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Satellites Climate

GRACE, Landsat, and how Earth observation changed environmental science.

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Earth observation satellites — instruments placed in orbit to continuously monitor Earth's surface, atmosphere, and oceans — have produced a continuous scientific record of environmental change from 1972 (Landsat-1, first Earth observation satellite) to present that would be impossible by any other means. This record has documented deforestation (Brazil lost 20% of Amazon in 46 years, measured from space), glacier retreat (97% of Himalayan glaciers are retreating, measured by GRACE gravity satellite), sea level rise (3.6mm/year and accelerating, measured by TOPEX/Jason altimetry satellites), and ocean warming. Key missions: Landsat (50-year continuous record of global land surface, most important long-term environmental dataset); GRACE/GRACE-FO (gravity field measurements reveal water storage changes — showed California's aquifer depletion, Greenland ice mass loss 270 billion tonnes/year); Sentinel (European, high-resolution daily monitoring); MODIS (daily global surface temperature, fire detection); and OCO-2 (Orbiting Carbon Observatory, maps atmospheric CO2 concentration by location, revealing each country's actual emissions). Planet Labs has achieved daily global coverage at 3-meter resolution using a constellation of over 200 small satellites (cubesats), democratizing Earth observation.

# Top 10 climate satellite facts

  1. 1Landsat (50-year record since 1972)
  2. 2GRACE (water storage, ice mass)
  3. 3sea level altimetry
  4. 4carbon monitoring (OCO-2)
  5. 5fire detection (MODIS)
  6. 6Amazon deforestation measurement
  7. 7Himalayan glacier loss
  8. 8Arctic sea ice record (1979-present, 40% decline)
  9. 9coral reef monitoring
  10. 10daily global coverage (Planet Labs)

Fascinating Facts

  • The GRACE satellite mission (Gravity Recovery and Climate Experiment) measured changes in Earth's gravity field precise enough to detect that California was losing 4 cubic km of groundwater per year during the 2011-2017 drought — by measuring the slightly reduced gravitational pull of the state as water was removed from underground aquifers
  • Landsat-1 (launched 1972) captured the first satellite image of the Amazon rainforest, beginning a 50-year continuous record that documents 20% of the Amazon being cleared; this dataset is the most important long-term environmental record ever assembled and has been central to every major deforestation policy debate
  • The OCO-2 satellite (Orbiting Carbon Observatory) can measure atmospheric CO2 concentrations with enough precision to identify the 'breathing' of individual cities and industrial facilities — making it possible to verify countries' reported emissions against actual atmospheric measurements, transforming the monitoring of climate commitments
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