The revolutionary wave that swept Arab nations beginning with 2011 displaced millions and cost the lives of hundreds of thousands. On the bright side, the dampened economic activity caused a significant lapse in greenhouse emissions. In some extreme cases, nitrogen dioxide values have decreased by 40 to 50% over Damascus and Aleppo, according to a new study published by the Max Planck Institute for Chemistry.

“It is tragic that the negative trends we observe in nitrogen oxide emissions accompany humanitarian catastrophes,” said Jos Lelieveld, the team’s lead and a director at the Max Planck Institute for Chemistry.

The team parsed the mountains of data gathered from NASA’s Ozone Monitoring Instrument to follow the atmospheric activity in the Middle East from 2005 to 2014.

Between 2005 and 2010 – a period of economic growth – the Middle East experienced a major surge in greenhouse gas buildup. Past 2011, however, the trendline was reversed. For instance, the Iraqi GDP rose by 5-7% yearly, accompanied by an increased in CO2 emissions of 4-5% yearly. Not coincidentally, the areas under control of ISIS registered the steepest decline in emissions. Specifically, nitrogen oxide (NO2) levels rose by 10% annually. Beginning 2011 though, NO2 levels fell each year by the same percentage.

“From 2005-10 the Middle East has been one of the regions with the fastest growing air pollution emissions. This also occurred in East Asia, but especially in the Middle East. This was related to economic growth in many countries. However it’s the only region in the world where this upward trend of pollution was interrupted around 2010 and then followed by very strong decline.”

Not all Middle Eastern countries which recently decreased their NO2 emissions ran into trouble because of it. Saudi Arabia, Kuwait and the United Arab Emirates – countries which have remained in state of civil peace for years – managed to lower NO2 by installing air control systems and environmental policies.

Expanding over the scope of their study, the German researchers also looked at possibly the hardest hit country by the economic crash of 2008, Greece. The country saw saw significant reduction in greenhouse gases. Nitrogen oxide levels registered in the air above Athens are 40% down compared to 2008, as reported in Science Advances.

Of course, the findings aren’t surprising. Greenhouse gas emissions are directly tied to economic development – when one increases, so does the other and vice-versa. Fortunately, some economies have already decoupled their economic growth from carbon emissions, but for most countries a growing economy means burning more fossil fuel. The study, however, identified some rather surprising tidbits which weren’t that obvious.

“These findings could not have been predicted and for this reason disagree with emissions scenarios used in the projections of air pollution and climate change in the future. Often these emissions are linked to energy use and CO2 but we find these are simply not good predictors for trends, at least not in the Middle East,” Lelieveld said. Unfortunately, the Middle East is not the only region in the world affected by economic recession and upheaval owing to war, although geopolitical changes appear to be more drastic than elsewhere. It is tragic that some of the observed recent negative NO2 trends are associated with humanitarian catastrophes.”