Presentation on theme: "Climate Science The climate system and the greenhouse effect. Skeptics and Deniers."— Presentation transcript:
Climate Science The climate system and the greenhouse effect. Skeptics and Deniers
A Synoptic View of the Earth’s Climate and Weather
Mitchell K. Hobish, Earth Systems Science, Section 16, Remote Sensing Tutorial The Bretherton Diagram- Complex
Earth Characteristics The Earth and its climate are both examples of self-organizing natural systems, that are self-regulating and self-corrective. Such systems tend towards stable equilibria, but are always subject to external forcing and the controlling effects of positive and negative feedbacks that can alter the apparent steady-state (equilibrium) of the system by amplification or suppression. The life-supporting properties of Earth are attributable to the biological activities of the progression of various living forms that have inhabited the planet throughout most of its history. Earth’s biology has altered the physical/chemical nature of the planet, and reversed entropy. For much of the Earth’s history, the world has been ice-free. This has been interrupted by several glacial epochs. Human history is encompassed by the most recent post-glacial epoch. This is a factor of our existence. We perceive it as a steady-state.
Forcing The Earth’s climate system is subject to four principal forcing functions that together control climate: INSOLATION: Radiative forcing. (sunspots, solar flares, Malankovich Cycles) GREENHOUSE GASES (CO 2, CH 4, N 2 O, Water Vapor) AEROSOLS and PARTICULATES POSITIVE FEEDBACKS and AMPLIFICATION These all interact on different time and spatial scales such that no one forcing is the sole agent of climate change.
Insolation Sunspots and solar flares increase the amount of energy coming from the sun across the total energy spectrum. Like all stars the Sun’s irradiance increases as the Sun ages. The Malankovich Cycles are:
Greenhouse Gases CO 2, CH 4 and N 2 O are naturally occurring gases that are also produced by human activity. Their increase in the atmosphere increases heat retention. H 2 O (water vapor) contributes to cloud formation. It can both increase heat retention (cloud cover acts as a blanket retaining heat) and decrease heat retention (clouds are highly reflective and prevent solar irradiance from reaching Earth. This is known as albedo.
Aerosols and Particulates Natural (volcanism) and man-made (pollution). Both increase albedo, and thus tend to cool the atmosphere, cooling the Earth. Both cool by shading the Earth (the eruption of Mt Pinatubo, Philippines). Both are important as sources of nucleation in cloud formation.
The Earth’s Atmosphere But the amount of CO 2 is very small… How can we possibly have an effect? And by the way, how does it cause the Greenhouse Effect ?
Solar Energy that Reaches the Earth
The Greenhouse Effect
Some Simple Facts The greenhouse effect was discovered by Joseph Fourier in 1824, first reliably experimented on by John Tyndall in 1858, and first reported quantitatively by Svante Arrhenius in The basic physics has been well known for nearly 200 years. Today the role of the major greenhouse gases (CO 2, CH 4, NO, H 2 O [water vapor]) in maintaining the Earth’s temperature within the limits required for life is settled science. Scientific proponents, including scientific skeptics all agree on the basic physical mechanisms involved in the so-called greenhouse effect. If the greenhouse gases were absent, Earth would be an ice planet.
Timeline of Increased Scientific Interest By the 1950s scientists noticed that climate was changing. Two schools of thought, either pollution/aerosols were reflecting sunlight and initiate cooling (start of a new glacial period) or the greenhouse gases were increasing and would overwhelm natural forcings causing warming. Both ideas have anthropogenic causation as their basis. The 1980s became the hottest decade. Concern focused on anthropogenically produced greenhouse gases as the source of warming.
The Keeling Curve NOTE: There are two categories of energy. Solar energy that reaches the Earth (Flow Energy). Solar energy stored in the Earth during earlier geologic time (Stock Energy). Since 1945 (Trinity Test) the atmosphere is enriched with C 14. Fossil C is not.
The Hockey Stick Model
Vostock Ice Core Data
Skeptical Scientists The overwhelming scientific consensus supports the observation that the Earth’s climate is in a dramatic warming phase and that this is being caused by human activity (i.e. the burning of fossil fuels). Within the scientific community there are also some skeptics whose work raises questions that have been addressed by broader research in the context of the scientific process. These include: Tropospheric temperature anomalies. 800 year time lag in the Vostock Ice Cores. The Ordovician Cooling Solar forcing. Cloud cover. All of these have been given substantial attention by climate researchers.
Tropospheric Temperature In the 1990s, Danish researchers identified tropospheric temperature anomalies in satellite data that contradicted evidence for anthropogenically enhanced warming of the climate ( Christensen and Larsen, Science) These data were re-examined by several other researchers in the normal process of science review and verification with these findings: Orbital degradation of the original satellite data caused the anomaly. Data from other satellites conforms to the general warming trend.
The 800 Year Lag Caused by the natural trigger of solar forcing. Once warming is initiated, a positive feedback loop begins the release of CO 2 from the permafrost, which reinforces warming.
Positive Feedbacks and Amplification
The Ordovician Cooling Does not correlate with solar forcings. Caused by sudden withdrawal of CO 2
Explained by the Breakup of Pangaea,400 million years ago The Appalachian mountains form, exposing vast deposits of CaSiO 3. This erodes and is Dissolved in the oceans where free Ca +2 ions combine with CO 2 forming CaCO 3
Solar Forcing Christensen and Larsen (Science, 1991) also reported that solar forcing had increased as a result of solar flares and sunspots in the period 1980 to 2000, thus accounting for the observed warming in this period. Two issues in their data analysis were identified: There were no ACRIM satellites operating between 1989 and 1991 due to the Challenger disaster. The data gap was projected. Similarly, the final data for 1996 to 2000 were not available at the time of publication, and these data points were assumed projections. As it turned out, sunspot activity was at its lowest in this time frame. Verified from other satellite data in this same period.
Cloud Cover There are two arguments here: Again, Christensen and Larsen also looked at the effect of cosmic rays emitted from the Sun. These reduce stratospheric cloud cover and thus increase warming. Post 9-11 jet contrails provide an elegant natural experiment. Richard Lindzen in the United States also reported that for the same period warm tropical oceans reduce cloud cover and also increase solar heating of the Earth. His satellite data from the ocean adjacent to Indonesia is unique. Other tropical areas of the ocean actually increase cloud cover.
El Niño/La Niña
Climate Deniers “If we begin with certainties, we shall end in doubts; but if we begin with doubts, and are patient in them, we shall end in certainties.” Francis Bacon
Climate Deniers A second look at Clouds “An Inconvenient Truth” v “The Great Global Warming Swindle” Not “Bush v Gore,” but “Gore v Durkin” Cinematic dueling banjos! A new Ice Age reported in the 1970s The Hockey Stick Climategate
Conspiracy Theories Are Not New In American Politics! Defined and described by the American historian Richard Hofstadter in the 1960s. The Paranoid Style in American Politics Anti-Intellectualism in American Life Identified as a broad narrative of national prejudice against serious critical thought and thinkers beginning in the 18 th C. Characteristic of both the left and the right in our politics. Identified with evangelical revivalism, populist politics, and the modern businessman’s cult of “practical” knowledge Belief that the country has been in thrall of a vast conspiracy to deny freedom and create a world government Assertions that a return to our historical religious and economic beliefs will be sufficient to discipline the national character. How does the public controversy over climate change fit within this narrative?
Clouds (revisited) A long history of assertions that clouds can be a substantial driver of climate (+ or – forcing). New papers on the variation of cosmic rays and stimulation of cloud formation. Popular press trumpets this as a refutation of mainstream climate science (Drudge Report) But it is simply science at work – you live or die by the scientific method. Consensus emerges in the body of peer reviewed literature The majority consensus remains that clouds are an important feedback, but not a forcing (driver) of climate change. Over 6000 papers published thus far in 2011 affirming climate change. They’ve looked at clouds from all sides now, as feedback and forcing, and still somehow, it’s clouds’ illusions most often recalled. More work is needed to know clouds at all. Andrew Revkin, Dot Earth
“An Inconvenient Truth” v “The Great Global Warming Swindle” Gore: A Progressive Democrat who has followed climate science since his undergraduate years at Harvard. The 20 foot sea level rise. Recent research shows an average sea level rise of 3.0 mm/year. More than half the rise is due to thermal expansion. Total rise at the end of 21 st C at least one meter. Muddying the relationship of temperature and CO 2 in the Vostock Ice Data (800 year gap). We saw earlier how initiation by changes in solar insolation causes this. Guilty of the selective use of model projections to feature the worst case scenario.
“An Inconvenient Truth” v “The Great Global Warming Swindle” Durkin: A degree in Ancient and Medieval History and a career as a financial journalist. Attributes this graph to H. Fries Christensen: -But its not his graph. -Durkin drew it himself. * -Christensen calls it a fabrication: “Parts of the graph were made up.” -Christensen was interviewed in the film. *Does this look familiar? Its actually the 800 year gap from the Vostock Ice Core data.
Durkin also attributes this slide to NASA: But this one was also redrawn by Durkin to isolate a small portion of the NASA temperature record and exaggerate the pre-1940 temperature increase.
Durkin also uses statements made in the film by Carl Wunsch (WHOI) to suggest that the oceans release CO 2, and are thus a natural source of global warming. True, but Wunsch has called this a mis-representation and deliberate fraud in a public letter to the TV station broadcasting the film. The argument that atmospheric CO 2 is such a small portion of the atmosphere also figures prominently in Durkin’s film.
The Coming Ice Age The state of Climate Science in the 1970s was marked by uncertainties about mechanisms of change. TIME (1974), Newsweek (1975) and the NY Times (1975) all published featured articles claiming that a new Ice Age was coming. None of the scientists cited in these articles suggest an Ice Age is coming. TIME cites “climatological Cassandras” but names none. These articles are widely cited by Penn & Teller, Senator James Inhofe, George Will and others, and are featured in Michael Crichton's book State of Fear. Senator Inhofe also cites the National Science Board report on climate (1974): “Judging from the record of the past interglacial ages, the present time of high temperatures should be drawing to an end … leading into the next glacial age.” He leaves out the end of the quote, “…20,000 years from now.” There were also abundant articles published in the same period expressing concern about warming (TIME, Newsweek, NY Times, Washington Post).
The Coming Ice Age Reviewing the scientific literature of the period: There is uncertainty about mechanisms and an under appreciation of the complexity of feedback systems. But, of papers on the next glaciation published in those years, those identifying warming as the issue outnumber those predicting an imminent Ice Age by a margin of 44 to 7. If there is a consensus, it was not in favor of global cooling. * Among conspiracy theorists, this is willful ignorance. In columns published in 1992, 2004 and 2008, George Will specifically cites the NY Times (August 4, 1975) article that concludes that the climate is warming. The title of the article is, “Warming Trend Seen in Climate.” * “The myth of the 1970s global cooling scientific consensus.” T. C. Peterson et al, Bulletin of the American Meteorological Society, January 2009.
The Hockey Stick “Just when you thought you finally saw the last of that silly, disproven "hockey-stick" model of global warming, it rears it's silly little head again (Washington Times 10/30/2009). Two sensible scientists discuss the background of the infamous graph that supposedly portrayed global temperature fluctuations over the last millennium as having been basically flat until the last 100 years, when "Evil Mankind" started that "Evil Industrial Revolution" thing, which has now doomed our planet. Only problem: the hockey stick was a fabrication. And yet, these scientists have found this bit of revisionist history in a new college climatology textbook.”* "hockey-stick" model of global warmingdiscuss the background “As Christopher Monckton observes (Sunday Telegraph 11/05/ 2006) global warming hysteria "is less about saving the planet than, in Jacques Chirac's chilling phrase, 'creating a world government.’”* *
The Hockey Stick
First published by Michael Mann, et al in 1999 as a follow-up to an earlier study published in 1998 (both in Nature) Since 2001, there have been repeated claims that the study is at best seriously flawed and at worst fraud. Details involve lengthy, arcane statistical arguments about data treatment. At the request of Congress, the National Academy examined the question (2006)
The Hockey Stick The NAS report states: "The basic conclusion of Mann et al. (1998, 1999) was that the late 20 th century warmth in the Northern Hemisphere was unprecedented during at least the last 1000 years. This conclusion has subsequently been supported by an array of evidence that includes both additional large-scale surface temperature reconstructions and pronounced changes in a variety of local proxy indicators, such as melting on ice caps and the retreat of glaciers around the world".
The Hockey Stick Climate scientists are only too aware of the problems inherent in proxy temperature data. Mann (1998, 1999) discusses this extensively The Medieval warming Based on historical accounts not temperature records Largely a regional phenomenon relating to changes in the Gulf Stream Following the NAS recommendations new reconstructions using larger data sets and a broader set of proxies have been produced The conclusion remains – it is hotter now than ever in the past 1000 years, possibly the last million years (ice core data) 2011: Richard Muller (Berkley Climate Group) The point is that human civilization emerged in the last 18,000 years in a cooler, more stable climate system
The Hockey Stick (Revised)
The Hockey Stick The IPCC Fourth Assessment now is more emphatic regarding the causation of climate change by human action. The Hockey Stick data are part of that conclusion But the controversy remains – In Virginia, the present Attorney General has subpoenaed Michael Mann’s data with suggestions of criminal misconduct and fraud. This was denied recently by the court. Claims regarding Mann’s data handling resurfaced within the s “hacked” in Climategate where data handling of tree ring proxies was referred to as “Mike’s Trick” Mann’s work has been reviewed and he has been exonerated in four separate enquiries by Penn State University, The University of Virginia, the National Academy of Science and the National Science Foundation, and in five enquiries in the UK and the US resulting from Climategate. Climate skeptics call these a “whitewash.”
Climategate In November 2009, thousands of s and other documents were hacked from servers at the University of East Anglia’s Climate Research Center. Dubbed “Climategate” by bloggers and critics of the climate change finding that humans are altering the composition of the Earth’s atmosphere, these documents were mined extensively for evidence of fraud and conspiracy. See for example Several high level government investigations in Britain and the US have followed, including a criminal investigation to identify the hackers.
Climategate In the UK: House of Commons Select Committee on Science and Technology Independent Science Assessment Panel The University of East Anglia Climate Research Center Phil Jones, Director of the Climatic Research Unit, Tim Osborne, Mike Hulme The Independent Climate Change Review (2011): review.org/pdf/FINAL REPORT.pdfhttp://www.cce- review.org/pdf/FINAL REPORT.pdf In the US: National Academy The National Science Foundation Penn State University International: The IPCC Directorate Report
Climategate The UEA and CRU issued rebuttals of the allegations, as did Penn State University. Reports by the House of Commons' Science and Technology Select Committee and an Independent Science Assessment Panel commissioned by the UEA concluded that there was no evidence of malpractice on the part of the CRU and Phil Jones, though they did find that there was room for improvement in some of the CRU's working practices. Many commentators quoted one referring to a "trick" used in Mann's graph to deal with the well-known tree ring divergence problem to "hide the decline" that particular proxy showed for modern temperatures after 1950.
Climategate Outcomes: Increased scrutiny has led to a more rigorous process in the review of data and assessments within the IPCC. The Fifth Assessment is due in The social nature of science is on full display in the Climategate s. As is the rivalrous nature of scientists.
Some Final Thoughts Hofstadter had it right. The public controversies surrounding climate change turn out to be a perfect storm within American political traditions and pose a serious impediment to reasonable action. The public debate is one of FACTS and VALUES – my facts and your values Arguing the facts of climate change may not be helpful. We should be asking this question – What do our facts tell us about the values we wish to argue for? Economic Security A Healthful Environment Energy Independence