Full Title: Climate Intervention: Reflecting Sunlight to Cool Earth
Author(s): Committee on Geoengineering Climate: Technical Evaluation and Discussion of Impacts; Board on Atmospheric Sciences and Climate; Ocean Studies Board; Division on Earth and Life Studies; National Research Council
Publisher(s): National Academy of Sciences
Publication Date: February 1, 2015
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Our planet has entered a period in which its climate is changing more rapidly than ever experienced in recorded human history, primarily caused by the rapid build-up of carbon dioxide (CO2) in the atmosphere from the burning of fossil fuels. Scientists have identified a number of risks from changing climate, including rising sea level, drought, heat waves, more severe storms, increasing precipitation intensity, and associated disruption of terrestrial and aquatic ecosystems. Additionally, elevated atmospheric CO2 is diffusing into the ocean, measurably acidifying surface waters and affecting marine ecosystems. Natural processes currently remove about half of our emissions from the atmosphere each year. Once emissions cease, it will take thousands of years before those processes eventually return Earth to something like pre-industrial levels of atmospheric CO2.
The two main options for responding to the risks of climate change involve mitigation— reducing and eventually eliminating human-caused emissions of CO2 and other greenhouse gases—and adaptation—reducing the vulnerability of human and natural systems to changes in climate. A third potentially viable option, currently under development but not yet widely deployed, is carbon dioxide removal (CDR) from the atmosphere accompanied by reliable sequestration. A fourth, more speculative family of approaches called albedo modification seeks to offset climate warming by greenhouse gases by increasing the amount of sunlight reflected back to space.1 Albedo modification techniques mask the effects of greenhouse warming; they do not reduce greenhouse gas concentrations.