Other than the classification of natural or human-made for climate forcings, another common classification is a positive forcing or a negative forcing. Positive forcings change the Earth’s energy balance and the effects are a warmer surface on Earth. Negative forcings are the opposite; they change the Earth’s energy balance but act to cool the surface on Earth [21].
An example of a positive forcing is a spontaneous increase in the sun’s brightness, leading to a warmer surface temperature on Earth. On the other hand, a negative forcing that cools the Earth is a volcano. Volocanos shoot out aerosols at high speeds into the atmosphere and the aerosols act to reflect light from earth; this causes a cooling of the earth’s surface [21].
The central problem recently is that climate sensitivity relative to positive forcings has begun to outweigh the sensitivity due to negative forcings. This has led to a very slight increase in recent years in the Earth’s surface temperature. If the problem is not solved, drastic consequences may ensue, such as the sea level rising due to thermal expansion.
