Climate
change rate to turn southern Spain to desert by 2100, report warns
Mediterranean
ecosystems will change to a state unprecedented in the past 10,000
years unless temperature rises are held to within 1.5C, say
scientists
Adam Vaughan
Thursday 27 October
2016 19.00 BST
Climate change rate
to turn southern Spain to desert by 2100, report warns
Mediterranean
ecosystems will change to a state unprecedented in the past 10,000
years unless temperature rises are held to within 1.5C, say
scientists
Southern Spain will
be reduced to desert by the end of the century if the current rate of
greenhouse gas emissions continue unchecked, researchers have warned.
Anything less than
extremely ambitious and politically unlikely carbon emissions cuts
will see ecosystems in the Mediterranean change to a state
unprecedented in the past 10 millennia, they said.
The study, published
in the journal Science, modelled what would happen to vegetation in
the Mediterranean basin under four different paths of future carbon
emissions, from a business-as-usual scenario at the worst end to
keeping temperature rises below the Paris climate deal target of 1.5C
at the other.
Temperatures would
rise nearly 5C globally under the worst case scenario by 2100,
causing deserts to expand northwards across southern Spain and
Sicily, and Mediterranean vegetation to replace deciduous forests.
Even if emissions
are held to the level of pledges put forward ahead of the Paris deal,
southern Europe would experience a “substantial” expansion of
deserts. The level of change would be beyond anything the region’s
ecosystems had experienced during the holocene, the geological epoch
that started more than 10,000 years ago.
“The Med is very
sensitive to climatic change, maybe much more than any other region
in the world,” said lead author Joel Guiot of Aix-Marseille
University. “A lot of people are living at the level of the sea, it
also has a lot of troubles coming from migration. If we add
additional problems due to climate change, it will be worse in the
future.”
He said that while
his study did not simulate what would happen to production of
Mediterranean food staples such as olives, other research showed it
was clear the changes would harm their production. Climate change has
already warmed the region by more than the global average – 1.3C
compared to 1C – since the industrial revolution.
The real impact on
Mediterranean ecosystems, which are considered a hotspot of
biodiversity, could be worse because the study did not look at other
human impacts, such as forests being turned over to grow food.
“The effect of the
human is to deforest, to replace with agriculture and so on. You
change the vegetation cover, the albedo, the humidity in the soil,
and you will emphasise the drought when you do that. If you have the
[direct] human impact, it will be worse,” said Guiot.
The researchers fed
a model with 10,000 years of pollen records to build a picture of
vegetation in the region, and used that to infer previous
temperatures in the Mediterranean.
They then ran the
model to see what would happen to the vegetation in the future, using
four different scenarios of warming, three of them taken from the
UN’s climate science panel, the IPCC. Only the most stringent cut
in emissions – which is roughly equivalent to meeting the Paris
aspiration of holding warming to 1.5C – would see ecosystems remain
within the limits they experienced in the Holocene.
“The main message
is really to maintain at less than 1.5C,” said Guiot. “For that,
we need to decrease the emissions of greenhouse gases very quickly,
and start the decreasing now, and not by 2020, and to arrive at zero
emissions by 2050 and not by the end of the century.”
He said the main
limitation of the study was the relatively simple model at its heart,
but this was offset by the fact it was used consistently, to
reconstruct the past and to forecast future vegetation.
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