This documentary by the BBC on Global Dimming is probably the most alarming global climate issue I have seen to date (and I was reminded of it this morning as the sun was dimmed from a local fire). It points out the simple long term agricultural measurements that show the amount of sunlight hitting the earth has been decreasing over the last century by anywhere from 10-30% (depending on the continent). If this is true, the ambient temperature should be cooling drastically, but the current trend is the opposite. This would mean that the soot and particulates being put into the atmosphere by human activity such as fires and industry, are actually masking the effects of global warming by a huge degree.
Discussed in the documentary are the ten days that planes stopped flying in the US after 9/11. This had a measurable increasing effect on sunlight and ambient temperature. The most daunting part about this dimming notion, is that it means that if we continue to clean up emissions that are dimming the planet, we might accelerate global warming. This would mean that we MUST also reduce greenhouse gases at the same time, and it must be coordinated globally. If these are not done in concert with one another, the countries that are decreasing their emissions, will be increasing their temperature instead of decreasing it. It is postulated in this documentary that the recent deadly heat waves of Europe and Africa are in fact the earths response to decreased emissions in Europe.
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