The political turmoil in the Middle East is so dramatic that scientists say they can see it from space.
Satellite data from the troubled region reveal marked drops in atmospheric pollutants that can't be linked to clean-air laws or other policy changes, according to a new study. However, the pollution trends are often right in line with armed conflicts and the resulting movement of refugees.
FOR THE RECORD
Aug. 31, 10:19 a.m.: An earlier version of this article described some of the air pollutants as nitrous oxide. They are nitrogen oxide.
Reductions in the levels of nitrogen oxide and sulfur dioxide contain clear signatures of the civil war in Syria, incursions by the so-called
The cleaner air is the result of "international boycotts, armed conflict and related mass migration of people," said study leader Jos Lelieveld, director of the atmospheric chemistry department at the Max Planck Institute for Chemistry in Mainz, Germany. "The changes are so large that they can be seen from space."
Lelieveld and his colleagues looked at 10 years of measurements taken by the Ozone Monitoring Instrument on NASA's Aura spacecraft, which is studying Earth's atmosphere. Nitrogen oxide and sulfur dioxide degrade the air and contribute to climate change, Lelieveld said.
Previous studies have estimated that 58% of nitrogen oxide emissions around the world are a byproduct of burning fossil fuels, primarily from generating power and traffic-related pollution. That figure is higher in the Middle East, where fossil fuels are plentiful. So the researchers thought the level of emissions there would provide a decent proxy of the economic activity in the region.
And that's what they found — in some places. In Saudi Arabia, for instance, nitrogen oxide emissions rose in line with general energy consumption between 2005 and 2010. After that, energy consumption continued to rise while nitrogen oxide emissions fell. That's probably the result of laws passed in 2008 aimed at reducing the country's "environmental footprint," the researchers wrote in their study published Friday in the journal Science Advances.
The story was similar in Kuwait and the United Arab Emirates, which implemented their own air quality standards in the late 2000s. Together, these findings "provide a first indication that air quality control in the Arab Gulf States" is working, the study authors wrote.
To the northwest, the atmosphere over the Israeli cities of Tel Aviv and Haifa became cleaner in the years after that country's Clean Air Law went into effect in 2011. Though economic activity and energy consumption rose, nitrogen oxide emissions "decreased substantially," according to the study.
Elsewhere in the Middle East, the explanation for falling emissions was far less benign.
Nitrogen oxide pollution has plunged 40% over Damascus and 50% over Aleppo since 2011, the year when
Similarly, emissions in parts of Iraq have declined since 2013 in places like Tikrit and Samarra after they were occupied by the Islamic State, according to the study. Emissions have also dropped off in Baghdad, which has weathered a series of deadly attacks but remained out of the hands of Islamic State.
Emissions over Egypt provide a clue of the regime change that occurred in 2011. Although carbon dioxide emissions held steady, nitrogen oxide emissions fell. The study authors wrote that higher relative fuel prices probably forced Egyptians to cut back on their driving, resulting in cleaner air. This change, they wrote, "was driven by political events."
The emissions data also show that the economic sanctions imposed on Iran in 2006 didn't have much effect until they were extended in 2010. Only then did the economy begin to slow down, and then shrink, resulting in a parallel drop in energy use. Most strikingly, the researchers wrote, a 50% drop in oil exports since 2010 reduced sulfur dioxide emissions over the Persian Gulf, "in particular near the main Iranian oil tanker terminal Jazireh Ye at Kharg Island."
Lelieveld said he didn't expect to find clues that some parts of the Middle East have "completely gotten out of control" by looking at the atmosphere. "That you can see these things from air pollution was to me a really big surprise," he said.
Normally, cleaner air would be something to celebrate. But in this case, they study authors concluded, "it is tragic" that some of the improvements "are associated with humanitarian catastrophes."