title: Abrupt recent trend changes in atmospheric nitrogen dioxide over the Middle East.
abstract: Nitrogen oxides, released from fossil fuel use and other combustion processes, affect air quality and climate. From the mid-1990s onward, nitrogen dioxide (NO2) has been monitored from space, and since 2004 with relatively high spatial resolution by the Ozone Monitoring Instrument. Strong upward NO2 trends have been observed over South and East Asia and the Middle East, in particular over major cities. We show, however, that a combination of air quality control and political factors, including economical crisis and armed conflict, has drastically altered the emission landscape of nitrogen oxides in the Middle East. Large changes, including trend reversals, have occurred since about 2010 that could not have been predicted and therefore are at odds with emission scenarios used in projections of air pollution and climate change in the early 21st century.
authors.affiliation: Max Planck Institute for Chemistry, 55128 Mainz, Germany. ; The Cyprus Institute, 1645 Nicosia, Cyprus. ; King Saud University, Riyadh 11451, Saudi Arabia.
authors.forename: Jos
authors.initials: J
authors.lastname: Lelieveld
authors.affiliation: Max Planck Institute for Chemistry, 55128 Mainz, Germany.
authors.forename: Steffen
authors.initials: S
authors.lastname: Beirle
authors.affiliation: Max Planck Institute for Chemistry, 55128 Mainz, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Hörmann
authors.affiliation: King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia.
authors.forename: Georgiy
authors.initials: G
authors.lastname: Stenchikov
authors.affiliation: Max Planck Institute for Chemistry, 55128 Mainz, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Wagner
keywords: Climate change; environmental