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AN ATMOSPHERE ALLIANCE/ENERGY OUTREACH CENTER SPECIAL REPORT

SOURCE:“Global-scale temperature patterns and climate forcing over the past six centuries,” Michael E. Mann, et al., Nature, v392, April 23 1998.

Northern Hemisphere Temperature Trend 1400 - 1998

Global Warming Is Here:The Scientific Evidence

EXTRAORDINARY HEAT WAVES, enormous drought-driven forestfires, raging storms, torrential downpours and massive floods—A rising wave of extreme weather events is sweeping the planet.In the first 11 months of 1998, the world saw almost $90billion in weather-related damage, half-again more than theprevious record set just two years before and more economicdamage in a single year than in all the years of the 1980scombined.1 The most destructive year in weather historywas also the hottest since people began taking regularthermometer readings in 1860, and probably

by Patrick Mazza and Rhys Roth

2 ■■■■■ Global Warming Is Here: The Scientific Evidence

Extremeflooding

alongChina’sYangtze

River wasone ofmany

weatherdisasters

spawned inthe record-

breakingglobal heat

of 1998.

"The pattern, or fingerprint, ofhuman-caused climate change isdistinctly different from a natural

warming pattern."

Yangtze Riverstraddled by

many temporarylakes

TROPICALSTORMPENNY

TAIWAN

the hottest in 1,200 years.Has global warming finally caused the world’s

weather to go haywire? Some people continueto dismiss this notion, arguing that there is noreal scientific evidence that the planet is heat-ing up or that humans are causing it. Is scien-tific evidence really lacking or, like the debateover smoking and lung cancer, are opponentscloaking ideology and economic self-interest inoutdated science?

These are questions of paramount impor-tance for human well-being in the new cen-tury. The 1990s’ upsurge in extreme weather istruly impressive. Pictures of human tragediessuch as Hurricane Mitch move us. But under-lying the record-breaking weather are long-termtrends emerging from scientific data that pointto a real global warming, and to heat-trappingpollutants from human activities as a primarycause.

If true, the situation is dire. The heating ofthe planet underway now cannot be reversed.In fact, scientists expect the worldwide heat-ing-up to continue for decades or centuries af-ter the point that heat-trapping pollutants leveloff.2 How much more greenhouse gases will weaccept in the atmosphere, keeping in mind that,if we could snap our fingers and stop the emis-sions now, 20-50 percent of the human-causedwarming will still be “in the pipeline”?3

This report for public understanding sum-marizes the new findings of scientists, as re-ported in published scientific papers and offi-cial announcements, that shed light on thequestion of whether people have altered theglobal weather systems of our planet.

What We Know For SurePut aside this question of human impact onglobal climate for a moment. Three scientificfacts are beyond debate:

1. Without the natural presence of heat-trapping greenhouse gases in the atmospherethe Earth would be a frozen planet unableto sustain life as we know it.

2. But greenhouse gases are accumulatingbeyond natural levels in the atmosphere andhuman activities, in particular fossil fuelburning, are responsible.

3. The amount of two of the most importantgreenhouse gases, carbon dioxide andmethane, present in the atmosphere hasswelled significantly higher than at any timein at least 220,000 years.4

These facts lead to two central questions.How will this remarkable buildup of heat-trap-ping gases alter the Earth’s climate system overtime? And, our question in this report, are weseeing the early effects on weather and ecosys-tems today?

Humanity’s FingerprintOn The PlanetIn 1990, over 2,000 of the world’s top climatescientists working under the auspices of theUnited Nations-sponsored IntergovernmentalPanel on Climate Change (IPCC) concludedthat the surface of the Earth had warmed overthe last century. The evidence was not clearenough, however, to conclude that this global

warming was human-caused and not naturalin origin.

The evidence for a human role grew stron-ger in the next five years, and in 1995 the IPCCissued its second state-of-the-science report5,adopted by 157 national governments. It con-cluded that, “The balance of evidence suggestsa discernible human influence on global cli-mate.” This is one reason why Dr. Jane

Lubchenco, past president of the AmericanAcademy for the Advancement of Science, says,“In the last few decades, humans have becomea force of nature.”

The breakthrough in scientific consensus wasa product of improved scientific techniques,particularly “pattern-based” studies. This kindof research dusts the climate for human finger-prints by tracking temperature trends region-ally, seasonally, and at different levels of the at-mosphere. The pattern, or fingerprint, of hu-man-caused climate change is distinctly differ-ent from a natural warming pattern. For ex-ample, when the planet warms naturally due tochanges in the Sun’s intensity the entire atmo-sphere warms. But a buildup of greenhousegases will warm the lower atmosphere whilecooling the upper layers.

The IPCC carefully comparedreal-world observations with theexpected pattern of human-causedglobal warming. The scientistsfound a close enough match to con-clude that the “probability is verylow” that this is a coincidence.6

Since 1995 respected scientistshave announced a stunning seriesof new findings that dramaticallystrengthen the IPCC’s conclusionthat humans are probably changingthe climate.

One important piece of evidencecame even as government delegatesgathered in Geneva to officiallyadopt the IPCC 1995 report. An-other pattern-based study was pub-lished by 13 co-authors, includingseveral of the most respected scien-tists in the field. Employing an evenwider set of observations than theIPCC, the study made a yet stron-ger case that global warming due

Atmosphere Alliance/Energy Outreach Center ■■■■■ March 1999 ■■■■■ 3

The last century's10 warmestyears have alloccurred since1983, each ofthe past 20 yearshas beenwarmer than theglobal average,and 1998 wasprobably thehottest singleyear in at least1200 years.

"Each of the last 20 years has beenwarmer than the long-term

global average"

SOURCE:“1998 Global Surface

Temperature Smashes Record,"NASA Goddard Institute for Space Studies,

www.giss.nasa.gov/research/observe/surftemp/

GLOBAL TEMPERATURE TREND 1866-1998

average about 57°

to greenhouse pollution is already gripping theplanet.7 Neville Nicholls, the convening leadauthor of the 1995 IPCC report, said the newstudy “provides the clearest evidence yet thathumans may have affected global climate.”8

Jerry Mahlman, director of NOAA’s Geophysi-cal Fluid Dynamics Laboratory described it as“by far the closest (we’ve gotten) to a smokinggun.”9

Hot And Getting HotterCertainly, something is warming up the globe.1998 goes down as the hottest year on the booksby far, breaking the record set only in 1997.Every one of the 18 months leading up to Oc-tober 1998 was the warmest on record, a featso statistically improbable that John Topping,president of the Climate Institute, likens theodds to that of bowling 18 consecutive perfectgames. Each of the last 20 years has beenwarmer than the long-term global average and,with 1998 breaking the record, the century’s10 warmest years have all occurred since 1983,seven of those in this decade.10

Temperatures are up about 1.25 degrees Fahr-enheit (deg F) at the end of the century com-pared to the beginning.11 While that increasemight not seem like much, distributed acrossthe planet it represents a tremendous amountof energy. It is also a huge spike in tempera-ture. While temperatures vary greatly place toplace, day to day and hour to hour, the averagetemperature across the whole surface of theplanet remains remarkably stable year to year.When it goes up just a small fraction of a de-gree, as it has in many recent years, it sets arecord. That is why the warm surge measured in1998 - about a full degree F above the 1961-90average - both impresses and worries scientists -“This number’s amazing,” said climatologist PhilipJones of the University of East Anglia in England,one of the world’s leading climate data centers.12

The startling 1998 record punctuates a com-pelling long-term trend. “The rapid warmingof the past 25 years undercuts the argument ofgreenhouse skeptics, who have maintained thatmost of the global warming occurred early thiscentury while greenhouse gases were increas-ing more slowly - In fact, the fastest warming isoccurring just when it is expected,” accordingto NASA Goddard Institute of Space StudiesDirector James E. Hansen.13

Late in 1998, scientist Thomas Wigley of theNational Center for Atmospheric Research andtwo colleagues, published results of rigorous sta-tistical testing of the last 115 years of tempera-ture data. They tested the observed recordagainst computer models of the climate systemto examine if a cyclic increase in the Sun’s in-tensity could have caused the global warming,

rather than greenhouse gases from humans.They found that the climate would have to be sixtimes more sensitive to solar changes than is be-lieved realistic to account for the warming trend.“These results provide another important piecein the jigsaw puzzle of climate change, strength-ening further our confidence that there has beena discernible human influence on climate.”14

Hottest In CenturiesWorldwide thermometer readings go back toaround 1860. But how does the warming thiscentury fit a longer-term picture? A recent Na-tional Science Foundation (NSF) study recon-

structs a 600-year temperature history usingnatural records such as tree rings, ice-cores andcorals. The study finds that 1990, 1995, and1997 were hotter than “any other year back to1400... (at) roughly a 99.7% level of certainty.”15

NSF scientists found that small temperaturesswings in earlier centuries were linked tochanges in solar brightness and, to a lesser de-gree, major volcanic explosions. When it comesto the rising temperatures in the 20th century,the correlation with these natural phenomenais weak. Instead, scientists said, the warmingstrongly correlates to growing greenhouse gases.

Says Herman Zimmerman, program direc-tor of the National Science Foundation’s Divi-sion of Atmospheric Sciences: “This study addssolid information to the growing base of datawhich points to the warming of our planet byhuman-related activities. The balance of evi-dence now firmly supports an important hu-man influence on the global climate system.This is a serious problem for people everywhere,

and it needs to be addressed at all levels of gov-ernment.”16

A climate record for the Northern Hemi-sphere that stretches back twice as long has beenpieced together by a team led by NOAA chiefpaleoclimatologist Jonathan Overpeck, using avariety of natural records and historical docu-ments. Their study concludes that the 20th cen-tury is the hottest in 12 centuries, and that 1998is probably the Warmest year in the last 1200.

Significantly, Overpeck’s research shows thatthe “Medieval Warm Period” extending fromaround 1,000 to 600 years ago, was not a pe-riod of global warmth as previously thought.The warmth was limited to northern Europeand North America. “Our study of the Medi-eval Warm Period supports the likelihood thatno known natural phenomenon can explain therecord 20th century warmth,” Overpeck said.“Twentieth Century global warming is a realityand should be taken seriously.”17

This conclusion is reinforced by a completelyindependent line of evidence in which scien-tists looked at temperature readings gleanedfrom the soil at 358 sites in eastern NorthAmerica, central Europe, southern Africa andAustralia. Temperature changes at the Earth’ssurface migrate down into the soil, providing arecord of long-term temperature trends that sci-entists recover and analyze. The soil record onthese four continents show temperatures haveclimbed about 1.8 deg F in the last 500 years -with nearly 1 deg F of that in the 20th centuryalone. That rate of warming is “well in excessof temperature trends of earlier centuries,” ac-cording to the scientists.18

Satellite Data Now ShowsSignificant WarmingA primary argument of those skeptical that glo-bal warming is underway has been that, whilesurface-based and balloon-borne instrumentsshow clear warming trends, satellite readingswith better global coverage contradict them,

4 ■■■■■ Global Warming Is Here: The Scientific Evidence

"The world's mountain glaciershave lost on average at least 60feet since 1961, and the rate at

which they are melting isincreasing."

Temperate and tropical mountain glaciers are in rapidretreat around the world.

ated toward space by the Earth. In contrast, inits upper reaches the atmosphere is expected tocool as greenhouse gases slow the flow of out-going heat.

Again, observations are reinforcing the glo-bal warming predictions. The IPCC reportedin 1995 that the stratosphere cooled rapidly inthe 15 years previous, by about 1.1 deg F.21

Further up, in the upper stratosphere and me-sosphere (18-37 miles up), a new study found“significant cooling” of 3 deg F per decade be-tween 1962 and 1991.22 Further still, research-ers recently found cooling throughout the me-sosphere and thermosphere regions (30-280miles up), even greater than predicted by green-house models.23

Deep in the ocean, there is also ominous evi-dence that suggests that excess heat may be fill-ing the deep ocean, which will continue towarm the atmosphere for decades or centuriesafter greenhouse gas levels stabilize. Measure-ments taken in 1957, 1981 and 1992 on trans-Atlantic voyages along 24 degrees N latitudeshow “the waters between 800 and 2,500 metersin depth have consistently warmed over the past35 years and...(the warming) is remarkablyuniform across the east-west extent of the NorthAtlantic.”24

Planet Warms, Glaciers ShrinkIn 1992, the IPCC was already reporting aworldwide mountain glacier retreat that “...isamong the clearest and best evidence for achange in energy balance at the Earth’s surfacesince the end of the last century. It providessufficient support...to show that global warm-ing has indeed occurred over the last century.”25

In 1998, glaciologists at the University ofColorado at Boulder reported that the world’smountain glaciers have lost on average at least60 feet since 1961, and the rate at which theyare melting is increasing. “In the last century,there has been a significant decrease in the areaand volume of glaciers, especially at middle andlow latitudes,” said Professor Emeritus MarkMeier of the geological sciences department.“The disappearance of glacier ice is more pro-nounced than we previously had thought.”26

The University of Colorado survey showssmaller, low-latitude glaciers seem to be takingthe biggest hit. The largest glacier on Africa’sMount Kenya lost 92 percent of its mass in thelast century and Mount Kilimanjaro glaciershave shrunk by 73 percent in that time period.Spain had 27 glaciers in 1980. That numberhas dropped to 13.

The retreat of mountain ice in tropical andsubtropical latitudes is proceeding at “a phe-nomenal rate,” confirm scientists at Ohio StateUniversity’s Byrd Polar Research Center, pro-

showing instead slight cooling from 1979 to1995 at about 5.5 miles in altitude. Satelliteexperts corrected a critical discrepancy in 1998,however. They found that drag from the atmo-sphere has caused satellites to drop into lowerorbits since they were launched in 1979, dis-

torting their readings. When corrected, the sat-ellite data actually show a warming trend of .13deg F per decade, which is consistent with sur-face-based measurements.19

”The supposed tropospheric cooling derivedfrom satellites was the strongest argument ofthe greenhouse skeptics,” said study lead au-thor Frank Wentz of Remote Sensing Systemsin Santa Rosa, Calif. “Now that we understandthe orbit decay correction, there is an evenstronger consensus that global warming is in-deed a reality.”20

Looking At The LayersGreenhouse gases raise the temperature at thesurface and lower atmosphere of the planet bytrapping some of the heat absorbed and reradi-

viding “some of the most compelling evidenceyet for recent global warming.” For example,the Qori Kalis glacier in the Peruvian Andesretreated 13 feet each year between 1963 and1978. By 1995, the annual rate of retreat was99 feet.27 Since 1970 the freezing level in theEarth’s atmosphere has been rising nearly 15feet each year.28

One of the scientists, Ellen Mosley Thomp-son, told the 1997 annual meeting of the Asso-ciation of American Geographers that thechanges to tropical and subtropical glaciers “aretaking place in water stressed areas already hav-ing problems feeding their people, and wherelarge population increases are expected.”29

Middle latitude glaciers are also showing sig-nificant shrinking. Both the European Alps andCaucasus Mountains have lost half their ice inthe past century. New Zealand glaciers haveshrunk about 26 percent since 1890. In the TienShan Mountain Range bordering China andRussia, 22 percent of the ice volume from thethousands of glaciers there has disappeared inthe past 40 years.30

”The rate of warming is unprecedented inthe last 600 years and the retreat of glaciers isprobably unprecedented, too, although we donot have the figures to prove it,” Mark Meiersaid . “But I’m convinced there is a detectablehuman influence in the pattern of climatechange we are seeing.” 31

The Sea Is Rising,Ice Shelves Are MeltingGlobal warming causes the level of the oceanto rise in two ways: by unlocking vast amountsof water from melting glaciers around the world,and because warmer waters expand. Records ofsea level drawn from around the world showthat the sea has risen by between 4 and 10inches in the last century, according to theIPCC, and “it is likely that much of the rise insea level has been related to the concurrent risein global temperature.”32

Scientists also predict that global warmingwill be greatest in the polar regions. A study ofthe Arctic shows that temperatures in the farNorth have climbed 2.7 deg F in the 20th cen-tury, significantly more than the planet as awhole, to levels warmer than any other time inat least the past 400 years. The effects are be-ing seen in “the widespread retreat of glaciersthroughout the Arctic in the last century,” themelting of permafrost and sea ice, and alter-ation of ecosystems, according to the reportauthored by a team of 18 scientists.33

At the opposite end of the world, warmingaround Antarctica is showing up in the decreas-ing amount of sea ice - This is ice that formsseasonally in the open ocean near the conti-

Atmosphere Alliance/Energy Outreach Center ■■■■■ March 1999 ■■■■■ 5

nent. In the middle of the century, extensiveice formed around the Antarctic Peninsula 4winters out of every 5. Since the 1970s thathas dropped to 1 or 2 winters out of 5.34 Scien-tists with the British Antarctic Survey haveuncovered another piece of evidence. Theyfound that with temperatures up about 4.5 degF since 1945 several of the Peninsula’s iceshelves, giant year-round lips of ice attached tothe continent but stretching into the sea, havebeen in dramatic retreat.35

What takes place on this Peninsula is par-ticularly significant - as the northernmost pointof the South Polar continent, it is most vulner-able to any warming trends. With the warmingnow taking place, its ice shelves are increasinglyprone to sudden disintegration. The Larsen Aice shelf, after years of slowly melting away,suddenly broke apart during a January 1995storm. “The speed of the final breakup was un-precedented, and followed several of the warm-est summers on record for this portion of theAntarctic,” said Ted Scambos of the Coopera-tive Institute for Research in EnvironmentalSciences, a joint institute of NOAA and theUniversity of Colorado.

A chunk of ice three times larger than Man-hattan Island broke off the Larsen B ice shelf inFebruary 1998. Two-thirds of Larsen B nowthreatens to dissolve. Scambos points out that,“The total size of the Larsen B Ice Shelf is morethan all the previous ice that has been lost fromAntarctic ice sheets in the past two decades.”36

A new study of ice shelf stability concluded thatfor Larsen B, “unless the situation changes dra-matically and ice-front retreat ceases almost im-mediately, it seems fairly certain that anotherice shelf will disappear, perhaps even this cen-tury.”37

Thawing PermafrostAlaska, most of which is cov-ered by permafrost - perma-nently frozen soil - is watchingroads and other human struc-tures collapse as permafrostmelts. Studies at the BonanzaLong-Term Ecological ResearchSite show that the layer of soilthat thaws each warm season ispenetrating deeper in recentyears. The permafrost that re-mains is warming to within afew-tenths of a degree of themelting point.38

Thawing of permafrost alsoraises concerns about releases ofgreenhouse gases that had beenlocked safely away in perma-nently frozen soil. Measure-

ments from northern Alaska in the early 1970sshowed tundra soils absorbing more CO

2 than

they released. Twenty years later, measurementsfrom the same region show tundra soils releas-ing more CO

2 than they absorbed.39

This is a crucial issue: the carbon now heldin the permafrost of the northern tundra equalsaround one-third of the total carbon floatingin the atmosphere, according to University ofMichigan biologist George W. Kling, who isworking on a National Science Foundationstudy of an 8,100-square-kilometer tundra onAlaska’s North Slope. “Our latest data show thatthe Arctic is no longer a strong sink for carbon.In some years, the tundra is adding as muchor more carbon to the atmosphere than itremoves. The concern is what will happen inthe future as global warming increases andmelting permafrost exposes more of this bur-ied carbon to be respired and released into theatmosphere.” 40 The frightening prospect is thatthe buildup of heat-trapping gases could accel-erate even if human emissions are stabilized.

Water Cycle “Intensification”The IPCC states that global warming “willlead to an intensification of the global hy-drological cycle.”41 This means that a warmeratmosphere will cause more evaporation glo-bally (over 2/3rds of the Earth’s surface isocean). More water and energy in the aircould translate into more deluges and flood-ing, while drier conti-nental interiors see sum-mertime soil evaporationintensify, worseningdroughts.

More water in the air may also mean an over-all increase in the cloudiness of the world. Howglobal warming will affect cloudiness and howcloudiness will in turn affect global warmingremains one of the key areas of uncertainty inclimate science. A 1997 study, however, doesreport strong evidence that cumulonimbus,nimbostratus and cirriform clouds increased sig-nificantly over Australia, Europe and the UnitedStates between 1951 and 1981. The research-ers conclude that the increase in thick, precipi-tation-prone clouds is “likely to be related” tothe human-caused increase in greenhousegases.42

Larsen Ice Shelf

The Antarctic Penisula haswarmed by 4.5 deg F since

1940 causing the disintegrationof the "Larsen A" ice shelf in1995. The satellite photos

show before and after a majoriceberg broke away during the

disintegration of Larsen A.

photoarea

9-Jan-95

12-Feb-95

6 ■■■■■ Global Warming Is Here: The Scientific Evidence

"Thawing of permafrost also raisesconcerns about releases of

greenhouse gases that had beenlocked safely away in permanently

frozen soils."

"Off the California coast,populations of zooplankton, the

tiny plant-eaters at the base of themarine food chain, dropped 70percent after a dramatic shift towarmer waters suppressed theupwelling of cool, nutrient-rich

waters."

If the world is heating up and gettingcloudier, nighttime temperatures should risefaster than daytime temperatures. That is be-cause cloud cover holds in heat after the sungoes down. Heat that normally escapes to spaceat night is contained, raising overnight tem-

peratures. Nighttime warming then is a signifi-cant indicator of global warming.

Nighttime temperatures are in fact going upmore than twice as fast as daytime tempera-tures, according to the largest study ever of sur-face temperatures. In it, a team of researchersled by David Easterling of NOAA’ s NationalClimatic Data Center surveyed 5,400 stationsthat monitor 54 percent of the planet’s land area.Between 1950 and 1993, daytime temperaturesclimbed at a rate of about 1.5 deg F per cen-tury, while nights warmed at about 3.2 deg Fper century.43

Another recent study found that extremesummer heatwaves are up sharply in the U.S.,with the biggest increases coming at night. Andhumidity, increasing several percent a decade,is making a growing contribution. NOAA sci-entists Dian Gaffen and Rebecca Ross used theheat threshold at which, according to earlierstudies, deaths increase sharply. The two scien-tists examined temperature and humidity recordsfrom 113 weather stations and found three-day-or-longer stretches of such killer heat increased88 percent in the U.S. between 1949 and 1995.“Extremes of summertime heat have a greaterimpact on human health than any other severeweather in the United States,” they noted.

More Extremes In 1996, the National Climatic Data Center,a division of NOAA, published findings of anew analysis technique that showed weather inthe U.S. has been growing more extreme.44

They scrutinized records for the last 80 yearsto track summer droughts, drenching rain-storms, wet winters and other types of wildweather events that are expected to increase ina greenhouse-heated world. They discoveredthat since the late 1970s, the climate has beenstuck in greenhouse-mode, with more weatherextremes. Statistical analysis showed only a 5%probability, in other words 1-in-20 odds, thatthe surge in extreme weather is a natural fluc-

tuation within a stable climate. NCDC re-searcher Tom Karl told the New York Times, “Iwould say the climate is responding to green-house gases.”

A new study45 looks at the percentage of theglobe that experienced severe drought or ex-treme rainfall from 1900 to 1995. The num-bers vary quite a bit through time, but the re-searchers identified “a distinctive change in char-acter” beginning around 1980. Droughts are com-ing more frequently in sections of the UnitedStates, Europe, Africa and Asia, while parts of theU.S. and Europe have become much wetter.

Particularly implicated in drying or drench-ing more parts of the planet is El Niño. ThePacific Ocean warming changes the pattern ofthe jet stream as it curls around the Earth. Thisreshapes the flow of clouds and moisture. Overthe past 20 years, El Niño has come more of-ten, and with record intensity. A statisticalanalysis of the data by Kevin Trenberth andTimothy Hoar, veteran El Niño researchers withthe National Center for Atmospheric Research,concluded that the odds against this happen-ing solely due to natural causes are 2,000 toone.46 “The main thing we can point to is glo-bal warming,” Trenberth says. “I think El Niñosare being changed by global warming.”47

A computer modeling study by NOAA/Geo-physical Fluid Dynamics Laboratory addsweight to that conclusion. Scientists determinedthat warming in the tropical Pacific Ocean isunlikely to be purely a product of natural cycles.“Instead, it is likely that a sustained thermalforcing, such as the increase in greenhouse gasesin the atmosphere, has been at least partly re-sponsible for the observed warming.”48 Climateis one of the basic factors that shape how wellplants and animals can survive in particular lo-cations. Scientists are beginning to documentsome profound effects that the changing cli-mate is apparently causing in plant and animalpopulations.

Plants Affected Over“Huge Spatial Scale”A study of the Earth’s annual carbon cycle maybe the first evidence climate change is affecting“the growth of plants on a huge spatial scale,”Pieter Tans of NOAA said. “This is quite sig-nificant.”

Every spring plants across the northern hemi-sphere soak up CO

2 from the atmosphere as

they grow, enough to cause CO2 levels to drop

measurably. In winter, decaying plants and soilsrelease CO

2 back into the atmosphere, so CO

2

levels “see-saw” back up. Charles D. Keelingof the Scripps Institution of Oceanography andkeeper of the world’s most important recordsof atmospheric carbon dioxide levels, found that

since 1964 the see-saw has been swinging morewildly in each direction - 20 percent more overHawaii and 40 percent more over the Arctic.And spring is arriving earlier. The yearly dropin CO

2 as plants start spring growth is now a

week earlier than it was 30 years ago.49

Keeling’s data show the Earth is, in a sense,breathing harder, like a person does when theybecome physically stressed. “I think we shouldfocus on the fact that the plants are being in-fluenced by the climate in a way that might beunprecedented,” Keeling told the San FranciscoChronicle.50

Plant Species Climb Warming AlpsPlant species are migrating to higher elevationsin the Swiss and Austrian Alps, where tempera-tures have climbed 1.25 degrees F this century.University of Vienna scientists collected dataon vascular plant species at high elevations inthe middle Alps and compared the modern datawith detailed historical records from early inthe century. They concluded that “there is nodoubt that even moderate warming inducesmigration processes, and that this process isunder way...global warming is already having asignificant impact on plant ecology.”51

Alaska’s Dying ForestsIn forests on Alaska’s south central coast, coolsummers and cold winters normally keep thespruce bark beetle under control. But tempera-tures there are up 3 deg F this century. Andspruce bark beetles have been running wild,killing most trees over a three-million-acre area.This is one of the largest insect-caused forestdeaths in North American history. Over inSoutheast Alaska forests have also experiencedinsect infestations, and are endangered byblowdown from the doubling in days with gale-force winds since 1950.52

Atmosphere Alliance/Energy Outreach Center ■■■■■ March 1999 ■■■■■ 7

Over its hugerange, fromMexico toCanada, theEdith'scheckerspotbutterfly hasresponded towarmingtemperatures byshifting its habitatnorthward.

Migratory Range ShiftsFor Entire SpeciesCamille Parmesan, a scientist at the Universityof California at Santa Barbara, surveyed therange of the Edith’s checkerspot butterfly andfound, “the clearest indication to date that glo-bal climate warming is already influencing spe-cies’ distributions.” The butterfly, which inhab-its North America’s West Coast, has shifted no-ticeably northward in response to warmer tem-peratures. Parmesan’s study was a breakthroughbecause it was the first to look at the entiremigratory

Species DevastatedBy Coastal WarmingUsing temperature records kept since 1916,Scripps Institution of Oceanography scientistsdetected a dramatic shift in 1977 to warmer,lower-nutrient waters along North America’swest coast. This warming has continued to thepresent. Simultaneously, populations of zoop-lankton, the microscopic plant-eaters that areat the base of the marine food chain, dropped70 percent because warmer waters suppressedthe upwelling of colder, nutrient-rich currents.The effect on higher animals has been cata-strophic. Ocean seabirds in the Southern Cali-fornia Bight have declined 90% since countsbegan in 1987. The long-term decline in com-mercial catch of ocean fish accelerated after theshift in ocean conditions. The health of kelpforests, critical habitat in coastal ecosystems hasalso been badly affected: they “are now system-atically smaller and depauperate”, biologicallyimpoverished in other words, according to thescientists.54

”Profound Change”In Monterey BayScientists at the Monterey Bay Aquarium Re-search Institute in the mid-90s returned to onestretch of the bay’s rocky intertidal beach thatwas surveyed in the 1930s. They wanted to seewhat had happened to populations of 45 spe-cies of limpets, barnacles, anemones, chitonsand sea stars. They found “profound change incommunity structure”. Over the past 60 yearsshoreline water has grown an average of 1 degF warmer, with summertime highs up by 4 degF. Eight out of nine species that favor warmerwaters to the south grew more abundant at thesite. Five out of eight that favor cooler habitatto the north declined. In all, the habitat of 32species was altered.55

Conclusion A sober and dispassionate assessment of theevidence emerging from a wide range of scien-tific disciplines leads to a compelling conclu-

sion: Global warming is here now and human-ity is driving the warming. The reality of glo-bal warming is a clear and present danger toglobal security and the well-being of billions ofpeople across the planet. The accelerated ex-tinction of species and the obliteration by therising sea of entire low-lying nations, as well asimmense social and economic disruption to thelives of virtually all nations, are in prospect.

The global climate crisis is as grave as anymilitary threat we have ever faced, and mustdraw a similar response. As we typically do whendrawn into military battle, we must mobilize amassive outpouring of resources against globalwarming - money, technology and human en-ergy - and strategically deploy them for maxi-mum effect. Only through a rapid transitionfrom fossil fuels to clean energy sources, andpreservation and restoration of the world’s for-ests, can we stop the buildup of greenhousegases that imperils us all.

Writing recently in the esteemed science jour-nal Nature56, 11 scientists examined the rate atwhich carbon-free energy sources must comeon line to stabilize the atmosphere in the 21stcentury at various carbon dioxide (CO

2) con-

centrations. For stabilization to happen, theynote, fossil fuels must be reduced at the sametime world energy use expands rapidly as richeconomies grow and developing countries in-dustrialize. Total primary energy use is expectedto double from about 10 terawatts (TW) in1990 to 20 TW by around 2020.

Stabilizing the CO2 level in the atmosphere

at current levels or less seems a prudent objec-tive, given that economic damages from globalwarming appear to be quite serious already, andthe heat will continue climbing after greenhousepollution levels off. To do so, the scientists esti-mate that we will need to supply about half ofour energy from carbon-free sources in 20 years,the equivalent of total world energy use in 1990,and virtually the entire 30 TW energy use ex-pected by 2050.

”This past century,” the scientists wrote, “ac-celerated technology development from wartimeand postwar research produced commercialaviation, radar, computer chips, lasers and theInternet, among other things. Researching, de-veloping and commercializing carbon-free pri-mary power technologies capable of 10-30terrawatts by the mid-21st century could re-quire efforts, perhaps international, pursuedwith the urgency of the Manhattan Project orthe Apollo space program... the potentially ad-verse effect of humanity on the Earth’s climatecould well stimulate new industries in the 21stcentury, as did the Second World War and the‘cold war’ in this century.”

All people stand to benefit from putting oursocieties and economies on an ecologicallysound footing. All stand to lose if we do not.Perhaps the greatest challenge in the history ofcivilization, the global climate crisis calls uponus to act—decisively and without delay. ■

The authors wish to thank Tony Haske for in-valuable research assistance and the scientists whoreviewed the paper for accuracy, especially Dr.Richard Gammon, atmospheric scientist at theUniversity of Washington, Dr. Jim Kerstetter, ChiefScientist at Washington State University’s EnergyProgram, and Dr. Daniel Lashof, senior scientistat the Natural Resources Defense Council.

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2 Climate Change 1995 -The Science of Climate Change, Contri-bution of Working Group I to the Second Assessment Report ofthe Intergovernmental Panel on Climate Change. CambridgeUniversity Press, p325.

3 IPCC First Assessment Report: Overview and Policymaker Summary,Intergovernmental Panel on Climate Change, August 1990, p30.

4 Nature, v364, July 29 1993. p.407-11.

5 Climate Change 1995 -The Science of Climate Change.

6 Climate Change 1995 - The Science of Climate Change, p37.

8 ■ ■ ■ ■ ■ Global Warming Is Here: The Scientific Evidence ■■■■■ MARCH 1999

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11 “1998 Global Surface Temperature - Highest by a WideMargin According to WMO Annual Statement on the GlobalClimate,” World Meteorological Organization.

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