Taxonomy term


Reconstructing ancient oxidant levels and their climatic effects

Oxidants in the troposphere, such as ozone and hydroxyl radicals, influence the life spans of other atmospheric components, including pollutants and greenhouse gases like carbon monoxide and methane. But how the abundance of tropospheric oxidants varies as climate changes is poorly understood. Part of the challenge is that these oxidants are too reactive to be preserved in paleo-records, such as ice cores.

29 Aug 2017

"Blob"-related warming contributed to Pacific Northwest ozone spike

In June 2015, instruments on Oregon’s Mount Bachelor recorded mean ozone for the month at 56 parts per billion, more than 20 percent higher than the average level for the 11 years prior. Other stations around the West noted similarly high readings, puzzling scientists over the cause of the rise. In a new study in Geophysical Research Letters, researchers describe a confluence of meteorological conditions that appear to have driven the phenomenon.

18 May 2017

Red Planet Roundup: February 2017

With two rovers patrolling the surface of Mars, six spacecraft orbiting above it, and scientists here on Earth studying the Red Planet from afar, new findings are announced often. Here are a few of the latest updates.

14 Feb 2017

Hydrogen chloride on the rise in Northern Hemisphere skies

Levels of the atmospheric pollutant hydrogen chloride have increased substantially in the lower stratosphere over the Northern Hemisphere since 2007, according to a new study. The increase, however, is not due to an influx of chlorine, but rather to a side effect of the recent slowing of stratospheric circulation that was first reported in 2005.
02 Jul 2015

Carbon tet still offensive to ozone layer

Earth’s ultraviolet light-shielding ozone layer is recovering, according to a report released in September by the World Meteorological Organization and the United Nations Environment Programme. The findings, authored by more than 250 scientists and presented as part of the latest Scientific Assessment of Ozone Depletion (SAOD), suggest the ongoing success of the 1987 Montreal Protocol and its amendments in cutting atmospheric levels of chlorofluorocarbons (CFCs) and other ozone-depleting substances (ODS’s), which have fallen by about 10 to 15 percent overall since peaking in the late 1990s.

22 Dec 2014

Benchmarks: September 16, 1987: Montreal Protocol Signed

Each year in late September to early October, atmospheric scientists watch with anticipation as ozone concentrations over Antarctica drop, opening a window in Earth’s defenses against harmful ultraviolet radiation. This ozone “hole” grew steadily in the 1990s and set a record for its size in 2006: At its peak, the hole covered an average area of 27 million square kilometers, approximately the size of North America. But scientists think that the overall ozone layer is on the slow road to recovery, thanks to the Montreal Protocol — one of the most successful international environmental agreements in history.
16 Sep 2009

Montreal Protocol affects more than just ozone

In 1987, nearly 200 nations signed the Montreal Protocol to restrict the use of ozone-depleting chemicals. The international treaty helped keep the ozone hole over Antarctica from growing further, preventing an increase in harmful radiation reaching Earth’s surface. Twenty years later, new research suggests that the treaty helped the planet dodge more than one bullet: The Montreal Protocol also prevented significant regional climate change.

13 Nov 2008