Global dimming.
The Guardian looks into the findings of researchers that levels of sunlight reaching the Earth have decreased significantly. It’s called global dimming. (*) We don’t know what causes global dimming, but we do know that it is not caused by a change in the sun. The dimming is occurring in that part of the electromagnetic spectrum made of visible light and infrared radiation.
A good guess of the cause is the level of dust and soot in the air, sometimes called “particulate matter.” These microscopic specks of free-floating matter may be absorbing sunlight, preventing it from reaching the surface of the earth.
The potential implications for the global warming debate are high. If the globe has not been warming up on average as fast as current models predict, it may nevertheless be the case that we are experiencing a greenhouse effect from carbon in the atmosphere. The lack of an increase in average global temperature may be attributed to reduced infrared radiation associated with global dimming. The greenhouse gas effect and global dimming could be acting together to occlude our insight into global warming.
It is not clear whether global dimming will become a major problem, or when. This phenomenon is very important and needs to be studied.