Global warming -- the trend toward increasing average temperatures over the entire planet -- is not a speculative notion that may someday be proven or disproven by further research: Global warming is a fact. Global warming is not a prediction about something that may happen in the future if we don't reduce our rate of combustion of fossil fuels and deforestation: Global warming is something that is happening right now and has been happening for years, and its literally disastrous consequences will continue getting worse and worse, until long after we have switched from fossil fuels to sustainable energy sources and stopped destroying forests.
In the U.S. Congress a "debate" over global warming is raging -- but this is no genuine discussion of the merits of the scientific evidence and what we should do about it. Almost all the scientists, world wide, who have been studying various aspects of the climate, from the perspectives of physics and chemistry and biology and human culture, agree on the main points of what the problem is, what is causing it, and what we must do about it. However, some of the immensely wealthy corporations in the coal and oil business are trying hard to block any government action that would reduce our consumption of coal and oil, and they've scoured the back woods to find "scientists" that would support their position.
This page offers a clear view of the basic evidence has warned scientists about the steadily worsening situation, followed by a look at some of the disastrous consequences that we are already seeing on the news. We then look at what individuals and corporations and nations can do about the problem.
There is no way that we can quickly stop the destructive effects of the greenhouse gasses that we've already released into our atmosphere. We can, though, work to improve the situation -- and in the process we can benefit our economies and our natural world in many ways.
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To begin with, the increase, over the past few decades, in the average annual temperature has been several times greater than the largest increase seen anytime in the preceding thousand years. You can see that in this graph, which displays the annual average temperature deviation for the Earth as a whole from the year 1000 A.D. through the year 2000 [click here to see a lager image of this graph]. Many other measurements lead to the same conclusion; for example, the five warmest years since the fifteenth century were all in the 1990s.
Although changes in the global average temperature occur naturally, the rate of increase during the past century has been five times greater than the rate of typical natural changes. It is clear from several lines of evidence that this increase is the direct result of human activity. The scientific basis of this conclusion is fairly simple.
Three gasses make up over 98% of our atmosphere: nitrogen, oxygen and argon. These gasses are all transparent to the heat (infrared) radiated from the surface when it is warmed by the sun. If these gasses were the only components of the atmosphere, all the heat radiated from the surface would go off into space. However, certain other gasses which make up a small fraction of the total -- notably carbon dioxide ( CO2 ), water vapor, nitrous oxide and methane -- absorb heat radiation from the surface. This warms the atmosphere, which radiates some of the heat back to the surface. This is a natural phenomenon -- without it the average temperature at the surface of the Earth would be over 50 degrees F (30 degrees C) colder than it is now.
This greenhouse effect is not a hypothetical construct about something that might happen, it is a geophysical fact about something that has been happening for hundreds of millions of years.
The average temperature of the Earth has changed over time as a result of various natural processes, among which are changes in the concentration of greenhouse gasses in the atmosphere. As the amount of greenhouse gasses increases, the global average temperature will tend to increase.
We now have good measurements, from deep ice cores taken from Greenland and Antarctica, of the changes in the concentration of CO2 in the atmosphere over time. Over the past 400,000 years, that amount has fluctuated over a range of plus-or-minus 20% from a mean of about 240 parts per million (ppm) [0.024%]. However, as this graph shows, the current concentration of carbon dioxide, 370 ppm, is 30% higher than at any time during that 400,000 year period -- and it is steadily increasing [click here to see a lager image of this graph].
This recent rapid increase in carbon dioxide concentration, over the past 150 years, corresponds with the burning of fossil fuels by human beings since the beginning of the industrial age. Recently, we have been adding roughly 2 gigatons (2 trillion pounds) of CO2 to the atmosphere every year. Until 1999. That year immense tracts of forest burned, raising the annual total increase to 6 gigatons.
This is not the whole story -- not at all. Many different factors contribute to the total warming effect. For example, conversion of forested land to agricultural use redistributes carbon dioxide from plants and soil to the atmosphere. Moreover, human activities release greenhouse gasses in addition to CO2: The concentration of methane is now 250% higher than the highest value recorded in the 400,000 years prior to 1850. But all in all, these complicating factors are only going to make the problem worse, not better.
The fact that scientists do not yet completely understand
all of these complications, and the fact that we do not yet know how much
increased warming will result from a given increase in atmospheric CO2,
is widely cited as reason for taking a wait-and-see, more-research-is-needed
approach to the problem of climate change. These objections are severely
misguided, if not intentionally deceptive: We do not need
to know exactly how much warming to expect if we continue to add CO2
to the atmosphere at the current rates, or if we reduce our emissions by
a certain amount. We are already experiencing severely destructive consequences
of the temperature increase that has already occurred, and we know that
they will get worse, even if we do everything we can possibly do to reduce
our rate of greenhouse emissions.
Here are a few examples of what's been happening. All these occurred in one year, 1998 (the warmest year on record):
- Unusually severe monsoon rains flooded two thirds of Bangladesh for over a month and destroyed the homes of over 20 million people. (The next year the monsoons failed to arrive on time, leaving millions of acres of forest burning in Indonesia for months.)
- Hurricane Mitch, with 180 mile-per hour winds, killed 11,00 people in Honduras, while destroying 70 percent of the crops, a third of the homes, and all of the sewage handling facilities.
- Severe drought affected 45 countries, intensifying already severe food and water shortages.
- Wildfires, some of them lasting for months, devastated many areas, all over the globe, including areas of rain forest which traditionally have been considered immune to forest fires.
In total, extreme weather events in 1998 forced 300 million people from their homes -- five percent of all the people in the world. Over the first 8 years of the 1990s, insurance companies paid out over 90 billion dollars in claims related to severe weather -- four times the total for the preceding ten years. Late in 1998, one of the largest reinsurance companies in the world, Munich Re, announced that large areas of the world, including the southeastern U.S., were likely to become uninsurable in the near future.
Many of the negative effects of global warming cannot be seen in the data for a single year. For example, climate changes force many plant and animal species to migrate, as temperature extremes make it harder for them to survive in their current ranges, or evolve into more temperature-hardy forms. However, two factors will make the current changes difficult to survive for many species. First, this change is happening faster than normal -- evolution, and even migration for some species, will be too slow. Second, man-made barriers of all sorts -- superhighways, dams on rivers, clear-cut forests, urban areas stretching for dozens and even hundreds of miles, and extensive agriculture will make migration difficult or impossible for many species, making the total rate of human-caused extinctions of species much higher than it already is.
Some species will benefit. Among them are heat loving insects that can fly. Already deadly tropical diseases like malaria are moving further north and to higher elevations.
One of the most frightening effects of global warming is the fact that it is somewhat self propogating: A warmer world makes some of warming more likely. For example, forest fires occur more often, more severe, and harder to control -- and forest fires release vast amounts of CO2, accelerating the warming trend.
The list of serious problems that we are already seeing is very long -- and some of the scientists' projections of what the situation might be like in a hundred years, predictions made just a few years ago, have already happened!
So, the situation is already very bad, and it is certainly going to get worse, no matter what people try to do about it. But, as we'll see in the next section, we can do something, many things, to reduce the rate of warming and even eventually begin to lower the temperature.
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The problem is not just the amount of energy we use, but
how that energy is produced. Most of our current energy comes from sources
that add CO2 to the air
-- fossil fuels. But some sources of electricity, like hydroelectric and
solar and wind generators, produce no CO2
at all, and bio-fuels, like alcohol made from corn and methane made from
agricultural waste and animal dung, don't produce any net increase in carbon
dioxide: The plants consume CO2
as they grow, and that CO2
is then released as the fuel is burned. But even among the fossil fuels,
substantial reductions in CO2
emissions can be made by switching from coal and oil to natural gas, which
releases about half as much CO2
as coal when used to produce electricity.
Another way to reduce CO2 emissions -- while saving money and reducing pollution at the same time -- is to reduce the amount of energy we use, and the amount we waste.
Next, let's look at forests. Many people who talk about global warming believe that cutting down forests increases the amount of CO2 in the air by removing plants that consume CO2 as they grows. However, it's not that simple: A mature forest produces as much CO2 as it consumes, because old trees and limbs and leaves are dying and rotting (a slow form of combustion) at the same rate that new plant material is growing. Clear cutting forests, however, adds lots of CO2 to the air, as the unwanted trees are burned or left to rot.
Even carefully harvesting trees from forests releases most of their CO2, because the root system will rot, and unwanted branches and leaves will rot. (The roots of a tree have roughly the same mass as the part above the ground.) If trees are replanted, though, either naturally with seeds from trees that are left standing, or by intentional planting by people, the CO2 equation will eventually balance out -- but it's a slow process.
Planting trees to replace forests removes CO2 from the air as the trees grow, and if the trees are allowed to continue growing or are made into durable products like houses or furniture, the CO2 may stay out of the atmosphere for many years. However, young trees don't produce much new growth each year. It takes many years for a tree to get large enough to be a really effective consumer of CO2. Moreover, nowadays most of the forest area destroyed each year is not replanted.
Most of these various ways of reducing Greenhouse emissions can be adopted by individuals. We may not be able to convert the local power plant from coal to gas by ourselves, but we can reduce the amount of power we waste. Even those of us who can't afford to switch to gas heat in our homes can caulk the leaks around our windows and take other steps to reduce the amount of fuel we need for heat. We can make sure that gas mileage is a major concern the next time we buy a car, and we can learn to drive in a more fuel efficient manner. But most of the things that must be done as soon as possible to limit the rate of climate change require the cooperation of communities and nations and the large multinational corporations.
Our various governments and other agencies began discussing the possibility that we must begin trying to reduce worldwide the levels of greenhouse emissions, and over the years a series of international agreements have been signed. Basically, the nations have agreed to work toward the goal of reducing the rate of greenhouse emissions, by the year 2010, to levels slightly below those recorded in 1990.
This would certainly be a step toward improving the situation, although many climate scientists believe that much a greater reduction is urgent. However, even this minimal level of corrective action has yet to go into effect. For example, the U.S. senate has not yet ratified the Kyoto agreement after several years of discussion. Meanwhile, the rate of greenhouse emissions is still increasing.
Let's be clear about that. We need to reduce the amount of CO2 in the atmosphere: The problem is not just that there will someday be too much -- there is already too much. That means that we have to get our rate of CO2 release lower than the amount that can be removed by natural processes, so that all of what we release each year will be removed, along with some of what we've released in the past. To attain that goal, the rate of release has to be falling. Right now, the rate of release is still increasing.
Part of the difficulty stems from the fact that many people think the evidence is unclear, which it is not. Climate scientists certainly would like to understand some aspects of the situation better that they do. They know that not all the CO2 released each year winds up in the atmosphere, and would like to know why not. They would also like to be able to predict how much increased warming will result from a given increase in atmospheric CO2. These and other aspects of the theory are still in question -- but the evidence -- that global warming is already happening, that the greenhouse gas concentrations that cause it are increasing, and that it is already having serious negative consequences -- that evidence is very clear.
The petroleum and coal interests, and the anti-environmental groups, are arguing that we should wait for more research to see what, if anything, we need to do about climate change. These objections are severely misguided, if not intentionally deceptive: We don't need to know any more than we already know to see the destructive effects of the warming trend, and to know that they will continue to get worse for a long time, even if we immediately begin doing everything in our power to reduce our greenhouse emissions.
The scientists who brought this problem to our attention are not tree hugging nut cases, as the strong vested interests would like us to believe. They are mostly very intelligent and devoted scientists, studying various natural processes that affect our weather and climate, who would much rather be working on their research than getting involved in political squabbles. They nearly all agree that the problem is real.
Just for the sake of clarity, let's imagine briefly what might happen if the data were misleading -- that the warming trends will not continue. What would be the negative consequences of making all these various efforts to reduce our rate of releasing carbon dioxide and other greenhouse gasses into the atmosphere, if, in fact, the warming trend were an illusion? The answer is that effects of these efforts would be beneficial anyway: Power companies and communities and individuals will save money. Pollution will be reduced. The quality and durability of the products we buy would be increased. The amount of junk and trash requiring disposal will be reduced. Topsoil and forests and oceans will be preserved for our grandchildren. The entire international economy will become more sustainable.
So there's no reason not to proceed with converting to clean, renewable energy sources as quickly as possible -- the work would require several decades even if we were all able and willing to begin immediately. We should not expect, however, that the problem can be solved by focusing on the climate crisis alone. A broader, more realistic perspective would look at some of the deeper causes of the situation, uncluding the mushrooming population of human beings and the obligatory greed of modern corporate culture.
Whatever our particular focus may be, let us please now come, all who can, to the aid of human beings, living now and in the future -- and to the aid of the natural world. Let us work together, whether our interest lies in protecting the environment, in making our economies more sustainable, in making our jobs more secure or our businesses more profitable, or preserving people's health. Diligent and intelligent efforts to resolve the climate crisis are essential for attaining any and all of these goals.
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books web sites
Way Too Many Links
Meteorological Organization: Annual Climate Statements
Past Global Changes - What significant climate and environmental changes have occurred in the past and what were their causes? - NewslettersEarth Haven
the Heat: Why and How We Must Combat Global Warming
- John J. Berger. Beating the Heat is for people who are neither scientists
nor technically trained but are concerned about the environment. It explains
in a non technical, friendly style what's causing climate problems, why
climate change is so dangerous, and how it can be remedied to make a safer
world. The author suggests steps that can be adopted immediately, by individuals,
by corporations, and by governments, to help fight global warming.
The Official Earth Day Guide to Planet Repair - Denis Hayes. "Everyone talks about the weather but no one ever does anything about it. Sadly, that old joke is no longer true. A large body of increasingly compelling scientific evidence is telling us that many things we do -- from the kinds of cars we drive to how we heat our homes -- are directly affecting our global climate in unprecedented and alarming ways. But what can any one person do about this vast, global problem? Help fix it! And it doesn't have to be a do-it-yourself project; we citizens and stewards of the earth can unite in greater numbers and power than ever before. [Here] Earth Day leader and renewable energy expert Denis Hayes tells us how changes in individual, local, and national energy choices can slow or even stop the dangerous build-up of greenhouse gases in our atmosphere, while at the same time saving us money, helping the economy, creating new jobs, and enhancing human health. A how-to home improvement guide for the planet..."
Environmental Change: Past, Present, and Future
- Karl K. Turekian. Intended for readers who have some familiarity with
basic physical science, the book focuses on the record of global environmental
change in the distant and more recent past. It explores the full range
of environmental changes that occur naturally and how they are being influenced
by the activities of human beings. The book's conclusions are grounded
in scientific studies of the fundamental structure and behavior of Earth.
Discusses the influence of climate change on natural catastrophes and human
hazards, and highlights global warming, acid rain, and ozone depletion.
This next book go beyond focusing on the climate crisis alone, to offer a broader perspective that looks at some of the deeper causes of the situation, uncluding the mushrooming population of human beings and the obligatory greed of modern corporate culture.
"For millennia, we lived in harmony with the Earth, taking only what we required to survive. But in just the past few centuries, we have used our powers to thrill and amuse ourselves, to satisfy our obsession with consumption and new technology, without regard for the consequences. And in doing so, we have exploited our surroundings on an unprecedented scale."
We are now at a turning point: "we can either push ahead on our path to destruction, or we can reshape our place in nature and prosper." Inspiring us to believe that taking the latter choice is possible, the book introduces us to "people who are fighting back, those who are resisting the inexorable advance of the 'global economy' juggernaut, the people whose voices are difficult to hear over the din of corporate PR machines."
In You Are the Earth, David Suzuki strives to help young people understand that we need to take care of the earth and thus ourselves before it is too late. This is not doom and gloom preaching, but a clear description of the actual situation and a positive statement of what people, including young people, can do about it.
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