A brief history of global climate change
At the level of scientific detail, most of us don’t know much about global climate change, though we tend to accept the idea that human activity is somehow changing our weather and that the root cause is the abundant use of fossil fuels. Burning fossil fuels at the accelerated global rate that is now underway means that we are too late to avoid some impact from greenhouse gases and subsequent rising sea water. Our global future is now, though what remains to be determined is how far we will let carbon dioxide accumulate in the atmosphere before we start to apply a brake that will prove effective. The best we can hope for now is changing the slope or the rate of rise of CO2, rather than reverse the levels, which seems completely unattainable. Will we run out of oil before we take action? We are now seeing recorded temperatures that are warmer than those of any on record, accompanied by weather disasters that include flooding and increased desertification. It is too late to completely reverse what we have started, for it looks like the earth will still be warming perhaps for decades if not centuries on the basis of what we have added to the environment already and the question that remains is whether nations that are burning high rates of fossil fuels, beginning with the United States, have the political and social fabric to make serious changes in their energy usage to avoid what climatologists call a “tipping point”–the point at which a new permanent, altered climate cycle comes about with much hotter temperatures and much higher ocean levels, such that many coastal cities will be threatened. The tipping point could involve a positive feedback system that removes humans from any possibility of controlling the outcome. Let us hope that this option is avoided, though one’s faith in capitalism as a system that can solve such problems is at an all time low. While we are already witnessing the impact of greenhouse gases on our weather system, it is likely that some of us will be around to see even more dramatic changes in our global climate patterns within the next few decades.
Climatologists used to think that changes in the weather would only take place over hundreds if not thousands of years, because the atmosphere was perceived to be a large, gigantic carbon sink. But that has all changed and the contemporary view favors the potential for dramatic changes in climate that can take place over decades or even in less time. The delicate balance that we have taken for granted throughout the centuries of human history, has been significantly altered by our behavior, which has cumulatively started to change our environment, beginning with the industrial revolution. But those early, seemingly innocuous beginnings, are projected to reach peak levels of greenhouse gases during this century and eventually these new levels are projected to have a far more dramatic impact on our weather, even compared to the trends we have witnessed over the last few decades. Climatologists are confident that dramatic changes will begin to accelerate as the planet continues to warm and carbon dioxide levels continue to rise. One must keep in mind that if our planet Earth had no means of losing heat from the Sun, but only absorbing it, like a perfect black body, the Earth would eventually, perhaps over millions of years or longer, become as hot as the Sun. In contrast however the Earth without an atmosphere loses sufficient heat through infrared radiation that, if that were the only thermal factor operating, would leave our planet at temperatures well below freezing. It is the atmosphere that keeps absorbing and reflecting infrared radiation that is responsible for keeping our planet warm and, atmospheric carbon dioxide, though a small constituent of our atmosphere, has always played a major role in regulating our global climate. Thus, the mean planetary temperature is created through the process of losing some heat through the atmosphere, while retaining some through heat capture and reflection; this dual process has served as the delicate balance by which we have faded into and out of warming and cooling cycles, including several ice-ages in our long geological history. While the causes of these past temperature fluctuations are still a matter of investigation and debate, scientists are in strong agreement that the carbon dioxide problem we face will dramatically change our weather, especially if we do nothing to control our carbon emissions.
The only way we can project our climate future is through computer models and base those models as rigorously as we can on data that we acquire through geological and other scientific disciplines. Today’s computer models are fairly sophisticated and have been gaining in precision and predictability as computer capabilities and measurement constraints have been slowly added to the modeling strategy. There is no other way. We are building these “General Circulation Models” and improving on them to make better predictions about our planetary future. Initially, models and early studies tried to focus on why the Earth went through the dramatic temperature fluctuations that included several ice-age periods. Was this a normal cycling of the atmosphere and if so, why and how did our weather change so drastically? But as the measurements and models got more sophisticated, climatologists, in collaboration with many other branches of science, including the biological and oceanic sciences, began to focus on a new problem, one that was increasingly created by man. This problem turned out to be not just an issue of greenhouse gases warming the Earth and the oceans, but also rising sea water levels that, in the near future, could threaten coastal cities and generate other, more dangerous possibilities created by alterations in the ocean currents that provide significant warm weather to Europe for example. In the latter case, models have demonstrated that that the Atlantic current that warms Europe, in which warm water travels north on the surface, as cold Arctic water travels in the opposite direction at deeper levels, could disappear in a relative heartbeat if the salinity of Arctic water goes down, as it might if significant melting in the region occurred. In an age of global warming, it seems counter-intuitive that Europe could get much colder, especially in the winter. But, not everyone is opposed to global climate change. Many Russians for example feel they would welcome a few degrees added to their winter. Then too excessive carbon dioxide can help support additional plant growth, but even this effect can turn negative if accompanied by excessive plant decay.
It was in 1938 that Stewart Callendar, standing in front of the Royal Meteorological Society in London, first suggested that the planet was gradually warming and that the principal culprit was humans burning fossil fuels and adding tons of carbon dioxide to the atmosphere. Few other scientists accepted Callendar’s idea at the time, simply because it seemed irrational that the atmosphere was so delicate and limited that it couldn’t absorb the results of burning fossil fuels without a blip on the radar screen. Was planet Earth really that small? Earlier work by British scientist John Tyndall had determined that the main gases in the atmosphere, including nitrogen and oxygen, are transparent to infrared radiation, but “coal gas” was opaque to infrared rays, caused mostly by its high carbon dioxide content. In this way, atmospheric carbon dioxide became known as a “greenhouse gas.”
No teaching tool is quite like history for learning about the sea changes that shape politics and attitudes and the evolution of ideas, both scientific and otherwise. An excellent book that traces the history of global climate change is Spencer R. Weart’s “The Discovery of Global Warming“ Harvard Press, 2008. Weart has also created a site where a hypertext presentation and a summary of global climate change history and facts can be sorted out as a kind of short cut for reading the book.
From my perspective, the salient features of this story begin with the realization that scientists studying the global climate in the late 1970s had started to converge on the idea that Callendar was right: we faced a serious problem in the future with man-made greenhouse gases, the most important of which was carbon dioxide. But scientists alone cannot force changes in public policy and without some divine interference, scientists generally have a hard time getting attention to their concerns, unless there is a major catastrophe that requires their input for understanding (we can see the public beginning to turn to scientists for explanations as an aid in understanding the impact of the on-going BP Gulf oil spill).
In 1979, the influential National Academy of Sciences issued a report that gave increased visibility to the global warming concept by suggesting that doubling atmospheric carbon dioxide would bring an increase in global temperature of 1.5-4.5 degrees Centigrade (2.7-8.1 degrees Fahrenheit), an alarming increase that could raise serious concerns about the safety of our planetary future. Unfortunately, in the U.S., just as scientific studies of the global climate were gaining momentum, the election of Ronald Reagan brought about a backlash and helped generate the Republican skepticism on global warming that is still with us (or them) today. About the time that Reagan was elected President, Greenland ice core studies revealed that drastic temperature changes had taken place in our history within the span of a century, suggesting that our climate is not an ultrastable, unmodifiable system at all, but may have a tendency to favor rapid shifts in average global temperature, depending on multiple kinds of feedback systems, not all of which were then identified (and still aren’t). Other alarming studies showed that carbon dioxide was not the only greenhouse gas we had to worry about, as methane and other trace gases might also make a significant contribution, and had to be included in the models to avoid their predictive failure. Antarctic ice cores also revealed that changes in atmospheric carbon dioxide levels went up and down together through past ice ages, which led scientists to conclude that our global atmosphere is highly dynamic and very modifiable–sort of like some synapses in our brains.
1988 was an important year in the history of global climate study. It was an unusually hot year for the United States. I remember that summer very well, as it was the year we moved from St. Louis to Minneapolis during heat spells that were uncharacteristic for the region and caused many well-established, older trees to die out. That was also the year in which U.N.’s Intergovernmental Panel on Climate Change (IPCC) was assembled, which, for the first time, formed a union between scientists and government representatives, whose function was to integrate scientific knowledge and help formulate public policy development to reduce greenhouse gases. The IPCC is the committee that shared the 2007 Nobel Peace Prize with Al Gore. The first report of the IPCC was made in 1990, in which the committee concluded that the planet had been warming in the recent past and future warming seemed likely. By 1995, the second report issued by the IPCC warned that serious warming would be likely in the coming century. Given that it was organized under the auspices of the United Nations, it is axiomatic that the Republican Party would be opposed to any information coming out of that committee. Fortunately, Al Gore formed an important relationship with the committee and helped to amplify their concerns with his popular documentary “An Inconvenient Truth.”
The hottest year on record, that of 1998, was associated with a “Super El Nino” which caused weather disasters and unrelenting heat. By the end of the 20th century, sophisticated computer models had been able to simulate global ice age climate changes and gain substantial credibility for their future climate projections. The third IPCC report in 2001 indicated that future global warming would bring the hottest period of the planet since the last ice age and may be attended with “severe surprises.” By then, the entire scientific community had agreed that greenhouse gases would likely be a serious problem and that the global reach of human societies needed to get busy to correct the excessive use of fossil fuels. A serious response was required of the major industrialized countries, but the U.S. has balked from entering into serious agreements, such as the Kyoto protocol. This was followed by numerous observations on collapsing ice sheets in Antarctica and Greenland that might cause sea levels to rise faster with far less predictably than previously thought. In many ways, it was beginning to look like we were facing a climate emergency.
The fourth IPCC report was issued in 2007 and argued that the cost of reducing emissions from fossil fuels would be offset by the benefits and savings of doing nothing to curb the further accumulation of greenhouse gases. In that year the level of carbon dioxide in the atmosphere reached 382 ppm and the mean global temperature for a five year average was 14.5 degrees Centigrade (58 degrees Fahrenheit), the warmest in hundreds, perhaps thousands of years. Some have argued that we are in a relative cooling period since 1998 because of reduced sunspot activity, but it’s unclear whether such activity unambiguously affects our climate: if it does, then we are in for a sudden increase in global heating when sunspot activity resumes.
Global Climate Parameters vs IPCC projections
The main problem with the IPCC reports is that they take the arguments and data from scientists and water them down, for more palatable public consumption, hoping the issue appears less alarmist by making the issue less stressful, which in turn makes the issue seem less significant. Some scientists who serve on the IPCC have published papers challenging the overly conservative nature of the IPCC reports; the political arm of the IPCC gets the last word on the tone of the warnings and the details of the projections. One such objection to the IPCC reports was published by Rahmstorf et al, in Science, 2007 (volume 316, p 709–available to the public without a subscription to Science). The graph on the left was taken from the Rahmstorf et al paper (published on line); in the top section, the monthly carbon dioxide data measured from Mauna Loa Hawaii (blue) is compared to the IPCC projection (dashed line; note that the yearly levels of carbon dioxide fluctuate because of the annual change in vegetation and hence carbon dioxide absorption, largely in the northern hemisphere). The middle portion shows annual global mean land and ocean surface temperatures combined from two different sources (red and blue) together with their trends. The bottom panel shows the most discrepancy in the sea-level measurements based on tide gauges (annual, red) and from satellite altimeter (blue) data. When compared to the dashed line and gray range representing IPCC projections, it is primarily the sea-levels that show the greatest discrepancies between measurements and projections. That in short is the main worry.
At the present time, most of the expansion of the oceans has been attributed to thermal expansion, since the ocean is warmer, with an added dash of mountain glacier melting. To date, melting ice from the Arctic, Antarctic and Greenland ice masses have added little to sea-level changes, but that picture could change dramatically in the coming decades. It is the sea-level discrepancy between measurements and the more conservative IPCC projections that stimulated Rahmstorf et al to publish a brief note in Science that brought more attention and focus on the politics of global climate projections within a body that is supposedly dedicated to a more complete and objective analysis.
We are now at a point in our understanding of the threat to global climate change, imposed by burning fossil fuels, that more science is not required. Yes, we will continue to refine our models, but by being forewarned, we should be forearmed and, as a global society, we should be sufficiently knowledgeable to act with a little long-term planning, as if we are facing a global emergency. We must recognize that our small blue planet, its oceans AND ITS CLIMATE are linked inseparably at the hip and that all three are being degraded by human activities. Ocean levels will rise and threaten coastal cities. The decrease in ocean salinity and pH could wipe out coral reefs, change the food chain in ways we cannot possibly comprehend and alter ocean currents which can dramatically change our weather. Water resources will become more scarce in some regions and more abundant in others. If one removes natural vegetation, it will have an impact on the regional weather. Remove the trees in a region and you will have less rain; remove the plants and expose the soil and you invite desertification in some areas through more moisture evaporation imposed by the elevated temperatures. Additional moisture in the air will bring more floods and storms, but not in all regions. Some regions of the world may simply become unlivable, especially those where the climate is already dry and hot. The Southwest region of the United States faces additional constraints on water and annual rainfall and regions of Africa are likely to become increasingly dry and more inhospitable. The global society in which we live, now numbering about 6 billion people are far more than the planet can tolerate if each society aspires to be like the us, as we continue to go about our business with an unlimited appetite for fossil fuels and forest depletion. If anything, the rate of ice melting from the polar ice caps has been underestimated and modelers are madly revising their computer simulations to account for more dramatic events, such as entire ice shelves dropping into the ocean. It is probably asking too much for a model to accurately tell us where and when giant fluctuations in ocean levels are likely to originate.
I think that Obama’s nation-wide address this past week was about right, despite its downplay in the press. We need to interpret the catastrophic Gulf oil spill to 1) recognize that giant oil companies are completely indifferent to the environment and are acting solely through a profit motive (no surprise here and let’s give Obama credit for establishing the $20 billion BP compensation fund and the elimination of the annual BP dividend to stockholders–this was using the bully pulpit with great aplomb and a sensible outcome) and 2) if we had started on a more conservative use of fossil fuels, with an objective of reducing levels of carbon dioxide emissions just ten years ago, when GW Bush came into office, at a time when the need felt more acute, we would not need the oil that is gushing out of a giant hole a mile beneath the surface of the Gulf. So, if we start immediately on the same quest, the next ocean oil gusher, whether in the Gulf of Mexico or the Arctic seas, will never occur, because that oil will not be required. Surely, with the Gulf oil spill, we are witnessing a source of oil that might be better left under the ocean floor. We should work towards the end of leaving some oil in the ground.
As Obama has pleaded with us to change our orientation about the use of fossil fuels, its an open question whether we will view this catastrophic Gulf oil spill to finally act and reduce our dependency on fossil fuels. There are several things we could do to give ourselves a dramatic boost in reducing our fossil fuel habit. Energy conservation and the development of fossil fuel alternatives is currently at a very primitive stage of development and needs dramatic new funding to alter its present course. One thing we must do is learn how to tax oil usage, eliminate subsidies to oil companies and come up with accurate accounts of what the true cost of oil is today, when you consider that a good part of our military is devoted to protecting our sources of oil, and in the process our military uses huge quantities of oil to run our ships and planes. So, Mr. Obama, help us arrive at a figure for the cost of gasoline at the pump, computed by adding up the cost of subsidies, correction for the cheap bargain-basement oil leases, add the cost of military protection of the sea lanes and our occupation of Iraq and Afghanistan and the then give us the future cost of gasoline, imposed by the expense of relocating major coastal cities to higher ground as a result of sea changes that are at present unknowable, but certainly on the way. Add to that the cost of this single Gulf oil spill and then try to calculate the financial impact it has had on the entire Gulf economy and the availability of Gulf seafood for the entire nation. I don’t myself have this number at the moment, but it should not be difficult to estimate with ballpark numbers and would have been a powerful additive to Obama’s national speech on energy, especially if approached honestly and with full and complete disclosure. We should all be concerned about this number and have a national discussion on what it means and how it should be used to motivate changes in our future.
The barn door has closed on avoiding global climate warming–it’s here today. But, there is still time to alter the slope or the rate of these changes and that should be a matter of concern for all of humanity, rich and poor, but most critically, it should deeply concern the citizens of the United States of America, as we are the biggest offender and historically the most insensitive nation in facing what should be a moral imperative. If we do not act with intelligence and dedication to this task, we can be certain that the rest of the world will go along with our own indifference on the subject. Never before has a single issue of global significance rested so squarely on the shoulders of the worst offender in the history of humanity. We are not only in a position to act, but we need to change our habits and consumption of fossil fuel so that we discourage the rest of the world from trying to emulate our fossil fuel gluttony. The globe cannot afford to have China grow up to look just as modern and fuel-consuming as the United States, but that is just where we are headed. Beijing adds 1000 cars a day to an already heavily congested street and highway layout. In 2030, not so far away, China will need and use the equivalent of Europe’s entire energy consumption. They will achieve this by investing $3.7trillion in energy over the next twenty-five years. The Global energy supply has never looked as small as it does today. Should the condition of global “peak” oil confront us, as it has in several countries, including the United States, then expansion of the kind that China is planning will be virtually impossible.
RFM
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