The concept of global warming will not be new to anyone in this day and age. There was a time when it was a radical new theory, when respected scientists could not believe it and when only those who took an active interest in such issues were even aware of it. That time has passed, and it is now a popular debate in schools, a phrase of popular culture and most importantly, a well researched and documented scientific phenomenon.
There is still much debate on the topic, both within scientific circles and in the general public. It can often prove to be a political hotbed, with strongly held views and reams of 'proof' bandied about by both sides. This write-up will attempt to state the facts such as they are, dispel some of the myths and bring the issues to light with the help of the best scientific data available at present.
To begin, let us try and define our terms, not in scientific jargon, but in a way that clearly shows the differences between them.
- Global warming:
- Exactly as the name states, this is the process by which the average global temperature is increasing. It does not mean that everywhere is hotter all the time, but simply that the earth's climate is on a trend to becoming generally warmer.
- The Greenhouse Effect:
- A natural phenomena of our earth that has been in place as long as life, and is a vital part in helping to sustain it. It is a way of explaining how the atmosphere acts in the manner similar to a greenhouse. By controlling how much energy is released back into space and how much is kept inside as heat, it helps to stabilize the world's temperature and climate.
- Climate change:
- Again, this is a natural characteristic of earth. There have been hot spells and ice ages, with everything in between and various changes tend to occur at regular intervals though the ages. No one is saying climate change is good or bad, it simply is.
- Climate vs. weather:
- Climate describes long-term weather patterns, with average temperatures and precipitation totals as well as typical occurrences of climatic extremes (such as tropical storms) being used to characterize the climate for a particular region. Weather is the state of the atmosphere at a given time and place, defined by variables such as temperature, moisture, wind, and barometric pressure. Changes in weather and climate are not the same thing.
Without further ado - global warming - real or malarkey?
Global warming is real. Now, before you get all upset and start talking about sunspots, just wait. In the beginning, there was a debate as to whether it was real or not, but today we know it is happening. Today the debate lies in whether or not it is humans that are causing it. Generally, when people say they do not believe in global warming, what they really mean is that they don't believe that driving cars and cutting down forests are responsible for it, or that even if that is the case, it isn't as much of a threat as certain people make it out to be.
Regardless of your beliefs in this matter, what follows should at least present you with the facts. Remember that even if you don’t believe humans are at fault, a change in climate will cause changes to us and our environment and that we are now in a unique position to study the complex causes and effects of climate change. Never before has there been so much research done and so much data and technology made available to people who study the earth. There is much to be observed, and much to learn for all from doing so.
So, how do we know that global warming is happening?
In 1995, the Intergovernmental Panel on Climate Change (IPCC) was formed in conjunction with the UN to study all available literature on the subject and come up with a consensus on the major scientific issues, as well as drawing up recommendations for governments and business. There first report was released in 1996, in which they stated:
"An increasing body of observations gives a collective picture of a warming world and other changes in the climate system."
The report was the first major work of its kind and had far reaching effects on many sectors. When the panel convened again in 2001 it had become a highly respected group. It included top scientists, economists and risk-calculators from more countries around the world than any other offspring of the UN. In the final reports there was an almost unprecedented, unanimous consensus that things were changing, that the world was heating up. After analysis of over 20,000 published papers, journals and other peer-reviewed work, the findings were more conclusive than ever before.
Below is a summary of some of the key points.
- Since the beginning of the 20th century, the mean surface temperature of the earth has increased by about 1.1º F (0.6°C). Half of that rise has occurred in the last 40 years, a period with very reliable data.
- Warming in the 20th century is greater than at any time during the past 1000 years.
- Eight of the ten warmest years in the 20th century occurred between 1990 and 2001.
- Mountain glaciers in every part of the world are receding.
- The Arctic ice pack has lost about 40% of its thickness over the past four decades and since 1978 (the date when satellites began to take reliable measurements of it) has decreased in area by about 9% per decade.
- The global sea level has been rising about three times faster over the past 100 years, between 4 and 8 inches total, compared to the previous 3,000 years.
- Studies have shown that plants and animals are changing their range and behaviour in response to shifts in climate.
There is an increasing amount of work being done by geologists, climatologists, palaeontologists and oceanographers into the nature of our climate, studying both its present state and records from its past. The hope being that if they can better understand what has happened before it will be easier to understand our current situation and predict the future.
The U.S Geological Survey Global Change Research Program has been constantly present in Montana’s Glacier National Park for over a decade to monitor the state of its namesake features. Records show that when the park was created in 1910 it contained about 150 glaciers. Today there are less than 30 surviving, and even they have shrunk in area by as much as two-thirds. Scientists in the program predict that within 3 decades all the glaciers will be gone. Glaciers in every country are suffering the same fate, melting and receding further up the mountains from where they came. Even researches in the Himalayas, a place so seemingly remote that we tend to think nothing can touch it, predict that if current melt rates continue, most central and eastern glaciers of the famed range will disappear within the century.
It is NASA's laser and satellite technology that shows us dramatic pictures of how the edges of the Northern hemisphere ice sheets are shrinking and sea ice is thinning and breaking up. The Spring break up of sea ice now occurs an average of 9 days earlier than it did in the mid 1800's and only begins to freeze nearly two weeks later. As many researches point out, these are things that do normally occur, but they take place in geologic time, over 1000's of years. Nowdays we are seeing them happen within a lifetime. In just 20 years, ice that used to stretch across the North Pole from the shores of Greenland to those of Russia, now never touches Russian shores, stopping in the sea about three-quarters of the way across.
America's National Oceanic and Atmospheric Administration has data collected from all the world's oceans that show a rise in average sea temperatures. A rise that is going down to depths that they thought would not be affected. They have also got the largest recorded change in any ocean from the subpolar seas neighbouring the North Atlantic, where the salinity of the water is falling at a tremendous rate.
On the islands surrounding the Antarctic Peninsula average temperatures have increased by 9º F since the 50's and the sea ice has retreated, causing major shifts in the populations of penguin species in the area. Species such as the gentoo that used to only be found in warmer habitats such as the Falklands have moved further south, encroaching on to other animal's land and driving their numbers downward. What used to be a polar region just a century ago is now classified as subpolar.
What is causing this global warming?
The IPCC has this to say;
“Emissions of greenhouse gases and aerosols due to human activities continue to alter the atmosphere in ways that are expected to affect the climate. There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities."
The unanimous consensus of the panel was that human activities are a prime factor in global warming. There are not many scientists working in the field today that will argue with that. Yes there are some - but there is also a flat earth society. But even though the members of the panel know we are the primary cause, they do not attribute the phenomenon solely to humans. No model that takes into account only human factors or only natural factors has come up with something close to what we know about the past and observe today. Only those which include a combination of the two produce a picture similar to the one we see around us.
The highest recorded concentration of carbon dioxide (CO2) in the earth's atmosphere from the past is about 280 parts per million. The level today sits at around 375ppm. There is no doubt that since the Industrial Revolution, the concentration of gases such as carbon dioxide in the atmosphere has skyrocketed. This is because CO2 is produced when fossil fuels such as oil and coal are burnt. Also, plants take up carbon dioxide as a part of photosynthesis, and release oxygen back into the air. Deforestation and huge land-use change has lead to a significant reduction in the amount of total plant cover on land, hampering the earths natural ability to absorb CO2 and maintain the composition of the atmosphere. Carbon dioxide is one of the main greenhouse gases. That means it is one of the main ones responsible for the greenhouse effect and the controlling of the earth's heat budget. More carbon dioxide means that less energy is let back into space and more is kept on earth as heat, thus the earth gets warmer.
Data from the past shows a direct correlation between the amount of CO2 in the air and the average global temperature, as one increases so does the other. With the current measurements of carbon dioxide in the air, and factoring in as many different scenarios as can be thought of, computer models predict a rise of anywhere between 3º F and 10º F between now and the end of the century. It may not sound like something terribly dramatic, but consider this. The difference between our average temperature now and that during the last ice age is only 9º F.
We also know that the earth goes through many different cycles which affect its climate, alternating between ice ages and warmer interglacial periods. Earth does not rotate perfectly; its spin around the axis wobbles slightly as does the exact angle of tilt of the spin axis. Combined with an expanding and contracting orbit around the sun which creates a sometimes more circular and sometimes more elliptical path through space. This is thought to bring on changes in climate by altering the distribution of sunlight on the earths surface. The suns energy output is also in constant flux, so the amount of heat the earth receives from it does vary over time. However no data leads scientists to believe that these natural cycles are the cause of the rapid changes we are observing today.
As there are obviously no direct temperature records from long ago, scientists use natural markers to find out about the past. Air temperatures affect the chemical makeup and structure of snow which is layered down year after year and eventually forms the polar ice sheets. By drilling down and taking core samples at different depths and in different areas, researchers can learn a lot about the climate at the time. Fossilized shells of tiny marine organisms also contain specific chemical signatures depending on the temperature of the water in which they lived. Fossils of pollen grains trapped in the sediments of lakes have also yielded a lot of data about the type of vegetation long ago which gives clues as to what the climate might have been like.
All of these means are used to try and relate what is happening now to what has happened before. Ice core samples that date back to about 400 000 years ago allow a time line that is long enough to show many significant trends to be drawn up. Thus we now know a lot more than we did about the natural cycles of the earth and its affect on climate, but never have changes of the like we see now taken place.
Scientists have learnt that climate change can happen at a rate they previously thought would be far too fast. For example, a study by paleoclimatologists at the University of Oregon, using samples of lake sediment from the area has shown that about 21 000 years ago a huge change took place. The type of trees covering the area switched completely in the space of about 300 years. This could only be due to an abrupt shift in climate, and as the signs indicate we are heading to something similar, understanding exactly what caused it then can help us predict how much of a factor we are now.
Despite all the work being done, there is still considerable doubt over the exact causes of global warming. It is a huge puzzle with so many influences and such complex systems involved that even if we could know for certain, it would unlikely for it to be attributed to just one cause, but rather to a chain of changes. But what we can be almost sure of, is that right now we are kick-starting something. Yes, nature is hardy and can adapt to amazing situations, the world is not going to disintegrate due to global warming, but never before has such a huge new factor like humans been introduced into the system. A report from climate experts at Princeton University concludes, "We are now geological agents, capable of affecting the processes that determine climate." And when you think how many of us there are, that should hardly be surprising.
Many of the effects of global warming are the things we see around us that show us it is happening in the first place. It is also a story of links and interdependencies, as a small change in one place can have large ramifications elsewhere.
One of the largest primary effects is the melting of ice, in glaciers, on land and floating in the sea. The melt all ends up in the ocean, raising its level as well as lowering its salinity. The sea itself also heats up, and as it does so thermal expansion takes place, making it rise even more. This in turn has many other effects. In human terms it could spell disaster for whole countries that lie at sea level as never before have so many people lived so close to the coast. Places like Bangladesh could be under water with only a seemingly tiny rise in sea level. As well as displacing millions of people it would also destroy land which is usually the only source of income or subsistence for such peoples. First world megacities such as Tokyo and New York are also at risk.
Small rises in sea level cause totally disproportionate amounts of coastal erosion – approximately 1 inch of sea level rise results in about 8 feet of horizontal retreat on shore. Considering that more than a hundred million people live within three feet of mean sea level, this has the potential to cause mass displacement of populations. The salt water would also seep into freshwater aquifers, threatening sources of water for both drinking and agriculture. The spread of water along with warmer temperatures also brings with it a greater threat of water and insect borne diseases spreading to areas which were previously safe.
As well as filling up the sea, melting ice can also have effects on land. For example, Peru's Quelccaya ice cap is the largest one in the tropics, but it is currently receding at the rate of up to 600 feet per year. Thousands upon thousands of people rely on its water for drinking and for generating power. If it dissapears in the next 50 years those people will have nothing.
Warmer seas also affect the animals that live in them. One of oceanographer's greatest concerns has been the mass bleaching of coral over the past few years. Records show
that in the past, short periods of warmer than normal weather have caused coral to bleach, however most of it is generally quite localized and the coral tends to recover. In the past decade large areas in the world's most precious coral reefs such as the Great Barrier Reef have been so extensively bleached that nothing has recovered. In 1998, 16% of the world's coral was left bleached or dead after the summer months. There is left a white and stale graveyard that cannot support any of the reefs marine life.
Another worry is the decreasing salinity of sea water. The ocean acts much like the transport system in the human body. Great currents that traverse across the globe help to distribute heat and nutrients. The North Atlantic conveyer is the most important of these systems, and affects the climate on both sides of the Atlantic. The force that causes this conveyer to run is called thermohaline circulation. Warm, salty water flows from the tropical Atlantic north toward the Pole in currents such as the Gulf Stream. This saline water loses heat to the air as it is carried to far reaches of the North Atlantic. The coldness and high salinity make the water denser and it sinks deep into the ocean. Surface water moves in to replace it. The deep, cold water flows into the South Atlantic, Indian and Pacific Oceans, eventually mixing again with the warmer water, rising to the surface and continuing the cycle. Changes in temperature and salinity would thus greatly affect the conveyer belt, slowing it down, or even stopping it completely. And in doing so bring about great changes in climate as much of the northern hemisphere would no longer receive the warmth it brings.
This can result in one of the seemingly paradoxical aspects of global warming. Although the earth as a whole will be warmer, many places will be colder. Britain is likely to be one such place, whereas Canada and Siberia would be more likely to have warmer, wetter climates. Many places along the tropics could become dust-bowls as droughts become more severe and temperatures hotter.
A study of nonmigratory butterfly species in Europe showed that in the last three decades, about a third of them have expanded their range northward by up to 150 miles. In Britain, birds breed an average of 9 days earlier than they did in the mid 20th century while frogs mate seven weeks earlier. Alpine plants are heading uphill and endangering mountain top species that have no where to go. Shifts in migration patterns have been noticed in the past, but as this warming is so much more rapid than before, scientists are worried that species may not have enough time to adapt and avoid extinction. An important factor here is once again humans. In the past, animals were much freer to change their habitat or migratory routes. Today, species that are forced out by others that move up may find themselves in populated areas with no where to breed, nest and hunt. Habitat destruction of this kind has caused more extinction of species in the last 100 years than at any time in history.
Another problem with this is that all species react differently, and this is already causing natural symbiotic relationships to fall out of sync. In the Netherlands, peak hatchings of flycatcher birds and moth caterpillars have always happened on the same day, June 3rd. Since 1980, the pattern has been shifting slightly each year. 20 years later it has meant that most caterpillars emerge two weeks earlier than the birds hatch, so many nestlings go hungry and die.
What can be done about it?
As it has been basically confirmed by the scientific establishment that human production of greenhouse gases is one of the main causes, it means that there is potentially a lot we can do. Just about everything we do these days, from producing electricity to driving a car to crowing crops and clearing forests, results in an end product of more carbon dioxide, methane and nitrous oxide in the air. Cutting back on these things would cut back on emissions and reduce the amount of such gasses in the atmosphere.
There are many organizations and websites which give people ways to help out just by doing things a bit differently each day. There are also drives to try and get governments and businesses to set strict standards about how much fuel they burn and to try and find alternate means of providing people and industry with power and heat. The most important of these so far has been the Kyoto Protocol, which aimed to try and reduce emissions enough to curb the rapid temperature rise.
However complying with its guidelines means that things would have to change and those in power are reluctant to change without 'absolute proof' as they fear serious economic repercussions. However as researchers point out, the very definition of the future means that we cannot ever know exactly what will happen. We can predict what is more likely and be fairly confidant, but no one can give absolute proof with regards to future events. All we can do is try to act on the knowledge we do have and plan as best as possible for possible events.
For the skeptics
To state today that one does not believe in global warming at all is not really a reasonable statement to make. Of course it can be made, but like saying that the earth is the centre of universe, it goes against everything we know. Almost the same can be said for those who do not believe humans are the major cause. The more evidence that points toward it, the more denying it seems counter-productive.
In 1989 the Global Climate Coalition was formed by 46 of the world's biggest multi-national corporations. The companies represent all aspects of the worlds industries and championed themselves as a "voice for business in the global warming debate." The group funded many studies, which were mostly dismissed by the scientific community as being deeply flawed, to try and show that the Kyoto Protocol was pointless and indeed even detrimental. They even launched a marketing campaign to get companies to boycott the protocol, saying that although global warming was real, it was far too expensive to do anything about it. Yet since 1997 major corporations have been leaving the coalition. It started with British Petroleum who were then followed by the likes of DaimlerChrysler, Texaco and General Motors. When even companies like that start to change their stance, you know something must be up. However the coalition remains a well organized, well funded and active organization.
There are also other organizations claiming that the science used to back up the IPCC reports is not to be trusted and that either global warming does not exist, or it is actually good for the earth, or that we are not to blame. All these organizations are based in the US and many of the major ones are funded by the Western Fuels Association, so you can probably conclude for yourself why they want everyone to keep burning coal and oil.
The story of global warming is one of the biggest events in human fields of study from climatology to geography to industry. We are in a unique position to study the causes and effects of past and present climate change and to do something about the problems we and the environment face.
Everything that we learn about our world helps us to better understand it and place ourselves in its future. Regardless of what harm you believe they do, the burning of fossil fuels cannot go on forever, they are simply not renewable. The research that is being done with regards to global warming can help us come up with better ways to manage our resources, better ways to predict the weather and climate and better ways to protect the fauna and flora of the earth. Although even the more dire predictions will probably not affect any of our lifetimes directly, what we leave behind for our children is determined now.
- Climate Change 2001, IPCC Third Assessment Report. Full report available online at: http://www.grida.no/climate/ipcc/tar/wg1/index.htm
- Union of Concerned Scientists, articles on global warming. Found online at: http://www.ucsusa.org/global/environment/global_warming/
- National Geographic, September 2004