1AC WarmingGlobal warming is real and human induced top climate scientists agreeAnderegg et al 10 PhD Candidate @ Stanford in Biology(William, Expert credibility in climate change, National Academy of Sciences, p. 12107-12109)//BBPreliminary reviews of scientific literature and surveys of cli- mate scientists indicate striking agreement with the primary conclusions of the Intergovernmental Panel on Climate Change (IPCC): anthropogenic greenhouse gases have been responsible for most of the unequivocal warming of the Earths average global temperature over the second half of the 20th century (13). Nonetheless, substantial and growing public doubt remains about the anthropogenic cause and scientific agreement about the role of anthropogenic greenhouse gases in climate change (4, 5). A vocal minority of researchers and other critics contest the conclusions of the mainstream scientific assessment, frequently citing large numbers of scientists whom they believe support their claims (68). This group, often termed climate change skeptics, contrarians, or deniers, has received large amounts of media attention and wields significant influence in the societal debate about climate change impacts and policy (7, 914). An extensive literature examines what constitutes expertise or credibility in technical and policy-relevant scientific research (15). Though our aim is not to expand upon that literature here, we wish to draw upon several important observations from this literature in examining expert credibility in climate change. First, though the degree of contextual, political, epistemological, and cultural in- fluences in determining who counts as an expert and who is credible remains debated, many scholars acknowledge the need to identify credible experts and account for expert opinion in tech- nical (e.g., science-based) decision-making (1519). Furthermore, delineating expertise and the relative credibility of claims is critical, especially in areas where it may be difficult for the majority of decision-makers and the lay public to evaluate the full complexities of a technical issue (12, 15). Ultimately, however, societal decisions regarding response to ACC must necessarily include input from many diverse and nonexpert stakeholders. Because the timeline of decision-making is often more rapid than scientific consensus, examining the landscape of expert opinion can greatly inform such decision-making (15, 19). Here, we examine a metric of climate-specific expertise and a metric of overall sci- entific prominence as two dimensions of expert credibility in two groups of researchers. We provide a broad assessment of the rel- ative credibility of researchers convinced by the evidence (CE) of ACC and those unconvinced by the evidence (UE) of ACC. Our consideration of UE researchers differs from previous work on climate change skeptics and contrarians in that we primarily focus on researchers that have published extensively in the climate field, although we consider all skeptics/contrarians that have signed pro- minent statements concerning ACC (68). Such expert analysis can illuminate public and policy discussions about ACC and the extent of consensus in the expert scientific community. We compiled a database of 1,372 climate researchers based on authorship of scientific assessment reports and membership on multisignatory statements about ACC (SI Materials and Methods). We tallied the number of climate-relevant publications authored or coauthored by each researcher (defined here as expertise) and counted the number of citations for each of the researchers four highest-cited papers (defined here as prominence) using Google Scholar. We then imposed an a priori criterion that a researcher must have authored a minimum of 20 climate publications to be considered a climate researcher, thus reducing the database to 908 researchers. Varying this minimum publication cutoff did not ma- terially alter results (Materials and Methods). We ranked researchers based on the total number of climate publications authored. Though our compiled researcher list is not comprehensive nor designed to be representative of the entire cli- mate science community, we have drawn researchers from the most high-profile reports and public statements about ACC. Therefore, we have likely compiled the strongest and most credentialed re- searchers in CE and UE groups. Citation and publication analyses must be treated with caution in inferring scientific credibility, but we suggest that our methods and our expertise and prominence criteria provide conservative, robust, and relevant indicators of relative credibility of CE and UE groups of climate researchers (Materials and Methods). Results and Discussion The UE [unconvinced by evidence] group comprises only 2% of the top 50 climate researchers as ranked by expertise (number of climate publications), 3% of researchers of the top 100, and 2.5% of the top 200, excluding researchers present in both groups (Materials and Methods). This result closely agrees with expert surveys, indicating that 97% of self-identified actively publishing climate scientists agree with the tenets of ACC (2). Furthermore, this finding complements direct polling of the climate researcher community, which yields quali- tative and self-reported researcher expertise (2). Our findings capture the added dimension of the distribution of researcher expertise, quantify agreement among the highest expertise climate researchers, and provide an independent assessment of level of scientific consensus concerning ACC. In addition to the striking difference in number of expert researchers between CE and UE groups, the distribution of expertise of the UE group is far below that of the CE group (Fig. 1). Mean expertise of the UE group was around half (60 publications) that of the CE group (119 pub- lications; MannWhitney U test: W = 57,020; P < 1014), as was median expertise (UE = 34 publications; CE = 84 publications). Furthermore, researchers with fewer than 20 climate publications comprise 80% the UE group, as opposed to less than 10% of the CE group. This indicates that the bulk of UE researchers on the most prominent multisignatory statements about climate change have not published extensively in the peer-reviewed climate literature. We examined a subsample of the 50 most-published (highest- expertise) researchers from each group. Such subsampling facili- tates comparison of relative expertise between groups (normalizing differences between absolute numbers). This method reveals large differences in relative expertise between CE and UE groups (Fig. 2). Though the top-published researchers in the CE group have an average of 408 climate publications (median = 344), the top UE re- searchers average only 89 publications (median = 68; Mann Whitney U test: W = 2,455; P < 1015). Thus, this suggests that not all experts are equal, and top CE researchers have much stronger expertise in climate science than those in the top UE group. Finally, our prominence criterion provides an independent and approximate estimate of the relative scientific significance of CE and UE publications. Citation analysis complements publication analysis because it can, in general terms, capture the quality and impact of a researchers contributiona critical component to overall scientific credibilityas opposed to measuring a research- ers involvement in a field, or expertise (Materials and Methods). The citation analysis conducted here further complements the publication analysis because it does not examine solely climate- relevant publications and thus captures highly prominent re- searchers who may not be directly involved with the climate field. We examined the top four most-cited papers for each CE and UE researcher with 20 or more climate publications and found immense disparity in scientific prominence between CE and UE communities (MannWhitney U test: W = 50,710; P < 106; Fig. 3). CE researchers top papers were cited an average of 172 times, compared with 105 times for UE researchers. Because a single, highly cited paper does not establish a highly credible reputation but might instead reflect the controversial nature of that paper (often called the single-paper effect), we also considered the av- erage the citation count of the second through fourth most-highly cited papers of each researcher. Results were robust when only these papers were considered (CE mean: 133; UE mean: 84; MannWhitney U test: W = 50,492; P < 106). Results were ro- bust when all 1,372 researchers, including those with fewer than 20 climate publications, were considered (CE mean: 126; UE mean: 59; MannWhitney U test: W = 3.5 105; P < 1015). Number of citations is an imperfect but useful benchmark for a groups scientific prominence (Materials and Methods), and we show here that even considering all (e.g., climate and nonclimate) publications, the UE researcher group has substantially lower prominence than the CE group. We provide a large-scale quantitative assessment of the relative level of agreement, expertise, and prominence in the climate re- searcher community. We show that the expertise and prominence, two integral components of overall expert credibility, of climate researchers convinced by the evidence of ACC vastly overshadows that of the climate change skeptics and contrarians. This divide is even starker when considering the top researchers in each group. Despite media tendencies to present both sides in ACC debates (9), which can contribute to continued public misunderstanding re- garding ACC (7, 11, 12, 14), not all climate researchers are equal in scientific credibility and expertise in the climate system. This extensive analysis of the mainstream versus skeptical/contrarian researchers suggests a strong role for considering expert credibi- lity in the relative weight of and attention to these groups of re- searchers in future discussions in media, policy, and public forums regarding anthropogenic climate change.shows, for the first time, that at least one of the CGCMs used to predict future climate is capable of reproducing both the timing and amplitude of climate evolution seen in the past under realistic climate forcing.CO2 is the causeORLCF 12 (Oak Ridge Leadership Computing Facility, 4/4/12, http://www.olcf.ornl.gov/2012/04/04/carbon-dioxide-caused-global-warming-at-ice-ages-end-pioneering-simulation-shows/)

Climate science has an equivalent to the what came firstthe chicken or the egg? question: What came first, greenhouse gases or global warming? A multi-institutional team led by researchers at Harvard, Oregon State University, and the University of Wisconsin used a global dataset of paleoclimate records and the Jaguar supercomputer at Oak Ridge National Laboratory (ORNL) to find the answer (spoiler alert: carbon dioxide drives warming). The results, published in the April 5 issue of Nature, analyze 15,000 years of climate history. Scientists hope amassing knowledge of the causes of natural global climate change will aid understanding of human-caused climate change. We constructed the first-ever record of global temperature spanning the end of the last ice age based on 80 proxy temperature records from around the world, said Jeremy Shakun, a National Oceanic and Atmospheric Administration (NOAA) Climate and Global Change postdoctoral fellow at Harvard and Columbia Universities and first author of the paper. Its no small task to get at global mean temperature. Even for studies of the present day you need lots of locations, quality-controlled data, careful statistics. For the past 21,000 years, its even harder. But because the data set is large enough, these proxy data provide a reasonable estimate of global mean temperature. Proxy records from around the worldderived from ice cores and ocean and lake sedimentsprovide estimates of local surface temperature throughout history, and carbon-14 dating indicates when those temperatures occurred. For example, water molecules harboring the oxygen-18 isotope rain out faster than those containing oxygen-16 as an air mass cools, so the ratio of these isotopes in glacial ice layers tells scientists how cold it was when the snow fell. Likewise, the amount of magnesium incorporated into the shells of marine plankton depends on the temperature of the water they live in, and these shells get preserved on the seafloor when they die. The authors combined these local temperature records to produce a reconstruction of global mean temperature. Additionally, samples of ancient atmosphere are trapped as air bubbles in glaciers, providing a direct measure of carbon dioxide levels through time that could be compared to the global temperature record. Being the first to reconstruct global mean temperatures throughout this time interval allowed the researchers to show what many suspected but none could yet prove: This is the first paper to definitively show the role carbon dioxide played in helping to end the last ice age, said Shakun, who co-wrote the paper with Peter Clark of Oregon State University. We found that global temperature mirrored and generally lagged behind rising carbon dioxide during the last deglaciation, which points to carbon dioxide as the major driver of global warming. Prior results based on Antarctic ice cores had indicated that local temperatures in Antarctica started warming before carbon dioxide began rising, which implied that carbon dioxide was a feedback to some other leading driver of warming. The delay of global temperature behind carbon dioxide found in this study, however, shows that the ice-core perspective does not apply to the globe as a whole and instead suggests that carbon dioxide was the primary driver of worldwide warming. While the geologic record showed a remarkable correlation between carbon dioxide and global temperature, the researchers also turned to state-of-the-art model simulations to further pin down the direction of causation suggested by the temperature lag. Jaguar recently ran approximately 14 million processor hours to simulate the most recent 21,000 years of Earths climate. Feng He of the University of Wisconsin, Madison, a postdoctoral researcher, plugged the main forcings driving global climate over this time interval into an Intergovernmental Panel on Climate Change (IPCC)class model called the Community Climate System Model version 3, a global climate model that couples interactions between atmosphere, oceans, lands, and sea ice. The climate science community developed the model with support from the National Science Foundation (NSF), Department of Energy (DOE), and National Aeronautics and Space Administration and used many codes developed by university researchers. Our model results are the first IPCC-class Coupled General Circulation Model (CGCM) simulation of such a long duration ,Scenario 1 is collapse warming will cause unprecedented economic devastation leading to extinction. Mazo 10 PhD in Paleoclimatology from UCLA(Jeffrey Mazo, Managing Editor, Survival and Research Fellow for Environmental Security and Science Policy at the International Institute for Strategic Studies in London, 3-2010, Climate Conflict: How global warming threatens security and what to do about it, pg. 122)//BB

The best estimates for global warming to the end of the century range from 2.5-4.~C above pre-industrial levels, depending on the scenario. Even in the best-case scenario, the low end of the likely range is 1.goC, and in the worst 'business as usual' projections, which actual emissions have been matching, the range of likely warming runs from 3.1--7.1C. Even keeping emissions at constant 2000 levels (which have already been exceeded), global temperature would still be expected to reach 1.2C (O'9""1.5C)above pre-industrial levels by the end of the century." Without early and severe reductions in emissions, the effects of climate change in the second half of the twenty-first century are likely to be catastrophic for the stability and security of countries in the developing world - not to mention the associated human tragedy. Climate change could even undermine the strength and stability of emerging and advanced economies, beyond the knock-on effects on security of widespread state failure and collapse in developing countries.' And although they have been condemned as melodramatic and alarmist, many informed observers believe that unmitigated climate change beyond the end of the century could pose an existential threat to civilisation." What is certain is that there is no precedent in human experience for such rapid change or such climatic conditions, and even in the best case adaptation to these extremes would mean profound social, cultural and political changes.Scenario 2 is extinctionDeibel 7 (Terry L. Deibel, professor of IR at National War College, Foreign Affairs Strategy, Conclusion: American Foreign Affairs Strategy Today Anthropogenic caused by CO2)

Finally, there is one major existential threat to American security (as well as prosperity) of a nonviolent nature, which, though far in the future, demands urgent action. It is the threat of global warming to the stability of the climate upon which all earthly life depends. Scientists worldwide have been observing the gathering of this threat for three decades now, and what was once a mere possibility has passed through probability to near certainty. Indeed not one of more than 900 articles on climate change published in refereed scientific journals from 1993 to 2003 doubted that anthropogenic warming is occurring. In legitimate scientific circles, writes Elizabeth Kolbert, it is virtually impossible to find evidence of disagreement over the fundamentals of global warming. Evidence from a vast international scientific monitoring effort accumulates almost weekly, as this sample of newspaper reports shows: an international panel predicts brutal droughts, floods and violent storms across the planet over the next century; climate change could literally alter ocean currents, wipe away huge portions of Alpine Snowcaps and aid the spread of cholera and malaria; glaciers in the Antarctic and in Greenland are melting much faster than expected, andworldwide, plants are blooming several days earlier than a decade ago; rising sea temperatures have been accompanied by a significant global increase in the most destructive hurricanes; NASA scientists have concluded from direct temperature measurements that 2005 was the hottest year on record, with 1998 a close second; Earths warming climate is estimated to contribute to more than 150,000 deaths and 5 million illnesses each year as disease spreads; widespread bleaching from Texas to Trinidadkilled broad swaths of corals due to a 2-degree rise in sea temperatures. The world is slowly disintegrating, concluded Inuit hunter Noah Metuq, who lives 30 miles from the Arctic Circle. They call it climate changebut we just call it breaking up. From the founding of the first cities some 6,000 years ago until the beginning of the industrial revolution, carbon dioxide levels in the atmosphere remained relatively constant at about 280 parts per million (ppm). At present they are accelerating toward 400 ppm, and by 2050 they will reach 500 ppm, about double pre-industrial levels. Unfortunately, atmospheric CO2 lasts about a century, so there is no way immediately to reduce levels, only to slow their increase, we are thus in for significant global warming; the only debate is how much and how serous the effects will be. As the newspaper stories quoted above show, we are already experiencing the effects of 1-2 degree warming in more violent storms, spread of disease, mass die offs of plants and animals, species extinction, and threatened inundation of low-lying countries like the Pacific nation of Kiribati and the Netherlands at a warming of 5 degrees or less the Greenland and West Antarctic ice sheets could disintegrate, leading to a sea level of rise of 20 feet that would cover North Carolinas outer banks, swamp the southern third of Florida, and inundate Manhattan up to the middle of Greenwich Village. Another catastrophic effect would be the collapse of the Atlantic thermohaline circulation that keeps the winter weather in Europe far warmer than its latitude would otherwise allow. Economist William Cline once estimated the damage to the United States alone from moderate levels of warming at 1-6 percent of GDP annually; severe warming could cost 13-26 percent of GDP. But the most frightening scenario is runaway greenhouse warming, based on positive feedback from the buildup of water vapor in the atmosphere that is both caused by and causes hotter surface temperatures. Past ice age transitions, associated with only 5-10 degree changes in average global temperatures, took place in just decades, even though no one was then pouring ever-increasing amounts of carbon into the atmosphere. Faced with this specter, the best one can conclude is that humankinds continuing enhancement of the natural greenhouse effect is akin to playing Russian roulette with the earths climate and humanitys life support system. At worst, says physics professor Marty Hoffert of New York University, were just going to burn everything up; were going to heat the atmosphere to the temperature it was in the Cretaceous when there were crocodiles at the poles, and then everything will collapse. During the Cold War, astronomer Carl Sagan popularized a theory of nuclear winter to describe how a thermonuclear war between the Untied States and the Soviet Union would not only destroy both countries but possible end life on this planet. Global warming is the post-Cold War eras equivalent of nuclear winter at least as serious and considerably better supported scientifically. Over the long run it puts dangers from terrorism and traditional military challenges to shame. It is a threat not only to the security and prosperity to the United States, but potentially to the continued existence of life on this planet.Extinction is forever the entire planet will be engulfed in the infernoerr aff. Extinction outweighs everythingBrandenburg, 1999 [John, PhD, Visiting Professor Researcher at Florida Space Institute, with Monica Rix Paxson, Science Writer, Dead Mars, Dying Earth, pp. 244-245]

The 20th century, and the second millennium, are drawing to a close. A new century, a new millennium and, hopefully, a new age dawns. In our journey across time and space we have searched for truths that would help us at this threshold. To live is to be exposed to danger; to experience -apprehension is a condition of existence. To follow reason and awareness, we must be responsible. We have seen how the storms of Mars first warned us of our collective madness. You now know how Venus became an inferno and how the Shoemaker-Levy impacts caused atmospheric firestorms as big as the Earth to erupt on Jupiter. We have been warned of potential threats to come. We cannot deny what we have seen, and we are responsible for this knowledge now. The planetary environment we possess is precious, it is fragileand events within our control, both human and natural, can destroy it utterly. We now know that a whole planet can die, and that we can expect no agency to help us if we do not help ourselves. With this knowledge, we become responsible. We are responsible because we can act. Carbon dioxide, that most rugged and simple of molecules, is the substance that remains when the inferno has burned itself out, when all that can draw breath breathes no more. Carbon dioxide is the lowest common denominator, the substance that remains after all the fine things, chlorophyll, water, and hope, have been lost. It inherits planets after all planetary disasters have run their course. We are in the beginnings of such planetary disaster now. Like passengers on the Titanic, weve only just felt a slight bump and noticed that the ship has stopped. Here in the First World, we note that the ships officers seem unusually activemaybe a bit too cheerful and reassuringand they seem to be locking all the doors between steerage and the open decks. This is how a disaster looks when it begins. We see the evolving probability field of the catastrophe around usScenario 3 is diseasesWarming unleashes new onesScienceDaily 8 [June 25, Extreme Weather Events Can Unleash A 'Perfect Storm' Of Infectious Diseases, Research Study Says, http://www.sciencedaily.com/releases/2008/06/080625073804.htm]

An international research team, including University of Minnesota researcher Craig Packer, has found the first clear example of how climate extremes, such as the increased frequency of droughts and floods expected with global warming, can create conditions in which diseases that are tolerated individually may converge and cause mass die-offs of livestock or wildlife. The study suggests that extreme climatic conditions are capable of altering normal host-pathogen relationships and causing a "perfect storm" of multiple infectious outbreaks that could trigger epidemics with catastrophic mortality. Led by scientists at the University of California, Davis, the University of Illinois and the University of Minnesota, the research team examined outbreaks of canine distemper virus (CDV) in 1994 and 2001 that resulted in unusually high mortality of lions in Tanzania's Serengeti National Park and Ngorongoro Crater. CDV periodically strikes these ecosystems, and most epidemics have caused little or no harm to the lions. But the fatal virus outbreaks of 1994 and 2001 were both preceded by extreme drought conditions that led to debilitated populations of Cape buffalo, a major prey species of lions. The buffalo suffered heavy tick infestations and became even more common in the lions' diet, resulting in unusually high levels of tick-borne blood parasites in the lions. (These parasites are normally present in lions at harmlessly low levels.) The canine distemper virus suppressed the lions' immunity, which allowed the elevated levels of blood parasites to reach fatally high levels, leading to mass die-offs of lions. In 1994 the number of lions in the Serengeti study area dropped by over 35 percent after the double infection. Similar losses occurred in the Crater die-off in 2001. The lion populations recovered within 3-4 years after each event, but most climate change models predict increasing frequency of droughts in East Africa. "The study illustrates how ecological factors can produce unprecedented mortality events and suggests that co-infections may lie at the heart of many of the most serious die-offs in nature," said Packer, Distinguished McKnight University Professor of Ecology, Evolution and Behavior at theExtinctionDaswani 96[Kavita Daswani, South China Morning Post Leading the way to a cure for AIDS, 1-4, L/N]

Despite the importance of the discovery of the "facilitating" cell, it is not what Dr Ben-Abraham wants to talk about. There is a much more pressing medical crisis at hand - one he believes the world must be alerted to: the possibility of a virus deadlier than HIV. If this makes Dr Ben-Abraham sound like a prophet of doom, then he makes no apology for it. AIDS, the Ebola outbreak which killed more than 100 people in Africa last year, the flu epidemic that has now affected 200,000 in the former Soviet Union - they are all, according to Dr Ben-Abraham, the "tip of the iceberg". Two decades of intensive study and research in the field of virology have convinced him of one thing: in place of natural and man-made disasters or nuclear warfare, humanity could face extinction because of a single virus, deadlier than HIV. "An airborne virus is a lively, complex and dangerous organism," he said. "It can come from a rare animal or from anywhere and can mutate constantly. If there is no cure, it affects one person and then there is a chain reaction and it is unstoppable. It is a tragedy waiting to happen." That may sound like a far-fetched plot for a Hollywood film, but Dr Ben -Abraham said history has already proven his theory. Fifteen years ago, few could have predicted the impact of AIDS on the world. Ebola has had sporadic outbreaks over the past 20 years and the only way the deadly virus - which turns internal organs into liquid - could be contained was because it was killed before it had a chance to spread. Imagine, he says, if it was closer to home: an outbreak of that scale in London, New York or Hong Kong. It could happen anytime in the next 20 years - theoretically, it could happen tomorrow. The shock of the AIDS epidemic has prompted virus experts to admit "that something new is indeed happening and that the threat of a deadly viral outbreak is imminent", said Joshua Lederberg of the Rockefeller University in New York, at a recent conference. He added that the problem was "very serious and is getting worse". Dr Ben-Abraham said: "Nature isn't benign. The survival of the human species is not a preordained evolutionary programme. Abundant sources of genetic variation exist for viruses to learn how to mutate and evade the immune system." He cites the 1968 Hong Kong flu outbreak as an example of how viruses have outsmarted human intelligence. And as new "mega-cities" are being developed in the Third World and rainforests are destroyed, disease-carrying animals and insects are forced into areas of human habitation. "This raises the very real possibility that lethal, mysterious viruses would, for the first time, infect humanity at a large scale and imperil the survival of the human race," he said.Scenario 4 is oxygenBurning fossil fuels leads to oxygen depletion causes extinctionTatchell 8 [Peter, 8/13/08, The oxygen crisis: Could the decline of oxygen in the atmosphere undermine our health and threaten human survival?, The Guardian, Aug 13, http://www.guardian.co.uk/commentisfree/2008/aug/13/carbonemissions.climatechange]

The rise in carbon dioxide emissions is big news. It is prompting action to reverse global warming. But little or no attention is being paid to the long-term fall in oxygen concentrations and its knock-on effects. Compared to prehistoric times, the level of oxygen in the earth's atmosphere has declined by over a third and in polluted cities the decline may be more than 50%. This change in the makeup of the air we breathe has potentially serious implications for our health. Indeed, it could ultimately threaten the survival of human life on earth, according to Roddy Newman, who is drafting a new book, The Oxygen Crisis. I am not a scientist, but this seems a reasonable concern. It is a possibility that we should examine and assess. So, what's the evidence? Around 10,000 years ago, the planet's forest cover was at least twice what it is today, which means that forests are now emitting only half the amount of oxygen. Desertification and deforestation are rapidly accelerating this long-term loss of oxygen sources. The story at sea is much the same. Nasa reports that in the north Pacific ocean oxygen-producing phytoplankton concentrations are 30% lower today, compared to the 1980s. This is a huge drop in just three decades. Moreover, the UN environment programme confirmed in 2004 that there were nearly 150 "dead zones" in the world's oceans where discharged sewage and industrial waste, farm fertiliser run-off and other pollutants have reduced oxygen levels to such an extent that most or all sea creatures can no longer live there. This oxygen starvation is reducing regional fish stocks and diminishing the food supplies of populations that are dependent on fishing. It also causes genetic mutations and hormonal changes that can affect the reproductive capacity of sea life, which could further diminish global fish supplies. Professor Robert Berner of Yale University has researched oxygen levels in prehistoric times by chemically analysing air bubbles trapped in fossilised tree amber. He suggests that humans breathed a much more oxygen-rich air 10,000 years ago. [] Further back, the oxygen levels were even greater. Robert Sloan has listed the percentage of oxygen in samples of dinosaur-era amber as: 28% (130m years ago), 29% (115m years ago), 35% (95m years ago), 33% (88m years ago), 35% (75m years ago), 35% (70m years ago), 35% (68m years ago), 31% (65.2m years ago), and 29% (65m years ago).[] Professor Ian Plimer of Adelaide University and Professor Jon Harrison of the University of Arizona concur. Like most other scientists they accept that oxygen levels in the atmosphere in prehistoric times averaged around 30% to 35%, compared to only 21% today and that the levels are even less in densely populated, polluted city centres and industrial complexes, perhaps only 15 % or lower. Much of this recent, accelerated change is down to human activity, notably the industrial revolution and the burning of fossil fuels. The Professor of Geological Sciences at Notre Dame University in Indiana, J Keith Rigby, was quoted in 1993-1994 as saying: [] In the 20th century, humanity has pumped increasing amounts of carbon dioxide into the atmosphere by burning the carbon stored in coal, petroleum and natural gas. In the process, we've also been consuming oxygen and destroying plant life cutting down forests at an alarming rate and thereby short-circuiting the cycle's natural rebound. We're artificially slowing down one process and speeding up another, forcing a change in the atmosphere. [] Very interesting. But does this decline in oxygen matter? Are there any practical consequences that we ought to be concerned about? What is the effect of lower oxygen levels on the human body? Does it disrupt and impair our immune systems and therefore make us more prone to cancer and degenerative diseases? Surprisingly, no significant research has been done, perhaps on the following presumption: the decline in oxygen levels has taken place over millions of years of our planet's existence. The changes during the shorter period of human life have also been slow and incremental until the last two centuries of rapid urbanisation and industrialisation. Surely, this mostly gradual decline has allowed the human body to evolve and adapt to lower concentrations of oxygen? Maybe, maybe not. The pace of oxygen loss is likely to have speeded up massively in the last three decades, with the industrialisation of China, India, South Korea and other countries, and as a consequence of the massive worldwide increase in the burning of fossil fuels. In the view of Professor Ervin Laszlo, the drop in atmospheric oxygen has potentially serious consequences. A UN advisor who has been a professor of philosophy and systems sciences, Laszlo writes: [] Evidence from prehistoric times indicates that the oxygen content of pristine nature was above the 21% of total volume that it is today. It has decreased in recent times due mainly to the burning of coal in the middle of the last century. Currently the oxygen content of the Earth's atmosphere dips to 19% over impacted areas, and it is down to 12