Ocean
Heat Spikes and Atmospheric Rivers: Two Thousand Homes Destroyed in
North Afghanistan Floods
27
April, 2014
The ocean-atmosphere system might well be described as an intricate pirouette between the forces of heat and moisture. Warming and cooling over the ocean and atmosphere alter the rate at which rains fall or lands dry. This interplay, called the hydrological cycle, is a primary governor the world’s weather, playing an integral part in both storm formation and dry spells alike.
As
the Earth has warmed by about .8 degrees Celsius since 1880, this
cycle of evaporation and precipitation, of drought and deluge at the
extremes, intensified by about 6% on average.
But this increase was uneven, pushed to an even greater abnormalities
when both the Earth’s atmosphere and ocean surface experienced
periods of either strong warming or relative cooling. It was from
this combined uneveness and overall warming trend which arose a
number of increasingly severe and dangerous weather events.
Most
recently, as of last week, global ocean surface temperatures hit a
very high +1.12 degrees Celsius above average temperature anomaly (vs
the 1979 to 2000 average). This warm pulse pumped both heat and
moisture into the world climate system. During recent years, major
ocean warming episodes have coincided with intense periods of extreme
rainfall and drought around the globe. So when anomalies hit severe
levels last week, risks rose that atmospheric rivers of moisture and
related extreme rainfall events would intensify.
By
April 24, two entrained storm systems had erupted from the much
hotter than normal Mediterranean Sea casting their long, dark shadows
over Western and Central Asia as they began a tortuously slow march
toward North Afghanistan:
The
result was a three-day-long rain event that destroyed over 2,000
homes in North Afghanistan impacting 10,000 families and resulting in
the loss of 180 souls. Severe losses also extended to crops and
livestock over a broad region of this Central Asian state as
individuals were forced to abandon farms and villages.
The
inundation left many besieged by a violent swirl of raging waters
spurring Afghanistan security forces to activation as helicopters
were used to ferry stranded people to higher ground. Jawzjan
provincial police chief Faqer Mohammad Jawzjani made this plea as the
most recent Afghanistan weather disaster stretched resources to their
limits:
“We
have carried 1,500 people to safe areas of neighboring districts by
helicopter. We need emergency assistance from the central government
and aid agencies.”
Jawzjani’s
pleas for assistance were echoed by local government officials
throughout the stricken region as many more people remained isolated
and without immediate help.
Afghanistan’s
rugged terrain is particularly vulnerable to intense rain events.
High volumes of rainfall channel through steep ravines and build up
into large, wave-like flood pulses in Afghanistan’s heavily
populated valleys. Low-lying homes constructed of mud and rock also
often lack resiliency and are in danger of either collapse or
inundation during severe storms.
As
the Earth continues to warm, it is likely that both severe drought
and rainfall events will continue to grown in frequency and
intensity. Unfortunately, it is those who are most vulnerable — the
poor and those who have contributed the least to the rapidly
intensifying climate shock — who will bear the first and heaviest
impacts.
Links:
Hat
tip to the ever-vigilant Colorado Bob
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