Causes of global temperature changes during the 19th and 20th centuries

• Published in: Geophysical research letters Vol. 27; no. 14; pp. 2137 - 2140
• Main Authors: Andronova, Natalia G., Schlesinger, Michael E.
• Format: Journal Article
• Language: English
• Published: Washington, DC Blackwell Publishing Ltd 15-07-2000; American Geophysical Union
• Subjects: Brackish; Climatology. Bioclimatology. Climate change; Earth, ocean, space; Exact sciences and technology; External geophysics; Freshwater; Marine; Meteorology; Century 20th; Biogenic factor; Atmospheric temperature; Radiative properties; Century 19th; Planetary scale; Theoretical study; Climate models; Climate modification; Anthropogenic factor; Ocean model
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2000GL006109

During the past two decades there has been considerable discussion about the relative contribution of different factors to the temperature changes observed now over the past 142 years. Among these factors are the “external’ factors of human (anthropogenic) activity, volcanoes and putative variations in the irradiance of the sun, and the “internal” factor of natural variability. Here, by using a simple climate/ocean model to simulate the observed temperature changes for different state‐of‐the‐art radiative‐forcing models, we present strong evidence that while the anthropogenic effect has steadily increased in size during the entire 20th century such that it presently is the dominant external forcing of the climate system, there is a residual factor at work within the climate system, whether a natural oscillation or something else as yet unknown. This has an important implication for our expectation of future temperature changes.