Some scientists had warned because the 1970’s that chemical compounds referred to as chlorofluorocarbons (CFCs) posed a menace to the ozone layer, however nobody knew for certain what should be blamed for the ozone gap to develop. The invention lent urgency to the dialogue: How may the world restore the ozone layer earlier than it was too late?
Ozone – a chemical manufactured from three oxygen atoms – is generally present in a layer about 8-30 miles above Earth’s floor, within the stratosphere. It absorbs dangerous ultraviolet (UV) radiation from the Solar, shielding vegetation, animals and people from injury starting from crop dying to pores and skin most cancers.
On September 16, 1987, Newman was a younger atmospheric scientist at Goddard, analyzing knowledge getting back from the Antarctic Airborne Ozone Expedition (AAOE) – the place one other NASA scientist, Susan Strahan, stood along with her colleagues a bulletin board in Punta Arenas, Chile. Strahan analyzed atmospheric chemistry knowledge from the smooth, long-winged ER-2 airplane flying into the Antarctic polar vortex to measure ozone and chemical compounds that might react with it.
That day’s knowledge would yield the well-known “smoking gun plot”: The information exhibiting that as a chemical referred to as chlorine monoxide elevated within the Antarctic stratosphere, ozone decreased. Chlorine monoxide was identified to be current within the ambiance, however had beforehand been noticed solely at decrease concentrations than the AAOE staff measured—these ranges got here from a posh set of chemical reactions occurring within the Antarctic following the breakdown of CFCs by UV radiation within the stratosphere. The information disproved different theories and gave scientists proof that CFCs have been inflicting the ozone gap.
Strahan and her colleagues’ knowledge wouldn’t be printed till later, however by the top of that day in 1987, twenty-seven nations agreed to the Montreal Protocol on Substances that Deplete the Ozone Layer: “Maybe the only most profitable worldwide settlement to this point,” mentioned former United Nations Secretary-Basic Kofi Annan in 2003. The Montreal Protocol created a timetable for controlling manufacturing and consumption of CFCs. Over the subsequent few years, the science of ozone depletion was extra firmly established, producers launched alternative chemical compounds that have been safer for the setting, and the Montreal Protocol was strengthened a number of instances to cease wide-scale manufacturing and use of CFCs and associated molecules.
The lengthy journey towards restoration had begun.
At the moment, Newman and Strahan are leaders in atmospheric science and each sit at NASA Goddard: Newman as chief scientist for Earth Sciences and co-chair of the Scientific Evaluation Panel (SAP) to the Montreal Protocol, Strahan as a principal scientist for the Universities House Analysis Affiliation. And as we speak, they each control Earth’s ambiance, persevering with NASA’s long-running analysis and monitoring efforts on stratospheric ozone (which return to the 1970s) into the longer term.
CFCs: Hazard at Excessive Altitudes
CFCs weren’t at all times the villain on this story. Invented to be used as refrigerants within the 1920’s, CFCs represented a technological breakthrough: They have been versatile, however extra importantly, they have been neither poisonous nor flammable. Older refrigeration chemical compounds have been deadly if leaked; CFCs didn’t hurt human well being or react with different chemical compounds within the decrease ambiance.
First Steps to Restoration
At the moment, 33 years later, the ozone gap is exhibiting its first indicators of restoration. Strahan and her colleague Anne Douglass printed one of many first research in 2018 confirming that atmospheric chlorine ranges are falling in line with diminished ozone depletion over Antarctica—proof that the Montreal Protocol is working.
These first hopeful indicators characterize a worldwide success story: Policymakers, scientists and corporations world wide joined forces to discover a answer to an pressing downside. A lot of the info that empowered these choices got here from NASA scientists and devices. Ongoing ground- and space-based monitoring of ozone and different hint gases, by NASA and different establishments, will assist inform growth of environmental insurance policies designed to ensure ranges proceed trending in a constructive path even within the midst of different adjustments, resembling Earth’s warming local weather.
At the moment, NASA displays ozone from house utilizing the Microwave Limb Sounder (MLS) and Ozone Monitoring Instrument aboard its Aura spacecraft, and the MLS additionally measures hint gases containing chlorine. Strahan and Douglass’ 2018 research used MLS measurements of hydrochloric acid, a kind that chlorine takes after destroying ozone, to calculate whole stratospheric inorganic chlorine above Antarctica. Inorganic chlorine compounds like hydrochloric acid haven’t any carbon molecules, which permits researchers to distinguish between them and chlorine nonetheless tied up in CFCs.
Moreover, the Stratospheric Aerosol and Fuel Experiment III measures ozone and hint gases from its vantage level aboard the Worldwide House Station, and the NASA-NOAA Ozone Mapping Profiler Suite aboard the Suomi-NPP satellite tv for pc measures each whole column ozone and ozone profiles. These devices had precursors on earlier NASA satellites, and so they—together with house, air and floor measurements from companion organizations just like the Nationwide Oceanic and Atmospheric Administration and world companions—will assist scientists maintain monitor of the ozone gap’s restoration.