We now turn our attention to the issue of Global Warming. As with any issue, there are a spectrum of views on it, with the inevitable, and unfortunate, extremes. This spectrum of views, combined with demagoguery, and the lack of scientific understanding for those coming out of the American public school system, all contribute to confusion on the issue. It would be best if people would read the scientific papers themselves, but most people rely on the mass media, politicians, and Hollywood for their information - and all three are hideously poor sources for accurate scientific information. So we will here attempt to clear the air. I have attempted to be concise, but the scope of the issue and the lack of knowledge of the "man on the street" requires a more lengthy article than usual.
Note: I will intentionally use the terms "mean" and "average" interchangeably herein. This will undoubtedly make statisticians cringe, but our audience is the average person (or is that the mean person?). It may be less accurate, but should have no relevance to the actual points we will make.
What is Global Warming?
It doesn't take a genius to see that the term is comprised of two words: "Global" and "Warming". But exactly what is meant by these terms?
Let's tackle "Warming" first. This means an overall increase of temperature over time. If the increase occurs over a long-enough period it can be considered a trend. There is no accepted definition, that I'm aware of, of how long a period of time is required for a trend. However, paleo-climatologist Bob Carter suggests that it has to be a minimum of one decade. The reason is that temperatures fluctuate - sometimes higher and sometimes lower. In a period of less than ten years it is difficult to tell if a dip in temperature is a temporary "glitch" in an overall warming trend, or if an increase in temperature is a temporary bump in an overall cooling trend. Therefore, to determine if there is warming, we must measure over relatively long periods of time.
Now about the term "Global". First, it is a reference to Earth. There have been reports that warming appears to be happening on Mars and Saturn. This is interesting, and might be used to support certain viewpoints, but is irrelevant to the definition of terms. Second, the term global is important in terms of measurement. In terms of global warming, the temperature refers to the temperature at, or near the surface of the planet. The inside of the Earth is very hot indeed, as are the uppermost reaches of the atmosphere. The bottom of the oceans is very cold and that is not likely to change anytime soon. But at the surface of the land and ocean, and in the lower atmosphere, where the main source of energy is from the sun, is where we measure the temperature. The "global temperature" is an average of all temperature measurements across a representative portion of the planet. Note that certain portions of the Earth may cool and others may warm over time, but as long as the average temperature increases then we can say there is warming. Further, seasonal variations mean that we can't analyze the average temperature for a given year until that year is over. An extraordinarily warm summer means nothing if the rest of the year is extraordinarily cold. So the annual mean of the aforementioned averages is what must be taken into consideration. The actual statistics used for calculating global warming are more complicated, but the basic idea as stated is, I think, adequate for non-statisticians.
So, to summarize, "Global warming" means that for periods of at least ten years the average of all temperature measurements for the Earth show an increase.
Is there Global warming?
Now that we've defined what is meant by Global Warming, the next question is whether or not there is any.
Over the course of history it is apparent that the global temperature has increased and decreased significantly. I am unaware of any scientist that would deny this. So certainly, there has been global warming in the past. The conditions that caused the cyclic climate changes are expected to continue in the future (again, I am aware of no scientist that would dispute this), so we can be fairly certain that there will be global warming in the future. The question, then, is whether there is global warming in the present.
The question is often phrased by non-experts as something like "Are we currently experiencing global warming?". Any respectable climatologist would respond "We don't know". The reason being that, as stated above, until the end of the period of measurement (say, annually) we do not have all the data necessary to make that determination. A better question would be something like "Have we experienced global warming up through last year?" On a personal level, the climatologist could believe one way or another. But to make a categorical scientific statement in the absence of supporting data (or any data) would be irresponsible. That is not to say that a probability could not be assigned based on incomplete data and the historical record. And perhaps a climatologist answering "yes" the the first question is simply using a short-hand means of saying that he believes the probability to be be greater than 50%. However, such an answer would be sloppy at best.
And now, let's examine the data being used to discern if we are presently experiencing global warming. Note that "presently" in this context means "up to the end of 2008".
With satellites, the surface temperature of any point on Earth is measurable. Prior to temperature-sensing satellites, the temperature measurements were almost entirely done on land - and specifically land where there were people available to regularly measure. I do not know when the first regularly temperature-sensing satellites began operation, but it certainly does not extend back before the 1970s. Thus, true global measurements have only been available for less than the last 30 years. However, in the absence of evidence to the contrary, there is no reason we cannot extrapolate back using the data we have. For the USA, we have a contiguous record back to the early 1900s for most of the country, and even earlier in certain populous locations. Likewise, temperature records go back to the late 1800s in parts of England. Before that, we have occasional measurements, but we need to rely on other techniques for determining past temperature. Fortunately, we have several "records" preserved in Antarctic and Greenland ice, lake and ocean sediments, tree rings, and even stalactites in caves. Although it is not possible to assign absolute daily temperatures using these methods, they can serve to provide a general idea as to global temperatures back to before the last ice age. For our purposes, that should suffice. Here I will recommend the first chapters of "Unstoppable Global Warming every 1,500 Years" which describe these techniques and what the record says. Note: the rest of the book is primarily an attempt to debunk the United Nations Global Warming reports. However, that issue is outside of the scope of our analysis.
So what does the data tell us? It seems pretty clear that temperatures have been rising, in fits and starts, over the last 150 years, with 1999 being officially the warmest year on record. Note that from 2000-2008 the global temperature has been stable, perhaps even cooling slightly from 2006-2008. However, as noted before, this is too short a time period to call the lack of temperature increase a trend. It could be a pause before increased warming. It could be a transition to a time of cooling. There is no way to tell at this point. Given that we had warming prior to 2000, and no trend toward cooling since, we can comfortably say - at present - that the warming trend has continued to the end of 2008. In another two years, if no additional warming occurs, we might want to revisit that conclusion. I must mention here that I have heard claims that global temperature has risen during the 2000-2008 period, but I've not seen any data to support this.
I would be remiss if I did not mention that, although we can say that temperatures have been increasing during the 1900s, we are less sure as to the amount of actual increase that has occurred. NASA's latest ocean temperature measurements indicate no increase in ocean temperature since measurements started. Further, the accuracy of land measurements has been called into question. It appears the the phenomena of urban heat islands has not be factored into temperature readings, and a significant, perhaps majority, number of NOAA weather stations were found to be out of specification in 2007. For instance, there is a requirement of minimum distance from man-made structures that has not been followed in many cases. Nonetheless, if we limit our data to those measurements which are not affected by urban heat islands, and those which are within specification, there has been a measurable increase in temperature during the 1900s. The only question is how much, which is irrelevant for answering our second question. Remember, by the definition of Global Warming that we adopted at the start of this analysis, any increase in average global temperature qualifies as Global Warming. It matters not how much.
Finally, there are people on both sides of the issue using other data to define whether or not there is Global Warming. For instance, one side claims sea ice is less in the Arctic, while the other claims sea ice has increased in the antarctic. One side claims glaciers in Africa are shrinking, while the other claims that glaciers in Asia are growing. One side claims that coastal ice in Greenland is less, while the other claims that ice inland is thicker. These may be interesting data points for other discussions, but they are useless to us in terms of our question as to whether or not there is global warming since they do not address the one point which defines Global Warming - that is, an increase in average global temperature over time.
Is Global Warming bad?
The third question is one that any critical thinker must ask. The assumption made by many is "of course, Global Warming is bad". But at The Analyst, we try to minimize assumptions. Understanding the answer to this question is essential for anyone who wants to be able to think clearly and analytically about the topic. The question itself is vague. Bad for whom? Bad in what ways? Here we find alarmists asking rhetorical questions or making outright statements that appear to be aimed at creating an emotional response, but are otherwise meaningless. To get to the bottom of these questions, I will have to try to infer meaning where there is none explicitly stated.
Is it bad for the planet? The planet doesn't care. No amount of climate change will affect the planet.
Is it bad for life on the planet? This is an ambiguous question, but I believe that those who state it in these terms are actually asking "Is it going to exterminate life on the planet". In terms of Life, life has been through several periods of much cooler and much warming global temperatures than anything in the last 150 years. Further, some of those temperature changes have been more abrupt than what we are currently experiencing. Life persists on despite this.
Is it bad for the environment? Climate is part of the environment. It could hardly, therefore, be called bad for the environment. Could it change the environment to something other than what someone would prefer? Quite possibly, but it must be admitted that at this point we have strayed into the realm of personal preferences and left behind any objectivity.
Is it bad for some species on the planet? Another ambiguous question. I think the actual question is "Is it going to make some species become extinct?". Finally we get to a question that is worthy of our consideration. Most of the species that have lived on Earth are now extinct, and some scientists suspect that some of these extinctions may have been caused by rapid climatic changes. One theory, for instance, states that many of the large herbivores of North America became extinct during a time of rapid temperature increase over a period of less than 100 years. However, this may not be provable; other factors may have contributed to the extinctions. What about during the last 150 years of warming? There is only one arguable claim of extinction related to global warming that I've found (a South American frog). However, again, this conclusion is controversial in the scientific community. But, if this extinction event was caused by global warming, then we could say that global warming was certainly bad for that species. At this point, the evidence that global warming has been bad for some species is simply insufficient to draw any conclusions. Could it become bad for some species? The answer is, a qualified, yes. Evolutionary theory says that species will adapt to changing environmental conditions. But evolution occurs over a period measured in millions of years, while climatic change can happen in mere hundreds of years. Thus, climate change exceeds the ability of species to adapt via evolution. For migratory species, such as many birds, global warming (or cooling) presents minimal problems since the species simply migrate to avoid extreme temperatures. For other species, they will naturally change their ranges in response to climatic change. This would be sufficient to prevent the extinction of species due to global warming except for two factors: 1) certain barriers may prevent the range from changing and 2) the rate of global warming may exceed the rate of natural range expansion. To illustrate the first point, consider a island-bound species which cannot swim or fly. Such a species cannot expand their range beyond the island. Other types of "islands" exist - created by mountain ranges, deserts, or human activity. To illustrate the second case, the "habitable zone" of the species may move northward at a rate of 100 miles per year, whereas the species can only move its range by 25 miles per year. Now let us assume the range of the creature is only 50 miles from north-to-south. In such a case, the species would no longer exist in its environment after a single year. So, theoretically, rapid global warming could cause extinctions. We will address the rate of global warming later on, but suffice it to say that this concern remains only theoretical at this point. From a scientific standpoint, it will be interesting to see how this plays out in the future. So, the answer to the question would have to be "possibly".
Is it bad for humans? Arguably, things that cause rapid extinction of species would have unpleasant ripple effects for humans as well. So the answer to this question is largely dependant upon the answer to the previous question. Beyond that, however, there are other relevant issues. 1) Significant global warming could result in changing precipitation profiles around the world. Some areas could get much less, or much more, rain. If less rain fell over croplands, the result would be lower crop yields, leading to food shortages. On the other hand, other areas that were unsuitable for crops would become productive, offsetting the loss of crops elsewhere. And doubtless, humans would move quickly to take advantage of this. Since most of the world's land mass is at high northern latitudes, global warming would actually increase arable land. So, overall, food production would increase. However, this would undoubtedly cause economic damage to some countries as well as economic benefit to others. That is, it would be good for some humans and bad for others. 2) Increased temperatures would require additional energy for cooling in the summer, but less energy for heating in the winter. This would probably average out, globally. Again, for those living in already hot climes, this would be bad. But for those living in colder areas, this would be a benefit. 3) many more people die from cold every year than from heat (though people die from both). Thus, an increase in global temperature - to a point - would result in less temperature-related human mortality. In conclusion, global warming would cause many changes, but whether these changes are beneficial or harmful to humans, overall, is impossible to predict. Again, the answer to the question is "possibly".
What is the rate of Global warming?
As with all processes in nature, global warming does not occur at a steady pace. Instead, we find relatively rapid warming for a few years, then several years of almost no change, then a decade of gradual warming, then a few years of colder temperatures, then more warming, and so forth. Thus, the rate of Global warming has to be measured over long periods of time to come up with an average rate of warming. Alarmists on one hand would use only the rate of rapid change during a carefully chosen few years. Deniers would only use the temperatures from the few years of colder temperatures. But if we look at the last 150 years (basically since the "little ice age"), we see a fairly consistent rise in temperatures that match older global warming periods fairly closely, if we take into account the slightly inaccurate temperature data mentioned above. The United Nations IPCC (International Panel on Climate Change) uses some computer models to predict future warming, and they draw some alarming conclusions from these projections. However, despite constant adjustments, the models have not accurately predicted global temperatures over the last ten years, nor do they accurately model global temperatures for the last 100 years. In the face of the inability of the models to generate any correct results, it would be illogical to consider the projections for the future to be accurate. As a consequence, in the absence of additional data, we cannot predict the ongoing rate of global warming. Some might be tempted at this point to simply project the past warming trend into the foreseeable future. However, anyone who has done this with the stock market just before a recession knows that this is a good way to lose your money. Responsible science can do no better than assign a probability of the rate of warming, over a period of several decades. I'm unaware of anyone having done this, but I would be willing to accept a probability of more than 50% chance of the same rate of change over the next 90 years due to the cyclical nature of global climate change.
What is causing Global Warming?
This is probably the most contentious issue in relation to the topic. There are many "inputs" into the Climate equation. From the natural side, there are several cyclical inputs, which overlay each other to create a complex picture. There are catastrophic and unpredictable events. There are the inputs we know about, and those of which we are undoubtedly ignorant. On the cyclical side, we have an 11-year solar cycle on one end and a 26,000-year precession cycle on the other. Catastrophic events include nearby supernovae and asteroid collisions. We also see cycles whose causes we are ignorant of, including a 100,000-year "ice age" cycle. This is why climatologists disagree on the cause of global warming, even when they agree that it is happening.
The equation for the cause of global warming is deceptively simple: we add the energy put into the system (Earth) minus the energy that escapes. If the result is 0, then the equation is balanced and global temperature would remain unchanged. If the result is less than 0, we have global cooling. If the result is more than 0, we have global warming. The main source, by far, of energy that enters the system is the Sun. Some heat also comes from inside the Earth. A minuscule amount, relative to the Sun comes from burning fossil fuels. In the absence of an atmosphere, the Earth would quickly radiate all of the energy away, resulting in a balanced equation. The atmosphere, however, has a dramatic effect on the equation. 1) clouds reflect some of the Sun's energy, thus reducing the energy put into the system. Cosmic rays from nearby Supernovae may stimulate cloud formation and help to cool the Earth. 2) the presence of an atmosphere allows the existence of a biosphere (plant life), weathering of the lithosphere (rocks), and a hydrosphere (the oceans). These bind up much of the energy and store it away. The burning of fuels releases this stored energy as heat. 3) some atmospheric gases act to either absorb the energy or trap it so that it does not radiate away as quickly. This is called the "greenhouse effect" although the mechanism that heats a greenhouse is different than the mechanism present in the atmosphere. The gas that most people focus on is Carbon Dioxide (CO2), but there are others. For instance, Methane is about three times as efficient as Carbon Dioxide as a "greenhouse gas".
So far, most scientists would be in agreement. Where things get dicey is when one attempts to determine the cause of, and effect of, increased greenhouse gases. Are they natural? Are they man-made? Are they a combination? The obvious answer is that they are a combination. What is not known is exactly how much is man-made, or how much the increase of greenhouse gases is affecting global warming. There are some scientists that even say that most CO2 is natural and is a result of global warming, not the cause of it. Others claim that most of the increase of CO2 is due to human industry and is a direct cause of global warming. My analysis of the arguments on both sides leads me to believe that the human contribution to global warming is probably 1) minimal, and 2) mostly due to factors other than CO2 and Methane. Without going into another whole issue of the Analyst on this subject, let me provide some of the arguments that lead me to these conclusions. 1) Prehistoric warming trends are associated with increased CO2 in the absence of human industry. 2) CO2 increase has lagged behind warming trends by a decade or more, both in historical and prehistoric times. This indicates that CO2 doesn't initiate warming trends, and the relatively steady warming indicates that the CO2 does not appear to accelerate the warming. Thus, CO2 seems to have a minimal effect on global warming. 3) Some Sulfur compounds in the air are very efficient at reflecting sunlight into space, thus cooling the planet. However, these pollutants have been largely eliminated due to air-quality laws during the 20th century. It is entirely possible that some of the warming during the last century is due to a rebound from cleaning up the air so that less energy is reflected away from the planet. 4) Ice is an extremely good reflector of solar energy. The ice caps and glaciers thus reduce the solar energy absorbed into the system. However, soot from air pollution during the first part of the industrial revolution doubtless reduced the efficiency of ice, worldwide, to reflect sunlight. In fact, it has been shown that soot absorbs heat and melts the ice that it mixes with. Thus it could be argued that soot reduced the efficiency of ice reflection, and later removal of sulfur compounds allowed the sun's energy to accelerate the melting of ice with the resulting loss of reflecting surface on the planet. Perhaps mankind's contribution to global warming has nothing to do with greenhouse gases.
Before continuing, I must address an argument I've heard used by some alarmists. Venus is used to point out the dangers of a run-away greenhouse effect due to CO2. This argument is flawed on several levels. First, Venus lies inside the inner bounds of our Sun's "Habitable Zone", which is the area where life (as we know it) could exist due to the presence of liquid water. Earth orbits within this zone, but Venus does not. Liquid water most likely never existed on Venus and slowly escaped from the atmosphere. Without liquid water, chemical weathering could not remove CO2 from the atmosphere. Further, a biosphere could not exist, which means no plants could absorb and store the energy from the Sun, nor convert CO2 to Oxygen. Finally, the amount of CO2 in the atmosphere of Venus is thousands of times that in Earth's atmosphere right now. It is most likely impossible for the level of CO2 on Earth to reach that of Venus, even if we burned every last drop of oil and every last piece of coal.
So, what can we say about the cause of Global Warming? First, that it is probably several factors. Second, we simply do not understand all of the variables involved. If we did, the UN IPPC would have better computer models. Third, the current period of global warming is not (so far) inconsistent with what we know of previous natural warming periods. Fourth, human contribution is most likely minimal. However, these conclusions are based on incomplete knowledge of the climate equation. But then, so are the conclusions of the global warming alarmists. They could be correct. Or not. Responsible scientists would have to admit that we simply do not know. Hopefully we will continue to learn more until we can create accurate models to answer the question.
What can we do about it?
Implicit in this question are the questions: can we do anything about it? and should we do anything about it, if we can? First, can we do anything about it? This is unclear. We are talking about truly awesome amounts of energy involved in the Earth's climatic system. For instance, a single hurricane contains more energy than that released by every nuclear explosion set off in human history, combined. There are many clever ideas that people have come up with. But they all suffer from two problems: 1) we don't know how effective they would be since we don't have a good understanding of the system, and 2) they all have the possibility of causing other problems. Second, should we do anything about it? There are those who talk of "stabilizing" the climate. Such individuals do not understand that the climate has been constantly changing through the history of the planet. It has never been "stable". Which human is invested with the authority to determine what climate is the "right one" for the planet? As mentioned earlier, global warming will benefit some at the expense of others. We don't want to penalize some people, of course, but why should we prevent others from enjoying more prosperity just to maintain the "status quo"? Do we want to risk plunging the planet into another Ice Age in a fumbled attempt to stop global warming? Who has the authority to make that decision for 6 billion humans? These are questions which must be answered before we attempt to "do" anything about global warming.
You may feel somewhat frustrated at this point. After all, we made few definite conclusions related to global warming. All I can say is "get over it". This is the way science works. Like history, it isn't until long after the events are over that there is enough data collected to allow valid conclusions. We are far too early in the process to be able to make categorical statements, if we choose to be responsible analysts. What I feel comfortable saying is 1) we appear to be in a period of global warming, as of 2008. 2) The warming might be harmful to humans and other species, or not. 3) The causes are mostly natural with, perhaps, minimal human input. 4) A great amount of thought and debate (and a whole lot more discovery) need to take place before any major attempt is made to address global warming.