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Air pollution has masked the full impact of Global Warming (http://www.pbs.org/wgbh/nova/sun/)

PBS - NOVA - April 18, 2006

http://www.cleanmpg.com/photos/data/501/NOVA_PBS_Dimming_The_Sun.jpg

New evidence that air pollution has masked the full impact of Global Warming suggest the world may soon face a heightened crisis. April 18 at 08:00 PM

"Dimming the Sun" investigates the discovery that the sunlight reaching Earth has been growing dimmer, which may seem surprising given all the international concern over global warming. At first glance, less sunlight might hardly seem to matter when our planet is stewing in greenhouse gases. But the discovery of global dimming has led several scientists to revise their models of the climate and how fast it's changing. According to one recent and highly controversial model, the worst-case warming scenario could be worse than anyone has predicted. "Dimming the Sun" unravels this baffling climate conundrum and the implications for Earth's future.

To find out what global dimming means for the fate of the planet, NOVA reports on the findings of the world's top climate detectives, including an American scientist who found a grim but crucial opportunity immediately following September 11, 2001, when the entire U.S. airline fleet was grounded for three days. This presented a unique opportunity to study the effects of airplane vapor trails on the atmosphere (see The Contrail Effect (http://www.pbs.org/wgbh/nova/sun/contrail.html)). Comparing changes in the daily temperature range showed that the absence of dimming from aircraft pollution alone made a marked difference to the temperature. This result hints at how much the effects of atmospheric pollution had been underestimated.

Working in Israel, Dr. Gerald Stanhill was one of the first to discover the surprising fact that less solar energy is reaching the Earth's surface. While his measurements were met with skepticism, a review of worldwide data by Stanhill and a German researcher demonstrated that during the 1980s and early '90s, sunlight reaching Earth's surface had dropped just about everywhere. Halfway around the world, independent studies by Australian scientists confirmed this disturbing diagnosis. (For more, see Discoveries in Global Dimming (http://www.pbs.org/wgbh/nova/sun/dimming.html).)

Scientists have long known that increasing air pollution-the smog that clouds urban skies-endangers our respiratory health. But they had underestimated the impact of pollution on the amount of sunlight reaching Earth. Some scientists now believe that global dimming may also disturb rainfall patterns such as the Asian monsoon. If they are right, global dimming may be one of many factors that contributed to severe droughts and famines in Africa during the 1980s.

The good news is that pollution controls have slowed and possibly even halted global dimming during the last decade. The bad news-and the ironic twist in NOVA's story-is that without pollution, more sunlight is reaching Earth, revealing the full impact of global warming. Although all climate models have important uncertainties, the unsettling implication is that, with dimming fading away in many regions, global temperatures may rise even faster than most models have predicted.

Additional airings:

4/22 2pm WMVX 10 Milwaukee
4/23 1am WTTW 11 Chicago
4/23 4am WMVX 10 Milwaukee

Check Your local listings.

Well there you have it.. if we want to turn off global warming, we just need to fly some jets around with smoke machines to blot out the sun. Problem fixed!

someone else's mistake will be your last moment.

Enjoy the time you have until then.

It's interesting to note the Venus Express (http://www.space.com/missionlaunches/060410_venusexp_prearrival.html) just orbited the nearest planet to us to study it's hot and murky atmosphere.

Nothing is done, till there is a crisis. It's an excellent, abit depressing, showing how we are heading toward less sunlight = less evaporation = less rain.
Apparently, all the stuff we are putting in the atmoshpere is attaching to the waterdroplets, making this droplets small, (too small for them to fall) and worse....reflecting the sun back to space (sun shines on the caught water droplets like a mirror, never reach our earth).

But, nothing is done till there is a crisis.

Hi Dave:

___I think you are right and it’s only a matter of time. I watched the show and it was scary to find out how particulate adds such a large negative feedback vs. GHG’s positive one in terms of the earth’s overall energy balance. At some point in the very near future, we will have to start CO2 sequestration and not just from our current Emissions but also pull it back out of the atmosphere to pay for our sins of the past in some form?

___The interesting thing about larger power plants (large Nuclear and small Hydro excluded due to the lack of CO2 output) is that they can be cleaned to the point of 0 CO2 emissions! The latest Coal-gasification tech can have its effluent stripped of CO2 in it’s entirely and the price is only ~ 35% more $’s/kWh including the sequestration afterwards!

___Until we get carbon trading credits or other GHG friendly incentives into the electrical generation pipeline and then again to take out transportation sector off of carbon based fuels (EV’s), the world is in for some serious hurt. I just hope we can survive.

___The extremely high temperatures many of the larger urban areas of the US has seen this spring as well as the ferocity of the storms over the past 2 or 3 years is a sign that heat is really starting to effect our daily livelihoods. I don’t know if you have followed some of the other posts here but I remember as a child the snowfall and accumulation in the Steven’s Point, WI. area throughout the winter months. You cannot buy snow accumulation that far south now and that all winter snow line is making its way up into the UP already!

___Good Luck

___Wayne

But, still....nothing will be done till there is a crisis.
Look how we, as a group, still stand out in the suv/low gas mileage country.
And, hybrids aren't the cure, helpful but not going to solve the emissions much. (but it make us feel better cause it's alittle helpful).
Wayne, I agree about the "childhood memory" of weather. I live two hours north of Stevens Point, and our winters have been reduce by the lack of snow. It could be just a cycle we are going thru, and all of the stuff we're putting in our atmosphere will go away (fall back to earth/ or happily out into space), yep, and I'm going to run a three hour marathon.
Seriously, zero emissions will be/have to be implemented sometime in the future, be it power plants (think nuclear) or cars (hopefully hydrogen).
But, as we both know, we're probably going to kill a lot of life on our planet before we figure we better start helping it.
But...but....god I hope I'm wrong about that last sentence.........

Couldn't agree more, DQDave. Society is like a lazy, apathetic college student. It'll turn in the assignment, but it'll get a terrible grade, miss lots of potential, easy points, and barely pass the class. Sometimes it fails or withdraws altogether.