While the dust storm engulfing the country on Tuesday and Wednesday might not be a rare event in and of itself, the increasing incidence of extreme weather in recent years continues to generate concern among experts.
“We had in the past events of dust storms, but this is not the important thing,” Prof. Uri Marinov, an environmental consultant who served as the Environmental Protection Ministry’s first director-general, told The Jerusalem Post on Wednesday. “The important thing is to look around here and around the world and see what is happening with the weather. There are more and more extreme events.”
Heavy air pollution continued on Wednesday, after strong southeasterly winds transported dust to Israel from Saudi Arabia and Jordan the day before. Maximum levels of PM10 – particulate matter with a diameter of 10 microns or less – reached up to 70 times typical values, peaking at different times on Tuesday and Wednesday depending on the location.
Although such hazy conditions occur much more frequently in the winter and spring – and originate during those seasons from the southwest – a Red Sea trough with strong and continuous easterly winds can result in the less common autumn dust storms, said Dr.
Amos Porat, head of the Climate Department at the Israel Meteorological Service. A meteorological trough features low atmospheric pressure, as opposed to a ridge, which features high atmospheric pressure.
While autumn haze events are less common, they tend to occur once every few years, with past recent storms happening in 2002, 1997 and 1991, Porat said.
Although the latest haze might not be rare, Marinov pointed out a collection of relatively recent incidents that have been considered extreme in Israel, such as early September’s more severe dust storm, as well as the scorching heat of this summer and the heavy snowfall in Jerusalem in 2013.
“We should look around the world and there is Patricia in Mexico [last month], which was the strongest hurricane ever recorded in America,” he said, also discussing the forest fires overtaking Indonesia and California’s drought.
“We might reach a situation of no return,” Marinov continued. “That means that a vicious cycle like this would cause real changes in climate.”
As countries head to December’s United Nations Conference of Parties (COP-21) climate convention in Paris, Marinov expressed hopes that the world’s leaders would take concrete action to ensure that global warming does not rise more than 2°C.
“We know exactly what needs to be done,” he said. “We need to decarbonize the economic system of the world. We have to do it before it’s too late.”
At home in Israel, meanwhile, researchers in the Water Authority have been working to determine why ever since September’s dust storm, rare flood conditions have hit southern wadis nearly every week.
The peak event occurred on Rosh Hashana, when a tremendous flood hit Nahal Paran, causing the wadi’s flow to reach an all-time high and breaking its record for the first time in 44 years, the Water Authority said.
Since that event, a number of extreme flooding incidents have occurred in the Negev and Arava wadis. Just last week, Water Authority teams measured 62 mm. of rainfall within only a few hours in Be’er Ora, near Eilat – twice the typical annual precipitation for that area.
Dr. Amir Givati, head of the surface water department at the Water Authority’s Hydrological Services, and Prof. Daniel Rosenthal, an expert in cloud and rain physics at the Hebrew University’s Earth Science Institute, have been working on determining the reasons behind this phenomenon.
They hypothesize that the intense flooding may be linked to the El Niño warm-water phenomenon in the Pacific Ocean, which has been thus far the strongest one since 1997.
Hydrological Services records from October 1997 show there were particularly heavy flooding in the Negev and Eilat regions that year as well.
Around the world, this El Niño has brought extreme dry or wet conditions, depending on the location.
El Niño heats up the eastern Pacific Ocean – by about 2.5°C this year – resulting in low air pressure and tropical humidity in the Persian Gulf and in the Red Sea, Rosenfeld explained.
These conditions have led to the formation of the trough from the Red Sea, bringing the southerly winds and the dust, he continued.
The El Niño conditions could also explain the very rare cyclone that hit the coasts of Yemen and Saudi Arabia in recent days, Rosenfeld said.
“We are witnessing increased instances of extreme weather around the world, including in our region,” Givati added, noting that the Water Authority has been taking many steps to adapt to the changing climate conditions.
Some such steps have included increasing the water supply in order to cope with irregular drought conditions and preparing for extreme flooding events, he said.
Regarding flooding in wadis and rivers, the Water Authority has a flood alert system that notifies local drainage authorities of the incoming forecast, so that they can take precautions such as setting up pumps or calling for evacuations, Givati told the Post on Wednesday evening.
However, when it comes to urban drainage issues, such as the major flooding that took place in the past two weeks, the municipalities are responsible for handling these events, he explained.
In Givati’s opinion, local water corporations that are already responsible for municipal sewage should also control urban drainage.
“We think that there is a need for a change, so that the drainage will be done not by the municipalities itself but by organizations that are experts in that,” he said.
An ever-increasing population, as well as urban sprawl and climate change, will only exacerbate the country’s flooding problems, Givati said.
“There is a need for new thinking with everything regarding drainage in Israel, due to two major reasons – changes in land use and climate conditions,” he said.
Although this week’s storm has featured some precipitation, its most pervasive feature has been dust and resultant air pollution.
The highest air pollution value measured from 6 p.m. Tuesday to 5 p.m. Wednesday was 4,207 micrograms per cubic meter on Wednesday at 5 p.m., at the Tel Aviv University Yad Avner monitoring station, the Environmental Protection Ministry said.
Average values during that 24-hour period for the station were 843 micrograms per cubic meter – 14 times typical daily values and 2.8 times ministry alert values.
On a typical non-stormy day, levels of PM10 are around 60 micrograms per cubic meter, according to the ministry.
In Ariel in Samaria, PM10 levels reached 4,054 micrograms per cubic meter at 4 p.m. on Wednesday, averaging 1,011 micrograms per cubic meter in the 24-hour monitoring period – 16.9 times typical daily values and 3.4 times ministry alert values.
Givatayim, east of Tel Aviv, experienced peaked PM10 values of 3,609 micrograms per cubic meter at 5 p.m. on Wednesday, and average values of 982 micrograms per cubic meter, the Environment Ministry data said.
At the Safra station in Jerusalem, PM10 levels peaked the previous evening – rising to 1,967 micrograms per cubic meter at about 6 p.m. on Tuesday, with average values amounting to about 833 micrograms per cubic meter.
Particularly high levels of PM10 were also recorded at the ministry air pollution monitoring stations in the eastern Negev and Beersheba, as well as in the central cities of Beit Shemesh, Modi’in and Rehovot.
Although dust levels were abnormally high on both Tuesday and Wednesday, maximum, as well as average values in most cases, did not come close to matching those recorded during the early September sandstorm – which meteorologists called the thickest such event in 15 years.
While the air pollution was expected to continue into Thursday, the Environment Ministry said that dust levels would gradually improve. Nonetheless, the ministry recommended that sensitive population members, including those with heart and lung conditions, the elderly, children and pregnant women, continue to refrain from strenuous physical activity.
Due to the poor weather, the Israel Airports Authority closed Ben-Gurion Airport to departures for under an hour on late Wednesday afternoon, although arrivals continued as normal.
The shutdown resulted in the delay of 11 flights, with some others experiencing light delays throughout the evening, the Airports Authority said.
The situation at Ben-Gurion Airport followed a chain of closures at the country’s other airports.
The Eilat Airport was temporarily shut down for the early portion of the day, while Sde Dov Airport in Tel Aviv was closed as of mid-afternoon.
Regardless of the closures, both Israir and Arkia airlines canceled all of their flights to and from Eilat on Wednesday. As of that night, Israir announced that its 6:30 a.m. Thursday flight from Eilat to Sde Dov was also canceled.
All in all, some 46 domestic flights were canceled on Wednesday, the Airports Authority said.
For Thursday, the IMS predicts partly cloudy to cloudy and hazy conditions, accompanied by isolated showers and thunderstorms in most regions and a risk of flash floods in the eastern wadis. Temperatures will be slightly cooler, and winds and haze should gradually subside.
On Friday, partly cloudy to cloudy conditions, with isolated showers and thunderstorms from the North to the northern Negev are expected, as well as a risk of flash floods in the eastern wadis and possible haze in the morning, the IMS said.
On Saturday, the IMS forecasts isolated showers from the North to the central Negev, with a chance of isolated thunderstorms and the same flash flood risk.
For Sunday, occasional showers from the North to the northern Negev will likely prevail, with possible isolated thunderstorms, flash flood risk in the eastern wadis and unseasonably cool temperatures all around.