Several Factors Required for Attribution to Extremes
Any
weather phenomenon can impact any location on Earth at any time, but
the probability of occurrence of each event varies. As the global
population increases and expands, more weather events are being reported
locally. This fact alone may lead to more extreme weather events being
observed. Global climatic changes may influence the actual number of
extreme weather event occurrences. Long term variability in atmospheric
circulations may be linked to natural or anthropogenic (human
influenced) effects. There are likely atmospheric impacts from both
scenarios.
Regional Variability in the Earth's Atmosphere
Without
weather, seasonal changes would not happen. All else being equal, your
climate would remain stagnant and boring. Interactions between regions
of different climates and their land, sea, and air interfaces drive
local weather patterns. To complicate things more, different elevations
exist among these boundaries. Vast mountain ranges and valleys extend
across multiple continental borders. Underwater canyons and ridges
spread out across all ocean basins. Atmospheric waves can affect the
heights of temperature, pressure, moisture, etc. In addition,
particulate matter interacts chemically, biologically, geologically, and
physically as particles are transported around the world.
Observed Precipitation Changes
Super-saturating a Warmer Atmosphere
Climate
scientists have shown that as global atmospheric temperatures rise due
at least in part to human activities, water vapor concentrations will
also rise. In terms of thermodynamics, a single water vapor molecule has
a higher heat capacity than that of dry air. This means that water
vapor molecules have the ability to hold more moisture at higher
temperatures. Oceans cover approximately 70% of the Earth's surface
area. As sea surface temperatures rise, evaporation rates into the
atmosphere increase the water vapor content in the atmosphere. Having
the greater quantity of moisture in the warmer atmosphere would allow
clouds to hold moisture longer before producing precipitation. Timing
between each weather event lengthens while clouds take longer to
condense. This results in both shorter-lived intense precipitation
events and longer-term droughts.
New Jersey Flooding from Hurricane Sandy
Source: Wikimedia Commons
Increased Vulnerability from Human Migrations
Populations
have increasingly been relocating towards coastal areas. These
migrations increase their vulnerability to being impacted from coastal
storms. Flooding from storm surges has the highest impacts along
coastlines. This is true with or without any statistical long term
trends in storm frequency or intensity. Any location can be impacted
from extreme events, but coastal residents should especially be aware of
their increased vulnerability.
