known or is assumed to be a function of surface temperature, T′ can be approximated by the surface temperature.

This definition is based on a simple concept, that as heat is introduced into a system (such as heating water on a stove), the temperature of the system (in this example the water) increases until the heat lost from the system is equal to the heat being input into it. If the heat input is suddenly turned off, the temperature immediately stops rising.

The definition of T’ reported in the 2005 National Research Council Report similarly uses a simple definition when the key assumption is made that

“since the lapse rate is assumed to be known or is assumed to be a function of surface temperature, T′ can be approximated by the surface temperature. ”

This simple concept is being used to promote global climate policy to prevent elevations of the global average surface temperature above specified thresholds.

However, while on a theoretical basis a global average surface temperature trend can be diagnosed from the radiative imbalance of the Earth, the reality is that it cannot be directly measured. The use of surface temperature measurement is an arbitrary choice. Why not use the tropospheric layer averaged temperature, for example?

There is an alternative, more effective approach that was summarized in Heat storage within the Earth system .

“• A snapshot at any time documents the accumulated heat content and its change since the last assessment. Unlike temperature, at some specific level of the ocean, land, or the atmosphere, in which there is a time lag in its response to radiative forcing, there are no time lags associated with heat changes.

• Since the surface temperature is a two-dimensional global field, while heat content involves volume integrals, the utilization of surface temperature as a monitor of the earth system climate change is not particularly useful in evaluating the heat storage changes to the earth system.The heat storage changes, rather than surface temperatures, should be used to determine what fraction of the radiative fluxes at the top of the atmosphere are in radiative equilibrium.”

By using ocean heat content, including its spatial structure, as the climate metric to communicate to policymakers, we would better represent the science of climate system heat changes, including global warming.

It is time to move beyond a focus on global average surface temperature trend as the icon of climate change science.

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Wall Street Journal Quotes on Climate Change Attribution-A Missed Opportunity for Balanced Reporting

The Wall Street Journal (WSJ) published an article entitled “Scientists Explain How They Attribute Climate-Change Data” by Sharon Begley in its May 12 2006 issue.

The article had a number of quotes by climate scientists. I give three examples of quotes in the WSJ below, followed by papers or other sources which contradict their claims. Why didn’t the Wall Street Journal reporter seek the perspective of other qualified climate scientists on these claims?

1. WSJ Quote: “‘For all the oceans to warm, you need to add heat to the system, which rules out natural variability’ on thermodynamics grounds, says Dr. Barnett.”

Rebuttal (from):

“…….the accumulation of heat at depth in the oceans that was reported in 2004 by J. Willis, D. Roemmich, and B. Cornuelle in the Journal of Geophysical Research ‘ Interannual variability in upper ocean heat content, temperature, and thermosteric expansion on global scales’ suggests that a significant portion of the observed recent global warming is unavailable for short-term feedback into the atmospheric portion of the climate system.”

� Maps of yearly heat content anomaly show patterns of warming commensurate with ENSO variability in the tropics, but also show that a large part of the trend in global, oceanic heat content is caused by regional warming at midlatitudes in the Southern Hemisphere. �

In their paper, they report that,

“……a strong, fairly linear warming trend is visible in the Southern Hemisphere, centered on 40°S. This region accounts for a large portion of the warming in the global average.â€?

Also,

“……..the warming around 40°S appears to be much steadier over the course of the time series, as seen in Figure 7. In addition, this warming extends deeper and is more uniform over the water column than the signal in the tropics. â€?

Finally,

“…..the warming rate in the early 1970s is comparable to the present rate. This suggests that the present rate is not outside the range of recent decadal variations. With the present time series, it is therefore not possible to identify whether the recent increase in ocean warming is due to an acceleration of heat uptake by the ocean or is simply decadal variability. An additional 5 to 10 years of data will be necessary before such a distinction is likely to be possible.â€?

Also, as we reported just a few days ago on the Climate Science weblog (see), there are large region of the World’s oceans that are currently cooler than average!

2. WSJ Quote: “‘We have never seen natural variability on a global scale like we’ve had in the last 100 years’ says atmospheric physicist Michael Oppenheimer of Princeton University.”

Rebuttal (from):

“Comparison of the MSD (mean summer deficit) reconstruction with the instrumental records of summer drought for northwest Montana leads to several observations. First, the most severe single-year summer droughts of the 20th century were probably matched or exceeded on only a few occasions in the prior four centuries. Second, the cumulative deficit during the extended period of dry summers in the 1920s and 1930s appears to be unprecedented in the 461-year reconstruction. This period was one of rapid retreat of glaciers in Glacier National Park (Pederson et al. in press). The current drought, though it includes two very dry summers, pales in comparison with that event and many other extended drought events seen in the tree ring record.â€?

“The current drought was very unusual in the speed of its onset, with PDSI (Palmer Drought Severity Index) dropping from slightly wet to severe drought in just five months. In the Illinois Division 1 instrumental record, this has occurred only once before, in 1936. But the drought’s current severity has been matched or exceeded on numerous occasions in the past, according to both the instrumental and tree-ring records. â€?

“All existing evidence has shown that earlier historic droughts and paleo-droughts in the United States clearly were of greater severity than what has occurred recently. This should be sobering to any climate scientist and policymaker.”

3. WSJ Quote: “…..climatologists refine “detection and attribution” studies, they are getting better at discerning the fingerprints of changes that are so physically or statistically anomalous that they couldn’t be natural. ‘Different factors that affect climate — human or natural — have unique signatures,’ says climatologist Ben Santer of Lawrence Livermore National Lab, California.”

Rebuttal (from):

“From MacCracken, Michael, Joel Smith and Anthony C. Janetos, 2004. Reliable regional climate model not yet on horizon. Nature Vol. 429, No 6993, p. 699, June 17, 2004,

‘The US National Assessment of the Potential Consequences of Climate Variability and Change (USNA) – in which we were involved-did not attempt to provide regional or even national predictions of climate change……’

Later in the letter in Nature, they conclude with,

‘ We strongly agree that much more reliable regional climate simulations and analyses are needed. However, at present,…….such simulations are more aspiration than reality.”’

While certain human climate forcings are obvious (such as land use change and biomass burning), other less spatially heterogenous climate forcings, such as the well-mixed greenhouse gases, have an unclear spatial signature. The quote by Santer needs more context.

We need, therefore, objective journalists to dig deeper into the climate issue and start to report on the wide diversity of views that exist, rather than asking the same scientists to repeatedly restate their perspectives.

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