Light reflection/magnification and other questions

[redhawk1974]

  When talking global warming and climate change and all the causes I have a question.  With all the pollution in the air and different types what, if anything, happens to the atmospheres reflection ability of sunlight?   Are the pollutants reflecting in any way, meaning less sunlight or less intense rays reaching the surface or do pollutants magnify the intensity of the rays or is just no effect at all?  Also NASA's ICESat has now showed that 70 percent of the earth is covered by clouds.  Will this change with climate change or stay the same and if changes do happen what would the effects be do to increased or decreased cloud coverage?   

 

[studiot]

18 hours ago, redhawk1974 said:

  When talking global warming and climate change and all the causes I have a question.  With all the pollution in the air and different types what, if anything, happens to the atmospheres reflection ability of sunlight?   Are the pollutants reflecting in any way, meaning less sunlight or less intense rays reaching the surface or do pollutants magnify the intensity of the rays or is just no effect at all?  Also NASA's ICESat has now showed that 70 percent of the earth is covered by clouds.  Will this change with climate change or stay the same and if changes do happen what would the effects be do to increased or decreased cloud coverage?   

 

This is a very complicated question.

Pollutants come in different forms, some have increased some have decreased over the last century and a half.

Pollutants also have different sources over geological timescales, so the aerial dust from some volcanic eruptions definitely significantly reduced the insolation of the Earth's surface for several years after the event.

A century ago the smoke from steam engines probably did so on a smaller scale.

More recently these heavy soot particles have declined but diesel generated 'particulates', which are much smaller, are reported to affect human health.

 

This is a big subject.

[pavelcherepan]

On 9/11/2017 at 0:50 AM, redhawk1974 said:

  When talking global warming and climate change and all the causes I have a question.  With all the pollution in the air and different types what, if anything, happens to the atmospheres reflection ability of sunlight?   Are the pollutants reflecting in any way, meaning less sunlight or less intense rays reaching the surface or do pollutants magnify the intensity of the rays or is just no effect at all?  Also NASA's ICESat has now showed that 70 percent of the earth is covered by clouds.  Will this change with climate change or stay the same and if changes do happen what would the effects be do to increased or decreased cloud coverage?   

 

There could be a negative feedback mechanism to come out of global warming, when global increase of temperature causes the increased evaporation and increased cloud cover, which, in turn, would increase the albedo of the planet, which is about 0.3 at the moment, so there is plenty of way up.

On the other hand, melting of ice caps due to increasing temperature would lower the overall albedo. Not sure which one of these effects would win.

Also important to note that high albedo doesn't always translate to lower temperature as we can see in the case of Venus. Same as clouds reflect sunlight back into the space, reducing overall energy influx, they also are quite good at doing the same with radiation coming from the Earth's surface, thus decreasing heat loss.

P.S. Apparently NASA does some work on measuring planet's albedo and you can read what they came up with so far in the link below. Overall, there is no apparent global change in albedo, but there are definitely areas that have seen significant increase or decrease over the 12-year period.

Areas, where albedo increased seem to be around tropical and equatorial regions over ocean most likely due to increased cloud cover and major decrease is observed around North pole, due to melting of the ice cap. 

https://earthobservatory.nasa.gov/IOTD/view.php?id=84499

Edited October 17, 2017 by pavelcherepan