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In addition, global warming causes changes in the vertical profile of the atmosphere and equator-to-pole temperature gradients, leading to changes in how the atmosphere and ocean move. The temperature difference between equator and the poles is the driving force for global wind. As the polar regions warm at much higher rates then the equator, the reduced temperature difference causes a weakening of global winds and leads to a more meandering jet stream.
Some of these changes can create conditions such as persistent high-pressure systems and atmosphere blocking that favor more frequent and more intense heat waves. The heat domes over the Southern Plains and South in June and the West in September are examples.
The initial warming can be further amplified by positive feedbacks. For example, warming increases snow melt, exposing dark soil underneath, which absorbs more heat than snow, further enhancing the warming.
Warming of the atmosphere also increases its capacity to hold water vapor, which is a strong greenhouse gas. Therefore, more water vapor in the air leads to more warming. Higher temperatures tend to dry out the soil, and less soil moisture reduces the land’s heat capacity, making it easier to heat up.
These positive feedbacks further intensify the initial warming, leading to more heat extremes. More frequent and persistent heat waves lead to excessive evaporation, combined with decreased precipitation in some regions, causing more severe droughts and more frequent wildfires.
Higher temperatures increase the atmosphere’s capacity to hold moisture at a rate of about 7% per degree Celsius.
This increased humidity leads to heavier rainfall events. In addition, storm systems are fueled by latent heat, or the large amount of energy released when water vapor condenses to liquid water. Increased moisture content in the atmosphere also enhances latent heat in storm systems, increasing their intensity. Extreme heavy or persistent rainfall leads to increased flooding and landslides, with devastating social and economic consequences.
Even though it’s difficult to link specific extreme events directly to climate change, when these supposedly rare events occur with increasing frequency in a warming world, it is hard to ignore the changing state of our climate.
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