The study was undertaken by professor of civil and environmental engineering Elfatih Eltahir and graduate student at MIT Alexandre Tuel.
Climate change: MIT study finds why the Mediterranean region is a hotspot for climate change! A study by the Massachusetts Institute of Technology (MIT) has examined why the Mediterranean region is a hotspot for climate change and found that even with different climate models, the outcome is that within the next few decades, the region would be significantly drier, the institute has said in a statement. The precipitation in the region is likely to reduce by up to 40% during the winter rainy season, the statement added.
The analysis by the team of researchers has revealed the underlying conditions which cause such anomalous effects in this region, especially northwest Africa and the Middle East. It added that the analysis could help in bettering the models, adding certainty to their projections, which would significantly impact the agriculture and water resource management in the region.
The study, accessed by Financial Express Online, was undertaken by professor of civil and environmental engineering Elfatih Eltahir and graduate student at MIT Alexandre Tuel, and it was published in the Journal of Climate last week.
Background of the study
Different models for climate change agree that temperatures will increase everywhere, and most places will also see an increase in rainfall, partly due to the fact that more water vapour can be carried by warmer air. However, the statement quoted Eltahir as saying that there is one major exception to all the models, and that is the Mediterranean region, which is showing the greatest decline of projected rainfall for any of the landmasses in the planet.
Despite their differences, the models have been able to agree on the projection for the Mediterranean region, even as the decline in rainfall differs among the models, varying from 10% to 60%. However, before this, the reason behind this projection was inexplicable.
Climate change in Mediterranean: Findings of the study
The researchers found that the projected drying up of the region is due to two different consequences of climate change acting together – one is an alteration in the dynamics of the circulation of the upper atmosphere, while the second is a decline in the difference of temperature between land and sea. While neither of these factors would singularly affect the rainfall to such a significant degree, the two effects combined can account for the trend shown by the models, the study believes.
Mediterranean region drying up: Two effects explained
The first effect – a change in the dynamics of circulation of the upper atmosphere – occurs at a large scale and is related to the powerful high-altitude winds, known as the midaltitude jet stream. This drives a strong and steady west-to-east pattern of the weather across North America, Europe and Asia. According to Tuel, the climate models show that climate change induces an increase in the strength of misaltitude jets as the global temperature rises.
However, in the Northern Hemisphere, mountain ranges like the Himalayas, Rockies and Alps obstruct the course of the winds, collectively imparting a wave pattern which results in alternating zones of lower and higher air pressure, the study said. While high air pressure is linked to clear and dry air, low pressure is associated with wetter air and storm systems. However, warming up of the air causes an alteration in the wave pattern.
Tuel explained that incidentally, the geographical location of such mountain ranges and the Mediterranean region led to an impact on the air flow pattern high in the atmosphere in a way which forms a high pressure area over this region, creating a dry zone with little precipitation. However, this phenomenon alone is not sufficient for a drastic drying up.
The reduction of temperature difference between the sea and the land is also an important factor as it helps drive the winds. However, climate change which is warming up the land faster than the seas, is leading to a great reduction in this difference of temperatures.
Tuel said that the unique fact about Mediterranean region is its geography as it consists of a big sea enclosed by continents, an arrangement not found anywhere else in the world. According to the climate models, while the landmasses are projected to warm up by 3-4 degrees Celsius in the coming century, this increase would only be around 2 degrees Celsius in the seas, leading to a decline in difference of temperatures. This would lead to an amplification of the pressure differential, the study said, and it would add to the high-pressure area formed over the region.
This high-pressure area would give rise to a clockwise circulation of winds in the region surrounding the Mediterranean basin. This change would affect northwest Africa and eastern Mediterranean region the hardest due to the local topography, the study explained.
Climate change hotspot: Effect on Mediterranean already visible
Researchers have noted that the trend noticed for Mediterranean is not merely a projection as it has already started becoming apparent in recent trends across the Middle East and western North Africa. According to Eltahir, these are the regions where they have already detected a decline in rainfall and there is a possibility that the political unrest in the region might have been partly triggered due to the decline in rainfall in an area which is already parched.
He added that from the records regarding the precipitations, it has been observed that the eastern part has already experienced a considerable fall in precipitation, saying that now that the underlying physical factors have been understood, it would help in ensuring that the authorities in these regions take the projections seriously.