Roger Pielke Sr. on the House global warming hearings
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The U.S. House of Representatives Subcommitee On Energy and Environment Hearing titled
A Rational Discussion of Climate Change: the Science, the Evidence, the Response
that Judy Curry has posted on; e.g. see
Uncertainty gets a seat at the big table: Part III
contains statements on climate science that are incomplete and are misleading. These statement can be read in the Hearing Charter where they write [highlighting added]
Climate and Weather
Climate can be defined as the product of several meteorological elements in a given region over a period of time.
In addition, spatial elements such as latitude, terrain, altitude, proximity to water and ocean currents affect the climate. We experience climate on a daily basis through the weather. The difference between weather and climate is a measure of time—weather consists of the short-term (minutes to months) changes in the atmosphere. Weather is often thought of in terms of temperature, humidity, precipitation, cloudiness, brightness, visibility, wind, and atmospheric pressure. Weather is what conditions of the atmosphere are over a short period of time, and climate is how the atmosphere “behaves” over relatively long periods of time. In most places, weather can change from minute-to-minute, hour-to-hour, day-to-day, and season-to-season. Climate, however, is the average of weather over a period of years to decades. Generally, climate is what you expect, like a very hot summer in the American Southwest, and weather is what you get, like a hot day with pop-up thunderstorms.”
and [highlighting added]
The Science
“Climate can be influenced by a variety of factors, including: changes in solar activity, long-period changes in the Earth’s orbit, natural internal processes of the climate system, and anthropogenic (i.e. human-induced) increases in atmospheric concentrations of carbon dioxide (CO2) and other greenhouse gases (GHGs). As described above, “climate” is the long-term average of a region’s weather patterns, and “climate change” is the term used to describe changes in those patterns. Climate change will not have a uniform effect on all regions and these differing effects may include changes to average temperatures (up or down), changes in season length (e.g. shorter winters), changes in rain and snowfall patterns, and changes in the frequency of intense storms. The scientific community has made tremendous advances in understanding the basic physical processes as well as the primary causes of climate change. And researchers are developing a strong understanding of the current and potential future impacts on people and industries.”
The preamble of the Hearing misrepresents the current understanding of the climate system and the role of humans within it. The staff who prepared the Hearing Charter either are unaware of the actual state of the science or have chosen to purposely misrepresent the science.
With respect to weather and climate, the writers of the Charter have chosen to use an old, limited definition of climate. The current definition of climate system, which is the one that appropriately should be used for the Hearing is given, for example, in
National Research Council, 2005: Radiative forcing of climate change: Expanding the concept and addressing uncertainties. Committee on Radiative Forcing Effects on Climate Change, Climate Research Committee, Board on Atmospheric Sciences and Climate, Division on Earth and Life Studies, The National Academies Press, Washington, D.C., 208 pp
where the climate system is defined as
“The system consisting of the atmosphere, hydrosphere, lithosphere, and biosphere, determining the Earth’s climate as the result of mutual interactions and responses to external influences (forcing). Physical, chemical, and biological processes are involved in interactions among the components of the climate system.”
The climate system is shown schematically in the NRC report
The statements in the Hearing Charter
“Climate can be defined as the product of several meteorological elements in a given region over a period of time.”
and
“Climate can be influenced by a variety of factors, including: changes in solar activity, long-period changes in the Earth’s orbit, natural internal processes of the climate system, and anthropogenic (i.e. human-induced) increases in atmospheric concentrations of carbon dioxide (CO2) and other greenhouse gases (GHGs).”
are misleading policymakers and the public with respect to the real climate system. Not only is their definition of climate archaic, but they left off other important first order human climate forcings, as reported in the 2005 NRC report, and summarized in our article
Pielke Sr., R., K. Beven, G. Brasseur, J. Calvert, M. Chahine, R. Dickerson, D. Entekhabi, E. Foufoula-Georgiou, H. Gupta, V. Gupta, W. Krajewski, E. Philip Krider, W. K.M. Lau, J. McDonnell, W. Rossow, J. Schaake, J. Smith, S. Sorooshian, and E. Wood, 2009: Climate change: The need to consider human forcings besides greenhouse gases. Eos, Vol. 90, No. 45, 10 November 2009, 413. Copyright (2009) American Geophysical Union
where we wrote
“In addition to greenhouse gas emissions, other first-order human climate forcings are important to understanding the future behavior of Earth’s climate. These forcings are spatially heterogeneous and include the effect of aerosols on clouds and associated precipitation [e.g., Rosenfeld et al., 2008], the influence of aerosol deposition (e.g., black carbon (soot) [Flanner et al. 2007] and reactive nitrogen [Galloway et al., 2004]), and the role of changes in land use/land cover [e.g., Takata et al., 2009]. Among their effects is their role in altering atmospheric and ocean circulation features away from what they would be in the natural climate system [NRC, 2005]. As with CO2, the lengths of time that they affect the climate are estimated to be on multidecadal time scales and longer.
Therefore, the cost-benefit analyses regarding the mitigation of CO2 and other greenhouse gases need to be considered along with the other human climate forcings in a broader environmental context, as well as with respect to their role in the climate system.”
When the Republicans take control of this Subcommittee in January, I recommend they correct and broaden the perspective on the climate system from what the November 17 2010 Hearing adopted. The Perpetuation Of Climate Misunderstandings By The U.S. House Of Representatives Subcommitee On Energy and Environment
