A Layman's guide in plain language
Why is it so Controversial?
@ Roger Halstead
Last updated 23 July 2010
As I'm still writing this, be sure to hit "refresh" to make sure you have the latest version.
North America and the Unite States is home to some of the most violent weather on the face of the earth so extremes are nothing new to us, but one *possible* result of research is beginning to point to the weather the world as a whole and the US in particular has experienced over the past few centuries is likely to have been more benign than would be considered normal according to geologic records.
Before I even start I should point out that one of the largest problems in the debate, both pro and con is a major portion of the population including those in our government do not know the difference between weather and climate. I'll repeat it later, but weather is what is happening now! Climate is weather *averaged* over a period, usually 30 years or longer. A single day, week, month, season, or even year that is above or below normal is no indication pro or con as to global warming. This past winter deniers pointed to both the heavy snows in New England and the deep South as an example that Global Warming is a hoax, but they conveniently neglected the warmer than normal North, and far above normal temps in both Greenland and Australia. By the same token those large areas with far above normal temps are weather, not climate. Also weather extremes including abnormally heavy snows "in some areas" are to be expected with a world wide warming. (Addressed latter in detail and with links) It naturally follows that if much of the world is warming, including the oceans which absorb far more heat than the land, then more water vapor will be given off to fall as snow in the colder parts of the planet.
I'm creating the following article in plain language for others like myself who may have a professional or scientific background, but who do not work in the field of climatology, or weather. I'm also including some background that may help in understanding why there is so much arguing and conflicting information *outside* of the mainstream science. I found taking introductory courses in weather and climate helped greatly in understanding beyond what "we said Vs what they said" in the news and on blogs. Although there are many blogs and some with good information, I've found that most on them who resort to questioning the credentials of the climatologists don't even have the credentials to question some one else's credentials. They are pretty much opinionated groups or individuals that are radically pro or con. Many of the arguments, pro and con, hang on political and financial reasons such as; if there is a financially or politically advantageous reason for something to be true or false then that must be the case. If they can find another way something can be done then any other way must be wrong, but any one who has done computer programming knows, most often there are many paths from point A to point B and often combinations of paths. There are a few who are capable of reasonably discussing the pros and cons, however if they are spending their time trying to discredit the top scientists they are unlikely to be legitimate sources of information. Also muddying the waters are the conspiracy theorists to whom it seems, everything must be a conspiracy.
Another point: Mistakes happen even in science. That is why they have the peer review process. Even then the occasional mistake makes it though. That mistake or those mistakes do not invalidate the science.
Unlike many pages by individuals or groups that are constructed in such a manner as to appear to be official, I'll tell you right up front, this is a personal view of the weather, the climate, global warming based on a basic knowledge of climate and weather, and the interpretation of a number of papers and articles published by those in the field along with agencies such as NASA, NOAA, and the IPCC . It is endorsed by no one, nor do I expect it to be. It is purely my interpretation of the information from those doing the work that is available to the public. At best, use the links for official information. It is also a work in progress and is far from complete. It will likely remain in a constant state of change as more is added, grammatical errors corrected, wording rephrased, content reorganized, new information becomes available, and my studies progress. Of course it may also stagnate due to periods of low ambition. In addition I'm trying to verify each statement with links back to, or traceable back to one of the prime sources of science while avoiding the lunatic left and right wings. They have a habit of latching onto a single point and then defending it beyond all logic, or common sense. If that fails they try to discredit the science and the people doing the science. Scientists who are also activists become a lightening rod for their discontent, but that does not invalidate the contributions made by that scientist.
I should add that Global Warming and Anthropogenic Global Warming are two different, but intertwined subjects with more or less the same outcome. It would be more accurate to call Anthropogenic Global Warming a subset of Global Warming referring specifically to the mankind's contribution to the cause. It's difficult to discuss one without the other and although the results are much the same they should not be confused. "Global Warming" is a generic term that refers to warming of the planet from all causes. Anthropogenic Global Warming refers only to how much, if any, mankind is contributing to the change. Using the term "Global Warming" as a generic term when talking about Anthropogenic Global Warming can be extremely confusing as well as diluting the overall subject of Global Warming. This article, being constrained by space (and time) will only touch on the high spots, but following the links should bring much more depth. Unfortunately understanding the issue requires a fairly good working knowledge of both climate and weather, or a lot of trust in those who are interpreting the data for you. As an aside, my degree is in Computer Science with minors in Math and Art along with a strong background in chemistry and physics. That experience alone has led me to the conclusion that "in general" most scientists are not well versed at explaining their fields or subjects in plain language, or in such a manner that "the-man-on-the-street" can understand well. And herein lies the problem, these scientists who are well versed in what's going on are competing against a well run, well paid, PR campaign run by non-scientists that do not care about science unless it agrees with their agenda. We would do well to remember that coal, oil, and the automotive industries are tremendously profitable fields (neglecting a few bumps and bankruptcies) that are likely to do all they can to maintain the status quo. On the other hand the automotive industry has not been in the best of health lately and is somewhat inclined to embrace "green" from both a mileage, technological, and PR approach. It is after all very good PR. You have probably already noted the add campaign supporting "clean coal". However they seem to be pointing out some misconceptions about "green power" and particularly solar and wind power. Remember how much the coal industry stands to gain or lose in the present controversy. I think it's also necessary to point out that the "popular press" and the "Network News" are not normally considered places to pick up reliable, scientific information. Politically and scientifically the press is not the place to expect accurate and unbiased results. Remember they quoted Al Gore as saying he invented the Internet, which he did not say or claim. On the other hand, he is pretty much responsible for the Internet as we know it today as he was head of, "and cheerleader for" a government committee that provided money to researchers to develop the Internet.
A quick search on the Internet will show that one of, if not the major difficulty in being properly informed about global warming and in particular, anthropogenic warming (caused by mankind) is the tremendous amount of information available with much of it conflicting and/or false. Quoting from the linked NY Times article, "George Monbiot, a British environmental activist and writer, said that by promoting doubt, industry had taken advantage of news media norms requiring neutral coverage of issues, just as the tobacco industry once had. “They didn’t have to win the argument to succeed,” Mr. Monbiot said, “only to cause as much confusion as possible.”
I dislike using a newspaper article as a reference, but in this case they do cite sources. Much of the misinformation is intentional, and/or opinion masquerading as facts. This makes it difficult to figure out what is real and what is just someone's opinion. Many fear the cost of admitting we need to do something about the problem and figure if they create enough confusion they can sway public opinion or create enough confusion that either future Administrations, or even future generations with have to deal with it and not them. Others figure if it does exist the results will not be noticeable in their lifetimes (which may not be true), so why bother. That leaves the mess for following generations to clean up much like the politicians and their deficit spending. Of course that is assuming the mess can be cleaned up or even moderated. The longer they can put off the inevitable the more money that can be made from fossil fuels and that is one big, well heeled lobby. That would be difficult if not impossible to overcome. Still, most of the things we need to be doing to become energy independent are the same we would be doing to counter Anthropogenic Global Warming, which is, or will likely become a security issue for many countries. Although there are many, accurate, and informative blogs available on the Internet, it is best to stick with the large organizations such as NOAH, NASA, the IPCC, and scientific institutions for reputable information. Many hotlinks are already included, but more will be included to the articles and papers to give each statement a logical and reputable reference.
One item of contention has been the accuracy of dating techniques, but with cross referencing multiple methods we can get within a few thousand years all the way back to the extinction of the Dinosaurs, 50 million years ago and that is normally "good enough". Even though we may not get the year we can get the order of progression. Another problem is many people have difficulty trying to understand the use of proxy data to infer temperatures and dates. Surprisingly we need only relative dating for many things with one being carbon forcing. There is an interesting page titled "Radiometric Dating, A Christian Perspective" that gives a very good scientific description of radiometric dating as well as multiple dating methods. It also explains and corrects many misconceptions about radiometric dating. Ice cores now go back over 400,000 years which includes over one complete period of glaciation including both recent warming periods along with the Younger Dryas period of glaciation between the warming periods. That gives us the ability to view basically two periods of warming along with carbon forcing. (Carbon forcing is the release of CO2 from the oceans due to warming). It also shows that the associated CO2 rise followed the previous cycles of warming. I will come back to that later. Another problem is local or even continental weather is often taken by many to include the rest of the world, which may be doing something entirely different such as a recent cooling period in Europe while most of the world was suffering from higher than normal temperatures. A good example is the extreme drought in the Atlanta GA area which suddenly reversed this past year with severe flooding. When the years are taken together they are within a few tenths of an inch for the average rainfall in the region. Here in Michigan we had slightly warmer than normal winter temperatures with just a few cool weeks being the exception while the southern states had notably colder temperatures due to the Jet Stream going much farther South than normal. While much of the Southern US was shivering in the cold and snow, Greenland in the North and Australia in the South were both suffering from temperatures far above normal. Here in Michigan our winter of 2009-2010 was above average except for only a couple of weeks that were normal or slightly below normal.
As time goes on, dating techniques are becoming more accurate and our knowledge of previous cycles of glaciation and warming is improving. Typically, older works are less likely to be representative of actual conditions and trends. For instance one page I found was talking about increased solar activity while we have been in an extended quiet period which "appears" to be ending with the beginning of a new sunspot cycle. Even then, the new cycle is *forecast* to be one of comparatively low activity. Current solar activity can be seen at the NOAA Space Weather page
Global Warming is a far more complex subject than it is typically presented in the press or on many blogs. Although an over simplification, there are basically three greenhouse gases of primary concern. Carbon dioxide (CO2), Methane (CH4), and water vapor (H2O). The primary effects of CO2 are pretty well known and fairly long lived in the atmosphere. Methane is about 20 times more effective than CO2 as a greenhouse gas, but it has a relatively short lifetime of about 12 years in the atmosphere where it breaks down into CO2 and water by reacting with the hydroxyl radical OH in the presence of Ultraviolet light. The amount of CH4 in the atmosphere has doubled in the last 200 years, but there is still considerably less CH4 than CO2. Although increasing at the rate of about 1% per year in the later 20th century, the amount appears to have leveled off.
If the Southern edge of the permafrost keeps moving Northward the amount of CH4 released could increase rapidly and to significant levels. Also, the indications from past warming trends show the amount of Methane in the atmosphere is related to the temperature, or CH4 forcing. The amount of water vapor on the other hand is dependent on temperature and also limited by the same. Unlike CH4 and CO2 the amount of water vapor can not exceed a specific amount for any given temperature. In Other Words, the only way to get more water vapor, or humidity is to first warm the atmosphere so it can hold more water vapor. Then the water vapor, although a very effective greenhouse gas (more effective than either CO2 or CH4), serves as a limited positive feedback system as the amount is limited by the laws of physics. We should not forget that burning fossil fuels also releases Sulfur Dioxide (SO2) which quickly combines with water to form sulfuric Acid (H2SO4) in the troposphere. H2SO4 is an aerosol which is quite effective in reducing, or counteracting the effects of CO2 and the other green house gases. But it is very short lived compared to most of the green house gases with a lifetime of only a few days. It's estimated that the total aerosols are effectively cutting the effects of the green house gases by as much as 50%
Depending on how you look at it; although we are still technically in an ice age, (the poles are still glaciated) the period of glaciation began its end about15,000 or 11,000 years ago with a relatively abrupt warming of about 10 degrees C or 18 F for each period. Surprisingly the warming was not slow and steady, but consisted of two of these abrupt warming periods separated by a drastic cooling period called "The Younger Dryas", that may have been more extreme than the peak of of the previous cycle of glaciation. Whether the Younger Dryas was created as a natural byproduct of the rapid warming or and external force is up to debate. There is competition between two theories on the creation of the Younger Dryas; The accepted has been the Younger Dryas was caused by an interruption to the North Atlantic "Conveyor Belt", but a mammoth asteroid air burst over Canada similar to the Tunguska event over Siberia, only much larger is gaining ground. Residue has been found well into the state of Ohio. More astounding, the Younger Dryas apparently ended far more quickly than was accepted as possible until recently. It appears the ending took only 40 to 50 years, or possibly as little as a couple of decades. If these events took place this quickly as the results of natural change then our climate is far less stable than we've believed and much more sensitive to abnormal input. However the confusing factor is equatorial and southern oceans cooled *before* the Northern areas which "to me" casts some doubt as to the cause. Although if the water flowing North from the Southern and Equatorial regions was already cool I would think it too could interrupt the "conveyor belt" once it reached the Northern waters where it normally warms Iceland and Northern Europe before descending and returning to the South as a deep ocean current.
These periods, apparently took less than a couple of decades each or at least less than the span of a person's lifetime. This is contrary to the belief held until recently that these changes took from centuries to millennia. The earth appears to be very good at trying to keep things "as they are". In other words, weather will try to compensate for abnormal conditions some where with the opposite some where else such as drought in the SW US and floods in the SE US, or abnormally hot seasons followed by abnormally cool, or cold seasons. A better way of thinking might be to look at this as the earth's climate "inertia" instead of using anthropomorphic terms. Assigning anthropomorphic processes, or names to natural processes confuses the issues. Since the peak of glaciation, ocean levels have risen about (400 feet) and about 9 million square miles of land have been submerged.
Although its highly unlikely to happen, (but not out of the question either) were all of the earth's current ice to melt (both polar ice caps, including Greenland as well the smaller inland glaciers ) ocean levels would rise about another 240'. The IPCC's estimates of ocean rise have remained ultra conservative and have been repeatedly updated to higher figures. On an additional note, Greenland reputedly holds enough ice, that were it to melt, it would add enough fresh water to raise ocean levels about 20 feet. Fossil records, some in old limestone quarries in Florida, show that sea level has been higher than that in the past. In addition adding all that fresh water from glacier melt could have dire consequences for ocean circulation and particularly temperatures in Iceland and Northern Europe. That is not to say they'd go into another ice age, but would probably enjoy the same temperatures of others at the same latitude rather than their current warmer status.
According to mainstream science the earth has warmed nearly one degree C on average over the last century, but that appears to be accelerating . While 2009 appears to be the 5th warmest year on record (NASA UPDATE 2009: Second Warmest Year on Record; End of Warmest Decade ), the 11 hottest years on record occurred in the last 13 making the last decade the hottest on record. IF the warming conforms to evidence for those periods in the past, the warming will not be a steady increase. It will rather consist of both warming and cooling periods and more extreme/abnormal weather. (As I type this the southern states are getting record setting winter storms and within the last two weeks the North East costal areas have received enough snow to set seasonal records, not just storm records. Conversely southern Greenland and Australia are setting records for high temperatures) The IPCC has consistently been overly conservative on their estimates of projected seal level rise for this century, but the latest forecast is close to one meter (more specifically 800mm) of sea level rise by the end of this century. This figure has been changing rapidly as they learn more about the dynamics of glaciers such as how fast they are melting, how fast that melting is accelerating, how fast their flow into the ocean is accelerating, and the effects of a tremendous amount of cold, fresh water entering the oceans. Even as estimates are revised, we find nature is out pacing us.
Few using scientific principles would deny that the earth has gone through many cycles of warming and cooling (glaciation) throughout it's existence. Although the reasons are complex the main underlying cause seems to be variations of the earth's orbit referred to as Milankovitch Cycles, or at least it has in the past. The effect is greatest when the three elements of the Milankovitch cycles coincide. These are the tilt of the earth's axis which varies from 21.1 to 24.5 degrees over a period of about 41,000 years. The eccentricity of the earth's orbit varies from nearly circular to oval over periods of 100,000 and 400,000 years which are believed to be caused by Jupiter and Saturn. A third component is the “Precession of the equinoxes” and occurs on a 22,000 year cycle. " The closest approach of the earth to the sun is called perihelion, and it now occurs in January (January 6th), making northern hemisphere winters slightly milder. This change in timing of perihelion is known as the precession of the equinoxes, and occurs on a period of 22,000 years. 11,000 years ago, perihelion occurred in July, making the seasons more severe than today. (Hotter summers and colder winters) The "roundness", or eccentricity, of the earth's orbit varies on cycles of 100,000 and 400,000 years, and this affects how important the timing of perihelion is to the strength of the seasons. The combination of the 41,000 year tilt cycle and the 22,000 year precession cycles, plus the smaller eccentricity signal, affect the relative severity of summer and winter, and are thought to control the growth and retreat of ice sheets." The energy the earth receives from the sun varies by over 100 Watts per square meter with these cycles. Plate tectonics has also been a major contributor to climate change as well, but not of the periodic type. It has served to either accentuate or moderate the changes. Before North and South America became attached there were ocean currents flowing between the two continents and most of the earth was much warmer than at present.
There is also the variation in the output of the sun, based on the sunspot cycle of roughly 11 and 22 years . However, according to the NOAA Climate and Global Warming Q & A page " the contribution of direct solar irradiance forcing is small compared to the greenhouse gas component. "
As to the “rate-of-change” a graph of the glaciation cycles looks like a “saw tooth” with a gradual decline in temperature followed by a relatively rapid increase to the peak. These periods of rapid change are also filled with the weather “seesawing” back and forth between warm and cool with lots of variability. Still there are those who argue the variability of the sun as if it were the only contributor (even though the change is almost negligible) while neglecting the Milankovitch Cycles along with all of the other contributors.
So that leads to the subject of Anthropogenic Global Warming, or global warming caused by mankind. Does it or does it not exist in whole or as part of the current warming trend?
Anthropological Global Warming is now almost universally accepted by those in the field. However due to the seeds of confusion sowed by industry, with the "man-on-the-street", the contention is whether anthropogenic global warming exists, or even if global warming exists. Not only are there individuals who deny global warming exists, there are politicians who also deny it let alone accept the possibility that mankind has made any contribution. Many think it is just a reason to raise taxes, while others think it's a way to hold the auto industry hostage. In other words, if it is possible for some one to gain by the existence of global warming, then it must be a conspiracy. This has led to some strong polarization between the two sides. Of course politics, economics, and even religion at times have been major players with some concern that any efforts to mitigate the release of CO2 will have damaging, or even catastrophic effects on manufacturing and the economy. Some the more passionate and powerful, hired think tanks to discredit the theory (Check History in the menu) and this has led in part to the publishing of false and/or misleading information. Many have done their own publishing. According to a recent news release, a large chemical company (Dow Chemical) has reduced its emissions and CO2 by well over 20% (while increasing profits) which is contrary to what others are saying would be too costly for the economy , let alone be profitable.
To even address the issue we first have to understand the differences between weather and climate.
In the simplest terms, weather is what is happening “now” while climate is long term. Like the swing between drought and flood in the South along with the frigid Southern temperatures and way above temperatures for Greenland and Australia. By convention climate temperature is measured on a 30 year running average. Shorter than that and the trends would be drowned out by short term noise of weather variations such as anomalous hot or cold, wet or dry seasons, or even years. Make the period too long and the trends would be lost.
First: Although there are local
short term variations, Global Warming is well documented and does exist. Cycles
of warming and Glaciation have existed for millions of years.
It should be noted that conditions such as El Nino and El Nina can greatly confuse the issue as El Nino is associated with warmer than normal equatorial Pacific surface waters, while El Nina is associated with cooler than normal Equatorial surface waters. El Nino has a strong effect on US weather patters including the amount of rain fall and tends to keep the jet stream farther to the North resulting in warmer than normal weather while El Nina has the opposite effect. The affects can be dramatic, affecting world wide temperatures and weather patterns to the point of over riding warming or cooling trends. At present we are in an El Nino warming cycle that started in mid 2009 and has apparently raised world wide land and sea temperatures. Taken by themselves El Nino and El Nina are weather pattern cycles. Only when we look at the long term trends does warming or cooling become a climatic problem.
Second: science has shown the periods of glaciation follow the Milankovitch cycles with the coincidence of those cycles leading to greater extremes.
Third: Each Interglacial period of rapid warming has been *followed* by increased CO2 in the atmosphere along with an increase of CH4.
Fourth: Dating techniques are sufficiently accurate to measure relationships within the previous warming trend and beyond that, relative dates serve as well. IOW we really do not need highly accurate dates, or ages when looking at *relationships* in ice cores and fossil records. Dating techniques are accurate enough to say what the climate has been like with 1% or better accuracy back into the millions of years.
Fifth: Even large volcanoes only affect the weather for a few years unless one refers to the Siberian and Decan (India) Traps which both appear to have been the precursors to mass extinctions. The Siberian Traps are believed to have initiated circumstances that lead to the Permian extinction where it's believed over 95% of all species on earth went extinct.
Sixth: Aerosols are estimated to be counteracting as much as 50% of the effects of the green house gases currently in the atmosphere. This has some rather dangerous connotations. If proven out it makes the green house gases a ticking time bomb because of the short lifetimes of the aerosols, while the green house gases are much longer lived. In other words the longer we keep building up the green house gases while adding short lived aerosols to counteract them, the more "potential warming" we have waiting to be released when we try to fix things.
Seventh: If the Younger Dryas ended as abruptly as is indicated by ice cores, then our climate is truly fragile to the point of being, or close to being, unstable and very sensitive to abnormal inputs. If on-the-other-hand the Younger Dryas was caused by external forces (high altitude asteroid burst) along with its very abrupt end, then it appears to me that our climate might be more stable.
Eighth: New studies are showing that the climate throughout known history has been quite stable, but this may not be the norm. On the contrary, Paleoclimatology appears to be showing that the climate has been highly volatile even in the interglacial periods and the relatively calm weather we've experienced over the past couple of centuries is atypical instead of typical.
Ninth: Yes the CO2 levels have been higher in the past along with higher temperatures, but that was on an earth quite different from what we see now, with sea levels several hundred feet higher and with a great deal of the land mass being desert. Also evidence shows the increased amount of CO2 in the atmosphere on previous warmings has followed the temperature rise while this time the increase of CO2 in the atmosphere is leading the temperature rise.
Tenth: The ocean's ability to absorb CO2 appears to have taken scientists by surprise. It is slowing the rate at which the amount of CO2 in the atmosphere is rising by absorbing a great deal. Unfortunately the unwanted side effect of this is the acidification of the ocean waters. CO2 in water forms Carbonic Acid which kills coral and dissolves limestone. Some areas of the oceans have shown alarming levels of acidification.
To be able to predict where the climate is going, we need to know where its been and how it got there. The problem is, with few exceptions, written information only goes back to to around the mid 1800's. Beyond that we have to resort to using what is called. proxy data The study of ancient or prehistoric climate is called, Paleoclimatology and includes tree rings, pollen, ice cores, sediments, sedimentary rock cores, and coral among other fields. NOAA has comprehensive information available that allows them to put together accurate representations of the climate far back in time. Ice cores which now go back 400,000 years contain samples of the actual atmosphere at any given time. When the dust, pollen, and their position in the ice core are analyzed, composition, order and dates can be calculated with sufficient accuracy to see what the climate was like and how it changed in the past.
Something else with which we need to become familiar with is the "Carbon Cycle". As a rough and short explanation; plants grow using photosynthesis by using CO2 from the atmosphere and releasing O2. The amount of CO2 cycles from a low through spring and summer growing seasons in the Northern hemisphere as the plants use CO2 to grow and release O2 in the process. In the fall the amount of CO2 increases as the plants die, or go dormant. However much of the Carbon is stored in the dead plant mass which given enough time under the proper conditions can form coal or crude oil. On a more human recognizable scale, large amounts of methane are also formed when the plant matter decays in an anaerobic environment (very little Oxygen present) such as in swamps and peat bogs. The reason for the cycle being tied to the Northern hemisphere is the majority of the earth's land mass is North of the equator. Water vapor absorbs CO2 to make a weak solution of Carbonic Acid. The ocean surface also is a great absorber of CO2 under normal conditions, also forming Carbonic acid. Microscopic foraminifera use the CO2 to grow their skeletons. When the foraminifera die their skeletons sink to the bottom of the oceans where they form layers of calcite which eventually becomes limestone. Under pressure and low temperatures (currently around 300 feet and beyond) Methane reacts with the water forming methane hydrate which looks much like frozen water. With the passage of millions of years the ocean floor, along with the lime stone is subducted below the continental plates where the heat and pressure cause the carbonates to decompose and the CO2 is eventually released through volcanoes along with SO2.
So, what is different that science can say with any degree of certainty that the climate change is faster than natural, or different than natural?
The major difference, this time the CO2 increase is leading the temperature rise by a notable margin while the oceans are taking up substantial amounts of CO2 rather than releasing it even though they are warming. CO2 increases have followed from carbon forcing in previous periods of warming according to ice cores and fossil records.
According to interpretation of the Milankovitch cycles we should be entering a gradual cooling phase , but nothing drastic for at least 25,000 to 50,000 years. Instead we are warming. As for direct solar forcing the sun has been in a rather inactive state for some time, but it may take the current solar cycle which has just started before we can be sure whether this is short term, or something more akin to the Maunder Minimum (roughly 1645 - 1715), but even another Maunder Minimum would not be enough to reverse the course of Global Warming. Another point of contention was the “We may be headed into another ice age” a few years back, but that was the press running with only a partial story. The original statement was based on increasing particulate pollution in the air causing cooling. As European nations have been reducing particulate pollution the temperatures down wind have been rising noticeably, but there isn't enough information available to make any real prediction. Also in Alaska the warming has been more than 5 degrees with the permafrost line moving North by about 350 miles in just the last few decades. Here in Central Michigan the winters are now over 5 weeks shorter than they were 50 years ago. The length of winter is determined by the Department of Natural Resources observing when specific lakes freeze over in early winter until open water is visible in the spring. We used to have our first real snow in October. This year it was in December. The Arctic is expected to possibly experience ice free summers in just a decade or so. Also due to the inconsistencies or warming and cooling periods within the warming trend, we may actually see some of the identifiable adverse effects within the next decade or two if we haven't already. If the oceans were not absorbing CO2 as fast as they are (which is far faster than expected) we would be seeing a much greater temperature rise. Were it not for particulate and aerosol pollution we would also be seeing about twice the increase. If the warming trend continues, eventually there will come a point where the effect will reverse and the oceans will be releasing CO2 in a positive feed back cycle that will accelerate the warming even faster. As the temperature rises still more, the oceans will start releasing CO2 as they have in all previous warming cycles, but if the warming continues long enough, the oceans will eventually reach the point where the vast reserves of Methane Hydrate will be released. It is conservatively estimated that these hydrates contain twice the amount of carbon contained in all of the world's known fossil fuels. The ability of the oceans to absorb and release CO2 is a complex issue of which part depends on water temperatures as well as temperature differences between equatorial and more Northern regions.
Based on both the timing of the temperature increases along with the rise in CO2 and CH4, when some of the natural drivers of the warming and cooling cycle indicate we should be moving into a cooling cycle, and aerosols are negating about 50% of the green house gas effects, it appears Anthropogenic Global Warming is quite real. However that raises the question: "How much affect do the green house gasses emitted by mankind play in the role of global warming. According to the NOAA page http://www.ncdc.noaa.gov/paleo/globalwarming/end.html " The best estimate is that about 50% of the observed global warming is due to greenhouse gas increases. (Their page last updated 18 Feb, 2009)
BUT Whether the warming is natural, Anthropogenic, or a combination, what can we expect and when? Can we stop or reverse the changes and if so, should we try? Would reducing the release of the primary greenhouse gases be possible soon enough to make a difference? Could we reduce their release enough to matter? Could we afford to do so? Could we afford not to do so (business as usual). Business as usual appears to be a very risky approach given the role played by aerosols. For the companies that have tackled the problem they appear to be doing quite well financially. Will the rest of Industry and power generation be capable of following suit? Only time will tell, but at least this tells us that it is possible to move to renewable energy in an economically viable way. At what scale remains to be answered.
What will global warming bring? That's where things get complicated as the climate is controlled by a number of interacting and sometimes delicate influences which are different in different parts of the world. Inland areas are affected differently than coastal areas. Polar regions are still different with warming in the Northern latitudes being far more than the world average. This is resulting in less snow cover which reduces the albedo ( reflectivity) of the surface be it land or water. This causes more heat absorption which again is a positive feedback cycle that increases the rate of warming as well as the magnitude. But with the North warming more than the equatorial regions, that reduces the difference in temperature and that affects everything from the trade winds to storm patterns over land and water. Unfortunately it's not at all that simple. Reducing the trade winds reduces ocean currents. Cold, polar water normally descends and heads back South as deep ocean currents. With glacier melt water being warmer and less dense than the present salt water there would likely be no down flowing water to keep the deep ocean currents running. This would result in a cooling for Greenland and Northern Europe, but it's unlikely to be the herald of another ice age. Instead those areas would probably end up with a climate similar to other areas at the same latitude which would drastically alter crop production in those areas. With the Northern warming, the permafrost line is moving North and that is releasing a lot of Methane which is a much more efficient greenhouse gas than CO2. In the past the desert in the SW US has extended from the Gulf of Mexico well into Canada. Desertification is presently spreading and there is no reason to believe that a wide area from the Gulf and well into Canada will not repeat the past. Sea level rise is certainly going to become a problem, but at present, when and how much is also complicated and still a question that depends on how much polar ice melts. Then there is the current warm area covering Iceland and Northern Europe while Greenland at the same latitude is covered by large and very thick glaciers. That area is warmed by the Gulf Stream and should it be disrupted, Iceland and much of Northern Europe could become rather frigid compared to their relatively mild climate at present. What that would do to the nutrient rich, cold water upwelling along the coasts and how it'd affect the fish populations is another matter. The effects of El nino are varied and wide reaching. When coastal waters are warmed by El nino the coastal upwelling along both North and South America are greatly reduced in size or disappear altogether in some instances. Without the nutrient rich waters from the depths, there is much less plankton at the bottom of the food chain to feed the fish. That affects every thing from the fish populations to the animals that eat the fish which includes the availability of food for humans. This also has a strong effect on the North American climate.
NOTE: This winter (2009-2010) while the Southern US and Europe have had abnormally cool, or cold conditions, Greenland and Australia have had far warmer temperatures than normal. Now, 6 months later (2nd week of July) the US is suffering from abnormally high and wide spread temperatures with a number of heat waves from New England/Washington DC to the West coast with floods in Northern Mexico, parts of Texas, and the central US.
Also in doubt are storms. Storms are powered by heat, moisture, pressure differentials and terrain. Warmer climate means the air can hold more moisture and that means stronger storms, but with the temperature differential between latitudes being less there should be less circulation between North and South resulting in milder winds. Unfortunately it's just not that simple. Certainly "it seems like" hurricanes over warmer ocean waters would become both more numerous and stronger because they are fueled by the warm water. Certainly hurricane Katrina and the damage to New Orleans would seem to bear this out, but as we've seen in the 2009 season, it isn't necessarily so. Although there were many, strong hurricanes in the Pacific, the Atlantic season was relatively mild due mainly to the presence of a moderate El nino and unfavorable, upper level winds. Are the storms on land and oceans truly becoming more frequent and stronger? The answer is "most likely", but only time will truly tell. The big problem is that with the tremendous inertia present in the climate, if we wait until evidence is undeniable, it may likely be far too late to be able to safely alter the outcome.
Another problem that has been identified, measured/confirmed and brought up at the IPCC conference is the acidification of the oceans that has already occurred. The acidification is due to the dissolving of CO2 in the water creating carbonic acid. Perhaps if the growth of foraminifera which uses CO2 to create it's calcite skeletons could be accelerated to remove more CO2 it would help offset the increase in the atmosphere. It is after all, natures own method for trying to keep the atmospheric CO2 in balance. The foraminifera grow, die, and their skeletons drop to the ocean floor forming layers of calcite that eventually becomes limestone.
To Summarize: Global warming of more than a few degrees would end up in substantial sea level rise which could vary from a few feet to maybe 20 feet although it could be much more. This could vary from a big problem to catastrophic, changes in weather patterns, spreading of desertification, excess precipitation in other areas, acidification of the oceans, severe shortages of fresh water, severe drops in fish production from the oceans, and large coastal areas around the world being inundated with millions being displaced. The possibilities are tremendous.
Why is Global Warming, and particularly Anthropogenic Global Warming so controversial? The short, quick, and accurate answer is money and mankind's innate inability (and often outright refusal) to take responsibility for our actions and the appalling inability to recognize and understand the difference between weather and climate. The slightly longer but more accurate is money, politics, and worry about having to change the way we do things. Whether pro or con, if you play to, or on people's fears you can gain a strong following. It is also far easier to find fault and/or condemn than to add constructive criticism and even easier to discredit the researcher particularly when one can remain anonymous on the Internet. Some individuals just like to be contrary and doing so anonymously gives them free reign. So, in this case we have ended up with two rather vocal groups, including politicians, with little or no expertise in climate science that have been convinced that Anthropomorphic Global Warming is bad, good, a scam, a dangerous problem, will cost jobs, will create jobs, will make our cars cost so much they will not be competitive, or will make them so efficient that everyone will want them. Of course there is also the "if you can't beat the opposing side's arguments with facts you try to discredit them. This gives the conspiracy nuts a lot to work with. I'm from Michigan where the unemployment is almost twice the national average as our government is grafted at the hip to the auto industry. Care to guess which side of the argument is predominant in this state? We are also one of the few states left without a "Right to Work" law with over 50% of our college graduates leaving the state. Now the Feds are trying to sneak through what would be forced unionism across the country. As of this date it has made it through the house.
Another argument is: "If the climate is warming why are we seeing more snow fall in Northern Greenland and central Antarctica? It's a relatively simple answer. Warmer air means more moisture. The areas in question are very cold with very low humidity. That cold air can not hold much in the way of moisture, so when the air over water warms, it takes on a lot of moisture. When it passes over these cold spots it shows up as increased snow fall. http://www.texasclimatenews.org/TCNJournal/21410Warmerclimateheaviersnow/tabid/1518/Default.aspx discusses this in detail.
Still another very narrow, jaundiced, and faulty logic is "Global warming is another way for big business and industry could make money, Therefore it must be true they are manipulating, or fostering a hoax." Faulty logic aside, it's to the advantage of big businesses, industry, and the government (and far more convenient) if global warming were not a reality.
I wanted to avoid politics in this but it turns out to be almost impossible to separate politics from Global Warming. A CBS "60 Minutes" interview with Dr James Hansen (head of NASA's institute for studying the climate) and references from other leaders in the field of Climatology titled " Rewriting the Science" (Story may require logging in) gives a peek at how far the previous administration went in limiting, or distorting information to the public so as to minimize the apparent potential of Anthropogenic Global Warming. This added a great deal of confusion that is still present in the public. I would be amiss if I didn't include the Clinton Administration tried to influence the research to maximize, or exaggerate the potential. So, distorting the science to present an administration's view to the public is nothing new. Being head of the NASA climate program and an activist makes Dr Hansen a lightening rod for those who disagree with him. Due to his position within NASA and his activities, he seems to have picked up a following that try to discredit both him and his information.
Whether natural, anthropogenic, or a mix, I have a feeling based on the past record that we are going to see the results of Global Warming far sooner than most have imagined.
Locally: In a state who's power usage has dropped between 12 and 20% the power companies still want to build new, coal fired power plants. Two plants were recently turned down as they couldn't show a need for the extra power what with the drop in use figures. The power companies have said these plants will create few, if any jobs. They've said they would be much cleaner and more efficient than the old plants in service, but they've refused to commit to shutting down any of the old plants. So what has happened. A House bill ( 5220 ) was introduced to make it illegal for the state to require the power companies to show need to build new plants. Now why would any one create such a bill unless they were getting something out of it? They will create few if any jobs according the the power companies, we don't need the power, and they will not commit to using them to replace outdated and inefficient power plants. Given that, what does the state have to gain by letting them build the plants? One additional note: They were given the "clean air permit" in early January after stating the new Essexville plant would add about 850 Megawatts of capacity, while they would be phasing out over 900 Megawatts of outdated and inefficient generating capacity. After stating the new plant would be creating well over 1000 construction jobs and 100 permanent jobs they were given the permit. This is the same plant they said would have little or no impact on the local economy and create few if any new jobs less than a year ago. If they are adding 850 Megawatts of capacity using a more efficient technology while eliminating over 900 Megawatts of the older and less efficient technology, I'm having a problem seeing where they are going to be adding 100 permanent jobs to the state, particularly after they originally said they would be adding few if any jobs. Then again, they may mean adding jobs here while eliminating others around the state? Note they said they will be phasing out capacity, not shutting down plants, nor did they commit to any schedule.
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