Increases in greenhouse forcing inferred from the outgoing longwave radiation spectra of the Earth in 1970 and 1997

• Published in: Nature (London) Vol. 410; no. 6826; pp. 355 - 357
• Main Authors: Harries, John E, Brindley, Helen E, Sagoo, Pretty J, Bantges, Richard J
• Format: Journal Article
• Language: English
• Published: London Nature Publishing 15-03-2001; Nature Publishing Group
• Subjects: Carbon dioxide; Climate change; Climatology. Bioclimatology. Climate change; Earth; Earth, ocean, space; Exact sciences and technology; External geophysics; Gases; Greenhouse effect; Greenhouse gases; Hydrologic cycle; Meteorology; Radiation; Spacecraft; Surface temperature; Methane; Greenhouse effect; Long wave; Radiative properties; Carbon dioxide; Satellite observation; Ozone; Effect on climate; Long term variation; Atmospheric radiation; Climate modification
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/35066553

The evolution of the Earth's climate has been extensively studied, and a strong link between increases in surface temperatures and greenhouse gases has been established. But this relationship is complicated by several feedback processes-most importantly the hydrological cycle-that are not well understood. Changes in the Earth's greenhouse effect can be detected from variations in the spectrum of outgoing longwave radiation, which is a measure of how the Earth cools to space and carries the imprint of the gases that are responsible for the greenhouse effect. Here we analyse the difference between the spectra of the outgoing longwave radiation of the Earth as measured by orbiting spacecraft in 1970 and 1997. We find differences in the spectra that point to long-term changes in atmospheric CH4, CO2 and O3 as well as CFC-11 and CFC-12. Our results provide direct experimental evidence for a significant increase in the Earth's greenhouse effect that is consistent with concerns over radiative forcing of climate.