Sun, Apr 14, 2013 -
The damage from rising seas and higher storm
surges is one of the most visible and costly
effects of climate change.
Washington, DC 14 April 2013 - Sea-level
rise-a growing threat that washes away beaches,
attacks costal development, and raises the
platform for launching ever more damaging
and deadly storm surges-can be cut significantly
by reducing local air pollution from black
carbon, methane, and tropospheric ozone,
along with factory-made coolants called
HFCs.
This is the conclusion
of a multi-year research effort led by Professor
V. Ramanathan at Scripps Institution of
Oceanography, University of California,
San Diego, to be published online 14 April
by Nature Climate Change. The study calculated
that the annual rate of sea-level rise could
be reduced up to 24% by 2100 by controlling
these four climate pollutants, and that
cumulative sea-level rise could be reduced
by 22%.
‘It is still not too
late to avoid disastrous climate changes,”
stated study-lead, Dr. Ramanathan. “If we
stabilize CO2 concentrations below 450 ppm
by 2100 and simultaneously reduce SLCPs,
we can limit the end-of-century warming
by 50% and keep below the 2°C (3.6°F)
safety guardrail, from the projected 4°C
(7.2°F).”
These four climate pollutants
are collectively known as “short-lived climate
pollutants” because they clear out of the
atmosphere in a matter of days to a decade
and a half. Previous research by Dr. Ramanathan
and a follow-on study by the United Nations
Environment Programme & the World Meteorological
Organization showed that cutting SLCPs,
using existing technologies and institutions
in most cases, can cut the rate of climate
change by half or more by mid-century.
The current study calculates
the significant additional benefits that
SLCP mitigation can provide by the end of
the century-a critical 1.1°C reduction
in future warming. This is the same avoided
warming aggressive carbon dioxide mitigation
can produce in this period. Cutting both
SLCPs and CO2 can avoid 2.3°C of warming
and keep the Planet under the 2°C guardrail
according to the study, and reduce the rate
of sea-level rise by up to 50%, with SLCP’s
providing two-thirds of the reductions.
“Combined mitigation
will reduce the cumulative sea level rise
by about 30% (from the projected 0.5 m to
2 m/ 1.5 ft to 6.2 ft),” added Dr. Ramanathan.
“It is encouraging that SLCPs contribute
about half of the warming reduction and
about two-thirds of the sea level rise reduction,
since we have technologies to reduce them.
Without CO2 stabilization below 450 ppm,
however, both the warming and sea level
can rise to dangerous levels beyond 2100."
The damage from rising
seas and higher storm surges is one of the
most visible and costly effects of climate
change. Populations and infrastructure of
coastal cities will become more vulnerable
to flooding and storm surges, which are
also expected to become more frequent and
stronger as global temperatures rise. Indirect
impacts can include impacts on job markets
and tax revenue, and changes in population
and migration. According to a 2010 OECD
study, a rise in sea-levels of only three
feet (1 meter) by 2070 puts at risk 150
million people and $35 trillion in assets
in just 20 of the world’s most vulnerable
and fastest growing port cities, more than
half of which are in developing Asian countries.
“This ground-breaking
study provides the blueprint for climate
justice this century,” stated Durwood Zaelke,
President of the Institute for Governance
& Sustainable Development. “Cutting
these air pollutants and chemical coolants
can cut warming in half for many decades,
and is essential for protecting vulnerable
people and places this century,” he added.
“Failure to cut SLCPs will halt the impressive
gains in poverty reduction of the past few
decades,” Zaelke said, “and drive millions
more into extreme poverty.”
Because three SLCPs
are potent air pollutants, cutting them
can save millions of lives every year, while
significantly increasing crop yields, making
this important for promoting sustainable
development. In South Asia, for example,
air pollution is the leading preventable
cause of disease, according to a recent
report by the World Health Organization.
"We need an all
of the above approach to controlling greenhouse
gases. Cutting carbon emissions is critical,
but we also need to take advantage of the
very substantial short term gains that can
be achieved by cutting emissions of non-carbon
climate pollutants," stated study co-author
Claudia Tebaldi of Climate Central. “Readily
achievable reductions of non-carbon dioxide
pollutants would do far more to slow sea
level rise this century than actions to
reduce carbon emissions alone, protecting
millions of people and billions of dollars
of real estate from rising seas," she
added.
Based upon data from
the U.S. Geological Survey and NOAA, without
engineering protection, five feet of sea-level
rise could permanently flood 94% of Miami
beach, 88% of New Orleans, 7% of New York
City, 63% of Atlantic City, 20% of Jersey
City, 68% of Galveston TX, 6% of San Francisco,
and 4% of Seattle. Approximately 2.6 million
homes and 5 million people reside on land
less than four feet above high tide in the
U.S.; approximately 50% of those people
are in the state of Florida.
The study found that
delaying mitigation of SLCPs by 25 years
will decrease the impact of CO2 and SLCP
mitigation, and will make it difficult if
not impossible to keep warming below 2°C
by the end of the century. Delayed action
on SLCPs could increase sea-level rise by
up to 11%.
The Climate and Clean
Air Coalition to Reduce Short-Lived Climate
Pollutants (CCAC) is the first-ever global
effort specifically dedicated to reducing
emissions of SLCPs, and has already undertaken
seven fast-action initiatives designed to
mobilize resources and accelerate global
action on SLCPs.
The sea-level report
drew heavily from the data collected by
Project ABC, a United Nations sponsored
study of pollution masses known as atmospheric
brown clouds, which are especially prevalent
in South Asia. SLCPs are the main component
of brown clouds emitted primarily from biomass
burning, diesel emissions, and methane from
landfills.
The study co-authors
include: Aixue Hu and Warren M. Washington
of the US National Center for Atmospheric
Research, and Yangyang Xu of Scripps Institution
of Oceanography.