Burn now, pay later - today’s emissions lock in long term sea level rise
- 30 Jul 2013, 17:30
- Freya Roberts
City dwellers in the distant future could be
squeezed out of the United States' biggest coastal cities by sea
level rise, if new research is right. Miami, Boston and Sacramento
are just some of the cities that could be locked in to serious
levels of flooding by 2100 if high emissions scenarios are
realised, it says.
That's not to say these cities would be entirely
underwater by 2100 - a mistake made but quickly corrected by
the Guardian. But the emissions released
over this century could mean these cities are unable to escape
flooding from sea level rise at some point over the coming
centuries or millennia. Here are the finer details of the
The idea of long term sea level rise caught
media attention earlier this month when
research in the journal Proceedings of the
National Academy of Sciences (PNAS) estimated that for each degree
Celsius of global warming, sea levels would rise by
This long term picture is important because sea
levels respond slowly to temperature rise. This means
that even if greenhouse gas emissions are cut and temperatures
level out, sea level rise will continue for some time.
Now, a new
comment article by Benjamin Strauss in the journal
PNAS takes the idea of long term sea level rise one step further.
By looking at the amount of carbon humans have emitted since 1850,
plus the amount we might emit by 2100, Strauss estimates the long
term effect of this century's emissions.
By 2050, we'd be locked into 2.1 m of long term
sea level rise under a low emissions scenario, or 3.1 m under much
higher emissions, according to his modelling.
Strauss estimates, the level of carbon
emissions in the atmosphere will have committed Earth to enough
long term sea level rise to threaten many of the United States
The scariest scenario occurs if emissions
continue to rise unabated out to 2100. At high tide, the locked-in
sea level rise would flood land where 50 per cent of the
populations of Miami, Boston, Virginia Beach and Sacramento
However, the research finds that if emissions
were to peak soon and fall for the rest of this century, the long
term sea level lock-in would be much less. Of the seven large
cities the study looks at, only Miami would be severely affected -
with residential areas housing 25 per cent of today's population
Even if floods affect less than 25 percent of
cities' residential areas, the effect could still be damaging
though. Where important infrastructure like power stations and
hospitals is very close to the shore lines, limited flooding could
have cause significant disruption
There are of course caveats with studies like
this. People in cities will probably adapt where possible -
building coastal defences and migrating inland, for example - so
the risk might not be so great in the future.
There could also be some regional difference in
sea level rise, so some cities may end up faring worse than others.
There are still questions as to whether Miami will end up
underwater, for example.
But the research carries a strong message.
Today's emissions represent a real threat to people living in
coastal cities hundreds or thousands of years from now. The
decisions governments make about emissions this century may not
change sea levels much by 2100, but they will affect climate for a
long time to come.
Strauss, B. (2013) Rapid accumulation of committed
sea-level rise from global warming. Proceedings of the National
Academy of Sciences. DOI: 10.1073/pnas.1312464110