Some people who question the verity of global warming and climate change use the argument that the world is getting cooler due to particulates in the air, and rely on information about volcanic eruptions that caused ice ages to try to disprove global warming theories. Some others think that the effect of global dimming is actually slowing down global warming: http://www.bbc.co.uk/sn/tvradio/programmes/horizon/dimming_prog_summary.shtml
Nobel Laureate Paul Crutzen has even suggested that we pump huge amounts of suphur into the stratosphere to cool the planet. http://www.springer-sbm.com/index.php?id=291&backPID=132&L=0&tx_tnc_news=2646. Somehow, I don’t think that putting out huge amounts of the ingredient that was the main cause of acid rain would be a good solution~I beg to disagree.
There is a factor where pollutants cause the reflection of solar radiation into the atmosphere before it reaches the earth (increasing the albedo), thereby preventing some of the global warming because those rays cannot be absorbed and reradiated back into the atmosphere. However, this global dimming is much smaller than the warming effect from greenhouse gases.
Global dimming is an important issue to understand if you are talking about government policy, because some policies advocate for addressing pollution (targeting gases that cause asthma and other health problems like sulphur dioxide), but ignore the carbon dioxide outputs. When companies address the sulphur problem (like Inco in Sudbury, which have significantly reduced SO2 emissions) but don’t reduce their CO2 emissions proportionally, they are adding exponentially to global warming~they are reducing the pollution that cools the earth and sending out more that warm it. Not to say that companies like Inco shouldn’t be working on improving air quality: far from it, I applaud their efforts. It is just that the GHG outputs should be reduced at the same level as the other pollution.
Encyclopedia of Earth author Stephen Nodvin (who is a Climate Project presenter & professor in Boston) wrote: The IPCC also found that anthropogenic contributions to aerosols in the atmosphere produce cooling effects, referred to as global dimming. However the cooling (global dimming) effects due to human-caused aerosols are equivalent to about half of the warming effects due to the combined radiative forcing of human-produced greenhouse gases, causing a net warming. http://www.eoearth.org/article/Global_warming
Wikipedia also has a big entry on global dimming: http://en.wikipedia.org/wiki/Global_dimming
One of the reasons that the general population gets so confused about global warming and climate change is that the ideas are so complex, that many factors need to be balanced, and noone’s prediction is exactly accurate (like weather forecasts). They have a very good idea of what will happen, but don't know exactly when.
As our science modelling and understanding of these transparent interactionsgets more accurate, it will be easier for us all to make decisions that have a net improvement for the environment. It’s clear to me that we need to deal with global dimming and global warming together to prevent climate change.
One of the reasons that the general population gets so confused about global warming and climate change is that the ideas are so complex, that many factors need to be balanced, and noone’s prediction is exactly accurate (like weather forecasts).
As our science modelling and understanding of these transparent interactions gets more accurate, it will be easier for us all to make decisions that have a net improvement for the environment.