When greenhouse gases rise, Mediterranean-type climates suffer from sudden drops in rainfall. This is a big problem because decreases in precipitation affect the entire year’s supply of water. The rainy season of Mediterranean climates provides the region with water for the hot, dry summers. Therefore, no rain in the winter means there won’t be enough water in the summer.
The good news is, this problem can be solved instantly with a quick cut of emissions – giving us yet another reason why reducing greenhouse gas emissions to keep global heating below 1.5°C is beneficial.
Dr. Giuseppe Zappa, who is the lead author of a study published in PNAS about the impacts of emissions on a Mediterranean climate, said:
Whenever greenhouse gases are emitted, they immediately begin impacting climate, but the impacts develop over several timescales. Greenhouse gas build-ups in the atmosphere can affect local climates immediately—on the scale of just a few years—or gradually develop a significant impact over decades or even centuries, like sea-level rise.
Since little was understood about how an increasing rate of greenhouse gas concentrations in the atmosphere affects Mediterranean climates, a team of scientists conducted an investigation. The study was led by the University of Reading in collaboration with Imperial College London and the National Research Council of Italy in Bologna.
The team’s research builds upon previous observational studies and modeling that revealed how most Mediterranean climates are apt to become less rainy as the planet warms, except for some reason California. They knew that Mediterranean climates, regions characterized by hot and dry summers, can be especially sensitive to decreases in wintertime rainfall. Such zones are typically described as ‘hot spots’ of climate change.
By modeling simulations of Mediterranean climates, the team was able to reveal new ways in which climate change causes these ‘hot spots’ – places such as central Chile, California, and the actual Mediterranean region itself. Their simulations showed how decreasing rainfall occurs rapidly alongside emissions rises (within a few years) because of ocean heating. The weather is affected differently depending on the patterns of ocean surface warming – hence why California doesn’t have a problem with rainfall.
Dr. Paulo Ceppi, from Imperial College London’s Grantham Institute, Climate Change and Environment at Imperial, explains:
The warming of the ocean surface is not uniform, with some regions warming faster than others. The resulting ocean warming pattern affects winds and rainfall globally. Those areas of the ocean that warm faster than average cause remote changes in atmospheric winds that make Mediterranean regions drier. By contrast, other ocean areas that warm more slowly tend to make California wetter, while having little impact on rainfall in other Mediterranean regions.
The study’s findings reveal how reducing emissions have a short-term effect on the planet too. Dr. Ceppi continued:
Our result implies that water resources in these regions would almost immediately benefit from stabilizing greenhouse gas concentrations since this would interrupt the rapid decrease in rainfall. In other words, climate action is positive not only in the long term but also after just a few years.
If we cut greenhouse gas emissions, it will benefit future generations to come, and this generation NOW. Isn’t that nice?
