Positive Effect of Global Dimming
Since Global Dimming is Environmental issues, we can easily assume it will provide bad affect to earth; however, Global Dimming has good effect considering global warming issues.
The point is that Global Dimming covers the drastic effects of Global Warming. As you can see in the definition part of "What is Global Dimming?" the Global Dimming prevents the Short Wave radiation going through the cloud and coming toward the Earth surface and it makes the earth dimmer. That means, the amounts of solar energy reaching to land is reduced as well as light, and it causes to make earth cooler.
It is predicted by the climate change models that 5 degrees increase in temperature over the next century, which is already considered extremely grave. However, global dimming has led to an underestimation of the power of global warming.
This graph shows that temperature change over global land surfaces from 1958 to 2002 with respect to 1960. While the temperature rise during the period of solar dimming from the 1960s to the 1980s is moderate, temperature rise is more rapid in the last two decades where dimming is no more present. (WILD ET AL, 2007)
This aspect of global dimming has led to fears that global dimming has been hiding the actual impact of global warming..
Negative Effect of Global Dimming
The pollutants that caused to global dimming lead to various human and environmental problems, such as smog, respiratory problems, and acid rain. However, there is also many devastating impact of global dimming itself.
It is related to hydrological cycle. The energy for the hydrological cycle comes from sunlight. As sunlight heats the ocean, water escapes into the atmosphere and falls out as rain. So as aerosols cut down sunlight by large amounts, less evaporation occurs. It causes less precipitation, then eventually they weaken the hydrological cycle of the planet. That brings about various issues.
[ Reducing rainfall → threaten fresh water supplies → more droughts and soil erosion→ vegetation die off quickly and food production fail → hunger]
In this process, million people died already. For example, the great famine of sahel in 70-80s are assumed to be caused by the global dimming.
The reflecting back of heat has turned the water of northern hemisphere colder.
With water’s temperature getting down less rain is generated and the required amount of rain is failed to reach The Sahel, Northern Africa.
It is now disclosed that the complex famines of 1970s and 1980s were caused by the less number of rains. More than a century of rainfall data in the Sahel show an extremely dry years from 1970 to 1990 (negative index values). The BBC documentary concluded that the smoke coming out of power stations and pipes of North America and Europe is responsible for the death of millions of people in Africa while making the life of more than 50 million people miserable. It is estimated that billions of people in Asia will be affected by the Global Dimming. The monsoon rains of Asia provide rainfall to almost half of the world’s population. If Global Dimming decrease the amount of rainfall then half of the world’s population around three billion people will be starving because of bad harvest.
