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Now available in PDF format: Abstract Book [7.4 Mb] (posted 10 November 2005)

Abstracts for Posters

General Climate Science (P-GC)

Sub-Theme 1: Earth System Analysis & Products

P-GC1.1

Warming of the World Ocean, 1955-2003

Syd Levitus, World Data Center for Oceanography-Silver Spring, NODC/NOAA, E/OC5, 1315 East West Highway, Room 4362, Silver Spring, MD, Sydney.Levitus@noaa.gov

Analysis of historical oceanographic temperature data documents that the world ocean has warmed since 1955. The magnitude of this warming is consistent with the amount of warming expected due to the observed increase of greenhouse gases in Earth's atmosphere since the Industrial Revolution began. Several atmosphere-ocean general circulation models exhibit a similar ocean warming in their model ocean, only if the atmospheric components of the models are forced by the observed increases of greenhouse gases. Ocean warming is a critical indicator of the state of Earth's climate system. Only the world ocean can store the additional heat expected to accrue in Earth's climate system as a result of increasing greenhouse gases. Thus the observed ocean warming provides Decision Makers tasked to deal with changes in Earth's climate system additional critical evidence that global; warming is occurring.

[Poster PDF]

P-GC1.2

Assessing the Risk of a Collapse of the Atlantic Thermohaline Circulation

Michael E. Schlesinger, Climate Research Group, Department of Atmospheric Sciences, University of Illinois at Urbana-Champaign, schlesin@atmos.uiuc.edu

In this paper we summarize work performed by the Climate Research Group within the Department of Atmospheric Sciences at the University of Illinois at Urbana-Champaign (UIUC) and colleagues on simulating and understanding the Atlantic thermohaline circulation (ATHC). We have used our uncoupled ocean general circulation model (OGCM) and our coupled atmosphere-ocean general circulation model (AOGCM) to simulate the present-day ATHC and how it would behave in response to the addition of freshwater to the North Atlantic Ocean. We have found that the ATHC shuts down "irreversibly" in the uncoupled OGCM but ‘reversibly' in the coupled AOGCM. This different behavior of the ATHC results from different feedback processes operating in the uncoupled OGCM and AOGCM. We have represented this wide range of behaviour of the ATHC with an extended, but somewhat simplified, version of the original model that gave rise to the concern about the ATHC shutdown. We have used this simple model of the ATHC together with the DICE-99 integrated assessment model to estimate the likelihood of an ATHC shutdown between now and 2205, both without and with the policy intervention of a carbon tax on fossil fuels. For specific subjective distributions of three critical variables in the simple model, we find that there is a greater than 50% likelihood of an ATHC collapse, absent any climate policy. This likelihood can be reduced by the policy intervention, but it still exceeds 25% even with maximal policy intervention. It would therefore seem that the risk of an ATHC collapse is unacceptably large and that measures over and above the policy intervention of a carbon tax should be given serious consideration.

[Poster PDF]

P-GC1.3

Estimating the Probability of Future Climate Shifts

David Enfield, NOAA Atlantic Oceanographic & Meteorological Laboratory, David.Enfield@noaa.gov

Recent research has pointed to the existence of natural, generation-scale (15-40 year) climate phases, or regimes, related to the influence of the Atlantic and Pacific Oceans. These decadal-to-multidecadal (D2M) swings in ocean temperatures have had significant impacts on air temperature, rainfall and severe storms in North America, Europe and Africa. Most importantly, D2M climate regimes have impacted the frequency of extreme events, such as droughts, floods, hurricanes and environmentally linked health problems. The natural D2M climate regimes have alternately camouflaged and exaggerated the effects of anthropogenic climate change, and are being studied, among other things, in order to reduce the uncertainty in regard to the magnitude of the anthropogenic influence. Modern computer models used for D2M studies—unlike those used for the more short-lived El Niño—are not yet capable of predicting future shifts in the D2M climate regimes. However, thanks to recent tree-ring reconstructions of past D2M regime shifts over a half-millennium or more, we now have the ability to project the probability of future regime shifts with useful accuracy. With further collaboration between climate scientists and risk managers, such as water management engineers, it is hoped that this new area of study will lead to the development of an increasingly useful suite of decision support tools for water, health, agriculture and disaster mitigation.

[Poster PDF]

P-GC1.4

More on Hockey Sticks: The Case of Jones et al. [1998]

Stephen McIntyre, stephen.mcintyre@utoronto.ca

Multiproxy studies purporting to show 20th century uniqueness have been applied by policymakers, but they have received remarkably little independent critical analysis. Jones et al. [1998] is a prominent multi-proxy study used by IPCC [2001] and others to affirm the hockey stick shaped temperature reconstruction of Mann et al. [1998]. However, the reconstruction of Jones et al. [1998] is based on only 3-4 proxies in the controversial Medieval Warm Period, including non-arms-length studies by Briffa et al. [1992] and Briffa et al [1995]. We show that the Polar Urals data set in Briffa et al [1992] fails to meet a variety of quality control standards, both in replication and crossdating. The conclusion of Briffa et al. [1995] that 1032 was the "coldest year" of the millennium proves to be based on inadequate replication of only 3 tree ring cores, of which at least 2 are almost certainly incorrectly crossdated. We show that an ad hoc adjustment to the Tornetrask data set in Briffa et al [1992] cannot be justified. The individual and combined impact of defects in the Polar Urals data set and Tornetrask adjustments on the reconstruction of Jones et al [1998] is substantial and can be seen to have the effect of modifying what would otherwise indicate a pronounced Medieval Warm Period in the proxy reconstruction. Inhomogeneity problems in the Polar Urals and Tornetrask data sets, pertaining to altitude, minimum girth bias and pith centering bias will also be discussed.

P-GC1.5

Assessment of U.S. Climate Variations Using the U.S. Climate Extremes Index
and the U.S. Greenhouse Climate Response Index

David Karoly, School of Meteorology, University of Oklahoma, Norman OK, dkaroly@rossby.metr.ou.edu

Aaron Ruppert, School of Meteorology, University of Oklahoma, Norman OK

David Easterling, National Climatic Data Center, NOAA, Asheville, NC

Jay Lawrimore, National Climatic Data Center, NOAA, Asheville, NC

Karl et al. (1996) developed two indices to quantify observed changes in climate within the contiguous United States, a US Climate Extremes Index (CEI) and a US Greenhouse Climate Response Index (GCRI). The CEI is based on a combination of climate extreme indicators, while the GCRI is a combination of indicators based on projected changes due to greenhouse climate change. These indices integrate changes in climate over several different temperature and precipitation measures and are likely to provide early detection of important changes in climate in the United States. The CEI and the GCRI should be useful for decision making because they provide concise summaries of changes in temperature and precipitation extremes over the US, relevant to many climate impact areas including energy and water use. The CEI is updated annually and used for operational climate monitoring at NCDC (available online). Karl et al. (1996) noted an increasing trend in the CEI in recent decades and a significant positive trend in the GCRI during the 20th century. However, attribution of these observed changes to specific causes was not possible, as they were not directly compared with climate model simulations.

An assessment of variations of the CEI over the twentieth century has been undertaken, including comparison of the observed indices with those calculated from global climate model simulations. Some issues with the interpretation of variations in the CEI have been identified. A new version of the GCRI has been developed. Significant increasing trends have been found in the components of the new GCRI associated with extreme maximum and minimum temperatures, due to fewer cold extremes and more hot extremes across the continental US. These variations are outside the range of internal climate variations simulated by climate models and are consistent with the models' responses to increasing greenhouses gases and sulfate aerosols. Hence, it is likely that anthropogenic climate forcing is contributing to changes in temperature extremes in the United States. There have also been recent changes in the components of the new GCRI associated with precipitation extremes, with more rain days and more intense rainfall, but it is harder to separate any anthropogenic influence from internal climate variations.

Karl, T.R., R.W. Knight, D.R. Easterling, and R.G. Quayle, 1996: Indices of climate change for the United States. Bull. Am. Meteor. Soc., 77, 279-292.

[Poster PDF]

P-GC1.6

Relative Sea Level Trends from Tide Stations: How Are They Determined and What Do They Tell Us?

Chris Zervas, NOAA/NOS, Chris.Zervas@noaa.gov

Stephen Gill, NOAA/NOS, stephen.gill@noaa.gov

Allison Stolz, NOAA/NOS

The NOAA National Ocean Service operates a National Water Level Observation Network to serve a variety of NOAA missions, including marine transportation, weather and water, habitat restoration, and climate. Many of the stations have been operating continuously for over 50 years and are accumulating time series from which accurate relative sea level trends can be determined. This is accomplished only through proper operation and maintenance of the tide gauges, maintenance and routine leveling of the local tidal bench mark networks for monitoring vertical stability, and quality control of the data and output products at various time steps. Sea level trends and variations determined from tide stations provide information relative to the land and contain vertical movement due to local and regional land movement as well as components due to long-term global sea level rise. Researchers have made estimates of global sea level rise from selected global tide stations by correcting them with large scale tectonic models, and tide stations are being used to calibrate and evaluate global sea level trend estimates from satellite altimeter missions. Recent research includes integration of relative sea level trends with long-term continuous GPS measurements. Estimates of sea level trends from tide stations are also a key component of trying to understand the current mass balance of the oceans and how the mass balance may be changing due to thermal expansion and freshwater input from melting glaciers and Antarctic and Greenland icepacks. In a practical sense, sea level trends derived from tide stations are used for a variety of decision-making and assessment applications, including surveying and mapping, coastal engineering, habitat restoration, and coastal management. NOAA produces an online product that gives the latest information on relative sea level trends at coastal and ocean island stations.

[Poster PDF]

P-GC1.7

A Maturity Model for Satellite-Derived Climate Data Records

Bruce R. Barkstrom, ASDC, NASA Langley Research Center, b.r.barkstrom@larc.nasa.gov

John J. Bates, NOAA's National Climate Data Center

There is considerable confusion in both the scientific community and the general public about how to define a climate data record (CDR) produced from satellite remote sensing data. This confusion appears in the diversity of vocabularies, experiences, and backgrounds used to describe the suitability of data for climate-related work. In this paper, we describe a set of metrics that provides an objective framework for evaluating the suitability of describing a data collection as a CDR. This framework should reduce the community confusion, improve the reliability of conclusions drawn from CDR data, and assist in strategic management of these data by identifying areas needing improvement.

We define the model in terms of three dimensions of maturity:

1. Scientific Maturity, particularly the quantification of measurement uncertainty,
2. Preservation Maturity, particularly the documentation of data collection, production, and provenance,
3. Societal Impact of the data.

Within each of these dimensions, we identify key attributes of maturity and then rank the maturity of a data collection for each attribute on a scale of 0 to 5. This approach avoids dependence on just one or two metric values and provides a balanced view of the different areas of maturity.

For scientific maturity, we heavily weight the ability of a CDR to reliably extract a meaningful measure of decadal or longer trends in a field of interest. We discuss a simple model of the measurement process that clearly identifies a trend and compares a simulated measurement of the trend with its true value. By running an ensemble of cases that cover the statistics of the measurements and their errors, we can quantify how far the true trend might lie from a measured value – a quantification we call the "fidelity interval" of the measured trend. The statistical approach we suggest is extensible to a variety of measurement approaches and is sufficiently realistic to allow us to incorporate a variety of calibration and validation activities. In addition, by quantifying the resource requirements and schedule for these activities, we can provide an initial estimate of the cost/benefit value of the proposed schedule in terms of reduced uncertainty.

For preservation maturity, we start with two fundamental principles: that long-term usability of data requires minimizing the probability of loss (whether through physical damage or through loss of ability to find relevant information) and minimization of the cost of archival operations. By extending these principles in practice, we are able to quantify maturity in terms of a modest number of attributes that can be ranked on a scale similar to the one we suggest for assessing scientific maturity.

For societal impact (or benefit), we are particularly concerned with assessing the change in social and economic terms of reducing the uncertainty of climate trends. This is, of course, a difficult task that again requires a probabilistic statement of maturity. As with several other approaches to climate change assessment, the maturity model needs to help decision and policy makers by providing realistic assessments of the probability of a wide range of impacts.

To increase the strategic management capability of the maturity model, we observe that each of the three axes can be associated with costs or benefits. Scientific maturity and preservation maturity both require expenditures, and may therefore be associated with "debit accounts" for a particular CDR. The benefit of making the measurement and using the data is associated with a "credit account." Thus, our maturity model provides both a an objective approach to assessing the suitability of calling a measurement set a Climate Data Record and provides a start at assessing the return on investment that is available by maturing the measurement and preservation processes.

[Poster PDF]

P-GC1.8

The Contribution of Earth Science Remote Sensing Data to Natural Resources Policymaking

Molly Macauley, Resources for the Future,

Fred Vukovich, SAIC, Inc.

This paper traces the evolution of space-derived remote sensing data and data products from their initial dissemination to their eventual impact on the nature and outcome of public policy addressing climate change issues. We focus on the example of renewable energy. Our approach is different from previous studies that have characterized the value of data in terms of the fundamental scientific phenomena they describe. Our research seeks to assist in answering the question posed by Congress, the Office of Management and Budget, managers at the National Aeronautics and Space Administration, and other decision makers about what, if any, have been other contributions of space-derived earth science.

[Poster PDF]

P-GC1.9

Accessing NOAA Daily Temperature and Precipitation Extremes
Based on Combined/Threaded Station Records

Timothy W. Owen, NOAA/National Climatic Data Center,

Keith Eggleston, Northeast Regional Climate Center

Art DeGaetano, Northeast Regional Climate Center

Robert Leffler, NOAA/National Weather Service/Climate Services Division

Daily records of both temperature and precipitation are of great interest to the public and many data users. However, numerous station relocations over the years have resulted in inconsistent approaches to combining multi-location data sets, resulting in disparate reporting of record and extreme values at many prominent large metropolitan observing sites.

In the interest of ensuring consistent reporting of climatological data, NOAA's National Climatic Data Center (NCDC), in partnership with the Northeast Regional Climate Center (NRCC), NOAA's National Weather Service/Climate Services Division, and numerous data users, has established a data set of combined (or threaded) period of record daily temperature and precipitation values at approximately 300 NOAA published Local Climatological Data locations. This new data set provides a consistent basis for the reporting of daily, monthly, and annual extremes for the longest period of time meaningful. The development of this data set is especially timely given the increasing availability of historic daily values in digital form for the first half of the 20th Century (and earlier in some cases).

This presentation provides a discussion on the methodology for establishing multi-location combined (or threaded) station data sets, preliminary applications of the data, and schedules for its public release.

[Poster PDF]

P-GC1.10

NOAA Climate Prediction Center Products for Decision Making

James Laver, NOAA/NWS/NCEP/CPC, jim.laver@noaa.gov

NOAA's Climate Prediction Center (CPC) continues developing a wide range of climate products for decision makers and applications. Information on climate variability, real-time climate "nowcasts," and climate outlooks from "Week-2" through seasonal to interannual time scales are important to decision makers in energy, agriculture, public safety and other sectors of the economy. In response to user needs, NOAA expects to continue developing scientific resources for decision making, and refined products and product presentations to enhance their utility for applications. Producers and consumers of climate information have developed adaptive management and planning capabilities. Improvements are being developed for communicating scientific information, including incorporation of information about levels of confidence and uncertainty in decision-making.

The CPC produces educational materials to help users better understand the role of the climate system in our lives, as well as the limitations and usefulness of climate forecasts. The partnerships that have developed through the production and use of climate variability products provides a nucleus and resource for understanding the process by which climate change products may be developed, improved, and applied for maximum utility.

The CPC is responsible for operational delivery of monthly and seasonal climate outlooks, extended range outlooks for Week-2 (6-10 and 8-14 days out), advisories and outlooks, for El Niño, La Niña, the Atlantic hurricane season, degree days, drought, and an ultraviolet (UV) radiation index. The CPC's outlooks and forecast products complement the short range weather forecasts issued by other components of the National Weather Service (e.g. local Weather Forecast Offices, and National Centers for Environmental Prediction). These weather and climate products contribute to NOAA's Seamless Suite of Forecast Products.

CPC's role as a "producer" in the above activities, with its partners inside and outside NOAA, results in a unique opportunity to assist the community of decision makers in understanding and applying the integration of weather, climate, and impacts across all time scales.

[Poster PDF]

P-GC1.11

Aerosol Direct Radiative Effects Over the Northwest Atlantic, Northwest Pacific, and North Indian Oceans: Estimates Based on In-Situ Chemical and Optical Measurements and Chemical Transport Modeling and Their Relation to Decision-Support Information

A. Ravishankara, NOAA, A.R.Ravishankara@noaa.gov

Timothy Bates, NOAA

Theodore Anderson, University of Washington

Greogory Carmichael, University of Iowa

Anthony Clarke, University of Hawaii

Caryn Erlick, The Hebrew University of Jerusalem

Lawrence Horowitz, NOAA

Patricia Quinn, NOAA

Stephen Schwartz, Brookhaven National Laboratory

H. Maring, NASA

Aerosols influence the climate system via scattering and absorption of solar radiation, changing cloud properties and altering precipitation. The largest uncertainty in the radiative forcing of climate change over the industrial era is that due to aerosols (IPCC-2001). This uncertainty arises in part due to the uncertainty in scattering and absorption of shortwave (solar) radiation by aerosols of anthropogenic origin in cloud-free conditions. Aerosols are short-lived and, hence, highly variable on local and regional scales. The forcing by aerosols varies on regional scales and depending on absorption differs can be higher at the surface than at the top of the atmosphere. Aerosols also influence local surface temperature and moisture. Therefore, aerosols impact all five major themes of this workshop: water, ecosystems, coastal issues, energy and air quality.

Reduction in the uncertainty in aerosol's influence on climate and building a better predictive capability are major goals of the CCSP activities. Quantitatively, evaluating the current capability is a distinct milestone in this endeavor. To this end, the measured aerosol properties over three regions of the globe downwind of major urban/population centers were used to calculate the aerosol forcing due to light scattering and absorption. Directly measured aerosol burdens (mass), aerosol extinction optical depth, and aerosol properties were used to calculate the climate forcing via scattering and absorption (change in radiative flux due to total aerosols) and compared against models. In-situ and remotely sensed aerosol properties for each region were used as input parameters to radiative transfer models to constrain the models. The "a priori" and "constrained" model results were then compared. The uncertainties in each step were determined and propagated through the analysis. The results demonstrate that when the radiative transfer models were constrained by observational inputs they have a lower uncertainty than the models with "a priori" parameterizations (e.g., IPCC- 2001), and thus help reduce uncertainty in the estimation of the impact of aerosols on climate.

The results from this study will (i) assist the IPCC (2007) assessment and will (ii) form input into future CCSP activities that will include evaluations of the radiative forcing by aerosols into specific 2007 decision-support information products. The use of observational constraints helps base choices on real world, observationally-vetted, decision tools that are expected to be more quantitative; they also help improve model development for future
predictions.

[Poster PDF]

P-GC1.12

Response of a Coupled Chemistry-Climate Model to Changes in Aerosol Emissions

Jean-Francois Lamarque, NCAR, lamar@ucar.edu

Jeff Kiehl, NCAR

Peter Hess, NCAR

Louisa Emmons, NCAR

Paul Ginoux, NOAA/GFDL

Chao Luo, UCSB

XueXi Tie, NCAR

In this study, we analyze the response of the coupled chemistry-climate (the NCAR Community Atmosphere Model, CAM3) system to changes in aerosol emissions in fully coupled atmospheric chemistry-climate-slab ocean model simulations. Using this model we have performed a set of simulations that highlights the role of aerosols over a wide range of emission scenarios. Under these conditions, we focus on the two most basic ways aerosols can impact a coupled chemistry-climate model: direct radiative forcing and chemical uptake. In particular, we have chosen to simulate the state of the atmosphere when many of the aerosol (or their precursors) emissions are explicitly set to 0. While this is an unrealistic scenario (all aerosol emissions have some natural component to them), it provides an interesting upper limit scenario to the results of a possible decrease in aerosol emissions from their present-day estimates. We show that, at the global scale, a decrease in emissions of the considered aerosols (or their precursors) produces a warmer and moister climate. Without aerosols, the globally-averaged surface temperature is approximately 0.5°C warmer. In addition, the tropospheric burdens of OH and ozone significantly increase when aerosol emissions are decreased. These chemical responses are shown to be a combination of the impact of reduced heterogeneous uptake and impact (such as increased ozone loss) of a moister atmosphere.

[Poster PDF]

P-GC1.13

Aviation and the Global Atmosphere: The State of the Science and Future Research Needs

Lourdes Maurice, FAA, Lourdes.Maurice@faa.gov

Curtis Holsclaw, FAA

Maryalice Locke, FAA

Ian Waitz, MIT

Stephen Lukachko, MIT

Rick Miake-Lye, Aerodyne

Greenhouse gas emissions from aviation have grown and should continue to increase commensurately with increasing aviation activity. However, the direct impact of aviation on climate via the emission of green house gases is small relative to other anthropogenic sources. Nevertheless, the potential impact of aviation on climate is unique and important because aviation associated sources occur at significant altitude where other anthropogenic sources are absent. Also, aviation's relative contribution to greenhouse gas inventories will likely grow against a background of other industries being able to switch to alternative forms of energy and significantly reduce greenhouse gas emissions.

In 1999, a major publication was written by authors from the broad community of aviation and atmospheric science under the auspices of the Intergovernmental Panel on Climate Change, Aviation and the Global Atmosphere [IPCC, 1999]. The report included a thorough documentation of the state of understanding of how emissions at cruise altitudes affect the atmosphere. The estimated impacts due to various emissions and the degree of confidence in the estimates of their impacts were presented and have been since been quoted often.

The authors of the IPCC Aviation and the Global Atmosphere report recognized that there were significant scientific uncertainties surrounding aviation's impact on the atmosphere. These include the influence of contrails and particles on cirrus clouds, the role of NO_X in changing ozone and methane concentrations, and the atmospheric processing of water near the tropopause. Furthermore, investigators have since noted that assessment of the relative impact of various emissions did not take into account the varying lifetimes of various emissions, an omission which could have significant impact and potentially lead to flawed policy decisions and mitigation options.

This presentation will review the present state of knowledge of aviation's impact on the global atmosphere, including uncertainties. It will highlight areas of needed research to reduce these uncertainties to levels that enable appropriate action. It will highlight potential options for mitigating aviation's greenhouse emissions. And ultimately, it will seek to catalyze debate and action on tackling these issues.

[Poster PDF]