The question posed 20 years ago by scientists at NASA was pretty straight forward: “Is the current human occupancy and activity of planet Earth sustainable?” The answer was complicated given the lack of data.
The Earth Observing System or EOS was conceived in 1990 as a way to systematically track changes on earth, from the sky. The first satellite was launched in December 1999.
Scientists already knew that CO2 atmospheric concentrations were increasing. According to a paper written by NASA-funded ecologist Steve Reading, “… CO2 concentrations have been measured carefully since 1957 at Mauna Loa, and the increase has been steady at about 0.3% per year since then, a direct result of fossil fuel combustion.” But was an increase in atmospheric CO2 concentrations a bad thing?
Until EOS, global biospheric health had been largely unmeasurable, and discussions and policy development had been “handicapped by a paucity of data,” according to Reading. The purpose of EOS was to provide this factual information on trends of change in our biosphere. Studying the entire “spaceship earth” as a functioning system had never been tried before. Today, NASA has more than a dozen Earth science spacecraft/instruments in orbit studying all aspects of the Earth system (oceans, land, atmosphere, biosphere, cyrosphere), with several more planned for launch in the next few years.
The NASA website provides almost real-time feeds from orbiting instruments documenting sea level, arctic sea ice, carbon dioxide concentrations, global average temperatures, and the ozone hole.
Using information from the Topex/Poseidon Measurement System flying 830 miles above the earth and covering the global oceans every 10 days , NASA scientists are estimating that sea level is rising an average of 3.3 millimeters per year. Sea level rise is associated with the thermal expansion of sea water due to climate warming and widespread melting of land ice (shown below).
The EOS network is providing valuable information to help scientists understand changes in our biosphere. The old axiom that what gets measured, gets managed hopefully applies to our planet.