Natural disasters - floods, volcanic eruptions, tornadoes - have always been unpredictable and completely natural. And if in most cases the human factor has little effect on this character, then the situation with hurricanes, as recent studies show, may be different. Increasingly, scientists today say that global climate change has a direct impact on the frequency and severity of hurricanes.
Climatologists do not argue that there is a direct causal relationship between human-induced climate change on the planet and the tendency to intensify hurricanes. However, they pay attention to more and more new evidence of this dependence. Time provides five of the strongest arguments for this theory.
1. Warm air
Hurricanes begin with atmospheric heat. As it heats up, the air rises upward, creating a low pressure area below. There is a kind of suction, attraction of warmer ambient air, which accumulates in the air mass constantly rising up. If on land this natural process usually occurs without sad consequences, then above the ocean, along with the air, water rises upward, which feeds the hurricanes. And the warmer the air, the more moisture it can lift up. Each degree increases the capacity of moisture in the atmosphere by an average of 7%. As you know, for decades, the temperature on Earth has been steadily increasing, and at present the average values are above the level of 1951-1980 by 0.99 degrees Celsius.
Experts warn that seasonal fluctuations could become even more significant. The previous two July were the hottest in 137 years of meteorological observations. This amount of heat is not dissipated immediately, but actually hangs in the atmosphere and becomes "fuel" for hurricanes when the new season begins.
2. Warm water
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When a hurricane starts, it needs constant recharge in the form of warm ocean water. Firstly, the heat provides energy to sustain the hurricane, and secondly, clouds form due to the water, which subsequently fall in the form of rain.
Scientists estimate that ocean surface temperatures have increased by 0.072 degrees Celsius every ten years from 1901 to the present, with the rate of ocean warming increasing exponentially in the past two decades.
As Earth science professor Gabriel Vecchi of Princeton University notes, a warmer ocean creates a warmer atmosphere, which in turn can hold more water. “Thus, other things being equal, a storm on a warmer planet will produce more precipitation,” the scientist explains.
3. Dangerous currents
In addition to generating more hurricanes, climate change also directs them to where they can do the most damage.
The world's oceans are dotted with a system of cold and warm currents. In the Northern Hemisphere, this process is partly regulated by the Atlantic Multi-Decade Oscillation (AMO), which assumes predictable temperature shifts in the Atlantic Ocean over long periods of the order of 60–80 years. However, a new study published last week in the journal Science showed that climate change is disrupting the well-established rhythm of AMO as a result, warm ocean currents rush to the coast of North America long before they have time to enter the cool phase. As a result, the authors of the study argue, hurricanes will travel to ever higher latitudes, which will threaten an increasing number of settlements that have not previously faced similar problems.
4. Deep oceans
The depth of the ocean does not play any role in the formation of a hurricane, but it has a significant impact on how much damage it can cause.
Ice cover on the planet - especially in Greenland and Antarctica - is today at its historic minimum. Since 1880, sea level has risen by an average of 20 centimeters and continues to rise. Meanwhile, storm surges that hit the coast during hurricanes wreak havoc on coastal areas.
5. Clear sky
Paradoxically, the struggle of developed countries for a clear sky by reducing the level of hazardous aerosols and particulate matter in the atmosphere has its negative consequences in terms of climate change. With a cloudless sky, more sunlight enters the Earth, which is then trapped by greenhouse gases, which only exacerbates global warming.
Of course, this does not mean at all that humanity should, as in the days of the industrial revolution, smoke the heavens again. It is just that the fight against lead and sulfur dioxide in the atmosphere should be replaced by the fight against greenhouse gases, experts say.