A climate change study conducted by researchers at Aix-Marseille University in France predicts that southern European areas abutting the Mediterranean — particularly southern Spain — could become deserts as soon as the year 2100 if the current rate of greenhouse gas emissions continues unchecked. Anything less than extremely ambitious and politically challenging carbon emissions cuts will see ecosystems in the Mediterranean change to a state unprecedented in the past 10,000 years, according to the researchers, Joel Guiot and Wolfgang Cramer.
The study, published in the journal Science, looked at what would happen to vegetation in the Mediterranean basin under four different paths of future carbon emissions. The worst case scenario assumed no steps were taken to reduce carbon emissions. The best case scenario assumes the measures anticipated by the COP 21 climate agreement agreed to in Paris last December are put into effect.
Assuming no action is taken to mitigate increased emissions, the pair predicts that temperatures will rise nearly 5º Celsius by 2100. That is a staggering increase that would significantly alter vegetation patterns in and around the Mediterranean. That would cause deserts to expand northwards across southern Spain and Sicily as Mediterranean vegetation replaces deciduous forests.
Even if emissions are held to the level of pledges put forward ahead of the Paris deal, southern Europe would still experience a “substantial” expansion of deserts due to climate change. The amount 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.”
The real impact of climate change on Mediterranean ecosystems, which are considered a hot spot 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 emphasize 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. Only the most stringent cut in emissions — which is roughly equivalent to meeting the Paris goal of keeping warming to 1.5º C — would see ecosystems remain within the limits they experienced in the Holocene.
“The main message is really to maintain at less than 1.5º C,” 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.”
Many people will read the report but how many people will listen to its message?
Source: The Guardian. Photo credit: Aix-Marseilles University