How We Know Global Warming Is Real And Human Caused
How We Know Global Warming is Real and HumanCaused:BY DONALD R. PROTHEROCI TED: PROTHERO, D, R, 2012, “How We Know Global Warming is Real and Human Caused,” ScepticMagazine, vol-17, number-2, 2012, pp.14-22, retrieved from, http://www.sceptic.com, on 10/05/2103.Pine Island Glacier(photo shown above)In mid-October 2011, NASA scientists working in Antarctica discovered a massive crack across the Pine IslandGlacier, a major ice stream that drains the West Antarctic Ice Sheet. Extending for 19 miles (30 kilometers), the crackwas 260 feet (80 meters) wide and 195 feet (60 meters) deep. Eventually, the crack will extend all the way across theglacier, and calve a giant iceberg that will cover about 350 square miles (900 square kilometers). This image from theAdvanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument on NAS’s Terra spacecraft wasacquired Nov. 13, 2011, and covers an area of 27 by 32 miles (44 by 52 kilometers), and is located near 74.9 degreessouth latitude, 101.1 degrees west longitude. (Image Credit:NASA/GSFC/METI/ERSDAC/JAROS, and U.S./JapanASTER Science Team)
On January 27, 2012, theWall Street Journal ran anOpinion Editorial written by16 people who deny the evidence of human-induced climate change. Most of the authorsof the editorial were not climate scientists; one of two actual climate scientists of thegroup, Richard Lindzen, is a notorious global warming denier who also denies thatsmoking causes cancer. Predictably, the Rupert Murdoch-owned Journalrefused to run astatement by 255 members of the National Academy of Sciences, although a “Letter tothe Editor” by 38 of the world’s leading climate scientists1 did manage to get publishedthere. The letter pointed out the numerous lies, mistakes, and fallacies in the editorial,along with a scathing rebuke by climate scientist Kevin Trenberth, whose remarks werequoted out of context to make them seem the opposite of what he actually said. As theTrenberth et al. letter pointed out, the 16 authors of the editorial were so far out of theirdepth in discussing the topic that they were the “climate-science equivalent of dentistspracticing cardiology.” And as if to answer the editorial, the earth sent a resoundingmessage in reply. On Feb. 2, 2012, an 18-mile crack appeared in Pine Island Glacier inAntarctica (see photo above and sidebar for details), a prelude to the calving off aniceberg 350 square miles in area, one of the largest icebergs ever seen.2Converging Lines of EvidenceHow do we know that global warming is real and primarily human caused? There arenumerous lines of evidence that converge to this conclusion.Figure 1. The Moberg et al. (2005) plot (updated from the Mann et al., 1999, plot) of the last 2000 years ofearth’s average surface temperature, which shows over 800 years of relative stability followed by the rapid warming ofthe past two centuries, giving it the shape of a “hockey stick.” The slight warming trend of the Medieval Warm Periodcan also be seen (data from 900–1200 A.D.) and is nowhere near the magnitude of the warming in the past century.(Click diagrams to enlarge them.)
1. Carbon Dioxide Increase. Carbon dioxide in our atmosphere has increased atan unprecedented rate in the past 200 years. Not one data set collected over along enough span of time shows otherwise. Mann et al. (1999) compiled the past900 years’ worth of temperature data from tree rings, ice cores, corals, and directmeasurements of the past few centuries, and the sudden increase of temperatureof the past century stands out like a sore thumb. This famous graph (see Figure 1above) is now known as the “hockey stick” because it is long and straight throughmost of its length, then bends sharply upward at the end like the blade of ahockey stick. Other graphs show that climate was very stable within a narrowrange of variation through the past 1000, 2000, or even 10,000 years since theend of the last Ice Age. There were minor warming events during the ClimaticOptimum about 7000 years ago, the Medieval Warm Period, and the slightcooling of the Little Ice Age from the 1700s and 1800s. But the magnitude andrapidity of the warming represented by the last 200 years is simply unmatched inall of human history. More revealing, the timing of this warming coincides withthe Industrial Revolution, when humans first began massive deforestation andreleased carbon dioxide by burning coal, gas, and oil.2. Melting Polar Ice Caps. The polar icecaps are thinning and breaking up at analarming rate. In 2000, my former graduate advisor Malcolm McKenna was oneof the first humans to fly over the North Pole in summer time and see no ice, justopen water. The Arctic ice cap has been frozen solid for at least the past 3 millionyears and maybe longer3, but now the entire ice sheet is breaking up so fast thatby 2030 (and possibly sooner) less than half of the Arctic will be ice covered inthe summer.4 As one can see from watching the news, this is an ecologicaldisaster for everything that lives up there, from the polar bears to the seals andwalruses to the animals they feed upon, to the 4 million people whose world ismelting beneath their feet. The Antarctic is thawing even faster. In February–March 2002, the Larsen B ice shelf—over 3000 square km (the size of RhodeIsland) and 220 m (700 feet) thick—broke up in just a few months, a story typicalof nearly all the ice shelves in Antarctica. The Larsen B shelf had survived all theprevious ice ages and interglacial warming episodes for the past 3 million years,and even the warmest periods of the last 10,000 years—yet it and nearly all theother thick ice sheets on the Arctic, Greenland, and Antarctic are vanishing at arate never before seen in geologic history.3. Melting Glaciers. Glaciers are all retreating at the highest rates everdocumented. Many of those glaciers, especially in the Himalayas, Andes, Alps,and Sierras, provide most of the freshwater that the populations below themountains depend upon—yet this fresh water supply is vanishing. Just think
about the percentage of world’s population in southern Asia (especially India)that depend on Himalayan snowmelt for their fresh water. The implications arestaggering. The permafrost that once remained solidly frozen even in the summerhas now thawed, damaging the Inuit villages on the Arctic coast and threateningall our pipelines to the North Slope of Alaska. This is catastrophic not only for lifeon the permafrost, but as it thaws, the permafrost releases huge amounts ofgreenhouse gases and is one of the major contributors to global warming. Notonly is the ice vanishing, but we have seen record heat waves over and over again,killing thousands of people, as each year joins the list of the hottest years onrecord. (2010 just topped that list as the hottest year, surpassing the previousrecord in 2009, and we shall know about 2011 soon enough). Natural animal andplant populations are being devastated all over the globe as their environmentchanges.5 Many animals respond by moving their ranges to formerly coldclimates, so now places that once did not have to worry about disease-bearingmosquitoes are infested as the climate warms and allows them to breed furthernorth.4.Sea Level Rise. All that melted ice eventually ends up in the ocean,causing sea level to rise, as it has many times in the geologic past. At present, sealevel is rising about 3–4 mm per year, more than ten times the rate of 0.1–0.2mm/year that has occurred over the past 3000 years. Geological data show thatsea level was virtually unchanged over the past 10,000 years since the presentinterglacial began. A few millimeters here or there doesn’t impress people, untilyou consider that the rate is accelerating and that most scientists predict sea levelwill rise 80–130 cm in just the next century. A sea level rise of 1.3 m (almost 4feet) would drown many of the world’s low-elevation cities, such as Venice andNew Orleans, and low-lying countries such as the Netherlands or Bangladesh. Anumber of tiny island nations such as Vanuatu and the Maldives, which barelypoke out above the ocean now, are already vanishing beneath the waves.Eventually their entire population will have to move someplace else.6Even a smallsea level rise might not drown all these areas, but they are much more vulnerableto the large waves of a storm surge (as happened with Hurricane Katrina), whichcould do much more damage than sea level rise alone. If sea level rose by 6 m (20feet), most of the world’s coastal plains and low-lying areas (such as the Louisianabayous, Florida, and most of the world’s river deltas) would be drowned.Most of the world’s population lives in coastal cities such as New York, Boston,Philadelphia, Baltimore, Washington, D.C., Miami, Shanghai, and London. All ofthose cities would be partially or completely under water with such a sea levelrise. If all the glacial ice caps melted completely (as they have several times before
during past greenhouse episodes in the geologic past), sea level would rise by 65m (215 feet)! The entire Mississippi Valley would flood, so you could dock yourboat in Cairo, Illinois. Such a sea level rise would drown nearly every coastalregion under hundreds of feet of water, and inundate New York City, London andParis. All that would remain would be the tall landmarks, such as the EmpireState Building, Big Ben, and the Eiffel Tower. You could tie your boats to thesepinnacles, but the rest of these drowned cities would be deep under water.Climate Deniers’ Arguments and Scientists’ RebuttalsDespite the overwhelming evidence there are many people who remain skeptical. Onereason is that they have been fed lies, distortions, and misstatements by the globalwarming denialists who want to cloud or confuse the issue. Let’s examine some of theseclaims in detail: “It’s just natural climatic variability.” No, it is not. As I detailed in my 2009book, Greenhouse of the Dinosaurs, geologists and paleoclimatologists know a lotabout past greenhouse worlds, and the icehouse planet that has existed for thepast 33 million years. We have a good understanding of how and why theAntarctic ice sheet first appeared at that time, and how the Arctic froze over about3.5 million years ago, beginning the 24 glacial and interglacial episodes of the “IceAges” that have occurred since then. We know how variations in the earth’s orbit(the Milankovitch cycles) controls the amount of solar radiation the earthreceives, triggering the shifts between glacial and interglacial periods. Our currentwarm interglacial has already lasted 10,000 years, the duration of most previousinterglacials, so if it were not for global warming, we would be headed into thenext glacial in the next 1000 years or so. Instead, our pumping greenhouse gasesinto our atmosphere after they were long trapped in the earth’s crust has pushedthe planet into a “super-interglacial,” already warmer than any previous warmingperiod. We can see the “big picture” of climate variability most clearly in theEPICA cores from Antarctica (see Figure 2 below), which show the details of thelast 650,000 years of glacial-interglacial cycles. At no time during any previousinterglacial did the carbon dioxide levels exceed 300 ppm, even at their verywarmest. Our atmospheric carbon dioxide levels are already close to 400 ppmtoday. The atmosphere is headed to 600 ppm within a few decades, even if westopped releasing greenhouse gases immediately. This is decidedly not within thenormal range of “climatic variability,” but clearly unprecedented in humanhistory. Anyone who says this is “normal variability” has never seen the hugeamount of paleoclimatic data that show otherwise.
Figure 2. The climate record from EPICA core from Antartica. It shows the normal range of climate variabilityover the past 650,000 years (450,000 years shown here) and the last 6 glacial-interglacial cycles. At no point in anyprevious interglacial was the carbon dioxide level higher than 300 ppm, or the temperatures so high, yet we arealmost to 400 ppm today. This is ironclad evidence that our present episode of warming is not “normal fluctuations.” “It’s just another warming episode, like the Mediaeval Warm Period,or the Holocene Climatic Optimum” or the end of the Little IceAge.” Untrue. There were numerous small fluctuations of warming and coolingover the last 10,000 years of the Holocene. But in the case of the Mediaeval WarmPeriod (about 950–1250 A.D.), the temperatures increased by only 1 C, much lessthan we have seen in the current episode of global warming (see Figure 1). Thisepisode was also only a local warming in the North Atlantic and northern Europe.Global temperatures over this interval did not warm at all, and actually cooled bymore than 1 C. Likewise, the warmest period of the last 10,000 years was theHolocene Climatic Optimum (5000–9000 B.C.) when warmer and wetterconditions in Eurasia caused the rise of the first great civilizations in Egypt,Mesopotamia, the Indus Valley, and China. This was largely a NorthernHemisphere-Eurasian phenomenon, with 2–3 C warming in the Arctic andnorthern Europe. But there was almost no warming in the tropics, and cooling orno change in the Southern Hemisphere.7 To the Eurocentric world, thesewarming events seemed important, but on a global scale the effect is negligible. Inaddition, neither of these warming episodes is related to increasing greenhousegases. The Holocene Climatic Optimum, in fact, is predicted by the Milankovitchcycles, since at that time the axial tilt of the earth was 24 , its steepest value,meaning the Northern Hemisphere got more solar radiation than normal—butthe Southern Hemisphere less, so the two balanced. By contrast, not only is thewarming observed in the last 200 years much greater than during these previousepisodes, but it is also global and bipolar, so it is not a purely local effect. Thewarming that ended the Little Ice Age (from the mid-1700s to the late 1800s) wasdue to increased solar radiation prior to 1940. Since 1940, however, the amount
of solar radiation has been dropping, so the only candidate for the post-1940warming has to be carbon dioxide.8 “It’s just the sun, or cosmic rays, or volcanic activity ormethane.” Nope, sorry. The amount of heat that the sun provides has beendecreasing since 19409, just the opposite of the denialists’ claims. There is noevidence (see Figure 3 below) of increase in cosmic radiation during the pastcentury.10 Nor is there any clear evidence that large-scale volcanic events (such asthe 1815 eruption of Tambora in Indonesia, which changed global climate forabout a year) have any long-term effect that would explain 200 years of warmingand carbon dioxide increase. Volcanoes erupt only 0.3 billion tonnes of carbondioxide each year, but humans emit over 29 billion tonnes a year11, roughly 100times as much. Clearly, we have a bigger effect. Methane is a more powerfulgreenhouse gas, but there is 200 times more carbon dioxide than methane, socarbon dioxide is still the most important agent.12 Every other alternative hasbeen looked at, but the only clear-cut relationship is between human-causedcarbon dioxide increase and global warming.Figure 3. Plot of solar energy input to the earth versus temperature of the last century. The two tend to trackeach other until the last 30 years, at which time the earth warmed dramatically even as solar input went down.
Figure 4a. The plot of global mean temperature over the past century, showing the yearly data (solid black lines)and the smoothed curve using a 5-year rolling average (blue line). Clearly, the trend has been dramatically increasing,and individual data points from one year do not tell the whole story. The anomalous El Niño warm year of 1998 is oneof those outliers.Figure 4b. A detailed plot of the past 20 years of global mean temperatures, showing how anomalous 1998 was.If you cherry-pick 1998 and the two years that followed it, it appears that climate is cooling. However, if you pick anytwo points other than 1998–2000, or any rolling average, it is clear that climate is warming. Indeed, most of the yearsfrom 2002 and on are as warm or warmer than 1998, so any claim that “it has been cooling since 1998” is a lie. Theshort-term cooling of the 2008 La Niña year can also be seen. “The climate records since 1995 (or 1998) show cooling.” That’s adeliberate deception. People who throw this argument out are cherry-picking thedata.13 Over the short term, there was a slight cooling trend from 1998–2000 (seeFigure 4 below), because 1998 was a record-breaking El Niño year, so the nextfew years look cooler by comparison. But since 2002, the overall long-term trendof warming is unequivocal. This statement is a clear-cut case of using out-ofcontext data in an attempt to deny reality. All of the 16 hottest years ever recordedon a global scale have occurred in the last 20 years. They are (in order of hottestfirst): 2010, 2009, 1998, 2005, 2003, 2002, 2004, 2006, 2007, 2001, 1997, 2008,1995, 1999, 1990, and 2000.14 In other words, every year since 2000 has been inthe Top Ten hottest years list, and the rest of the list includes 1995, 1997, 1998,1999, and 2000. Only 1996 failed to make the list (because of the short-termcooling mentioned already). “We had record snows in the winters of 2009–2010, and in 2010–2011.” So what? This is nothing more than the differencebetween weather (short-term seasonal changes) and climate (the long-termaverage of weather over decades and centuries and longer). Our local weathertells us nothing about another continent, or the global average; it is only a localeffect, determined by short-term atmospheric and oceanographic conditions.15 In
fact, warmer global temperatures mean more moisture in the atmosphere, whichincreases the intensity of normal winter snowstorms. In this particular case, theclimate denialists forget that the early winter of November–December 2009 wasactually very mild and warm, and then only later in January and February did itget cold and snow heavily. That warm spell in early winter helped bring moremoisture into the system, so that when cold weather occurred, the snows wereworse. In addition, the snows were unusually heavy only in North America; therest of the world had different weather, and the global climate was warmer thanaverage. And the summer of 2010 was the hottest on record, breaking theprevious record set in 2009. “Carbon dioxide is good for plants, so the world will be better off.” Whodo they think they’re kidding? The people who promote this idea clearly don’tknow much global geochemistry, or are trying to cynically take advantage of thefact that most people are ignorant of science. The Competitive EnterpriseInstitute (funded by oil and coal companies and conservative foundations16) hasrun a series of shockingly stupid ads concluding with the tag line “Carbon dioxide:they call it pollution, we call it life.” Anyone who knows the basic science ofearth’s atmosphere can spot the deceptions in this ad.17Sure, plants take in carbondioxide that animals exhale, as they have for millions of years. But the wholepoint of the global warming evidence (as shown from ice cores) is that the delicatenatural balance of carbon dioxide has been thrown out of whack by ourproduction of too much of it, way in excess of what plants or the oceans canhandle. As a consequence, the oceans are warming18 and absorbing excess carbondioxide making them more acidic. Already we are seeing a shocking decline incoral reefs (“bleaching”) and extinctions in many marine ecosystems that can’thandle too much of a good thing. Meanwhile, humans are busy cutting down hugeareas of temperate and tropical forests, which not only means there are fewerplants to absorb the gas, but the slash and burn practices are releasing morecarbon dioxide than plants can keep up with. There is much debate as to whetherincreased carbon dioxide might help agriculture in some parts
How We Know Global Warming is Real and Human Caused: BY DONALD R. PROTHERO CITED: PROTHERO, D, R, 2012, “How We Know Global Warming is Real and Human Caused ,” Sceptic
controversies. This article discusses amongst cause of global warming and consequences of global warming on the environment. Keywords:Global warming, Greenhouse gas, Global environment, Atmosphere. *Corresponding Author: Ranjana Bhatt, ranjanabhatt83@gmail.com INTRODUCTION Global warming is a very large area of scientific uncertainty.
Humans can't reduce global warming, even if it is happening. Humans could reduce global warming, but people aren't willing to change their behavior so we're not going to. Humans could reduce global warming, but it's unclear at this point whether we will do what's needed. Humans can reduce global warming, and we are going to do so successfully. 12.
talks about global warming. They say gasoline cars cause the problem and that the gasoline tax needs to be increased to stop it. Gee, you are so smart, Mol! Greenhouse gases such as CO2 and methane emitted from burning fossil fuels contribute a lot to global warming. Various measures are studied to cut those gases. The introduction of
caused global warming, worry about the threat, and support for several climate policies over the past 14 months. Global Warming Beliefs and Attitudes Most registered voters (74%) think global warming is happening, including 98% of liberal Democrats, 85% of moderate/conservative Democrats and 70% of liberal/moderate Republicans.
a primary factor in reducing their potential to affect global warming. This paper examines the calculated greenhouse effects of several one and two carbon halocarbons. Esti-mates of these effects will be quantified in terms of a relative potential to enhance global warming (halocarbons global warming potential or HGWP).
are contributing to global warming without quantifying the contribution) and quantified (e.g., humans are contributing more than 50% of global warming, consistent with the 2007 IPCC statement that most of the global warming since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations).
Global Warming Acceleration 14 December 2020 James Hansen and Makiko Sato Abstract. Record global temperature in 2020, despite a strong La Niña in recent months, reaffirms a global warming acceleration that is too large to be unforced noise - it implies an increased growth rate of the total global climate forcing and Earth's energy imbalance.
a paper animal. She tried over and over until she could finally fold a paper dog and wished that she could see Son just once more even though she knew that it was not possible. Looking at the paper dog she had made, she felt so weird that the paper dog seemed smiling at her. She felt that she would make more, many more animals out of paper. She collected all the papers in the house and started .
