-Mike from NYC-
Storms have happened throughout our history, and they will continue to happen as long as we live on this earth. The impact climate change has on storms deals with the one thing we know about climate change: overall temperature is rising. What does that have to do with storms? The same thing it has to do with storms is the same thing it has to do with droughts: warmer air holds more water and more energy. This has to do with a science called psychrometrics.
Psychrometrics is the study of the interrelation of temperature, moisture content, density, and energy content of air. Developed in the early part of last century, the interrelation of these parameters means much to those designing comfort systems for buildings and meteorologists predicting weather patterns. The chart that links all these characteristics of humid air is shown below:
The horizontal axis (along the bottom) is dry-bulb temperature, the temperature reported during the weather forecast. The vertical axis (along the right side of the chart) notes the amount of moisture contained in the air expressed as the weight of water relative to the weight of air. This is not something we are used to seeing, but the curved lines moving from low end to high end (left to right) that indicate relative humidity. We are familiar with the fact that areas like the desert southwest where we experience high temperature but low "relative humidity" and the northwest of the country where we have mid-range temperatures and high "relative humidity". The last two lines of interest are the highest curved line which notes the energy that is contained in the air and the slightly tilted vertical lines that represent the density of the air (air to the left is more dense than air to the right).
So what does this have to do with storms? Currently, according to the National Oceanic and Atmospheric Administration, the average increase of temperature above the pre-warming level is a little over 1.1 F (about 0.62 C). If the average temperature increases by a degree (moving one line to the right), that means approximately a 1-3% increase in the energy content of the air and a decrease of 0.3% in the density of the air. Neither of these sound like much of an increase, but when you spread these over an 800 mile in circumference it adds energy to an already energetic storm, then for every loss of density of air you pick up more moisture. Picking up more energy and more moisture adds to the destructive nature of the storm. In the same sense, in drought areas, warmer air draws more moisture from the ground and deposits that moisture in other locations. Each of these severely changes the micro-climate of the region affected. The other impact climate change had on Sandy in particular was the change of the jet stream that changed the pressure around the northern end of the storm (pressure = energy). This change fueled what would have been a less damaging category 1 storm into a significantly more charged storm as it hit land (and therefore stopped being a hurricane).
As Mayor Andrew Cuomo stated, New York is now seeing a 100-year storm every other year. The cities in the areas hardest hit by these types of storms were not designed to handle this type of weather because they have never seen it before. The hallmark of our era of civilization will be how we both adapt to this changing climate and how we change our relationship with the environment to mitigate the increase in temperature.
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