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1955 She sells sea shells by the sea shore. Cesare Emiliani (1922-1995), Geochemist He used the newly established technique of investigating different isotopes of oxygen (Oxygen-18 vs. Oxygen-16). By measuring how much of these two different isotopes there is, one can determine the temperature at which sea shells (like a clam) grew. (Photo: Archives of the Rosenstiel School of Marine and Atmospheric Science, University of Miami) From Wikipedia. 1 Looking at fossil shells in a core, he looked back over 1,000,000 years of geologic time and realized that there are lots of ice ages, that they happened every 100,000 years. 1955 This meant that Milankovic was right about variations in Earth’s orbits causing major climate changes, but wrong about which orbital variation was the most important. Drat. (Photo: Archives of the Rosenstiel School of Marine and Atmospheric Science, University of Miami) From Wikipedia. 2 Portrait by Paja Jovanovic 1955 Drat. It turns out that Emiliani was also wrong in detail. He was completely sure that the Oxygen isotope record provided temperatures. It turns out that it does not – it provides an estimate of the evaporation from the ocean, because the heavier Oxygen-18 sticks around in the ocean when there are large ice sheets. Another great example of how scientists can be wrong in detail, but very useful. (Photo: Archives of the Rosenstiel School of Marine and Atmospheric Science, University of Miami) From Wikipedia. 3 "The young specialist in English Lit ... lectured me severely on the fact that in every century people have thought they understood the Universe at last, and in every century they were proved to be wrong. It follows that the one thing we can say about our modern 'knowledge' is that it is wrong. ... My answer to him was, '... When people thought the Earth was flat, they were wrong. When people thought the Earth was spherical they were wrong. But if you think that thinking the Earth is spherical is just as wrong as thinking the Earth is flat, then your view is wronger than both of them put together.” - Isaac Asimov 1956 Ewing and Donn explain the connection of feedbacks on the Earth’s globe. This includes the single most important feedback: Solar radiation and albedo. Maurice Ewing Did someone say libido? No! Albedo, albedo, you psychologist. Image from LIFE photo Archive Photo from Columbia University A random Freud appearance 5 Albedo Albedo - extent to which an object reflects light (the ratio of reflected to incident electromagnetic radiation) In short, white objects reflect a lot (absorb a little) and black objects reflect little (absorb a lot). This was figured out a long time ago by…… 6 I’m back. Benjamin Franklin, again. The year, about 1729. Image from Wikimedia Commons. ". . . AS to our other subject, the different degrees of heat imbibed from the sun's rays by cloths of different colors, since I cannot find the notes of my experiment to send you I must give it as well as I can from memory… My experiment was this. I took a number of little square pieces of broad cloth from a tailor's pattern-card, of various colors. There were black, deep blue, lighter blue, green, purple, red, yellow, white, and other colors, or shades of colors. I laid them all out upon the snow in a bright sunshiny morning. In a few hours (I cannot now be exact as to the time) the black, being warmed most by the sun, was sunk so low as to be below the stroke of the sun's rays; the dark blue almost as low, the lighter blue not quite so much as the dark, the other colors less as they were lighter; and the quite white remained on the surface of the snow, not having entered it at all.” 7 Image from Wikipedia Although, in 1761, it is Johann Heinrich Lambert in Germany who introduces the term "albedo" in order to describe the differing reflective properties of planets Image from NASA Planets Lambert 9 Credit: Steve Ackerman and Tom Whittaker 1957 Source: Air Force photo, from Wikipedia 1957 Sputnik satellite, launched by the Russians (the old USSR). The political response was to allocate an enormous amount of money for basic science research in the US for the next ~30 years. Science became a priority. Source: Air Force photo, from Wikipedia 11 Image from Wikipedia. Promising students were encouraged to become scientists, with the highest form of scientists being a physicists (this will come up later). Hence the term… Source: Air Force photo, from Wikipedia She’s so smart that she’ll grow up to be a rocket scientist. Image: Wikipedia, from Bronisław Duda 1957 -The first GCM (Global Climate Model) Phillips and Charney (atmospheric scientists) run the first GCM, in an attempt to model the Earth’s atmosphere. It was amazing for its time. Source: AIP Emilio Segrè Visual Archives Charney Phillips Although, in the simulation, after 20 days of model time it started to look a little funky and after 30 days it looked like nothing that ever happened on Earth. For the first time scientists could see, for example, how giant eddies spinning through the atmosphere played a key role in moving energy and momentum from place to place. Philips's and Charney’s model was quickly hailed as the first true General Circulation Model (GCM). 13 What is a GCM (General Circulation Models)? These models consist of connected sub-modules that deal with radiative transfer, the circulation of the atmosphere and oceans, the physics of moist convection and cloud formation, sea ice, soil moisture, etc.. 14 Source: Australian Bureau of Meteorology 1957 CO2 in the atmosphere: ~312 ppm CO2 Concentration (ppm) 324 322 320 318 316 314 312 310 308 1940 1945 1950 1955 1960 1965 1970 1975 1980 Year 2 major events -Launching of Sputnik -The first GCM (Global Climate Model) 15 1960 The Breakthrough The Place Keeling (atmospheric scientist) Source: NOAA Image: NSF, from Wikipedia T h e P e r s o n Mauna Loa, Hawaii 16 1960 Image from Wikipedia The Keeling curve is first published. 17 BBC World News Sunday, 2 December 2007, 20:13 GMT 50 years on: The Keeling Curve legacy It is a scientific icon, which belongs, some claim, alongside E=mc2 and the double helix Its name - the Keeling Curve - may be scarcely known outside scientific circles, but the jagged upward slope showing rising carbon dioxide (CO2) levels in the atmosphere has become one of the most famous graphs in science, and a potent symbol of our times. It was 50 years ago that a young American scientist, Charles David Keeling, began tracking CO2 in the Earth's atmosphere at two of the world's last wildernesses - the South Pole and the summit of the Mauna Loa volcano in Hawaii. His very precise measurements produced a remarkable data set, which first sounded alarm bells over the build-up of the gas in the atmosphere, and eventually led to the tracking of greenhouse gases worldwide. "Without this curve, and Professor Keeling's tireless work, there is no question that our understanding and acceptance of human-induced global warming would be 1020 years less advanced than it is today," adds Dr Manning. 18 "Keeling's data put the capstone on the structure built by Tyndall, Arrhenius, Callendar, Plass, and Revelle and Seus. This was not quite the discovery of global warming. It was the discovery of the possibility of global warming". - Weart Human-induced addition of CO2 to the atmosphere becomes a legitimate scientific theory. . 19 CO2 in the atmosphere: ~315 ppm 324 CO2 Concentration (ppm) 1960 322 320 318 316 314 312 310 308 1940 1945 1950 1955 1960 1965 1970 1975 1980 Year The concentration is finally being measured in the atmosphere. It is now clear that CO2 concentration is going up. Human-induced global climate change become a research focus. 20 Image from Wikipedia. 1968 Beginning of the Source: National Digital Library Environmental movement. Source: The Climate Community Rachel Carson Image from Wikipedia. A simple, but elegant, book that starts the environmental movement. Carson was a science writer. 21 1970 John McConnell first introduced the idea of a global holiday called "Earth Day" at a UNESCO Conference on the Environment in 1969. Responding to widespread environmental degradation, Gaylord Nelson, a United States Senator from Wisconsin, called for an environmental teach-in, or Earth Day, to be held on April 22, 1970. Image from Wikipedia 22 Image from Wikipedia. United States Congress image at Wikipedia CO2 in the atmosphere: ~ 328 ppm 340 CO2 Concentration (ppm) 1970 335 330 325 320 315 310 305 1940 1945 1950 1955 1960 1965 1970 1975 1980 Year 23 On October 24, 2009, environmental activists around the world gathered in support of a geophysical data point. With their bodies, banners, and balloons, they formed the numeral 350, advocating that governments should adopt 350 ppm as a target for atmospheric carbon dioxide concentration (some climate scientists suggest that this is the highest amount of CO2 possible not cause significant climate change). Image from Wikipedia Source: The Standard Source: The Standard The 450 number came from the various graphs and tables of the 2007 report of the Intergovernmental Panel on Climate Change—but Rajendra Pachauri, who chairs the IPCC, has said repeatedly in the last year that that science is out of date. Recently, asked why he’d endorsed a 350 target instead, he said: “As a human being, I just couldn’t keep quiet in the face of all this overwhelming evidence. I know it’s probably not right for me to take a position such as this, but on the other hand, I think it would be totally immoral on my part not to take a position, so I came out and said so.” The Atmosphere Bryson’s chapter: Into the Troposphere Source: NASA Source: NASA Source: National Business Aviation Association Aftern 1975, it is all about Global Climate Models • 1956 – first GCM (Phillips) • 1975 – model of 2xCO2 predicts several degree warming (Manabe) • 1981 – models show sulfate aerosols = cooling (Hansen) • 1991-1995 – model predicts cooling via Pinnatubo. Verified in 1995. (Hansen) • 1998 – models can recreate ice-age climates 1988 The community acceptance that that humaninduced global warming is likely accurate, results in the formation of a group - the IPCC (or Intergovernmental Panel on Climate Change) - that meets every 5 years to discuss the state of the Earth’s climate. IPCC -Consists of more than 2500 scientific and technical experts from more than 60 countries all over the world. -The scientists are from widely divergent research fields including climatology, ecology, economics, medicine, and oceanography. -The IPCC is the largest peer-reviewed scientific cooperation project in history. -It has issued 4 reports:1992, 1996, 2001, and 2007. Images from IPCC report Images from IPCC report IPCC 1992: Still trying to sort out effects of natural variation and human impacts 1996: “The balance of evidence suggests a discernible human influence on global climate” 2001: Humans are “likely” to cause global warming 2007: Humans are “very likely” to cause global warming. Two notes: 1) In scientific talk, it does not get much more certain than “very likely”; and 2) The IPCC is inherently conservative and often supports minimum possible climate change (rather than maximum possible change). Why the change? • More research • Better Global Climate models • More available data: 1998 is globally the warmest year on record, followed by 2002, 2003, 2001 and 1997. The 10 warmest years on record have all occurred since 1990. Images from IPCC report Radiative Forcing To compare different variables, you need a common unit (to compare apples with apples, as the saying goes). Radiative forcing is the difference between the incoming radiation energy and the outgoing radiation energy in a given climate system. A positive forcing (more incoming energy) tends to warm the system, while a negative forcing (more outgoing energy) tends to cool it. 36 37 Credit: Steve Ackerman and Tom Whittaker A Watt (as in James) A unit of power = Work / time (Your standard household bulb uses 60 Watts) Because we care about the Earth’s surface, we use Watts/meters2 I like steam engines. A lot. 38 Image from Thinkquest So, what causes radiative forcing? Solar input - relatively constant, but can be slightly higher or lower than usual Chinese records of sunspots go back to Book of Changes (800 B.C.E.): "A dou is seen in the Sun" and "A mei is seen in the Sun". ”Dou" and "mei" are taken to mean darkening or obscuration. Image from nasa.gov Sunspots Author: Hans Bernhard So, what causes radiative forcing? Solar input - relatively constant, but can be slightly higher or lower than usual CO2 (& other greenhouse gases) - increases radiative forcing Aerosols - decreases radiative forcing 2.5 CO2 2.0 W/m2 1.5 1.0 Solar 0.5 0.0 Temperature -0.5 -1.0 1800 Aerosols 1850 1900 Year AD 1950 2000 Components of a fully coupled general circulation model Removed image due to copywright. It can be found at the Australian Department of Meteorology. GCMs contain our best current understanding for how the physical processes interact (for instance, how evaporation depends on the wind and surface temperature, or how clouds depend on the humidity and vertical motion) while conserving basic quantities like energy, mass and momentum. These estimates are based on physical theories and empirical observations made around the world. Development of climate models over time IPCC, adopted by Australian Department of Climate Change and Energy Efficiancy Models We cannot predict how one variable will inherently influence another. Therefore, we have to make models. Models lead to “emergent” properties, which is large scale behavior that is not a priori predictable from the small scale interactions that make up the system. Models are inherently theoretical. As such, they are often very quantitative. Models (con’t) All models are wrong; some models are useful. -G.E. Box (UW Professor) These models are all simplifications of the actual phenomena. But these models can still be valuable. Image removed due to copyright; available at Data Analysis Australia The problem with models (or any theoretical approach) lie in the assumptions. IPCC: Critical aspects Validation - assessment of the accuracy of the model Attribution - the ability to assign causes to effects (distinguish causation from correlation) Prediction - specification, in advance, of events or changes in a system Validation Validation reflects an assessment of the accuracy (not precision) of the model. This is done by attempting to duplicate current climate data, or “backcasting” (as opposed to forecasting) past climates when the Earth was very different (such as 18,000 years ago, during the maximum extent of the ice age). Image from IPCC Science is the investigation of the natural world, based on the rules of reason and logic. Science is testable and/or predictable. How do you test a model, particularly of a GCM (Global Climate Model)? 1981 Image from USGS Image source: New York Times We can test our GCM! 1963 Mount Agung (Indonesia) volcanic eruption (ok, really, this is a picture of the 1991 Mount Pinatubo eruption) Jim Hanson They found that the changes calculated by their simple model corresponded in all essential respects — including timing and approximate magnitude — to the observed global temperature changes. The GCM worked! But, more importantly, the the results also showed that volcanic aerosols could significantly cool the surface. Image source: New York Times Hot dog! It works! Attribution The ability to assign causes to effects. This is a problem inherent in systems with multiple variables. The simplest approach is “sensitivity analysis”, in which each variable is tested for its possible effect. The IPCC report is all about attribution. Is CO2 the only greenhouse gas that is important? It turns out (unfortunately), no. 1) Methane (CH4) - From rice paddies and cows. 2) N2O - from agriculture, including fertilizer 3) Ozone (O3) - not anthropogenic and… 4) CFCs (Chloroflorocarbons) - From refrigeration and spray (and fire retardant) The big problem is that these gases could be much more potent than CO2. But, an even bigger problem was,…… Image from NOAA Image from NASA Despite the fact that these gases are much less abundant, they are much more potent than CO2. But, for the case of CFCs, there was an even bigger problem….. The Ozone hole In addition to being greenhouse gases, CFCs destroy ozone (O3). Consequently, they cause an ozone hole over the South Pole. Note that the ozone hole has no effect on global warming (except that the presence of CFCs both destroys the ozone AND causes global warming). Source: NASA The Ozone hole CFC’s in the stratosphere = Ozone hole. CFC’s in the troposphere = global warming Source: NASA The Ozone hole This ozone debate plays out like this: 1. Scientists report that CFCs are causing problems with ozone layer. 2. Industry denies that this is a problem. 3. Scientists confirm this problem. 4. Industry maintains that it is too expensive to switch to other propellants in spray bottles. 5. Under international pressure, CFCs are outlawed* in the 1997 Montreal accords. 6. Industry finds new propellants (there is no major loss in the spray industry and some indications that there is some economic gain by switching away from CFCs). *CFCs are still being produced in some third world countries. Source: NASA IPCC Prediction Specification, in advance, of events or changes in a system. Again, the IPCC includes many predictions, based on the outcomes of the GCMs. IPCC & GCMs The IPCC reports are based on the composite results of a variety of different GCMs. It is important to realize that the GCMs just act to quantifiy (“put numbers on”) the effects that are already occurring. Source: Wikipedia National Center for Atmospheric Research laboratory in Boulder, Colorado IPCC 2007 Image from NASA Image from NASA Image by Robert A. Rohde for Global Warming Art GCMs are a different approach to science: Although we can separate the variables and treat each individually, they interact with each other. This type of interaction requires that you do science in a different way than has been done in the past: Integrated and with a systems approach. This is sometimes known as holistic. This approach must be done IN ADDITION to the reductionist approach. Source: Robert A. Rohde This is the second of the major divisions in science: 1) Empirical-theoretical 2) Reductionistic-holistic Holistic science An analogy (Image of doctor and patient) The doctor can help a patient who has cancer. But, this solves a symptom, not the cause. Society is usually willing to solve a symptom. But, if you want to really solve the problem, you have to study the system. This requires a systematic approach, looking at environmental, genetic predisposition, and individual facts (the field of epidemiology) as well as basic understanding of cell processes (molecular biology). (Image of scientists studying a town) The medical community has been extremely successful at getting both funded. This is less true for the scientific community. Holistic science & Science of the future Problem based Interdisciplinary Problems of society, not problems of science (such as, How do we maintain a habitable Earth?) Emphasis on predictive power of science Systems with multiple variables 1) Sensitivities 2) Positive feedbacks 3) Negative feedbacks 4) Thresholds (“Tipping points”) 5) Complexity (non-linear feedbacks) Thresholds Source: Wikimedia Commons, Bart de Goeij Side view Source: Wikimedia Commons, Gertjan R. Back view Aftern 1975, it is all about Global Climate Models • 1956 – first GCM (Phillips) • 1975 – model of 2xCO2 predicts several degree warming (Manabe) • 1981 – models show sulfate aerosols = cooling (Hansen) • 1991-1995 – model predicts cooling via Pinnatubo. Verified in 1995. (Hansen) • 1998 – models can recreate ice-age climates