From: Plataforma SINC
Published March 3, 2009 09:25 AM
Mediterranean Sea Level Could Rise By over 2 feet
A Spanish-British research project has come up with three future
scenarios for the effects of climate change on the Mediterranean over the
next 90 years, using global models from the Intergovernmental Panel on
Climate Change (IPCC). The conclusions show that ocean temperatures in this
area will increase, along with sea levels.
In order to understand and correctly predict risks for the Mediterranean
coast, researchers from the Mediterranean Institute for Advanced Studies (IMEDEA,
a joint centre run by the University of the Balearic Islands (UIB) and the
Spanish National Research Council, CSIC) and the National Oceanography
Centre of Southampton in the United Kingdom have analysed simulations based
on three scenarios related to climate change and the rise in greenhouse
gases. Their goal was to predict the temperature, sea level and salinity of
the Mediterranean in the 21st Century.
"The most positive scenario assumes that greenhouse gas concentrations
remain constant at their levels in the year 2000, and even in this case
climate change still has an impact. The most negative scenario is based on
diverse levels of economic development all over the world, with an ongoing
increase in greenhouse gas production throughout the 21st Century," Marta
Marcos, the study's lead author and a researcher at the UIB, tells SINC.
The study, which has been published recently in the Journal of Geophysical
Research-Oceans, shows what could happen in the Mediterranean. The models
predict that higher concentrations of gases will lead to an increase in
temperatures throughout the entire sea.
In the most positive scenario, the changes are least, with temperature
increases of less than 1ºC expected to be recorded in the Mediterranean by
the end of the 21st Century. The other two scenarios envision an increase in
greenhouse gases over coming decades, and foresee an increase in the
temperature of the sea of up to 2.5º C. In addition, the results show that
the temperature increase will accelerate during the 21st Century.
In the long term, sea levels could alter due to changes in temperature
(warming leads to an increase in volume) as well as additional mass. "The
level of the whole Mediterranean will rise by between 3cm and 61cm* on
average as a result of the effects of warming," says Marcos.
There is "greater uncertainty" in terms of the mass likely to be added as a
result of melting ice at the poles and from continental glaciers, and this
aspect is not incorporated in the study. The most important area in terms of
understanding sea level rise is the coasts, "but it is here that we know
least because of the low spatial resolution of the models" the expert adds.
In search of greater clarity
The conclusions of this study are not based on observations, but rather on
global climate models that include a whole range of possible future
socio-economic scenarios in order to predict what is likely to happen in the
Mediterranean. According to the scientists, climatic conditions are going to
change greatly, and for this reason it is impossible to make a completely
precise prediction of what the future really holds.
In these circumstances, Marta Marcos and Michael Tsimplis say that, aside
from temperature changes, the models show that the Mediterranean will also
become saltier over the coming century. However, this prediction is also
very uncertain because "the variations in salinity in the Mediterranean are
controlled by the exchange of water through the Straits of Gibraltar, and
this has not been incorporated as an indicator, meaning the related results
are not very reliable".
This is due to the fact that IPCC models have very low spatial resolution,
which means they can show global processes "reasonably well", but not always
regional ones. In particular, the 14km-wide Straits of Gibraltar, which are
of key importance in the processes of water exchange between the
Mediterranean and Atlantic, are not well reproduced in the models.
The global models are of no use in estimating the impact of sea level rise
in coastal areas, because of the high level of regional variability for this
factor. The solution would be to use high-resolution, regional climate
models to show the Mediterranean straits with greater clarity, as well as
the oceanic processes that take place within the ocean's basin and coastal
areas.
This is a strategy currently being pursued by European research groups
working to predict the effects of climate change at a regional level, and it
is expected that the level of uncertainty in predictions will be reduced
over the short term. In Spain, IMEDEA is working to produce data on ocean
levels in collaboration with the Spanish Port System. Without such
resolution in the models "we cannot be sure of the scale of the changes",
the researcher concludes.
*61 cm is just over 2 feet Imperial measure.
Larger Chart :
http://www.sciencedaily.com/images/2009/03/090303084057-large.jpg |