Monthly Archives: September 2008

Comment On The September 13, 2008 Article in The Economist “Adapt Or Die”.

The Economist published an article this past week titled “Adapt or die” [subscription needed]. It is an informative article and starts to address the issue of vulnerability that has been emphasized on Climate Science (e.g. see).

A focus on critical resources (e.g. energy, food, water, medical support) which is local and regionally focused, is a much more effective framework to assist society in reducing the risks from the diverse range of threats that face society and the environment.  This resource based emphasis is a much needed replacement to the almost exclusive focus on downscaling from multi-decadal global models as promoted using the IPCC and CCSP perspectives.

There are a two glaring errors, however, in the Economist article. The first is their statement that two things have changed attitudes towards adapation;

“One is evidence that global warming is happening faster than expected. Manish Bapna of the World Resources Institute, a think-tank in Washington, DC, believes ‘it is already too late to avert dangerous consequences, so we must learn to adapt.’”

and

“Second, evidence is growing that climate change hits two specific groups of people disproportionately and unfairly. They are the poorest of the poor and those living in island states: 1 billion people in 100 countries.”

The author(s) of the Economist article have ignored that global warming has actually halted, at least for now. The upper ocean heat content data indicates that there has been no warming since 2004 (see), while the tropospheric temperature data indicates no warming for about 7 years (e.g. see Figure 7).  Global warming is actually “happening more slowly than expected”.

With respect to the second comment, climate has always affected the poor more significantly than the rich. Climate variability has always been a major issue in those societies in which their food, energy, water and health facility infrastructures are underdeveloped. These poor societies face threats from famine and disease regardless of the role of humans within the climate system! Adaptation is common sense and should be a much higher priority than it has been given. The IPCC emphasis on CO2 as the reason for increased risk ignores the need for a much broader perspective to reduce vulnerability. A more inclusive framework is presented in Chapter E in the IGBP book 

Kabat, P., Claussen, M., Dirmeyer, P.A., J.H.C. Gash, L. Bravo de Guenni, M. Meybeck, R.A. Pielke Sr., C.J. Vorosmarty, R.W.A. Hutjes, and S. Lutkemeier, Editors, 2004: Vegetation, water, humans and the climate: A new perspective on an interactive system. Springer, Berlin, Global Change – The IGBP Series, 566 pp

See, for example, the first paragraph in

Pielke, R.A. Sr., and L. Bravo de Guenni, 2004: Conclusions. Chapter E.7 In: Vegetation, Water, Humans and the Climate: A New Perspective on an Interactive System. Global Change – The IGBP Series, P. Kabat et al., Eds., Springer, 537-538.

Thus, while the Economist article is a good start, the authors should recognize that a local and regional focus on societal and environmental vulnerability is a much more effective framework to reduce the threats that humanity and the environment face, than to rely on multi-decadal global model predictions.

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Kudos To Andy Revkin At Dot Earth For A Balanced News Article

Climate Science has been critical of news articles that are clearly biased in their presentation of our understanding of Climate Science. Thus, it is a pleasure to report on a balanced article by Andy Revkin on September 17, 2008 titled

Arctic Ice Retreat Misses Last Year’s Mark

Except for the last sentence of the article, where he speculates, this news story accurately summarizes the end of the 2008 Arctic sea ice melt season. We need more well written articles of this type to properly communicate our understanding of climate to the public and policymakers.

There was a question in the comments at the end of his weblog on the effect on ice albedo feedback (in which a greater arctic sea ice coverage when there is more sunlight reflects a larger fraction of sunlight back into space).  We have published on this topic in our papers

 Pielke Sr., R.A., G.E. Liston, and A. Robock, 2000: Insolation-weighted assessment of Northern Hemisphere snow-cover and sea-ice variability. J. Geophys. Res. Lett., 27, 3061-3064

Pielke Sr., R.A., G.E. Liston, W.L. Chapman, and D.A. Robinson, 2004:Actual and insolation-weighted Northern Hemisphere snow cover and sea ice — 1974-2002. Climate Dynamics, 22, 591-595 DOI10.1007/s00382-004-0401-5

where we proposed a new metric that monitors the sea ice-albedo feedback using a solar-insolation weighted sea ice coverage. This is a more appropriate metric for this assessment since clearly the ice- albedo effect is more effective for the same areal coverage when the Sun is higher in the sky and is above the horizon for a longer part of the day [of course, cloud cover complicates the assessment, but the insolation weighted effect is still an improvment over just using areal coverage by itself].  We urge the adoption of this additional climate metric.

As we wrote in our 2004 paper

The comparison of general circulation model simulations of changes over the last several decades to observed changes in insolation weighted sea-ice and snow cover should be a priority research topic.”

Added to this recommendation should be the routine presentation of this metric by those who monitor climate variability and trends.

 

 

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Limits on CO2 Climate Forcing from Recent Temperature Data of Earth by David H. Douglass and John R. Christy, 2008

There is an important and informative new paper on the role of the radiative forcing of CO2 on the climate system. It is

Douglass, D.H., and J.R. Christy, 2008: Limits on CO2 Climate Forcing from Recent Temperature Data of Earth. Energy and Environment, accepted.

The abstract reads

“The global atmospheric temperature anomalies of Earth reached a maximum in 1998 which has not been exceeded during the subsequent 10 years. The global anomalies are calculated from the average of climate effects occurring in the tropical and the extratropical latitude bands. El Nino/La Nina effects in the tropical band are shown to explain the 1998 maximum while variations in the background of the global anomalies largely come from climate effects in the northern extratropics. These effects do not have the signature associated with CO2 climate forcing. However, the data show a small underlying positive trend that is consistent with CO2 climate forcing with no-feedback.”

This is an excellent paper which provides a new perspective on the role of CO2 as a radiative climate forcing.

There is one statement in the paper that should be clarified

“The atmospheric CO2 is well mixed and shows a variation with latitude which is less than 4% from pole to pole [Earth System Research Laboratory. 2008]. Thus one would expect that the latitude variation of delta T from CO2 forcing to be also small”

The actual radiative forcing is not as small as indicated from 4% value. We have explored this issue in two Climate Science weblogs; i.e.

Relative Roles of CO2 and Water Vapor in Radiative Forcing

Further Analysis Of Radiative Forcing By Norm Woods

While much smaller than the effect of the more heterogeneous climate forcings {as we reported for example, in

Matsui, T., and R.A. Pielke Sr., 2006: Measurement-based estimation of the spatial gradient of aerosol radiative forcing. Geophys. Res. Letts., 33, L11813, doi:10.1029/2006GL025974,

it is larger than 4% since i) the temperatures within the atmosphere vary latitudinally, and ii) the higher water vapor levels in the lower latitudes reduces the fraction of absorption that can be attributed to CO2.

The conclusions of the Douglas and Christy paper, however, are not altered by this issue, and all of us should look forward to objective scientific scrutiny of their study [after all, that is the scientific method].

The paper should be required reading for all climate scientists, and the conclusions tested to order to build confidence or to refute their findings. Climate scientists who ignore this paper (as seems to be a frequent policy by some) must mean that they agree with the science in the Douglas and Christy paper, but elect to ignore it since it conflicts with their narrow perspective of the dominance of the radiative effect of human-added CO2 as an anthropogenic climate forcing. Of course, ignoring peer reviewed papers, is not the scientific method.

[ADDED 10am EDT: I have been informed that the journal Energy and Environment is not scientifically peer reviewed nor in any citation index. Unfortunately, this significantly diminishes the impact of this very important paper. While the publication process is a difficult road for research that differs from the IPCC type perspective, papers must stll be submitted and published in peer reviewed journals that appear in science citation indexes].

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Filed under Climate Change Forcings & Feedbacks, Climate Models

Uncertainty In Multi-Decadal Global Climate Model Predictions Associated With Snow Albedo Feedbacks

There is a paper which documents a large uncertainty of the feedback of snow albedo on the climate system. It is

Hall A., X. Qu (2006), Using the current seasonal cycle to constrain snow albedo feedback in future climate change, Geophys. Res. Lett., 33, L03502, doi:10.1029/2005GL025127.

The abstract reads

“Differences in simulations of climate feedbacks are sources of significant divergence in climate models’ temperature response to anthropogenic forcing. Snow albedo feedback is particularly critical for climate change prediction in heavily-populated northern hemisphere land masses. Here we show its strength in current models exhibits a factor-of-three spread. These large intermodel variations in feedback strength in climate change are nearly perfectly correlated with comparably large intermodel variations in feedback strength in the context of the seasonal cycle. Moreover, the feedback strength in the real seasonal cycle can be measured and compared to simulated values. These mostly fall outside the range of the observed estimate, suggesting many models have an unrealistic snow albedo feedback in the seasonal cycle context. Because of the tight correlation between simulated feedback strength in the seasonal cycle and climate change, eliminating the model errors in the seasonal cycle will lead directly to a reduction in the spread of feedback strength in climate change. Though this comparison to observations may put the models in an unduly harsh light because of uncertainties in the observed estimate that are difficult to quantify, our results map out a clear strategy for targeted observation of the seasonal cycle to reduce divergence in simulations of climate sensitivity.”

This paper reinforces the conclusions we reached in our papers

Strack, J.E., R.A. Pielke Sr., and J. Adegoke, 2003: Sensitivity of model-generated daytime surface heat fluxes over snow to land-cover changes. J. Hydrometeor., 4, 24-42

with the abstract

“Snow cover can significantly suppress daytime temperatures by increasing the surface albedo and limiting the surface temperature to 0C. The strength of this effect is dependent upon how well the snow can cover, or mask, the underlying surface. In regions where tall vegetation protrudes through a shallow layer of snow, the temperature-reducing effects of the snow will be suppressed since the protruding vegetation will absorb solar radiation and emit an upward turbulent heat flux. This means that an atmospheric model must have a reasonable representation of the land cover, as well as be able to correctly calculate snow depth, if an accurate simulation of surface heat fluxes, air temperatures, and boundary layer structure is to be made. If too much vegetation protrudes through the snow, then the surface sensible heat flux will be too large and the air temperatures will be too high.

In this study four simulations are run with the Regional Atmospheric Modeling System (RAMS 4.30) for a snow event that occurred in 1988 over the Texas Panhandle. The first simulation, called the control, is run with the most realistic version of the current land cover and the results verified against both ground stations and aircraft data. Simulations 2 and 3 use the default methods of specifying land cover in RAMS 4.29 and RAMS 4.30, respectively. The significance of these variations in land-cover definition is then examined by comparing with the control run. Finally, the last simulation is run with the land cover defined as all short grass, the natural cover for the region. The results of this study indicate that variations in the land-cover specification can lead to differences in sensible heat flux over snow as large as 80 W m2. These differences in sensible heat flux can then lead to differences in daytime temperatures of as much as 6C. Also, the height of the afternoon boundary layer can vary by as much as 200–300 m. In addition, the results suggest that daytime temperatures are cooler over snow in the regions where short grass has been converted to cropland, while they appear to be warmer over regions where shrubs have increased.”

and

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

with the abstract

“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.”

There is very significant (and difficult) challenge of accurately representing the role of snow albedo effects on climate, as well as the role of human activity in altering this albedo over time and space.

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Filed under Climate Change Forcings & Feedbacks, Climate Models

Increasing Eolian Dust Deposition in the Western United States Linked to Human Activity by Neff et al 2008

There is an important new paper that presents further evidence of the complexity of the climate system. It is

Neff, J.C., Ballantyne, A.P., Famer, G.L., Mahowald, N.M., Conroy, J.L., Landry, C.C., Overpeck, J.T., Painter, T.H., Lawrence, C.R., and Reynolds R.L., 2008, Increasing eolian dust deposition in the western United States linked to human activity.Nature – Geosciences. doi:10.1038/ngeo133

The abstract reads

“Mineral aerosols from dust are an important influence on climate and on marine and terrestrial biogeochemical cycles. These aerosols are generated from wind erosion of surface soils. The amount of dust emission can therefore be affected by human activities that alter surface sediments. However, changes in regional- and global-scale dust fluxes following the rapid expansion of human populations and settlements over the past two centuries are not well understood. Here we determine the accumulation rates and geochemical properties of alpine lake sediments from the western interior United States for the past 5,000 years.We find that dust load levels increased by 500% above the late Holocene average following the increased western settlement of the United States during the nineteenth century.We suggest that the increased dust deposition is caused by the expansion of livestock grazing in the early twentieth century. The larger dust flux, which persists into the early twenty-first century, results in a more than fivefold increase in inputs of K, Mg, Ca, N and P to the alpine ecosystems, with implications for surface-water alkalinity, aquatic productivity and terrestrial nutrient cycling.”

This effect is a consequence of human landscape change, which, as Climate Science has repeatedly emphasized, is at least as important as the radiative effect of CO2 in altering the climate system.

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Filed under Climate Change Metrics

Comprehensive Data Set of Global Land Cover Change for Land Surface Model Applications by Sterling and Ducharne (2008)

There is yet another paper that documents the very important role of land cover change as a component of the climate system [and thanks to Laure M. Montandon for alerting us to this article!]. The paper is

Sterling, S., and A. Ducharne (2008), Comprehensive data set of global land cover change for land surface model applications, Global Biogeochem. Cycles, 22, GB3017, doi:10.1029/2007GB002959.

The abstract reads

“To increase our understanding of how humans have altered the Earth’s surface and to facilitate land surface modeling experiments aimed to elucidate the direct impact of land cover change on the Earth system, we create and analyze a database of global land use/cover change (LUCC). From a combination of sources including satellite imagery and other remote sensing, ecological modeling, and country surveys, we adapt and synthesize existing maps of potential land cover and layers of the major anthropogenic land covers, including a layer of wetland loss, that are then tailored for land surface modeling studies. Our map database shows that anthropogenic land cover totals to approximately 40% of the Earth’s surface, consistent with literature estimates. Almost all (92%) of the natural grassland on the Earth has been converted to human use, mostly grazing land, and the natural temperate savanna with mixed C3/C4 is almost completely lost (~90%), due mostly to conversion to cropland. Yet the resultant change in functioning, in terms of plant functional types, of the Earth system from land cover change is dominated by a loss of tree cover. Finally, we identify need for standardization of percent bare soil for global land covers and for a global map of tree plantations. Estimates of land cover change are inherently uncertain, and these uncertainties propagate into modeling studies of the impact of land cover change on the Earth system; to begin to address this problem, modelers need to document fully areas of land cover change used in their studies.”

Since, as we have shown in

Strack, J.E., R.A. Pielke Sr, L.T. Steyaert, and R.G. Knox, 2008: Sensitivity of summer near-surface temperatures and precipitation in the eastern United States to historical land cover changes since European settlement. Water Resources Research, accepted,

long term temperature and precipitation variations and trends do strongly depend on the time evolution of the landscape in the eastern United States, the same effect must also be true wherever humans have altered the landscape. Based on the Sterling and Ducharne article, this corresponds to directly to about 40% of the Earth’s land surface, and from teleconnections (i.e. advection by winds, alteration of atmospheric pressure fields) to effecting the weather throughout large areas of the rest of the Earth, as shown, for example, by

Chase, T.N., R.A. Pielke, T.G.F. Kittel, R.R. Nemani, and S.W. Running, 2000: Simulated impacts of historical land cover changes on global climate in northern winter. Climate Dynamics, 16, 93-105 [in which only about 15% of the Earth’s land surface was modified by humans in the model].

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Filed under Climate Change Forcings & Feedbacks

Conference Marie Curie-iLEAPS – Feedbacks-Land-Climate Dynamics – Key Gaps

There is an upcoming meeting that will inform us further on the role of landascape proceeses within the climate system. It is the Marie Curie – iLEAPS conference
Date: 17-21 November 2008  to be hel at the Hotel Club “Le Continental” Hyeres, France

The contact is Dr. Nathalie de Noblet-Ducoudré

 Conference Marie Curie-iLEAPS – Feedbacks-Land-Climate Dynamics – Key Gaps

The objective …. is to bring together most scientists (young and senior) involved in the field of understanding the role terrestrial biosphere plays in the climate system (changes, transitions, extremes) at the regional to global scale, and to make a firm status on the present knowledge of these interactions and the remaining parts to be explored. Talks and posters will initiate discussions that should lead to a synthesis paper on the state-of-the-art knowledge on this topic. Actions to carry out in the next 5 years should emerge from these discussions. These actions will include coordinated modelling experiments as well as synthesis of surface data at the regional to global scales. At the end of the workshop will set up a web site with the main papers, overheads, and reports on discussions to help the dissemination of the knowledge gained, and to help the writing up of the synthesis paper.

Call for abstracts and application for this International Conference on Biosphere-Atmosphere Interactions is open. The deadline for sending abstracts and application is 12 September.

On-line registration and submission of abstracts is now available.

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