A Prominent Climate Skeptic Now Affirms that Global Warming is Real

Summary.  Richard A. Muller, professor of physics at the University of California, Berkeley, has long been a skeptic concerning the validity of the temperature trends that characterize recent global warming.  His doubts related to the accuracy and statistical significance of the temperature records used, and to the methods of statistical analysis employed, in support of global warming.  Now, he and a team of researchers have reanalyzed the data, extended the size of the database of temperature records, and developed improved statistical methods to analyze the data.  Their results confirm that  global warming is real, having warmed by just under 1.0ºC (1.8ºF) since the mid 1950’s.

Introduction.  Richard A. Muller, a respected professor of physics, but not a climate scientist, at the University of California, Berkeley has been a long-standing skeptic concerning the reality of global warming.  Paul Krugman wrote in the New York Times  that he criticized former U. S. Vice President Al Gore and others who warned of the hazards of continued global warming as being “exaggerators” of the phenomenon, and that he was active in the 2009 controversy over emails from climate scientists at the University of East Anglia (“Climategate”).  The Sydney, Australia Morning Herald writes that Muller used to dismiss alarming climate research as “polluted by political and activist frenzy”. Don Shelby, on Minnpost.com, writes that Muller has long been critical, in particular, about the temperature measurements that climate scientists around the world use in assessing global warming.

Prof. Muller has now confirmed that global warming is occurring.  He has recanted his former skepticism concerning the validity of the rise in global temperature.  Over the past two years he directed the Berkeley Earth Surface Temperature Project (BEST) whose objective was to reexamine all temperature records available for two hundred years in order to arrive at an authoritative assessment of temperature changes.  BEST has received important funding from the Lee and Juliet Folger Fund ($20,000), the William K. Bowes, Jr. Foundation ($100,000), the Fund for Innovative Climate and Energy Research (created by Bill Gates) ($100,000), the Charles G. Koch Charitable Foundation ($150,000), and the Ann & Gordon Getty Foundation ($50,000).  The Koch family, for example, with business interests in fossil fuels, supported the failed attempt in California to overturn by referendum the state’s ambitious program to reduce greenhouse gas emissions.  BEST has posted its methods and results online, in four manuscripts, simultaneously with having submitted the papers for peer review by a scientific journal. At the same time, Muller described the BEST project in a recent op-ed in the Wall Street Journal.

Summary of Muller’s doubts about temperature measurements.  In the Wall Street Journal, on the web site, and in the written papers Muller identified specific problems in earlier analyses by other groups of the temperature record that have concerned him.  First, as many as 757 weather stations in the U. S. recorded a cooling over the past century, many of which are in the southeast where tornadoes and hurricanes are prevalent.   Second, because of poor siting of stations in the U. S., many have reported temperatures that may be in error by as much as 2-5ºC (3.6-8.0ºF), according to the U. S. government.  He surmises that there may be many more stations reporting inferior data around the world.  The consequence of this could be that although the U. N. Intergovernmental Panel on Climate Change (IPCC) has reported a rise of 0.64ºC (1.15ºF) in the planet’s average temperature in the last 50 years, the margin of error of that evaluation may be larger than the increase itself.  Third, weather stations sited in cities may record higher temperatures than warranted because of the known effects of asphalt pavement and absence of foliage on urban temperatures.  Additionally, sites that originally may have been isolated may have become urbanized as time passed, possibly altering the attributes of the sites.  Fourth, the major research groups analyzing temperature records selected stations preferentially having long-term data available, thus eliminating many other data sources that are available.  Fifth, methods and sites of measurement have changed or moved over the years, adding uncertainty to the results.  In Muller’s view, previous attempts to compensate for such variability may have introduced significant errors into the results.

BEST’s research methods.  In order to address these and other problems, BEST, directed by Muller, analyzed 1.5 billion discrete records from 15 preexisting temperature archives. Their objectives were to

1. create a single comprehensive raw data set in a common format for existing surface (land only) temperature data,
2. review existing data and methods of error analyses to assess their advantages and limitations,
3. develop improved and alternative methods of analysis to overcome some of the limitations identified, and
4. publish the new global surface temperature record, and its analysis, in order to  provide a basis for all parties to examine the data for further study.

The BEST project has concluded that global warming is real. The results are presented in four manuscripts, all available online (see Details below). There is also a summary available here.  The BEST study finds that “global warming is real”, having warmed by just under 1.0ºC (1.8ºF) since the mid 1950’s.  This conclusion should contribute significantly to eliminating doubts that global warming has been occurring since the 1950’s.  The reports address the major potential sources of error or bias raised by skeptics of global warming and identified by Muller, and show with high confidence that they do not affect the important conclusion reached.  This affirmation confirms the results of earlier studies, which skeptics had belittled because of their concerns over uncertainties in the data. 

Muller’s team made no effort address the question of whether the observed warming is due to human activity (mainly burning of fossil fuels to yield greenhouse gases), nor to predict future trends or effects on the planet.

Details

The first paper is titled “Berkeley Earth Temperature Averaging Process”.  The new statistical methods developed to analyze the merged data are described here.  They permit use of short, and discontinuous, records, permitting virtually all available data to be analyzed.  Such data had been ignored previously.  It develops a statistical weighting method that accounts for reliability of the data, and of their spatial distribution.  The method includes weighting only for spatial differences at fixed times, as well as “weather” effects, i.e., short term fluctuations due to local weather events.  In addition, a statistical “scalpel” is applied, with weighting, when discontinuities in the data arise.  The scalpel creates two distinct records from one original, broken at the point of a discontinuity. Such records can be included here, but would have been omitted in earlier analyses, because BEST developed methods of including short-term records.  This accommodates data of varying levels of quality without compromising the final result.  Methods for removing outliers, for assessing reliability of data points, and for weighting uncertainties were also developed for the BEST analysis.  The results are applied to develop a new global land temperature reconstruction from 1800 to the present with due accounting for identifiable sources of error, as summarized above.  Data from 7280 weather stations in the Global Historical Climatology Network (GHCN) were analyzed in the BEST assessment.

The overall result shows an increase in the earth’s long-term average temperature from the 1950’s to the present of 0.911 ± 0.042ºC (1.640 ± 0.076ºF; 95% confidence for statistical and spatial uncertainties; see the following graphic).  This result is stated to be consistent with the extent of global warming previously reported by the IPCC (0.64 ± 0.13ºC (1.15 ± 0.23ºF) from 1956 to 2005 at 95% confidence), but carries a considerably lower extent of uncertainty because of the new data included and the new methods of analysis. 

Result of the Berkeley Average Methodology applied to the GHCN monthly data from 1800 to 2010. Top plot shows a 12-month land-only moving average (red) and associated 95% uncertainty from statistical and spatial factors (grey with black edges). The lower plot shows a corresponding 10-year land-only moving average and 95% uncertainty. 
Source: BEST; http://www.berkeleyearth.org/

The following graphic shows the temperature differences, or “anomalies”, for all land areas of the planet, identified from the results of the BEST analysis, for two time intervals.  The color coded “anomalies” are based on the average temperatures in the earlier decade as the reference values. Warming is observed over all continents, with the greatest warming at high latitudes (northern regions of the map) and the least warming in southern South America.

Color-coded global projection maps showing the decadal average changes in temperature on the planet’s land areas, using the temperature scale on the right. In the upper plot, the comparison is drawn between the average temperature in 1900 to 1910, used as the reference, and the average temperature in 2000 to 2010. In the lower plot, the same comparison is made but using the interval 1960 to 1970 as the starting point.

           Source: BEST; http://www.berkeleyearth.org/

The time dependence of temperature changes arrayed across the land surfaces of the earth on a projection of the globe, from 1800 to the present, are also presented by BEST in this video.

In a second paper, “Influence of Urban Heating on the Global Temperature Land Average Using Rural Sites Identified from MODIS Classifications”, Muller et al. compared temperature records from urban settings to those from a selection of rural weather stations.  Their results confirm earlier analyses by others that urban warming has no biasing effect on assessing the extent of recent increases in global temperature.

The third paper, “Earth Atmospheric Land Surface Temperature and Station Quality in the United States”, assesses use of weather stations in the U. S. ranked by the National Oceanic and Atmospheric Administration to be “poor”, compared to those ranked “OK”.  The analysis finds no statistically significant difference in temperature trends between the two groups of stations.  This suggests that trends remain apparent even when individual stations have large uncertainties in their data.

The fourth paper, “Decadal Variations in the Global Atmospheric Land Temperatures”, examines correlations between variations, in the range of years to decades, in global average temperatures and pronounced ocean circulation trends.  In the past, many climate scientists have emphasized the role of the El Nino Southern Oscillation (ENSO) in global climate patterns.  The analysis in this paper from BEST finds the strongest correlations not with ENSO, but with the Atlantic Multidecadal Oscillation.  In addition, this paper separately includes an analysis of data from 30,964 world-wide weather stations with data available from 1950.  This number is much greater than had been used in earlier studies (the National Oceanographic and Atmospheric Administration, NASA Goddard Institute for Space Science, and a collaboration of the Hadley Centre of the UK Meteorological Office with the Climate Research Unit of East Anglia).  The new analysis conforms well to the earlier results.    

Conclusion.  Richard. A. Muller, a former skeptic concerning the validity of temperature trends that establish global warming, has conducted a rigorous analysis of all available land-based temperature records around the earth.  He and the BEST team developed new statistical methods to overcome several objections that he and others had raised earlier concerning historical temperature records.

Muller and the BEST team concluded that global warming is real.  This eliminates one argument that skeptics of global warming can use in denying the reality of the effect.

BEST did not at this time seek to evaluate whether the global warming they confirm is due to man-made effects.  The IPCC, however, has shown convincingly that man-made contributions to greenhouse gases in the atmosphere are required, in climate models, to reproduce the historical record of global changes in temperature.  The following graphic

Pale Blue shading: 5 to 95% range for 19 distinct simulation runs from five climate models using only natural processes that may affect global temperature.  Pink shading: 5 to 95% range for 58 distinct simulation runs from 14 climate models using both natural processes and man-made contributions (greenhouse gas emissions) that may affect global temperature.  Black line: actual temperature observations, averaged.

Source: IPCC ; http://www.ipcc.ch/publications_and_data/ar4/syr/en/figure-spm-4.html

shows specific continental, overall global, global land, and global ocean temperature simulations from climate models, compared to actual observations (black line).  The pale blue simulations omit man-made contributions to global warming, such as emissions of greenhouse gases.  It is seen that in none of the regions or global cases do the pale blue simulations reproduce the temperature observations beyond about 1950, but do satisfactorily trace the temperature data before 1950, before emissions became significant.  The pink simulations include man-mad contributions to global warming.  These simulations satisfactorily trace the observed temperature record over the entire time period from 1910 to 2005.  It may be concluded from these comparative simulations that man-made emissions of greenhouse gases are highly likely to be responsible for the increase in global temperature since about 1950.

© 2011 Henry Auer


 

Americans Are Losing Sight of Global Warming as an Important Issue

Summary.   Elisabeth Rosenthal in the New York Times on Oct. 15, 2011 has documented the decreased attention that the issue of global warming is receiving in the U. S., in contrast to the rest of the world.  The portion of Americans who believe the earth is warming fell from 79% in 2006 to 59% in 2010.  This issue breaks out along lines that follow differences between the Democratic (liberal) and Republican (conservative) parties.  This reduction in importance is so even though the U. S. is a major world emitter of greenhouse gases.  According to the article, many aspects of individual and corporate attitudes reinforce America’s reluctance to embrace global warming as an important issue.  In contrast, nations of the remainder of the world, including Europe, China, and other developing countries, accept that global warming is an important issue facing the world, and are implementing policies to reduce emissions of greenhouse gases.

Climate scientists from all over the world have set a goal of limiting overall warming of the planet to 2ºC (3.6ºF) above the temperature prevailing in pre-industrial times.  This important objective requires limiting the accumulated amount of carbon dioxide in the atmosphere, not simply reducing the annual rate that greenhouse gases are emitted.  One motivation to stimulate the U. S. to implement suitable policies could be the recognition that economic and societal harms brought about by extreme weather events are balanced by the economic and societal benefits arising from new investments in mitigation projects.

Introduction.  Climate scientists the world over, as a result of efforts going back several decades, have concluded overwhelmingly that our planet is undergoing a warming trend  due to the greenhouse effect arising from man-made carbon dioxide (CO₂) emitted into the atmosphere.  Our ever-increasing use of fossil fuels for mankind’s expanding needs for energy creates CO₂ in large quantities as the direct product of burning the fuels.  Other gases added by man to the atmosphere also add to the greenhouse effect.  The warming of the planet has resulted in several effects, many of which are detrimental to life on earth, and in extreme weather events that inflict severe harms to humans in their paths.

In spite of this situation, the public in the U. S. has grown less concerned about the dangers posed by global warming, as described by Elisabeth Rosenthal in the New York Times on Oct. 15, 2011.  This post addresses topics raised in Ms. Rosenthal’s article.

U. S. public support to address global warming is waning.  Ms. Rosenthal reports that the portion of Americans who believe the earth is warming has fallen from 79% in 2006 to 59% in 2010 (citing the Pew Research Group).

Political denial and backtracking on global warming.  Perhaps reflecting this changing attitude, at least one Republican presidential hopeful, Gov. Rick Perry of Texas has stated “the science is not settled” concerning man-made global warming.  On Aug. 17, 2011 (accessed Oct. 19, 2011) he stated "a substantial number of [climate] scientists … have manipulated data so that they will have dollars rolling in to their projects…..We're seeing weekly, or even daily, scientists who are coming forward and questioning the original idea that man-made global warming is what's causing the climate to change".

Further in seeming recognition of this changing sentiment among the public as well as in Congress, Ms. Rosenthal reports that President Obama is promoting the administration’s “green” energy project proposals in economic terms, omitting any mention of beneficial effect such projects would have in combating greenhouse emissions.  The administration appears to support final approval for construction of the TransCanada Keystone XL oil pipeline carrying oil from Alberta’s tar sands to the Gulf of Mexico (see the recent post on this subject).  It is also seeking an exception from Europe’s planned landing fee for air travel to the continent based on CO₂ emissions.

Nevertheless, the U. S. emits about 18% of the world’s greenhouse gases as of 2009, even though it has only 4.6% of the world’s population.  Until recently the U. S. was the nation with the highest annual emissions rate of all.  It was overtaken by the emissions originating from China.  Ms. Rosenthal identifies aspects of American culture, such as its preference for larger cars and homes, and the skepticism among many of its people toward the role of science and government policies in their daily lives, as factors that contribute to skepticism toward or rejection of global warming.

In addition, the article states American industries such as coal mining and oil and gas production oppose constraints on fossil fuels, since their financial well-being depends on continued production, if not expanded production.  The current protracted recession also makes it more difficult to accept higher costs for fossil fuels, or energy in general, that could accompany policies supporting renewable energy.

The rest of the world is moving to constrain greenhouse gas emissions.  As noted in Ms. Rosenthal’s article, a report on global energy by the London bank HSBC finds that the U. S. is the sole nation not implementing a program to reduce greenhouse gas emissions.  Other important emitters are actively pursuing such efforts.

Europe. The nations of the European Union have the significant goal of reducing greenhouse gas emissions by at least 80% by 2050, including an interim objective of a 25% reduction by 2020 (see this post).  According to the New York Times article, Europe is currently on track to achieve this interim goal. John Ashton, Britain’s special representative for climate change, points out that even in the face of economic hardship brought on by the global financial crisis, European countries view moving toward a “green” economy favorably, as an economic opportunity, not negatively due to the imposition of greater costs. “In the E. U. … despite the economic and financial crisis, the momentum on climate change has … continued”, Mr. Ashton states.

Developing countries.  China’s current 12^th Five Year Plan covering 2011-2015 projects continued major expansions of electric power generation based on coal (see this post).  Its energy consumption is scheduled to increase about 5% per year in this period.  Nevertheless, it is greatly expanding its small renewable energy sources.  China emphasizes energy intensity rather than overall emissions.  It plans to reduce its emissions intensity per unit of economic output by 17% by 2015, and by 40-45% with respect to the 2005 level by 2020.  India is also pursuing aggressive efforts to reduce greenhouse gas emissions, according to the Times article.

Extreme weather events.  As noted in the Times article, climate scientists predict that with increased levels of atmospheric greenhouse gases accumulating in the future, the resulting increased global temperatures will produce more, and more intense, episodes of extreme weather events.  These include, in different regions on the earth’s surface, excessive heat with drought, increased rainfall with severe flooding and intense storms, loss of ice cover and higher sea levels.  These occurrences inflict sudden and severe harms to populations and societies.  This blog has developed several posts dealing with this issue in recent months, summarized here.  Ms. Rosenthal points out that developing countries are less well equipped to deal with these events than are developed countries.  They therefore embrace worldwide efforts to implement mitigating strategies.  The article cites a 2010 Pew survey finding that 70% of people in China, India and South Korea were prepared to pay more for energy in order to mitigate the effects of global warming.

Discussion

The United States is alone among the major emitters of greenhouse gases not to have a national policy directed toward reducing the rate of emissions.  Without such a policy, annual emissions from the U. S. will increase at an accelerating pace, as economic development and its population continue to grow.  If anything, fiscal incentives from the federal government for promoting mitigation efforts in the private realm have been increased and reduced in fits and starts, hindering the ability of new enterprises to make long-term plans for development. 

In the absence of a single national policy, various state and regional greenhouse gas accords have been implemented (reported in this blog in the following posts: California’s Global Warming Solutions Act, The Western Climate Initiative, Midwestern Greenhouse Gas Reduction Accord, and The Regional Greenhouse Gas Initiative of the New England and Mid-Atlantic States).  These programs establish disparate emission reduction goals over the coming decades.  Most encourage or rely on a market driven cap-and-trade regime to bring about emissions reductions.

Changes in climate patterns, including increases in sea level and reduced glaciation that are predicted to worsen because of global warming, depend not on the annual rate of global greenhouse gas emissions, but rather on the absolute amount of greenhouse gases accumulated in the atmosphere.  Carbon dioxide, the major greenhouse gas, which originates from mankind’s burning of fossil fuels for energy, remains stable in the atmosphere for at least one century, once emitted into the air (remaining after absorption into the oceans and reincorporation into growing green plants).  Thus it is important to reduce emissions as drastically as possible as soon as possible, in order to keep the accumulated level of atmospheric carbon dioxide as low as possible.

The atmospheric CO₂ concentration can be conceived of as an atmospheric bathtub of CO₂.  Burning fossil fuels contributes more CO₂ through the “faucet”, but there is minimal “draining” of CO₂ from the bathtub because there are few natural mechanisms for removing CO₂ from the atmosphere.  Worldwide, mankind has to reach agreement on ways to turn the CO₂ faucet off as fast as possible.

Currently the global average CO₂ concentration is 392 parts per million (ppm, volumes of CO₂ per million volumes of the atmosphere).  It has been increasing, and increasing at an ever-accelerating pace, since the beginning of the industrial revolution, when the concentration was about 280 ppm.  The climate scientists of the world, at their meeting in Copenhagen in 2009, under the auspices of the United Nations Framework Convention on Climate Change, agreed to seek the objective of limiting the overall increase in the global average temperature above the temperature that prevailed prior to the industrial revolution to 2ºC (3.6ºF), estimated to require that the global average atmospheric CO₂ concentration be constrained to about 450 ppm.

In a series of recent posts this blog has shown that, on the one hand, economic and societal harms brought about by extreme weather events are balanced, on the other hand, by the economic and societal benefits arising from new investments in mitigation projects such as renewable energy programs and energy efficiency projects (summarized here, which contains further links to the remaining posts giving details of the analysis).  To the extent that U. S. investment in mitigation measures reduces the damages inflicted by extreme weather events, those investment costs are returned because the need to remedy disasters is reduced.  We conclude that the U. S. should implement a long-term national policy of developing mitigation measures intended to reduce greenhouse gas emissions, ultimately to near zero.  In this way the U. S. will join much of the planet in a world-wide strategy to stabilize atmospheric CO₂ at the lowest possible level.

© 2011 Henry Auer