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Why Basic Research is Absolutely Necessary
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IMAGE 1 - Keeling Curve
Charles David Keeling
It all began with the International Geophysical Year (1957-58) when newly minted Ph.D.s like Charles David Keeling received grants to study the basics of planet Earth. Keeling used his grant to placed gas analysers at several remote locations around the Earth, away from urban areas, including the South Pole and atop Mauna Loa in Hawaii. What was learned from this was that atmospheric concentrations of Carbon Dioxide were (and still are) rising. Also of note was the periodicity of the concentrations within one year, the "wiggle" in the graph that is superimposed on the general upward curve. Concentrations of CO2 increase during the Northern Hemisphere winter months, then decrease during summer months - inversely related to the amount of active photosynthesis that takes-up CO2. Keeling discoverd Earth's breething! Of interest here is that the vast majority of land is in the Northern Hemisphere - a fact that will be discussed later.
Fifty years later, the Weather Channel listed Keeling's curve as "Number One" of the "100 Greatest Weather Events" of the century. Indeed, the Keeling Curve is the most important geophysical record ever made. All things "global warming" are a result of basic research begun decades before there was a Weather Channel, and have given a foundation for subsequent research in the field. Money well spent, in my opinion.
Global Warming versus Climate Change
I should warn you that I'm about to be difficult, that I do not agree with the media's representation of the science behind the debate, nor do I like the term "Global Warming". After all, global warming is a requirement for liquid water and for our kind of life. You may think that I'm just playing with words or being a bit antiquated like those who insist on a certain usage of grammer, and you would be correct in this instance. I am trying to preserve the up-to-now meaning of "global warming" by insisting on use of the phrase "climate change" instead. In the end, I hope you will come to believe that the latter phrase is actually far more sinister, not to mention being more accurate, than the now confused meaning of "global warming."
I will start with an "introductory" explanation of global warming - the way a Geology or Climatology student would be exposed to the topic during his or her first course on Atmospheric Science. For example, an oft-used text by Oliver and Hidore Climatology, An Atmospheric Science includes chapter titles of Natural Causes of Climate Change, The Warming of Planet Earth, The Human Response to Climate, and Climate, Agriculture, and Industry. Hopefully, the first thing you noticed is that these chapter titles are not provocative, so you will likely never see anything similar used as a headline. That's good, in my opinion, because science is supposed to be unemotional - the facts should persuade - and if one isn't willing to test a conclusion, well then it (whatever it is) isn't science. Second, you have probably figured out that I'm offering a lot more than a few paragraphs to convince you of my perception of climate change and Mankind's role in it (and, yes, we do play a role).
I will begin by discussing what global warming is and how today's average global temperature compares to the paleoclimatic (ancient climate) record. This will include a discussion of the "greenhouse effect", a natural Earth process integral to global warming, and how other natural atmospheric process work to distribute heat from the equatorial regions toward the poles.
Ancient Climates, The Little Ice Age, and Proxy Records
How do we know if average temperatures today are warmer or cooler than in the past? How do we know how much CO2 was in our atmosphere 100,000 years ago? The answer lies in what are called "proxy records". Proxy records include things like tree rings that not only tell us how old a tree is, but whether a given year (ring) was wet (a wide ring) or dry (a narrow ring). More useful is the proxy record constructed from ice cores. These cores have layers not unlike tree rings that can be counted and measured for thickness. Additionally, dust and pollen from each layer can be examined and trapped bubbles of air analysed for their chemistry, like the ratio of Oxygen isotopes and Calcium levels. Similarly, ocean sediment cores, stalagtites, landforms, etc., are all used to piece together a picture of past climate.
I like to think in terms of graphs. I also like to start with the big picture, if possible, and move into the details. Of course, sometimes you have to build the big picture from pieces in the same way as one completes a puzzle. Like a puzzle, not only must the pieces fit, but the resulting picture must make sense. So, a graph that tries to represent the "big picture" should be examined to see if it makes sense, and that the same sort of "big picture" emerges from different sources of information - different proxy records.
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IMAGE 2 - 150,000 year Climate Record
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Where then are we in the "big picture" of Earth's climate record? If you want a full answer, you should read Paul Mayewski's book The Ice Chronicles and Richard Alley's book The Two-Mile Time Machine. I'll summarize by saying that we are at the end of the "Little Ice Age" that began roughly in 1200 AD when the Medieval Warm Period ended.
A quick look at the graph at left demonstrates two things: First, that we have been as warm 130,000 years in the past as we are today and second, this graph does little to help you understand the relationship between the Medieval Warm Period and the Little Ice Age! The point here is to make sure you are working with data that represents the timeframe you are interested in!
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The graph to the right shows an even longer timeframe of the Earth's climate record. This is a better graph to use, for example, when discussing how many past ice ages we have had - 20 documented so far.
This graph is also a good examle of what I mentioned above, that the "big picture" built from multiple sources of data should match in order to have some confidence that you are on the right track! This graph shows the relationship among Solar energy (Insolation), Oxygen Isotopes, Methane (CH4), Temperature, and CO2.
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IMAGE 3 - 400,000 year Climate Record
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So then, Image 4 below is a graph of temperature data plotted against a timeframe more appropriate to show how global temperatures have changed form the Medieval Warm Period (about 900 AD) through the Little Ice Age.
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IMAGE 4 - MWP & LIA Chart
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Then again, this graph is little more than an approximation - notice the lack of values on the Y-axis, and notice the dashed line... While this chart does impart an understanding of relative temperature changes for the past 1,000 years or so, which is its intended purpose, it does not give you specifics. The dashed line represents the average global temperature since 1900 and is plotted to show "departure from normal". The questions you should be asking yourself now are "what is normal?" and "has the Y-axis been stretched to exaggerate the differences?" The latter is not "bad", indeed it can be very useful, provided the exaggeration is made obvious to the reader.
I hope that you are beginning to realize that it is very easy to misinterpret the meaning of a graph if you don't understand by what characteristics the data were selected - what data to plot and how the chart will look are decisions made in order to convey certain information - in order to make a specific point. The timeframe characteristic turns out to be what matters most in our above example.
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Today's average global temperatures certainly are unusually warm when compared to those of the 18th century, but not so unusual when compared to the height of the Medieval Warm Period, a time when England had vinyards that rivaled those of France! Of course, you are probably saying "but wait - I have heard news reports stating that we are now experiencing the warmest climate than at anytime in the previous 1,000 years." Perhaps this claim was more accurate 10 years ago, before more data had been collected and analysed, but it is just not true today. A quick review of IMAGE 4 doesn't support the "1,000 year claim" and, while the media is still repeating this claim today, the National Acadamy of Science refuted this timeline in 2006 when it concluded that the available data can support a claim of at most 400 years. Essentially, the valid statement is that today's average global temperatures are the warmest since the end of the Little Ice Age (LIA), but not quite as warm as the Medieval Warm Period (MWP).
The nice thing about the MWP and the LIA is that we have actual written records that verify what the proxy records tell us. We know when vinyards grew in England, and when the River Themes froze solid. We know when the norse settle Iceland, and Greenland, and when Greenland was abondoned due to cooling and an increase in sea ice. Given the agreement among historical records and various proxy records, the scientific community feel confident that the proxy records, therefore, are just as reliable going back tens and hundreds of thousands of years into the past.
If one looks at the available data, it becomes clear that there is a natural variability in Earth's climate. It also become quite clear that all of the cycles of "ice ages" and "warm periods" took place prior to when Humans learned how to burn fossil fuels.
The Greenhouse Effect, Sun Cycles, Continental Drift, and Climate
Am I making the claim that Humans have nothing to do with Gloabl Warming? Well, yes and no. Global Warming is nothing more than a different name for the so-called greenhouse effect. The greenhouse effect is so-named because of the effect our atmosphere has on planetary temperatures is similar (in concept only) to what happens in a greenhouse during the winter months.
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The greenhouse effect refers to the trapping of long-wave infrared radiation (heat) by greenhouse gases such as water vapor, methane, and CFCs, all of which are far stronger greenhouse gases than the oft-mentioned carbon dioxide, as well as several other gases that contribute even less to "global warming." The other metaphore used to describe greenhouse gases is that of a blanket - add additional layers of blanket, and you warm up. These metaphores do not, in fact, describe how greenhouse gases actually work. However, in this age of technology, if you replace the old fashioned blanket with the new high-tech "foil" blanket (also known as survival blankets), then you are pretty close. Like the millimeter-think space-age foil blanket, greenhouse gases trap long wavelength energy (infrared energy) that would otherwise radiate out to space.
This may be hard to accept, but the greenhouse effect is natural! Without greenhouse gasses, we would not be here now - without the greenhouse effect, global average temperatures would be at or just below the freezing point of water instead of the balmy 50°F we experience today (or at least what we experienced a few years ago). Greenhouse gases warm the troposphere (the lower layer of the atmosphere where our day-to-day weather takes place) allowing for liquid water and, therefore, making life as we know it possible.
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IMAGE 5 - The Greenhouse Effect
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And by the way, I did say 50°F! Remember, the expression used is "global average temperature", so this includes the average year-round temperatures at the poles as well as at the equator and in desert regions.
So far, we know that the greenhouse effect is natural and is required for our kind of life. We know too that greenhouse gases cause the greenhouse effect. We also know that CO2 is one among several greenhouse gases, but not the one with the greatest influence on global temperatures. Finally, we know that "global warming" is really the same thing as the greenhouse effect, except that global warming suggest an increase in the greenhouse effect while global cooling suggests the opposite.
The last thing to touch upon is the idea that the greenhouse effect is a balanced system. The amount of short-wave radiation we receive from our Sun (visible light, as well as UVa and UVb, the stuff of Sun burns) is balanced by the amount of long-wave radiation Earth re-radiates into space. That balance results in the global average temperature of 50°F I spoke of earlier. If the amount of long-wave radiation emitted to space decreased, global temperatures would increase because the short-wave radiation from the Sun (Insolation) remains constant. The system gets knocked out of balance and the planet warms. But, eventually, the system would reach a new steady-state and the system would come back into balance, but at a higher temperature.
IMAGE 6 - Milankovitch Cycles
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If only it were that simple! I neglected to mention that Insolation does not remain constant, but is known to vary over time resulting from a complex interaction of several cycles corresponding to:
- changes in the shape of Earth's orbit (eccentricity - from a more elliptical to a more circular orbit over a 100,000 year period),
- the wobble of our axis of rotation (obliquity - from an inclination of 21.5° to 24.5°, presently at 23.45°, over a 41,000 year period), and
- something called precession; the slow change (over a 26,000 year period) in position along our annual orbit when our seasons take place. (Think of a fan belt that slips, or how the movement of the hand-rail on an escallator slowly moves relative to the steps). Precession results in summer sometimes taking place when the Earth is farther from the Sun (cool summers) and sometime taking place when it is closest to the Sun (hot summers) during an elliptical orbit. Taken together, these Milankovitch Cycles result in changes in the amount and location of insolation (solar forcing) that will result in changes to climate.
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There are other factors that can alter Insolation itself, like sulfurous emissions from volcanoes, but as it turns out, the greatest effect on climate over time comes from the configuration of the continents!
As you already know, climate is very different along the coast as compared to farther inland. Large bodies of water moderate climate - this is one of the "controls of climate", as is elevation (higher tends to be cooler), and so on. The center of a continent tends to have hotter summers because land heats more quickly than does water. Water takes longer to get hot becuse of something called "latent heat", and water takes longer to cool off for the same reason. (Latent heat is the amount of heat required to energize the molecular bonds of a water molecule.). Another reason for greater extremes in the center of a landmass is because the moisture from the ocean simply doesn't make it that far inland before it is precipitated out of the atmosphere as rain or snow. This helps explain why in the center of North America, for example, we have grasslands instead of forests - you need more precipitation to support a forest than you do grasslands (which are the same as cereal crops like wheat and corn).
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In their current configuration, the continents offer thousands upon thousands of miles of coastine, which provide many diverse habitats from estuaries to coral reefs, and allow for many different climate zones. Back in the Permian, 290 to 250 million years ago, there was one "super" continent known as Pangaea (pan = all, gaea = land) that had many thousands of miles less coastline and, therefore, more homogeneous climate over more land surface (like the interior of Australia), and fewer habitats with less diversity.
As Pangaea broke apart, the climate changed dramatically.
The single, world-wide ocean of Panthalassa broke into the Pacific, Atlantic, Indian, and so on, in the same way as the single continent broke into the seven new continents of North and South America, Europe, Asia, Africa, Australia, and Antartica. This reconfiguration of land and sea also gave rise to new atmospheric and ocean circulation patterns. The Gulf Stream is one of the end results, and it is this current that brings warm water from the Equator to the North Atlantic that ulitmately keeps Northern Europe's climate far warmer than it would otherwise be.
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IMAGE 7 - Pangaea
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Do yourself a favor and find London, UK, on a Globe. Now, rotate the globe counterclockwise (the direction Earth rotates on its axis), while keeping your finger at the same latitude as was London, until you arrive at the North American continent. Now, consider how much warmer London is than the equivalent latitude over Canada - either at the coast or inland!
Incidentially, it was during this Era when the largest mass extinction known took place - the "Great Permian Dying" - when nearly 90% of all life on land and in the ocean took place.
The (really) Big Picture - Feedback
It is as this point where it would be instructive to think about how the few example factors mentioned above combine to influence climate. We have atmospheric compostion - gasses, dust, etc., and the relative configurations of land and ocean and the changing proportion of coastal perimeter to interior area, and we also have the Earth-Sun relationships described above. Each of these is a variable that can and do change independently of one another, sometimes adding their climate influences together and, at other times, cancelling out some or all of their influences. In fact, we are only just beginning to understand this multi-varibale system (and, trust me, I have left out many other variables that come into play).
So, we now know that there is more going on with climate change than just CO2. A change in just one of the Earth-Sun relationships can change climate, as can a volcanic erruption (if it is at the right latitude), as well as where the continents happen to be at any given time. As I mentioned above, it is the combination of changes that sometimes add together to exhert a greater influence on climate, and sometimes one change negates another leading to little influence. These are termed "positive" and "negavtive" feedback.
Positive feedback is easy to understand because we have all heard the ear-piercing feedback between a microphone and a loudspeaker. We know not to place a microphone directly in front of a loudspeaker, but why? The microphone-loudspeaker system works when the energy received by the microphone is amplified by the speaker, and if the microphone is in a position to recevie the energy from the loudspeaker, that energy is then amplified again by the speaker, and so on. The soundwaves emitted by the loudspeaker get more and more energetic - louder and louder - and the microphone-speaker "system" continues to build upon itself until the system itself fails. Positive feedback systems, more properly termed self-reenforcing systems, are not self-sustaining.
Negative feedback describes the tendency of a system to resist change. For instance, when we get hot, we prespire in order to cool down through evaporation. Negative feedback maintains the status quo.
Some of the changes in our natural systems can be dampened through negative feedback, and some can be amplified through positive feedback. Multiple changes taking place at the same time will have varying combinations of positive and negative feedbacks all taking place at the same time and, when taken together, may result in a "step change" - a transition to a new steady-state at a higher or lower temperature from before.
The problem with the idea of "getting warmer" or "getting cooler" as a result of feedback is that it doesn't happen gradually. Climate change is anything but smooth, even if you think about a "step change". Think of it this way: parts of the climate system are pushing, some harder than others, at random intervals while other parts of the climate system are pulling, some harder than others, at random intervals. Sometimes, the climate gets pushed a little, then pulled a lot, then pushed a lot, then pulled a lot, then pushed a little, then pulled a little, then... well, you get the idea. But, how does this description translate to real numbers?
IMAGE 8 - Younger Dryas - Ca Proxy
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Ice cores have revealed that global climate - thought to change only very gradually until the late 1990s - can shift with unimaginable speed, in some cases over just a few years. As the graph in IMAGE 8 shows, one such jump occurred about 12,000 years ago, as the last glacial period (the Wisconsinian at the close of the Pleistocene) was giving way to our current warm "interglacial" period (the Holocene). Suddenly, possibly in fewer than five years, average global temperatures, which were just slightly cooler than today's (inclusive of recent warming), plunged by about 27°F, returning the world to the near-glacial conditions of the Wisconsinian.
How do we know this? As the graph of Ca proxy records indicate, Calcium levels tend to go up and snow accumulation down with temperature, which is estimated by comparing the ratio of oxygen isotopes in water (lighter isotopes allows water to evaporate more easily). The Younger Dryas(YD), as this cool period is known, lasted about 1,300 years before it returned - just as abruptly - to the temperatures typical of the period immediately preceding it.
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Now take a closer look at the line that traces the changes in temperature (the middle graph of Temperature in °C) for this time period. Not very smooth, is it! In fact, temperature swings of 10° and 20° are a regular occurance before, during, and after this period in time, which itself is arguably just another unstable transition from "ice age" to the warmer "interglacial" period of the Holocene!
This rapid "bouncing around" that is the transition into and out of the YD looks similar to that for the LIA and MWP described above, except for smaller magnitudes in temperature shifts. Still, the smaller magnitude of change that ended with a "step down" to lower average temperatures was enough to change the face of agriculture in the UK from vinyards to frozen rivers and (almost) back again.
Now for the best part of the story - all of this climate change history happened before Humans learned how to burn Fossil Fuels!
When Did The Little Ice Age End, & When Did Human Activity Begin to Change Climate?
The answer to both may well be the same! Mayewski's book The Ice Chronicles does a nice job of describing the "remarkable discovery" (See Chapter 5) that we may, in fact, still be in the LIA Little Ice Age!
How can this be - things are warming up after all! Where I live in New England, for example:
- Average winter temperatures have risen 4.4 degrees Fahrenheit since 1970.
- Lakes in northern New England are thawing eight days earlier than they did in 1970.
- There are 15 to 25 fewer days when snow is on the ground, compared with 1970.
- Lilacs bloom four to five days earlier than they did in 1965.
(For more of this sort of information, check out NEISA's Climate Change Data.
This info is from Cameron Wake, Climate Change Research Center, UNH.)
Well, all of the previosuly described variables (orbital shape, position of continents, ocean and atmospheric ciculation patterns, and many others) do produce recognizable patterns in the proxy records. We have all heard of "El Nino", the periodic warming of Pacific Ocean waters that build up off the West Coast of South America that affect storm patterns around the globe (from monsoon failures in Southeast Asia to the collapse of fisheries in the Eastern Pacific to a marked decrease in huricane activity in the Atlantic). This phenomina is more properly termed ENSO - El Nino Southern Osciallation - and by monitoring several variables inclusive of sea surface temperatures, patterns emerge that can be helpful in predicting the next El Nino, or the other part of the oscillation, La Nina. Systems like ENSO are not unique. Another oscillation (swinging back and forth) of particular interest is the NAO - North Atlantic Oscillation. The NAO's "back and forth" refers to the position of the semipermanent pressure centers near Iceland - the Icelandic Low. When a Low pressure center is over Iceland, a corresponding High pressure center sets up over Europe. Conversly, a "High" over Iceland translates to a "Low" over Europe. Wind is a result of air moving from areas of high pressure to areas of low, with the "Low" being the location of stormy weather. By looking at proxies like amount of snow fall, dust, isotopes, etc. in ice cores, one can associate quantities of each with what phase the NAO was in for each of the warm and cold periods of climate.
One of the observations resulting from the second Greenland Ice Core Project (GISP2) is that the proxy patterns typical of the LIA are still present today. We should, therefore, be as cold today as was Goerge Washington when he crossed a nearly frozen Deleware River. (Yes, the ice in the famous painting of this historic crossing by Leutze is accurate!)
The obvious reaction is to look for anthropogenic (Human) causes. Indeed, an argument can be made for Humans having "ended" the LIA as a result of our industrialization and our ever increasing population. Today's climatological indicators seem to resemble those present at the height of the Little Ice Age (position of semi-permanent pressure centers like the Bermuda High and the Icelandic Low, NAO, ENSO, et al., derived from climate proxy records), so we humans may be superimposing warming on top of a natural cycle of cooling - a clear recipe for instability and unpredictability.
I often quote (paraphrase, actually) Paul Mayewski (UNH - GISP2 ice core project Director) who says something along the lines of "we humans are complicating things just when we might be in a position to begin to understand how the climate system has operated over the past hundreds of thousands of years". I also have come to understand why he and others like H. J. DeBlij (MSU) say we are still in an ice age. Richard Alley (PSU) refers to past RCCEs (Rapid Climate Change Events, pronounced "rickies") documented in proxies like the GISP2 Ice Core climate record as "one day - boing - the world changed" - climate shifts in a human lifetime that are unimaginable. (Yes, he really does say "boing".)
So, we have a climate system that, for various physical reasons described above, tends to oscillate between cool periods (galciers, sea levels lower by hundreds of feet) and warm periods (few if any glaciers, sea levels somewhat higher than today), with transitions between the two that oscillate wildly before settling into the new warmer or cooler state.
Consider this: Mayewski's research suggests that recent "warming" is far more significant than we have generally realized when we place it into a context of the ~1°F rize in gloabl average temperature may be only that part of the warming left over after reversing the LIA! If this is in fact what has really taken place, we have not yet realized our species' precarious position!
A Few More Variables To Add To The Uncertainty?
In addition to the numerous examples presented above, lets add Pan Evaporation Rates. Researchers literally measure evaporation of water from a standards-sized pan from locations around the globe. Their data show remarkable decreases (in excess of 20% in some areas) in insolation (incoming solar radiation) over the last 100 years - meaning aerosols associated with industrialization may actually be reducing the magnitude of global warming in much the same way as volcanic emissions lower global temperatures. Similarly, jet aircraft exhaust produces cirrus clouds (contrails) that also reduce insolation. After 9/11, when the entire U.S. commercial air fleet was grounded for several days, a few researchers measured a nontrivial increase in insolation and a warming over North America during the same time period roughly equal to the total warming attributed to the period of the industrial revolution to today (~1°F). Until 9/11, no one realized the magnitude of the effect contrails have on reducing the magnitude of global warming. SO, if we shut-down all "emissions" tomorrow, thereby reducing aerosols as well as greenhouse gases, we might well see a fairly immediate increase in global warming to roughly double the current measured amount! Neither of these two additional examples have been included in climate models (to my knowledge) mentioned above. Despite all this, recent studies indicate these climate models do a pretty good job of predicting increases in sea surface temperatures that have actually been measured.
A Technical Digression...
I wanted to mention an American Geophysical Union Journal Highlight by Mohi Kumar titled Synchronized chaos: Mechanisms for major climate shifts in EOS volume 88, number 31. The article summarizes research by Tsonis et al., and begins by describing the mid-1970s climate shift that cooled sea surface temperatures in the central Pacific Ocean while warming the coast of western North America and resulting in long-range changes to the Northern Hemisphere. With the weakening of this climate shift came frequent El Ninos and rising global temperatures. The article notes the difficulty of trying to link effect with cause because of the complicated mechanisms underlying climate. Tsonis et al. investigated known climate cycles (Pacific Decadal Oscillation, NAO, ENSO, North Pacific Oscillation) over the last 100 years. They found that these systems synchronized several times during the study period and in cases when that synchronization was followed by an increase in the strength of these cycles (positive feedback), the synchronization collpased and a new climate state emerged that was closely associated with global temperature changes and ENSO variability. Tsonis et al. showed that this mechanism explained all global temperature change tendencies and ENSO variability in the 20th century. I mention this becuase this would seem to be a small-scale equivalent to the paleoclimatic record that has seen large-scale variability and also to point out that transitions between climate regiems are not gradual.
Media Effects - Climate versus Weather - More Hurricanes?
With the above attempt at offering a glimps of the uncertainties associated with climatology, its time to turn back to the original question raised during lunch: Is "global warming" causing an increase in the frequency of severe weather events such as hurricanes? This question is a wonderful example of asking a question of one discipline (meteorology) in an attempt to draw a conclusion about another discipline (climatology). No, I didn't say that backwards...
Yes - Climate and Weather are related, but one can't predict the other. Weather changes hour-to-hour while climate tells you something about the elevation, proximity to large bodies of wather, latitude, and so on, of the location of interest. An often used quote sums this up nicely: "Climate is what you expect, weather is what you get." I like to state this idea in a different way: "There is a reason why you don't find a 'Climate Channel' on your TV!" This means that while you can predict the climate of Florida for a given time of year, say when planning for a vacation, you can't say if it will rain while you are there!
Yes - Climate constrains weather. Certain climates, say Am (Koëppen classification for Moist Tropical, no dry season) will not allow for snow, but it also doesn't guarantee rain every day. And, it doesn't say anything about the presence, absece, or frequency of severe weather.
As for more numerous and more severe hurricanes resulting from warming sea surface temperature - all of the models show that most of the Earth's warming will be located in the polar regions, not in the tropics. (And data collected to date clearly demonstrate this to be the case.) Keep in mind that a difference in temperature causes wind, and therefore storms... But, even with warming sea surfaces in the tropics, the air above the sea surface will also warm. Therefore, it would take warmer water to initiate tropical storm development, so the net impact on the number and intensity of storms would not necessarily increase. The predicted increases in number and severity of hurricanes would begin only when equatorial waters warm significantly more than the equatorial air above. Since air is primarily warmed by the Earth's surface, it would be difficult to see how a large temperature difference between the two could develop. Dr. Landsea and the Tropical Prediction Center have done some interesting research on that. (Dr. Landsea is such a great name for someone at NOAA!) He is very skeptical of whether global warming can cause a significant increase in tropical activity (has believes the maximum increase would be on the order of 1%, which translates into a couple of MPH for any given hurricane).
Check out an interview with Dr. Landsea , especially his remarks towards the end of the interview when he comments on data quality.
I am starting to believe that the effect of the media embracing "global warming" has swung the pendulum too far in the other direction. (And don't get me started on the movie The Day After Tomorrow!) For example, I occasionally correspond with Doug Gilham (MSU) via email, and we both pine for something that will probably never happen: that the media would report on the fact that global tropical activity was actually down in 2005 and 2006 - it was just that most of the activity that did take place in 2005 was in the Atlantic Basin while the Pacific was unusually quiet. Why haven't the media presented the questions I raised above concerning "more severe weather"? After all, if you decrease the temperature gradient between the tropics and the polar regions (through global warming), how will this lead to an increase in severe weather over the mid-latitudes?? Imagine advancing ice sheets across Canada while the Gulf of Mexico warms - now that would lead to some massive temperature gradients and really severe weather (you think tornadoes in "tornado alley" are bad now?)!!! I really do think it is reckless stupidity to continue to pollute our air and water, but equally reckless is the specter of politicians and the media abusing science for their own agenda, and even more so when some scientists play along for personal gain (fame, etc.). Just my two cents worth - that you probably already knew. :-)
As an example of this "over exhuberance", check out NASA's Global Warming Update. On the first page of this site (as of this writing in May, 2007), you will notice some rather sweeping statements that are based on real data, but are overstated nonetheless. (I can't really blame the folks who put this together - the world is finally seeing things for what they are and that makes it easy to get carried away.) I take great exception, however, to the statement of "Moreover, global warming will last thousands of years." This just isn't known, and there are no climate records to back this statement. In fact, our current climate is an anomaly - climate usually doesn't stay stable for as long a time as it has for the last 8,000 years. Further, abrupt changes in both directions have happened long before we learned how to burn fossil fuels.
Then again, research by Mann and Emanuel [2006] found regionally enhanced anthropogenic aerosol-based cooling over the North Atlantic. This would, in fact, give us a region where difference in temperatures (increased temperature gradient) would support increases in number of hurricanes. The approach by Landsea [2007] assumes the count of total tropical cyclones (hurricanes) making landfall is constant over time. However, Holland and Webster [2007] show that the greatest warming of tropical sea surface is shifting to the eastern tropical Atlantic. As we know, tropical cyclones move west when close to the equator, then curve and move to the east once they move north of topical waters. This "starting farther to the east" and then curving "to the east" suggests that Landsea's assumpiton is incorrect - that the number of hurricanes making landfall is not constant over time.
SO, with increasing temperatures in higher latitudes, severe storms would seem to be less likely (e.g., the 35 yr average for the Cape Cod area getting a direct hit from a hurricane would increase to say a 50 year average or greater) and England could grow grapes once again. With the temperature gradient flattening between the equator and the poles, where would the severe weather come from? Shouldn't we be thinking more about what a lack of storminess might mean to agriculture, and where? Recent data suggesting a significant increases in storminess resulting from the energy sink (cooling) in the North Atlantic translates into more storms taking place over the Atlantic. How would more storms over the Atlantic impact weather systems over the North American Continent? (In other words, where spatially the temperature difference sets up is important to weather patterns.)
Maybe increased melt water from Canada and Greenland (so-called "freshening") will combine with the developing North Atlantic sink (Mann and Emanuel) to disrupt the so-called "great ocean converyor" (Thermohaline Circulation: cold salt-water sinking to the ocean floor, which helps warm surface water to take its place). With warm surface water from the Gulf Stream/North Atlantic Drift no longer traveling as far north as it does today, and less-dense fresh water melt from Greenland not being able to sink below the cold salt water, we may see a slow-down in the Thermohaline Circulation that could nudge Eruope into LIA-like conditions. Will the aerosol-based cooling quantified by Pan Evaporation measurements reduce the amount of "freshening" required to substantisally slow, or even stop Thermohaline Circulation and forcibly return both North America and Europe to LIA proper? (Rember, the LIA spanned the 13th to (at least) the 19th century - frozen rivers in the UK and in North America during winter.)
I take the position that "warming" would be much easier to adapt to than "cooling" (assuming a willingness to adapt at all) as indicated by the differences between the MWP$ (900 AD to 1,200 AD, vineyards in England) and the LIA (1200 AD on, no vineyards in England and "ice fairs" on the frozen Themes). The climate of the MWP is comparable to what we have today (so, what caused it to warm after the YD?), perhaps a bit warmer than today, followed by the LIA that lasted until the mid 19th century. The graph of the transition into and out of the MWP looks similar to that for the YD above, except for smaller magnitudes.
A Look At Climatology
To begin, it is important to note that the word "climate" is not used as rgiorously as one might believe. Climate may refer to seasons, or it may be used to describe so-called "microclimates" within a season. Climate is a well defined concept and, at the same time, a loosly applied word. Several systems that describe one or more aspects of "climate" are in use, even though this may not have been their intended application.
If you garden, you have most likely heard of "haridness zones." The USDA defines Hardiness Zones based on average low temperatures in a region to help farmers select appropriate plant varieties for their location. However, other environmental factors, such as prevailing wind, soil fertility, moisture regeims, heat, humidity, drainage, and day length have a great effect on crops. Consequently, one or more of these limiting factors may not be evident when matching a USDA "climate" with a given crop. This makes for great entertainment among gardeners when discussing why the same variety of a given vegetable does well in one backyard, but poorly across town.
The previously mentioned "semi-permanent pressure centers", like the Bermuda High, play a major role in steering wind and, consequently, storms through the atmosphere. A high pressure center like the Bermuda High will force storm tracks to follow a clockwise path around the high pressure cell as the general movement of air flows from west to east in the Northern Hemisphere. This can direct storms, and the precipitation they carry, to certain areas that a Climate Classification System would summarize as having X amount of precipitation at certains times over the course of a year. As these semi-permanent systems shift slightly back and forth in response to seasonal heating (e.g., the NAO), weather changes (e.g., summer versus winter precipitation). For more on this, you might be interested in reading my brief intro to Climate and Weather for Massachusetts.
The NAO (North Atlantic Oscillation) seminar presented at the 2006 Southern New England Weather Conference was very interesting, and indicates the NAO is getting some of the attention once reserved for ENSO (El Nino Southern Oscillation). All of these systems affect climate regeims and impact hurricane development. I was pleased to have been present to hear Dr. Emanual present:
During that session, he went over forecast model refinements, hurricanes, etc.
The conference put Kerry Emanuel and Joe D'Aleo (former director of meteorology for the Weather Channel, former chief forecaster for WSI/Intellicast and now working with investors) together to present opposite sides of the debate. Emanuel is a strong proponent of "global warming is happening and Man plays a majr role" and D'Aleo was not. When it was D'Aleo's turn to present, he finished with a beautiful digital picture of Polar Bears "embracing" (probably fighting!) while he declared "the good news is that global warming is a hoax!" The reaction of the crowd (perhaps 150 weather and climate types inclusive of area forecasters from various New England TV Stations) was very instructive regarding scientific bias...
Another couple of sessions I thought were interesting:
This latter session touched on how Tropical Cyclones (a.k.a. named storms like hurricanes) can have an effect on more general weather systems for some future period of time. In other words, a big storm's effects on atmospheric patterns last longer than the big storm itself. This ties in with the idea of feedback and, some might incorrectly say, allows weather to alter global climate.
The Debate Goes on...
During the 2007 Southern New England Weather Conference, another debate on "Global Warming" was held. This time, Joe D'Aleo was a bit more precise in his position regarding Man's role in global warming. He, none the less, represented the "natural cause" side of the debate, while Dr. Stephen Nodvin represented the "anthropogenic cause" side. Unfortunately, Dr. Nodvin's background (Ecology and Evolutionary Biology) was not sufficient to address many of the physical-science aspects of the pre-submitted questions as was D'Aleo (Meteorology and Climatology, and is a fellow of the American Meteorological Society).
Here are just a few of the question from that debate:
If there were as many as 20 previous galcial periods with warm periods in between, why do we think Humans have caused this one?
Well, the typical answer involves the Milankovitch cycles previously mentioned. As Eath's orbit changes, as well as wobble and precession, varying amounts of insolation will reach the Earth and result in temperature fluctuations. Add to this the relative positions of the continental land masses and you get a reasonable answer.
The other answer is a "philosophical" one, where the question itlself is attacked as being one of a "false choice", or the answer is along the lines of "just because the others wern't caused by Humans doesen't mean this one wasn't."
In 2004 and 2007, Oreskes presented research titled "Scientific Concensus on Climate Change", wherein she claims that of the 928 peer-reviewed publications, none questioned that Humans caused Global Warming.
Peiser [2007] however, pointed out that over 12,000 peer-reviewed publications covered the topic of "Global Warming", and only 1% of that total numnber explicitly endorsed the anthropogenic cause for global warming and Shulte [2007] found 45% either explicitly or implicitly endorsed this view. The remaining 6,000 or so publications didn't address this question at all. Oreskes conclusions are based on only about 1/12 of the available publications on the subject.
If you can't trust a 3-day model to forecast the next storm, how can you trust models to predict climate 50 years in the future? (This question drew applause from audience members who are well-known meteorologists on Boston TV as well as the Weather Channel.)
Many will claim that climate models over-estimate warming becuase of too much positive feedback - a slight positive increase tends to be magnified by models over time. Also, most models do not include at all, or adequately include the effect of the Oceans on climate. A recent Science article (October 2007) point out that the models are too complex - that what we have now is as good as it gets.
Others will claim that climate models are too conservative and most likely underestimate the rate of climate change. Also, rightfully so, models also can't predict Human behavior and that there is no evidence to suggest Humans will reeduce their consumption of energy.
How can climate change be "good" - why is it always portrayed as being "bad"?
One answer is that only wealthy countries would stand to benefit, that only wealthy countries have the resources to be "winners", but there will be more "loosers" than "winners" because developing countries [World Resources Institute and IPCC] do not have the capacity to repond to associated natural disasters.
On the other hand, "Global Cooling" would be far worse. In 2000, climate change related losses were estimated to be ~$13 Billion with a ~5°F warming [Menhehlson 2000]. Cold-related La Nina events are many time worse than warm-related El Nino events [Changnon].
When will we reach a "tipping point" when we won't be able to have an impact on global warming?"
Many scientists believe we have already reachd a tipping point due to Solar (Milankovitch) Cycles. Some believe this will cuase sea-levels to rise, and present other apocolyptic visions. The tipping point associated with the Arctic melting to the point where the Northwest Passage has now opened, however, will not result in seal-level rise! This ice is already floating on water and, therefore, can't rise sea-levels (try this wtih a full galss of ice water).
Others say that a 1' to 2' rise in sea level will result from thermal expansion alone (as water warms, it expands like any other material), and if Greenland and the Antarctic ice sheets melt sea levels would rise an additional 20' for each (both sit on land, so melting would add volume to the world's oceans.) Many claim we are closer to this "worse-case" tipping point than the IPCC has stated due to underestimated positive feedback like changes in albedo (reflectivity) from loss of sea ice and melting glaciers [Hanson, et al.].
To Try To Summarize...
Those involved in the actual research of climate change will not say that Humans definitely caused global warming as we understand it today - one only need look at past climates over hundreds of thousands of years to verify this. You will hear a concensus that Humans are causing massive changes to local climates (e.g., desertification, heat-island effects, etc.) and are having an ever-increasing impact on global climate that may well result in a RCCE that Mankind is ill equipped to handle. You will also hear a good deal of speculation about climate shifting in either a warmer or cooler direction, but the scientific predictions will be tempered by "if the following hypothesis proves correct" or "the data thus far seems to indicate" - there is a difference between offering hypothesis and claiming something as a fact.
What you will hear is this: the faster the rate of climate change, the more likely we are to see a massive disruption of our current civilization (transportation, agriculture, technology, fisheries, population dislocation / migration). Modern technologies/conveniences will probably prove more harmful than helpful because of our dependence upon them and subsequent separation from the realities of our natural world ( e.g., food production), and our "world" will become very unpredictable (politically, economically, as well as shifting weather and climate).
What Does This Mean To You And Me?
Based on the data showing warming ( e.g., like those above for New England), whether one concludes Humans have caused global warming, accelerated global warming, or have reversed the Little Ice Age to Mankind's benefit, and how one defends their interpretation based on the complexities of the data and associated uncertainties is, in my opinion, irrelevant (if not amusing)... What matters is preparing for the economic and social disruption we absolutely know will result from rising sea levels that are already affecting water tables at the coast, shifting climate/agricultural zones, increase disease vectors, loss of species, etc.
As an aside, did you know that ~1/3 of US food production depends on bees for pollination, and that those bees now seem to be dying off (colony collapse disorder)? No one is sure of the cause, but a virus from Australia is among the leading suspects. I mention this just to make you stop and consider what might happen if the US lost 1/3 of its food supply! For instance, what effect would climate change have on the North American "bread basket"? Will the region in which we currently grow crops be reduced in area as climaet regions begin to shift, or will agricultural regions simply shift along with changing climate, given enough time to do so?
We should be working to minimize the magnitude of "disruption" by removing the extra variables (fossil fuels emissions) introduced by mankind so that we can better understand and model the natural systems and so that RCCEs don't catch us unawares. (Consider the Canadian ice storms of 1998 - what would you do in the middle of winter, no power for weeks, with 4 inches of ice on your roof? Or, consider the August 2003 heat wave that killed some 35,000 Europeans in just over one month, ~15,000 in France alone!) Besides, air and water pollution does a lot more than affect global temperatures, like stress the environment we depend on for life (desertification of particular concern for the US - believe it or not, perhaps Colony Collapse Disorder as well), so there are other reasons to change our lifestyles.
The following quote should lend some perspective...
The Pentagon has begun scenario-planning for abrupt climate change. A DoD-commissioned report from 2003 begins by noting that "there is substantial evidence to indicate that significant global warming will occur during the 21st century" and goes on to envision the consequences of one abrupt-change scenario that has increasingly captured the attention of scientists: the shutdown of the Gulf Stream, which could plunge most of Europe into a deep chill while the rest of the world continues warming. The report isn't terribly imaginative or grammatical, but it is based on sound fundamentals: "With at least eight abrupt climate change events documented in the geological record, it seems that the questions to ask are: When will this happen? What will the impacts be? How can we best prepare for it? Rather than: Will this really happen?"
The authors go on to conclude that, while superior wealth and resources would allow the US to adapt moderately well to such a scenario, we would find ourselves in a world "where Europe will be struggling internally, large numbers of refugees are washing up on [US] shores, and Asia is in serious crisis over food and water. Disruption and conflict will be endemic features of life." Such conclusions force us to consider the most cynical of all possible interpretations of our indifference to global warming: on some level, we believe not only that we'll be fine, but that our relative advantage over other countries will actually increase. Instead of yielding aspects of our dominance to bigger nations like China and India, we'll maintain our hold over a troubled world, an idea as unethical as it is dubious.
I chuckle regarding the statement of "superior wealth and resources" in light of Hurricane Katrina... I wonder what will happen when Miami gets hit (a 1 in 9 chance for category 3 or better storms, if memory serves.) in the same year as another coastal city - say New York City or Washington D.C.
Can We State Any Conclusions?
SO, the simple way of thinking about all of this is to first except that there is genuine scientific uncertainty regarding the magnitude of human contributions to global warming, but there is no debate (at least not among those actually doing research in the field!) that climate change is indeed happening, that humans play a central role, and there will be more losers than winners in the long run (despite claims by groups like the Western Fuels Association, for example, who spent $250,000 to produce The Greening of Planet Earth - a video that argues global warming is good because carbon dioxide is a fertilizer for trees and other plants, but didn't cite supporting research. And to be fair, Al Gore's documentary isn't exactly perfect either, but not intentionally so).
If you have actually stayed with me to this point, you might be wondering if I'm saying stop all pollution as quickly as is possible and take our chances with "cooling" even though I believe "warming" is easier for our civilization to handle. Yes, that is exactly what I'm saying. Why? Because "cooling" (or "warming" for that matter) that takes place over a few hundred years beats the hell out of living through (possibly) a RCCE with a global temperature change of 10°C (that's 50°F for us non-metric Americans) in a few as 10 years (some argue one to two years) as indicated by the climate record (from GISP2 in Greenland, Vostok Ice Core in Antarctica, etc.)! If that "flipping of a climate switch" were to take place now, well, just think about a winter in central MA with mean temperatures around 0°F for weeks. Remember to consider fuel supply and costs, demand for resources by other nations, etc. I think you get the idea this isn't a simple case of one bad winter.
Forget about global warming or the environment for just a minute and consider this: Can you imagine what might have been done with the ~$500 Billion spent on "Gulf War II" (so far) if that money were put towards the development of sustainable energy, rather than defending the very energy source that required the military intervention in the first place? Economically (and politically) we would be far better off. Add to this the concerns over global warming and the environment, and you have to wonder what the government we are responsible for is thinking about!
And just so you don't mistake me for someone wanting to live the life of our forefathers (check out 1900 House, Pioneer Valley , or Colonial House on PBS - no thanks!), whenever I hear someone advocating the idea that "ancient cultures" respected their environment (which is completely untrue) and that we should return to some bucolic age where man and nature peacefully coexisted - all was green and abundance the rule, no hunger or warfare, predator and prey living together side by side, etc., etc., I find it instructive to say something like "How far back in time would you like to go to restore your preferred natural systems? I'm partial to 18,000 ybp..." Once they figure out what I'm really saying is that I'm partial to the last ice age, and they would not likely agree, they realize they need what my climatology professor, Charles Wax (MSU), has been heard to recommend - perspective! ;-) Then I tell them to read two of Jared Diamond's books (Guns, Germs, & Steel, and Collapse) back-to-back, and in that order.
I admit that I have not covered as much material as I might have, probably more than you will actually read, but there is a lot of bad information out there on both sides of the debate, so I always appreciate having reputable sources. The references on this page are a good start, and there are others available.
-- Steve,
March, 2007
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