The show went on to say that the burning of fossil fuels has two major effects on the earth's climate; the first is the release of green house gases, which trap heat from the sun in the atmosphere, creating an overall rise in global temperatures - there is a vast amount of information about this and virtually no dispute among atmospheric scientists - and the second major effect is air pollution. When we burn these fuels we send billions of very small particles of sulphur dioxide, soot, and ash into the air, called aerosols by scientists. We all know about the health damaging effects of smog, but what has more recently come to light is that these small solids change the properties of clouds.
Clouds form when moisture gathers around airborne particles such as pollen. What has now been observed in several scientific studies is that the particles emitted by the burning of fossil fuels, create clouds that are made up of many more tiny droplets than "natural" clouds. These smog created clouds have a twofold effect: they shield sunlight from getting to the earths surface and because of the reflective nature of water they reflect light back into space from the millions of tiny droplets held suspended in them. This has been duped the "global dimming" effect.
Many scientist now believe that global dimming caused by these pollutants have been mitigating the temperature rises brought about by Global warming. Over the last thirty years or so we have increased the earths temperature by about one to one and half degrees Fahrenheit. Without global dimming our planet would be two to three degrees warmer than it currently is. So there is a sort of tug-a-war between the green house gases and the particulates released by burning fossil fuels.
We know that airborne pollutants effects human health in a variety of dangerous ways and are responsible for a sharp rise in asthma and other respiratory diseases. We have responded to these dangers in Europe and the United States by placing catalytic converters in our automobiles and smog scrubbers in factory smoke stacks. These efforts have shown a marked improvement in the air quality of cities. However they have also allowed the green house effect to become more pronounced. If we continue to decrease smog while pouring CO2 and other green house gases into our atmosphere we will rapidly warm our planet.
Dr. James E. Hansen of Columbia University and the head Goddard Institute for Space Studies, believes this warming could be as much as five degrees in the next thirty years and ten to fourteen degrees over the course of this century. Such a temperature rise would be devastating to life on Earth, and would likely bring on a cascade of self-promoting warming effects such as: forests drying and burning, a steady thawing of the Greenland and arctic ice sheets, and (most dangerous of all) a release of the methane hydrates that are now frozen at the bottom of the oceans.
These responses to human activity by the earth's climate could remake the planet into something that is very inhospitable to human life. Dr, Hansen warns that his research shows that man has just 10 years to reduce greenhouse gases before global warming reaches what he calls a tipping point and becomes unstoppable.
What these climate models do not take into consideration is what could happen if humans started focusing our energies on fixing the life threatening problems we face. If we consider all of the effort, thought and inventiveness that we have put into our modern lives, from the complex and incredible industry we have shown to get these fossil fuels out of the ground and into our gas tanks, and then to get our cars on the intricate and vast systems of roads we have produced for them, to the technological innovativeness that we have poured into warfare and consumer products in the last forty years we must conclude that we can have a positive effect on promoting our own survival if we decide as a people to focus on protecting life rather then destroying it.
To do this we will have to define our basic values. We all want, our families, ourselves, and the people we love to enjoy good health and have a decent standard of life. The information presented above makes it clear that we will not be able to make this happen on the old model, of individual achievement and acquisition. We will have to co-operate on a global scale if we want to survive this next century. If we continue to make warfare, and short-term corporate profit taking, our priorities we will literally ignite and burn away our life here on earth. However if we embrace the cooperation and openness to innovation that appears at present to be our only way to survive we may gain a new way of understanding and living in the world.
--sources and additional reading--
* David Sington "Dimming the Sun"
PBS/ NOVA, April 18 2006
* Guest posting from Beate LiepertLDEO "Global Dimming and climate models"
Real Climate, April 17, 2006
* David Sington "Why the Sun seems to be 'dimming'". BBC News, January 13.2005
* Horizen Radio "Global Dimming" BBC Co. UK,
* David Appel "The Darking Earth"
Scientific American.com, August 2, 2004
* none given "Pollution, cloud may solve global evaporation puzzle"
ABC,net, Friday, 15 November 2002
* Catherine Herrick/Bill Owens "Rewriting The Science"
CBS News, March 19 2006
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