John Christy

Last updated
John Raymond Christy
Born
California, USA
Nationality American
Alma mater California State University, University of Illinois, Golden Gate Baptist Seminary
Known for UAH satellite data
Spouse(s)Babs (Joslin) Christy, 1975. Died 2014. Sherry (Upshaw) Christy, 2015
Awards1991 Medal for Exceptional Scientific Achievement, NASA; 1996 Special Award, American Meteorological Society
Scientific career
Fields Atmospheric Science
Institutions University of Alabama in Huntsville (UAH)
Thesis An investigation of the general circulation associated with extreme anomalies in hemispheric mean atmospheric mass  (1987)
Doctoral advisor Kevin Trenberth
Website nsstc.uah.edu/users/john.christy/

John Raymond Christy is a climate scientist at the University of Alabama in Huntsville (UAH) whose chief interests are satellite remote sensing of global climate and global climate change. He is best known, jointly with Roy Spencer, for the first successful development of a satellite temperature record. [1]

Contents

Early life and education

A native of Fresno, California, Christy became interested in the weather when he was a child. He became curious why the weather in the San Joaquin Valley was so different from that of the Sierra Mountains. He has recalled that "I built my first climate datasets when I was 12, using a mechanical pencil, graph paper, and long-division (no calculators back then.) I've been a climate nerd ever since." [2] He received a BA in mathematics from California State University, Fresno in 1973, and an MS and PhD in atmospheric sciences from the University of Illinois at Urbana–Champaign in 1984 and 1987. [1] His doctoral thesis was titled, An investigation of the general circulation associated with extreme anomalies in hemispheric mean atmospheric mass. [3]

Prior to his scientific career, Christy taught physics and chemistry as a missionary teacher in Nyeri, Kenya from 1973 to 1975. After earning a Master of Divinity degree from Golden Gate Baptist Seminary in 1978 he served four years as a bivocational mission-pastor in Vermillion, South Dakota, where he also taught college math. [1]

Career

He is the distinguished professor of atmospheric science and director of the Earth System Science Center at the University of Alabama in Huntsville (UAH). [1] He was appointed Alabama's state climatologist in 2000. For his development of a global temperature data set from satellites, he was awarded NASA's Medal for Exceptional Scientific Achievement and the American Meteorological Society's "Special Award." [1] In 2002, Christy was elected Fellow of the American Meteorological Society. [4]

Satellite temperature record

Since 1989 Christy, along with Roy Spencer, has maintained an atmospheric temperature record derived from satellite microwave sounding unit measurements (see: satellite temperature record). This was once quite controversial: From the beginning of the satellite record in late 1978 into 1998 it showed a net global cooling trend, although ground measurements and instruments carried aloft by balloons showed warming in many areas. Part of the cooling trend seen by the satellites can be attributed to several years of cooler than normal temperatures and cooling caused by the eruption of the Mount Pinatubo volcano. Part of the discrepancy between the surface and atmospheric trends was resolved over a period of several years as Christy, Spencer and others identified several factors, including orbital drift and decay, that caused a net cooling bias in the data collected by the satellite instruments. [5] [6] Since the data correction of August 1998 (and the major La Niña Pacific Ocean warming event of the same year), data collected by satellite instruments have shown an average global warming trend in the atmosphere. From November 1978 through March 2011, Earth's atmosphere has warmed at an average rate of about 0.14 C per decade, according to the UAH satellite record.

Christy was a lead author of a section of the 2001 report by the IPCC [7] and the U.S. CCSP report Temperature Trends in the Lower Atmosphere – Understanding and Reconciling Differences. [5] Christy also signed the 2003 American Geophysical Union statement on climate change. [8]

Christy has also performed detailed reconstruction of surface temperature for Central California. He found that recorded temperature changes there were consistent with an altered surface environment caused by increased irrigation for agriculture, which changed "a high-albedo desert into a darker, moister, vegetated plain." [9]

Views

In a 2003 interview with National Public Radio about the 2003 American Geophysical Union (AGU) statement, he said he is "a strong critic of scientists who make catastrophic predictions of huge increases in global temperatures and tremendous rises in sea levels". He added, though, that "it is scientifically inconceivable that after changing forests into cities, turning millions of acres into irrigated farmland, putting massive quantities of soot and dust into the air, and putting extra greenhouse gases into the air, that the natural course of climate has not changed in some way." [8]

In a 2009 interview with Fortune magazine about signing the 2003 American Geophysical Union (AGU) statement, he said: "As far as the AGU, I thought that was a fine statement because it did not put forth a magnitude of the warming. We just said that human effects have a warming influence, and that's certainly true. There was nothing about disaster or catastrophe. In fact, I was very upset about the latest AGU statement [in 2007]. It was about alarmist as you can get." [10]

In a 2007 editorial in The Wall Street Journal , he wrote: "I'm sure the majority (but not all) of my IPCC colleagues cringe when I say this, but I see neither the developing catastrophe nor the smoking gun proving that human activity is to blame for most of the warming we see." [11]

In a 2009 written testimony to the U.S. House Ways and Means Committee, he wrote: "From my analysis, the actions being considered to 'stop global warming' will have an imperceptible impact on whatever the climate will do, while making energy more expensive, and thus have a negative impact on the economy as a whole. We have found that climate models and popular surface temperature data sets overstate the changes in the real atmosphere and that actual changes are not alarming." [12]

In 2014, Christy and his UAH colleague Richard McNider wrote an op-ed in The Wall Street Journal, arguing that climate models projected temperatures consistently higher than real-world satellite and balloon data. The authors also pointed to past instances where scientific consensus turned out to be incorrect. [13]

Awards

See also

Selected publications

Articles

Peer-reviewed papers

Related Research Articles

<span class="mw-page-title-main">Causes of climate change</span> Effort to scientifically ascertain mechanisms responsible for recent global warming

The scientific community has been investigating the causes of climate change for decades. After thousands of studies, it came to a consensus, where it is "unequivocal that human influence has warmed the atmosphere, ocean and land since pre-industrial times." This consensus is supported by around 200 scientific organizations worldwide, The dominant role in this climate change has been played by the direct emissions of carbon dioxide from the burning of fossil fuels. Indirect CO2 emissions from land use change, and the emissions of methane, nitrous oxide and other greenhouse gases play major supporting roles.

<span class="mw-page-title-main">Satellite temperature measurement</span> Measurements of atmospheric, land surface or sea temperature by satellites.

Satellite temperature measurements are inferences of the temperature of the atmosphere at various altitudes as well as sea and land surface temperatures obtained from radiometric measurements by satellites. These measurements can be used to locate weather fronts, monitor the El Niño-Southern Oscillation, determine the strength of tropical cyclones, study urban heat islands and monitor the global climate. Wildfires, volcanos, and industrial hot spots can also be found via thermal imaging from weather satellites.

<span class="mw-page-title-main">General circulation model</span> Type of climate model

A general circulation model (GCM) is a type of climate model. It employs a mathematical model of the general circulation of a planetary atmosphere or ocean. It uses the Navier–Stokes equations on a rotating sphere with thermodynamic terms for various energy sources. These equations are the basis for computer programs used to simulate the Earth's atmosphere or oceans. Atmospheric and oceanic GCMs are key components along with sea ice and land-surface components.

<span class="mw-page-title-main">Global cooling</span> Discredited 1970s hypothesis of imminent cooling of the Earth

Global cooling was a conjecture, especially during the 1970s, of imminent cooling of the Earth culminating in a period of extensive glaciation, due to the cooling effects of aerosols or orbital forcing. Some press reports in the 1970s speculated about continued cooling; these did not accurately reflect the scientific literature of the time, which was generally more concerned with warming from an enhanced greenhouse effect.

<span class="mw-page-title-main">Global dimming</span> Reduction in the amount of sunlight reaching Earths surface

Global dimming is a decline in the amount of sunlight reaching the Earth's surface. It is caused by atmospheric particulate matter, predominantly sulfate aerosols, which are components of air pollution. Global dimming was observed soon after the first systematic measurements of solar irradiance began in the 1950s. This weakening of visible sunlight proceeded at the rate of 4–5% per decade until the 1980s. During these years, air pollution increased due to post-war industrialization. Solar activity did not vary more than the usual during this period.

<span class="mw-page-title-main">Roy Spencer (meteorologist)</span>

Roy Warren Spencer is an American meteorologist. He is a principal research scientist at the University of Alabama in Huntsville, and the U.S. Science Team leader for the Advanced Microwave Scanning Radiometer (AMSR-E) on NASA's Aqua satellite. He has served as senior scientist for climate studies at NASA's Marshall Space Flight Center. He is known for his satellite-based temperature monitoring work, for which he was awarded the American Meteorological Society's Special Award. Spencer disagrees with the scientific consensus that most global warming in the past 50 years is the result of human activity, instead believing that anthropogenic greenhouse gas emissions have caused some warming, but that influence is small compared to natural variations in global average cloud cover.

<span class="mw-page-title-main">Radiative forcing</span> Concept for changes to the energy flows through a planetary atmosphere

Radiative forcing is a concept used to quantify a change to the balance of energy flowing through a planetary atmosphere. Various factors contribute to this change in energy balance, such as concentrations of greenhouse gases and aerosols, and changes in surface albedo and solar irradiance. In more technical terms, it is defined as "the change in the net, downward minus upward, radiative flux due to a change in an external driver of climate change." These external drivers are distinguished from feedbacks and variability that are internal to the climate system, and that further influence the direction and magnitude of imbalance. Radiative forcing on Earth is meaningfully evaluated at the tropopause and at the top of the stratosphere. It is quantified in units of watts per square meter, and often summarized as an average over the total surface area of the globe.

David H. Douglass is an American physicist at the University of Rochester.

<span class="mw-page-title-main">Greenhouse gas</span> Gas in an atmosphere with certain absorption characteristics

Greenhouse gases (GHGs) are the gases in the atmosphere that raise the surface temperature of planets such as the Earth. What distinguishes them from other gases is that they absorb the wavelengths of radiation that a planet emits, resulting in the greenhouse effect. The Earth is warmed by sunlight, causing its surface to radiate heat, which is then mostly absorbed by greenhouse gases. Without greenhouse gases in the atmosphere, the average temperature of Earth's surface would be about −18 °C (0 °F), rather than the present average of 15 °C (59 °F).

<span class="mw-page-title-main">History of climate change science</span> Aspect of the history of science

The history of the scientific discovery of climate change began in the early 19th century when ice ages and other natural changes in paleoclimate were first suspected and the natural greenhouse effect was first identified. In the late 19th century, scientists first argued that human emissions of greenhouse gases could change Earth's energy balance and climate. The existence of the greenhouse effect, while not named as such, was proposed as early as 1824 by Joseph Fourier. The argument and the evidence were further strengthened by Claude Pouillet in 1827 and 1838. In 1856 Eunice Newton Foote demonstrated that the warming effect of the sun is greater for air with water vapour than for dry air, and the effect is even greater with carbon dioxide.

Remote Sensing Systems (RSS) is a private research company founded in 1974 by Frank Wentz. It processes microwave data from a variety of NASA satellites. Most of their research is supported by the Earth Science Enterprise program. The company is based in Santa Rosa, California.

Carl Mears is a Senior Scientist, at Remote Sensing Systems, since 1998. He has worked on validation of SSM/I derived winds, and rain-flagging algorithm for the QuikScat scatterometer. He is best known for his work with Frank Wentz in developing a satellite temperature record from MSU and AMSU. Intercomparison of this record with the earlier UAH satellite temperature record, developed by John Christy and Roy Spencer, revealed deficiencies in the earlier work; specifically, the warming trend in the RSS version is larger than the UAH one.

Frank Wentz is the CEO and director of Remote Sensing Systems, a company he founded in 1974, which specializes in satellite microwave remote sensing research. Together with Carl Mears, he is best known for developing a satellite temperature record from MSU and AMSU. Intercomparison of this record with the earlier UAH satellite temperature record, developed by John Christy and Roy Spencer, revealed deficiencies in the earlier work; specifically, the warming trend in the RSS version is larger than the University of Alabama in Huntsville (UAH) one. From 1978 to 1982, Wentz was a member of NASA's SeaSat Experiment Team involved in the development of physically based retrieval methods for microwave scatterometers and radiometers. He has also investigated the effect of climate change on satellite-derived evaporation, precipitation and surface wind values. His findings are different from most climate change model predictions.

<span class="mw-page-title-main">Microwave Sounding Unit temperature measurements</span>

Microwave Sounding Unit temperature measurements refers to temperature measurement using the Microwave Sounding Unit instrument and is one of several methods of measuring Earth atmospheric temperature from satellites. Microwave measurements have been obtained from the troposphere since 1979, when they were included within NOAA weather satellites, starting with TIROS-N. By comparison, the usable balloon (radiosonde) record begins in 1958 but has less geographic coverage and is less uniform.

The UAH satellite temperature dataset, developed at the University of Alabama in Huntsville, infers the temperature of various atmospheric layers from satellite measurements of the oxygen radiance in the microwave band, using Microwave Sounding Unit temperature measurements.

<span class="mw-page-title-main">Global surface temperature</span> Average temperature of the Earths surface

Global surface temperature (GST) is the average temperature of Earth's surface. More precisely, it is the weighted average of the temperatures over the ocean and land. The former is also called sea surface temperature and the latter is called surface air temperature. Temperature data comes mainly from weather stations and satellites. To estimate data in the distant past, proxy data can be used for example from tree rings, corals, and ice cores. Observing the rising GST over time is one of the many lines of evidence supporting the scientific consensus on climate change, which is that human activities are causing climate change. Alternative terms for the same thing are global mean surface temperature (GMST) or global average surface temperature.

<span class="mw-page-title-main">Solar activity and climate</span> Field of scientific study

Patterns of solar irradiance and solar variation have been a main driver of climate change over the millions to billions of years of the geologic time scale.

Jennifer Logan is an atmospheric scientist known for her research on how human activities influence the atmosphere, particularly with respect to biomass burning and the ozone hole.

Joyce Penner is an atmospheric scientist known for her research on climate change, especially on the impact of aerosols and clouds.

References

  1. 1 2 3 4 5 "Dr. John Christy Biography". University of Alabama in Huntsville. Retrieved November 14, 2019. See also archived version (archivedate=16 July 2012).
  2. ↑ John Christy website at UAH.
  3. ↑ An investigation of the general circulation associated with extreme anomalies in hemispheric mean atmospheric mass. University of Illinois. 1987. OCLC   18286111.
  4. ↑ "List of AMS Fellows". American Meteorological Society . Retrieved October 8, 2008.
  5. 1 2 Tom M. L. Wigley; et al. (April 2006). "Temperature Trends in the Lower Atmosphere – Executive Summary" (PDF). U.S. Climate Change Science Program. Archived from the original (PDF) on 2007-04-23.
  6. ↑ Roy Spencer; John Christy; Phillip Gentry (May 5, 2004). "New Climate Study Finds 'Global Warming' by Subtracting Cooling That Wasn't There". University of Alabama in Huntsville.
  7. ↑ "Appendix III – Contributors to the IPCC WGI Third Assessment Report". IPCC. 2001. Retrieved April 4, 2007.
  8. 1 2 David, Perlman (December 18, 2003). "Earth warming at faster pace, say top science group's leaders". San Francisco Chronicle. Archived from the original on March 26, 2007. Retrieved April 4, 2007.
  9. ↑ John R. Christy; William B. Norris (February 2006). "Methodology and Results of Calculating Central California Surface Temperature Trends: Evidence of Human-Induced Climate Change?". Journal of Climate. 19 (4): 548–563. Bibcode:2006JCli...19..548C. doi:10.1175/JCLI3627.1.
  10. ↑ Jon Birger (May 14, 2009). "What if global-warming fears are overblown?". Fortune Magazine.
  11. ↑ John Christy (November 1, 2007). "My Nobel moment". Wsj.com . Dow Jones & Company.
  12. ↑ John Christy (November 25, 2009), House Ways and Means Committee – Written Testimony (PDF), U.S. House Ways and Means Committee, archived from the original (PDF) on July 10, 2010
  13. ↑ Christy & McNider (19 February 2014). "McNider and Christy: Why Kerry Is Flat Wrong on Climate Change". Wall Street Journal. Retrieved 6 April 2014.
  14. 1 2 "John R. Christy: Short biography". NASA. Archived from the original on March 7, 2007. Retrieved April 4, 2007.
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