The study examined rainfall distribution in Israel from 1975 to 2020. In general, the rainy season in Israel begins in October and ends in May.
The study found that while the annual amount of rainfall has not changed in the past 46 years, the number of rainy days has fallen and the length of the rainy season has been reduced as less rainfall is recorded in the spring and autumn and more rainfall is recorded in the middle of the winter from December to February.
In the period studied, the length of the rainy season fell by about 7.3 days, or at a rate of losing 1.6 days every decade.
"The prolongation of the dry season can have implications for vegetation and natural ecosystems, as well as agriculture," said Dr. Efrat Sheffer, lead scientist of the study, in a press release. "Understanding the current trend will help farmers adapt – and policymakers prepare for what's coming, adapt urban infrastructure to prevent disasters and try to minimize damage to the environment and water sources."
The researchers stressed that this is the first study that doesn't support the drying trend which past studies have projected. Despite projections that the amount of rainfall will decrease, there has been no such trend yet recorded. The trends observed by the new study imply that while the number of rainy days will continue to fall, the intensity of rainfall when it does rain will grow.
Sheffer explained that these findings mean that more rain is falling on stormy days than in the past and that most rainy days are concentrated in the middle of the season.
"We have witnessed such incidents of intense rain in a short time in recent years in Israel, and similarly in the recent incident in Western Europe," Sheffer said, referring to large floods that recently impacted the region, killing dozens of people. Such rainfall distribution has a number of consequences in terms of drainage systems, streams and how much rainwater is absorbed into the ground and into aquifers compared to how much flows into the sea.
ONE OF the main goals of the study was to examine whether there's been a change in the seasonal distribution of rainfall that could affect the future adaptation of local plants to climatic conditions, Sheffer explained.
"For example, the grove and forest vegetation in Israel is adapted to survive for a long season without rain, but it is not clear whether the same plants can survive even if the length of the dry season is even longer, or if the amounts of rain in the wet season are smaller," he said. "The ability of plants to survive is very important for what can be grown here and under what conditions."
The study stressed that changes in Israel's rainy season could have vast impacts, including an increase in flood risks, water shortages, an increase in irrigation demands and an enhanced risk of fires.
"Climate change did not pass over Israel," said the researchers in a press release. "The findings show a trend that will put the urban infrastructure in trouble, but may also change the entire ecosystem in our area in the coming years."The study comes amid heightened concerns surrounding climate change after severe floods ravaged Germany, Belgium and China recently and extreme wildfires hit the western US.
DR. ORI ADAM, head of the academic committee of the Hebrew University Climate Science Center, recently noted that a warmer atmosphere can hold more moisture but also takes much cooler temperatures in order to spark rainfall. With temperatures rising, this means that rain will likely accumulate for much longer before rainfall occurs, leading to heavier downpours.
Adam added that the East Mediterranean region is "perhaps the most rapidly warming-up area in the world," with current climatic conditions in Hadera, located north of Netanya, being similar to those in Beersheba 20 years ago.
Environmental Protection Minister Tamar Zandberg called on Prime Minister Naftali Bennett recently to have the government declare climate change a strategic threat in order to prepare for emergency situations that could occur as a result.
"The extreme events all over the world are only an introduction to what is yet to come," wrote Zandberg on Facebook this week. "Israel is located in one of the most sensitive areas to climate change on Earth, and is warming at a rate higher than the world average."
A report by State Comptroller Matanyahu Englman in June found that Israel suffers from deficiencies in the state’s confrontation of flooding problems. According to the report, seven people drowned in floods in Israel during the 2019-2020 winter season.
There are 11 authorities involved in flooding issues, which creates bureaucratic problems and allows each of them to try to pass on responsibility to others.
Specifically, the comptroller warns of the Agriculture Ministry and local municipalities trying to pass off responsibility to each other.
In addition, the report said that the severity of flooding has increased as open spaces where water can spread out have been reduced, while closed urban spaces where water builds up have grown.Yonah Jeremy Bob and Rossella Tercatin contributed to this report.