Since the Industrial Revolution began in the eighteenth century, we would have been altering our thin atmosphere to the point that we may be increasing its temperature. The solution to this problem would have a high economic cost. But due to some uncertainties, there is still no consensus on how to act.
An analysis of the scientific reality of this is difficult, because unfortunately the issue of global warming has been politicized. But lets suppose that the hypothesis at vogue ends twisting the wills.
In addressing this issue, we first need to clarify that greenhouse effect and global warming are two different things. Heat comes from the Sun mostly in the form of visible light, and leaves in the form of infrared light from the heated surface. There is a balance between what comes in and what goes out, and the temperature is kept constant. Estimates say that, because of the distance, the light from the Sun is insufficient to warm the Earth to more than 20° C below zero as average global temperature. However, because of our atmosphere the temperature is actually 14° C positive on average. There is a warmth that "wanders" before leaving, due to certain gases in the air, like carbon dioxide. This is called the greenhouse effect, and prevents our planet from freezing.
If we change the concentration of any of these gases we change this equilibrium temperature, and if the balance point moves up we are talking about a global warming.
AIR POLLUTION WORLDWIDE
No region or country in the world therefore escapes from these problems which would put the planet in jeopardy. For example, data from the World Wildlife Fund (WWF) show that the Interior Atlantic Forest of the Upper Paraná River is being turned into smoke so fast that in five years could disappear completely, mainly to make room for farming. It is an economic problem, and the solution is difficult, to the point that environmental organizations have to go buying forests.
In the case of Third World cities, watching from any traffic light is easy to be convinced that its inhabitants are breathing a huge amount of toxic smoke. The solution is that all vehicles (Diesels too) must follow a heavy, thorough maintenance, but for this we must reach into our pockets. It's much easier to blame everything on public transportation, right?
But a more complex problem is carbon dioxide, also known as carbon anhydride, carbonic gas, or CO2. This gas, transparent to our eyes and odorless, forms whenever we burn anything containing carbon (such as gasoline, Diesel oil, alcohol, cooking gas, wood, etc.) with oxygen from the air. It is non-toxic, but in recent centuries we have released it in such quantity that we may be altering the chemical composition of the atmosphere. Data published by James Hansen in 2005 show that since the 60s the overall concentration has increased by 20% and it continues to rise. And coincidentally, something that is also raising is the temperature of the Earth. Are we disturbing the natural balance of the greenhouse effect?
OIL IN THE MODERN WORLD
A look at the list of the 500 largest companies published by Fortune® magazine reveals that the major firms are those directly related to oil, either as producers or as consumers, for energy or for raw materials, for transport or to generate electricity. And it's not easy to ask them to stop using it the overnight. The world economy is moving forward thanks to oil. In fact, it is so important that the Persian Gulf War and the current Iraq invasion were for control of what is under the sands of this region of the world, not to mention other wars like the Chaco War.
According to the study published in 2007 by the UN Intergovernmental Panel on Climate Change, by 2100 the average temperature will be 1 to 6 degrees C higher than today. In the coming decades we are likely to see more and more droughts, with its impact on agriculture and livestock, the difficulty of finding drinking water, food shortages and even famine. Rainforests would give way to arid landscapes, with the inevitable extinction of entire species. The ice masses would melt with the consequent increase in sea levels by up to half a meter, enough to flood many of the world's inhabited areas. Tropical pests, such as the dengue mosquito, would thrive in the new climate. All this would have economic consequences, thereby increasing social tensions and possibly even armed conflict.
THE COST OF LOOKING FOR ALTERNATIVES
It is believed that the increase of carbon-dioxide levels in the atmosphere could be prevented by stopping burning carbon-containing fuels. Some propose going back to the seventeenth century, but probably neither you nor I want that.
But we can write laws mandating the use of fuels that absorb carbon in their production, such as alcohol or biodiesel, or encourage the use of hydropower, wind power, solar, or who knows, clean nuclear reactors: those of fusion. Maybe all of the above combined.
But it is not easy to choose these alternatives. Fusion reactors are experimental and none have worked but for only brief moments. Large rivers are few and dam reservoirs destroy forests. Wind energy is still more expensive than that obtained by burning oil, and the same is true for solar energy, and alcohol and biodiesel compete with food agriculture and they depend on the success of each harvest. Alternative sources of energy will cost us money. And not just to a few big capitalists: simply to all of us who like heavy and powerful vehicles, use plastic bags, want supermarkets with fresh products brought from far away and buy products manufactured in countries that have almost no hydroelectricity.
By using more expensive sources of energy the price of almost everything will go up. The world standard will therefore be the use of the three "Rs": reduce our consumption, reuse our products and recycle our wastes.
NOT TO DO ANYTHING
Or if these sacrifices seem too much, we can continue being addicted to oil and see what happens.
Senior officials from some industrialized countries and many business executives still say that oil is our friend. Some scientists say that the villain is perhaps Nature, since it is known that the Earth usually has cycling variations of temperature. In this case, all that is left for us to do is trying to adapt to a warmer world.
We will have to spend money in huge systems for the irrigation of agricultural fields, for research on new plants and cattle that need little water, invest in pest control spraying and in mass vaccinations and move coastal cities inland. In terms of reducing social tensions, that should be done with or without global warming. And what about the little animals in the forests? Well, they do not vote, right?
But the UN, the EU and most scientists say climate change is avoidable because this time we are at fault.
KYOTO AND PRUDENCE
Only 5° C cooler was enough to create the last Ice Age, when the sea between Russia and Alaska dropped so much that the first inhabitants of the Americas could easily arrive by walking. Nobody knows the actual consequences of the opposite, 5° C warmer, and if we can actually do something about it. Would not be good to be cautious and reduce carbon dioxide levels in the air right now, just in case?
In 1997 a global agreement was signed in Kyoto that intends to do that, but it is struggling to move beyond the paper: the problem is that it ask us all a change in our lifestyle.
The studies have still many unknowns, specially because no one knows if the climate will stabilize if we stop burning oil. The current philosophy of the hypothesis in vogue says it is better to be cautious and stop experimenting with our planet's atmosphere, because if we destroy it neither the Moon nor Mars could offer us an equivalent habitat. Everyone of us should reflect and form her or his own opinion. Then, time will tell us whether we were right or wrong.
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Based on a lecture from the series "End of the World", given at USP, on 20 November 1999. Originally published in ABC Color on 19 March 2006. Photograph: The Earth is a virtually self-contained ecological system whose only interaction of importance with the outside is given through the light that comes from the Sun. In this photo, the Russian space station Mir, on 4 July 1995, flying at 400 km altitude, over the thin layer of gases coating the surface of our planet. Credit: mission STS-71 (space shuttle "Atlantis") from NASA.