11 INTRODUCTION TO GLOBAL CLIMATE CHANGE “Everybody talks about the weather, but nobody does anything about it.” This comment, attributed to Mark Twain in 1897, is no longer valid. Today, human activities infl uence climate, long- term trends in weather, on both local and global scales. Aver- age temperatures are rising. Storms and forest fi res seem to be increasing in severity (Figure 1.1). The vagaries of weather may obscure specifi c cause and effect relationships, but humans are defi nitely part of the problem. Humans are also part of the solution. To diminish the potential damage from climate change and the extreme weather events that result, governments have implemented policies that range from limiting carbon emissions to reinforcing levees. As the public has become more aware about this issue, their behaviors in matters ranging from recycling of materials to the purchase of refrigerators, vehicles, and windows, increasingly refl ects their concerns. On contentious issues such as global climate change, a broad understanding of the subject generally contributes to the quality of debate. This book considers the factors respon- sible for climate change; the geophysical, biological, eco- nomic, legal, and cultural consequences of such change; and 2 CHAPTER 1 FIGURE 1.1 Extreme weather Hurricane Katrina extends on August 28, 2005. (Imagery from the GOES-12 weather across the Gulf of Mexico as it approaches New Orleans satellite.) various strategies to diminish some of the undesirable oping effective policies when the information available consequences. It compares methods that researchers in may be sparse and vague. different disciplines employ to evaluate past and future Most textbooks concentrate on a single discipline conditions, and it highlights the complexity of devel- (e.g., geophysics, biology, or economics) or subdisci- pline (e.g., glaciology, plant physiology, or mac- roeconomics); they introduce the major con- cepts and then apply them to several examples involving a variety of issues. This book, by con- trast, focuses on a single issue—global climate change—and relates concepts from a number of natural and social sciences to it. Nearly every- one will fi nd certain topics from this wide spec- trum to be challenging; nonetheless, stretching to maintain flexibility becomes critical as one matures. Articles on environmental issues frequently evoke fear, uncertainty, and doubt (FUD) that fur- ther exploitation of natural resources might cause irrevocable damage. Excessive exposure to FUD, however, desensitizes the public to such issues (“crying wolf”) or, worse, elicits fatalistic despair. This book strives to present a more balanced per- FIGURE 1.2 “Doom and Gloom with Bloom” The author, spective and occasionally unbridled optimism, Arnold J. Bloom, is shown marching in Times Square, New York but will deserve the subtitle Doom and Gloom with City in this manipulated image. Bloom (Figure 1.2) if this attempt fails. This material cannot be copied, disseminated, or used in any way without the express written permission of the publisher. Copyright 2010 Sinauer Associates Inc. INTRODUCTION TO GLOBAL CLIMATE CHANGE 3 1995 This chapter recalls the last 70 years of research ) –1 300 1997 on global climate change. The next three chapters 1999 constitute a geophysical section that examines the 2001 month 2003 past, present, and future of Earth’s climate: Chap- 2005 ter 2 presents historical reconstructions of temper- 200 Typical ature and a few other indicators of climate, Chap- ter 3 details factors that influence climate, and Chapter 4 describes global climate models and the 100 changes they predict during the next century. Sub- Precipitation (mm sequent sections of the book introduce additional aspects about climate change: direct and indirect effects on organisms, mitigation strategies and the 0 economics thereof, international cooperation and Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month accords, and, fi nally, the interplay of culture and public opinion. The book strives to support every FIGURE 1.3 Precipitation (millimeters) in Davis, California statement with data in graphical or tabular form. Plotted are data for each month of every other year during the last The number of graphs and tables that results from decade and typical precipitation values (long-term averages). such an effort disrupts the continuity of the text and may overwhelm readers who are less quanti- tative in orientation. For this reason, some of this documentation is presented on the book’s web site, instrument that permitted precise, continuous record- www.sinauer.com/bloom, for readers who are ing of temperatures. Guy Stewart Callendar worked as more inquisitive and quantitatively inclined. a steam engineer for the British Electrical and Allied Industries Research Association, but he had inherited his father’s interest in temperature measurement and, Climate as a hobby, scrutinized weather records from around Long-term weather patterns, as mentioned in the previ- the world. ous section, characterize the climate. The weather page Callendar examined historical trends in global aver- in your local newspaper includes information on daily age temperatures by grouping temperature data from maximum and minimum temperatures; humidity; pre- the most reliable weather stations in given regions of cipitation; and wind speed and direction. Long-term the world and weighting the importance of each group averages of these measures defi ne the climate in your according to the geographic area represented by its sta- area. For example, a Mediterranean climate is charac- tions (Callendar 1938). He calculated 10-year moving terized by relatively hot, dry summers and cool, wet averages (the average of the values 5 years before and winters. In Davis, California, more than 80% of the rain- 5 years after a given date) to smooth out year-to-year fall occurs during the winter months (Figure 1.3), thus fluctuations (Figure 1.4). Callendar’s analysis sug- Davis is considered to have a Mediterranean climate. gested that world temperatures had increased by more “Climate is what we expect; weather is what we get,” than 0.2°C between 1890 and 1935. Based on crude is another statement attributed to Mark Twain. In other measurements of carbon dioxide (CO2) concentrations words, weather conditions are highly variable from in the atmosphere and a simplistic model, Callendar day to day or year to year. Over an 11-year period, total proposed that rising CO2 levels were responsible for precipitation during the month of December in Davis over half of this warming. ranged from 0 to 250 millimeters (see Figure 1.3). Con- The ideas of Callendar, an amateur encroaching sequently, predicting daily weather based on climatic on the domain of climatologists, licensed profession- trends over time is seldom worthwhile. Subtle changes als who focused on climate, were not well received in climate over a few decades are sometimes diffi cult to (Weart 2003). Most climatologists of the day believed discern from normal fl uctuations in weather. that temperature data, because they were so variable, The fi rst person to note the recent warming trend in could be statistically manipulated to support nearly Earth’s climate and associate it with fossil-fuel emis- any conclusion. For example, Helmut E. Landsberg sions was Guy Stewart Callendar (1898–1964). Callen- (1906–1985), perhaps the most renowned climatologist dar’s father, Hugh Longbourne Callendar, a professor of the twentieth century (Baer 1992), did not acknowl- of physics at the Imperial College of Science, London, edge any signifi cant historical changes in global aver- had developed the platinum resistance thermometer, an age temperatures and declared, “There is no scientifi c This material cannot be copied, disseminated, or used in any way without the express written permission of the publisher. Copyright 2010 Sinauer Associates Inc. 4 CHAPTER 1 FIGURE 1.4 A graph from Callendar’s 1938 publication This graph shows temperature patterns (°C) for various climatic zones and of Earth. Plotted here are 10-year running averages (the average of 5 years before the date and 5 years after) with respect to the average temperatures from 1901– 1930. (From Callendar 1938). reason to believe that our climate will change radically small portion of the CO2 released from fossil-fuel burn- in the next few decades, hence we can safely accept the ing would dissolve in the oceans: the bulk would remain past performance as an adequate guide for the future” in the atmosphere, and atmospheric CO2 concentrations (Landsberg 1946). would increase substantially. The larger scientific establishment also doubted By the mid-1950s, technological advances had whether atmospheric CO2 concentrations had changed increased the precision of CO2 measurements ten- signifi cantly (Weart 2003). Readings of CO2 concentra- fold. C. D. (Dave) Keeling (1928–2005), also of Scripps, tions would fluctuate with the winds because local obtained funds suffi cient to equip two weather stations sources that released CO2, such as nearby factories, and with instruments that monitored atmospheric CO2 with sinks that absorbed CO2, such as nearby forests, infl u- unprecedented accuracy. To minimize the infl uence of enced every sample. The consensus of the scientifi c local disturbances, he chose sites that were remote from community was that nearly all the CO2 released from industrial and biological sources of CO2 and were sub- fossil-fuel burning would dissolve in the immense vol- ject to strong prevailing winds (Figure 1.5A). One site ume of Earth’s oceans, and thus atmospheric changes was at the South Pole and the other was on the Island would be negligible. of Hawaii, at the Mauna Loa Observatory atop the With the dawn of the nuclear age at the end of World northern fl ank of the Mauna Loa volcano, at an eleva- War II, atmospheric and oceanic scientists became tion of 3,397 meters (Figures 1.5B and C). preoccupied with other products of human ingenu- Monitoring at the South Pole began in September ity, namely radioactive wastes.