AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
Geoengineering for Climate Change: Nature Has Already Demonstrated the Process and Effects
RUSSELL SCHNELL, National Oceanic and Atmospheric Adminstration
Abstract Number: 33 Working Group: Aerosols, Clouds and Climate
Abstract Geoengineering to reduce atmospheric air temperatures is becoming a hot topic with recent articles in Science,Nature and the Bulletin of the American Meteorological Society discussing the pros, cons and methods of “solar engineering.” A proposed method is to inject millions of tons of sulfur dioxide or calcium carbonate into the stratosphere to reflect solar radiation back to space.
Through volcanic eruptions that spewed mineral particles and sulfur dioxide into the stratosphere, nature has provided excellent examples of geoengineering: El Chichon, Mexico (29 March, 1982, ~7 MT) and Mount Pinatubo, Philippines (June 14, 1991, ~20 MT).
Reductions in solar radiation measured at the Mauna Loa Atmospheric Baseline Observatory (MLO), Hawaii from these eruptions showed a 14% reduction from El Chichon and 11% reduction from Pinatubo at the peak of the stratospheric aerosol loadings. Lidar measurements of the eruption aerosols showed they were concentrated between 15 and 30 km altitude and took 4-5 years to return to background levels. These aerosols reduced northern hemisphere temperatures by ~0.50C for Pinatubo and ~0.70C for El Chichon.
NOAA WP-3 aircraft measurements in the Arctic stratosphere off Greenland, one year after the El Chichon eruption, collected crustal debris in the 100 to 101 micron diameter range in concentrations of 10-3 to 10-2 cm-3 and H2SO4 droplets in the 100 to 10-1 micron diameter range in concentrations of 10-1 to 102 cm-3.
Peak aerosol optical depth anomalies measured at MLO were 0.2 for both El Chichon and Pinatubo aerosols and 0.17 and 0.21 respectively at the Barrow, AK, Baseline Observatory (BRW). From NOAA WP-3 measurements in the stratosphere over BRW on April 22, 1992 (Pinatubo, 10 months post-eruption), stratospheric aerosol depth was in the 0.19 to 0.2 range.