climate change—another perspective

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He’s not an NMU alumnus, but for many of you who attended NMU in the past few decades, TV6 meteorologist Karl Bohnak has been the voice of U.P. weather. Visit www.upweatherhistory.com to learn more. am often asked what I think about “Global Warming.” It is an issue that ignites passion in many of us because it has crossed over from the scientific into the political realm. As a weather observer, forecaster and communicator, I have a point of view I would like to share. To start, let us examine the current warming trend we have experienced over the last few decades. To put this trend into perspective, I turn to a friend and colleague, Jon Davis. He is a Chicago-based meteor- ologist, forecasting for energy concerns and commodities. He has been watching global weather patterns for decades. “There is no question we have been in a warming trend for the last 50 years,” states Davis. “It kind of started in the fifties, then you cooled a little bit in the sixties and parts of the seventies, then you’ve really warmed up from that point on. Unquestionably, we’ve warmed, and not only here, but everywhere.” Davis uses this information when putting together a seasonal forecast. He catalogs the variables that he and his team feel will be keys in driving the weather over the sea- son in question. One of the variables he now uses regularly is what fore- casters call “trend.” In this case, it is the warming trend over the last half century. “You have to add that warming component into a seasonal forecast,” he explains. “If we think all the variables equal each other out, then trend would point us in the warm direction.” As to why we are warming, that question crosses the line into our greatest climate debate. “I don’t think there is any question that human activity has caused some of the warming,” says Davis. The data is so overwhelming.” But this does not answer the question to his satisfac- tion. Natural factors are responsible for the warming, too. “Over the last 10 years, there’s been really sparse volcanic activity,” he explains. “Simply put, the earth’s greatest polluters—volcanoes—have been relatively quiet for some time now. “If you look at aerosol projection globally [the material volcanoes throw into the atmosphere], they’re about as low as they’ve ever been,” he explains. Volcano debris, pushed high into the atmosphere, interacts chemically with certain gases, blocking sunlight, which results in global cooling. Davis also says the ocean has put more warmth into the atmosphere over the last quarter-century or so. “We’ve trended to an environment with more El Nino events [the warming of the equatorial eastern Pacific]. That means more warmth over the long haul.” When asked what he believes is the most important factor in this warming, he states candidly, “I have no idea. That’s a question that nobody can answer. Is this human factor 10 percent of the equation’s influence or is it seventy?” If you pay attention to the news, it would appear that man’s activities are the main—possibly the only— catalyst in this warming and that the planet will continue to warm with catastrophic consequences. Further, those legitimate scientists with studies countering these claims are marginal- ized and placed in the category of “deniers” or “industry shills.” This aspect of the global warming debate is what riles me up the most— there seems to be no willingness to debate. How often have you heard or read, “The science is settled.” As one who has been an observer of the atmosphere for most of my profession- al life, this statement is absurd. There are many aspects of the interaction between the oceans and the atmos- phere as well as the sun and the atmos- phere that are poorly understood. perspective Climate Change—Another Perspective By Karl Bohnak I Atlantic (AMO) and Pacific (PDO) ocean temperature cylces compared to a running mean of U.S. temperatures. Courtesy of ICECAP

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Page 1: Climate Change—Another Perspective

He’s not an NMU alumnus, but formany of you who attended NMU inthe past few decades, TV6 meteorologistKarl Bohnak has been the voice of U.P.weather. Visit www.upweatherhistory.comto learn more.

am often asked what I think about“Global Warming.” It is an issue

that ignites passion in many of usbecause it has crossed over from thescientific into the political realm. Asa weather observer, forecaster andcommunicator, I have a point of viewI would like to share.

To start, let us examine thecurrent warming trend we haveexperienced over the last few decades.To put this trend into perspective, Iturn to a friend and colleague, JonDavis. He is a Chicago-based meteor-ologist, forecasting for energyconcerns and commodities. He hasbeen watching global weatherpatterns for decades. “There is noquestion we have been in a warmingtrend for the last 50 years,” statesDavis. “It kind of started in thefifties, then you cooled a little bit inthe sixties and parts of the seventies,then you’ve really warmed up fromthat point on. Unquestionably, we’vewarmed, and not only here, buteverywhere.”

Davis uses this informationwhen putting together a seasonalforecast. He catalogs the variablesthat he and his team feel will be keysin driving the weather over the sea-son in question. One of the variableshe now uses regularly is what fore-casters call “trend.” In this case, it isthe warming trend over the last halfcentury. “You have to add thatwarming component into a seasonal

forecast,” he explains. “If we think allthe variables equal each other out,then trend would point us in thewarm direction.”

As to why we are warming, thatquestion crosses the line into ourgreatest climate debate. “I don’t thinkthere is any question that humanactivity has caused some of thewarming,” says Davis. The data is sooverwhelming.” But this does notanswer the question to his satisfac-tion. Natural factors are responsiblefor the warming, too. “Over the last10 years, there’s been really sparsevolcanic activity,” he explains.“Simply put, the earth’s greatestpolluters—volcanoes—have beenrelatively quiet for some time now.“If you look at aerosol projectionglobally [the material volcanoesthrow into the atmosphere], they’reabout as low asthey’ve ever been,”he explains.Volcano debris,pushed high intothe atmosphere,interacts chemicallywith certain gases,blocking sunlight,which results inglobal cooling.Davis also says theocean has putmore warmth intothe atmosphereover the lastquarter-century or so. “We’ve trendedto an environment with more ElNino events [the warming of theequatorial eastern Pacific]. Thatmeans more warmth over the longhaul.”

When asked what he believes is

the most important factor in thiswarming, he states candidly, “I haveno idea. That’s a question thatnobody can answer. Is this humanfactor 10 percent of the equation’sinfluence or is it seventy?”

If you pay attention to the news, itwould appear that man’s activities arethe main—possibly the only—catalyst in this warming and that theplanet will continue to warm withcatastrophic consequences. Further,those legitimate scientists with studiescountering these claims are marginal-ized and placed in the category of“deniers” or “industry shills.”

This aspect of the global warmingdebate is what riles me up the most—there seems to be no willingness todebate. How often have you heard orread, “The science is settled.” As one

who has been an observer of theatmosphere for most of my profession-al life, this statement is absurd. Thereare many aspects of the interactionbetween the oceans and the atmos-phere as well as the sun and the atmos-phere that are poorly understood.

perspectiveClimate Change—Another Perspective

By Kar l Bohnak

I

Atlantic (AMO) and Pacific (PDO) ocean temperature cylcescompared to a running mean of U.S. temperatures.

Cour

tesy

of

ICEC

AP

Page 2: Climate Change—Another Perspective

Another statement you will hearis, “The warming we are experiencingis outside of the realm of naturalclimate variability.” I personally donot agree with this statement. Forexample, there is evidence to showthat the North Atlantic has been aswarm as it is now in the recent past.Godthab Nuuk, a village on thesoutheastern coast of Greenland, wasjust as warm or warmer as recently as1940. This warming appears to berelated to a recently discoveredtemperature cycle of the AtlanticOcean called the Atlantic Multi-decadal Oscillation, or AMO. TheNorth Atlantic was in a warm cycleof the AMO back in 1940. Around1995, the AMO “flipped” from thecold cycle (that it was in for roughly30 years starting in 1965) to thewarm cycle again. With this warm-ing, there was also an increase in hur-ricane activity beginning in 1995.Before this, there were a relativelysmall number of Atlantic storms cor-responding to the cold cycle of theAMO.

When a warm cycle of the AMOis combined with a warm cycle of thePacific (called the Pacific DecadalOscillation or PDO) good correlationis displayed with warm temperaturesin the United States (see figure atleft). This makes perfect sense. Righthere in Upper Michigan we knowhow much warmer it is near LakeSuperior in the fall than at pointsinland awayfrom the lake.That is becausewater holds thesummer heatlonger than theland. Now imag-ine two largebodies of wateron either side ofa relatively smallmass of land(compared to thesize of the oceanson either side) both in their warmcycles at the same time. The landmass would also be relatively warm.This happened in the 1930s and it

occurred again beginning in the ’90s.The Pacific is now undergoing asubstantial cooling with one of thestrongest La Ninas (cooling of theequatorial Pacific) on record, whilethe Atlantic is still warmer thanaverage (see satellite image above).

There is no doubt that carbon diox-ide (CO2) is increasing in the atmos-

phere and a good share of thisincrease is from human activity.However, CO2 is a small constituentof the “greenhouse” gases. Water

NOAA

sat

ellit

e de

rive

d da

ta

Carbon dioxide in parts per million, represented by the thin black line,graphed against U.S. temperature anamolies. (Courtesy of ICECAP)

Latest sea surface temperature anomaly. Note the colder than average water through most of the equatorial Pacific and along the WestCoast of the United States through the Gulf of Alaska, indicative of a La Nina and cold phase of the PDO.

Page 3: Climate Change—Another Perspective

vapor (H2O) is much more plentifuland we produce very little of the totalamount. When temperatures over thelast decade are graphed with CO2,correlation strength is very low (seegraph on previous page). Correlationdoes not necessarily mean causation,yet the global temperature patternsince the super El Nino of 1998 hasbeen flat even while CO2 continuesto increase. You can view correlationas circumstantial evidence. Thecircumstantial evidence for oceancycles playing a big part in ourwarming is much stronger than thatpresented by CO2.

Another factor in climate variabilitythat cannot be ignored is the role ofthe sun. Obviously, the sun affectstemperature based on the the move-ment of the earth in relation to it. Inaddition, the sun goes through aregular series of waxing and waningactivity. Astronomers have longknown of the sun’s 11-year sunspotcycle. During peaks in sunspot

activity, the sun is more active or“hotter.” The record also showsstrong evidence of longer-term cyclesof the sun. Nineteenth-centuryastronomers Sporer and Maunderconducted historical searches ofsunspot records and found an almostcomplete absence of sunspot activity

between about 1645 and 1715. Thisdearth of sunspots, called theMaunder Minimum, presents strongcircumstantial evidence for pro-nounced global cooling during thepeak of the “Little Ice Age.” Today,astronomers and solar physicists areable to accurately measure solarirradiance—energy received from thesun. Another strong correlation existsbetween temperature and solarirradiance (see graph below). Theearth was bombarded with more ofthe sun’s energy during the last warmspell centered on the 1930s and ’40sand, more recently, during the periodcentered on the ’90s. Solar physicistspredict a relatively weak sun as the21st century progresses. Could thismean a period of extended globalcooling? Some scientists think so.

Bottom line, climate has beenanything but static through time. Itis a very complex phenomenon toobserve, let alone forecast. A plot oftemperatures over time, say

thousands ofyears, goes upand down inirregular fashion.While scientistshave madeprogress indeducing climatepatterns, manyof these naturallyoccurringfluctuations arestill poorlyunderstood.Furthermore,

looking at just a 10-year or even a50-year snapshot of the climate willnot help answer the questions as towhy we are warming and if we willcontinue to warm. One climatologistlikens our observation of climate to anant watching the hands of a clock,while he is perhaps perched on the hour

hand. We cannot know exactly wherewe are, let alone where we are headed.

Studying the past and compar-ing it to the warming we are nowexperiencing, I do not believe we areheading for climatic disaster. I dothink that, just like our ancestors inthe Middle Ages who thought thesun rotated around the earth, we,too, may now be suffering from ego-delusion, thinking we are the primaryinfluence on this planet’s climate.Along this same line, there are thosewho believe we can control theclimate and nurture it back to somesort of ideal state. The record showsthis idea of an ideal state could notbe farther from the truth.

My advice is to be skeptical offuture predictions. Next time you areconfronted with a story on climatechange, be aware of how often yousee or hear words like “may,” “could”and “if.” The climate models thathave been developed to project futuretemperature are not infallible.

Renowned mathematician JacobBronowksi stated that “no science isimmune to the infection of politicsand the corruption of power.” Thescience of climate change is noexception—it is a classic example ofthis fact. Politicians court voters withdubious legislation proposed to solvethe “climate crisis.” At the same time,scientists who feed at the trough ofpolitical favor seek to squelch dissent-ing opinion from other scientistslabeled as “climate change deniers.”We need skeptics, because a truescientist is a skeptic. As the lateastronomer Carl Sagan noted, “It isthe tension between skepticism andcreativity that has produced thestunning and unexpected findings ofscience.” Without this doubt,without this admission ofuncertainty, climate science will notreach the goal of all science, which is truth. n

Total solar irradiance (TSI), energy received from the sun, comparedto U.S. mean temperatures. (Courtesy of ICECAP)