Lesson plan
Iris hypothesis
The iris hypothesis was a hypothesis proposed by Richard Lindzen and colleagues in 2001 that suggested increased sea surface temperature in the tropics would result in reduced cirrus clouds and thus more infrared radiation leakage from Earth's atmosphere. His study of observed changes in cloud coverage and modeled effects on infrared radiation released to space as a result seemed to support the hypothesis. This suggested infrared radiation leakage was hypothesized to be a negative feedback in which an initial warming would result in an overall cooling of the surface. The idea of the iris effect of cirrus clouds in trapping outgoing radiation was reasonable, but it ignored the larger compensating effect on the blocking of incoming sun's rays, and effects of changes in altitude of clouds. Moreover, a number of errors were found in the papers. For this reason, the iris effect no longer plays a role in the current scientific consensus on climate change.
Article summary
The iris hypothesis was a hypothesis proposed by Richard Lindzen and colleagues in 2001 that suggested increased sea surface temperature in the tropics would result in reduced cirrus clouds and thus more infrared radiation leakage from Earth's atmosphere. His study of observed changes in cloud coverage and modeled effects on infrared radiation released to space as a result seemed to support the hypothesis. This suggested infrared radiation leakage was hypothesized to be a negative feedback in which an initial warming would result in an overall cooling of the surface. The idea of the iris effect of cirrus clouds in trapping outgoing radiation was reasonable, but it ignored the larger compensating effect on the blocking of incoming sun's rays, and effects of changes in altitude of clouds. Moreover, a number of errors were found in the papers. For this reason, the iris effect no longer plays a role in the current scientific consensus on climate change.
Key claims
No claims recorded.
Discussion questions
- Summarise the article in your own words. Which single claim would you verify first, and why?
- Which claim in this article is most likely to be revised as the sources update? How would you check its current status?
- If two sources disagreed about one of these facts, what would you need in order to trust one over the other?
Bibliography
No sources recorded.
Key claims and bibliography are generated from the same tracked claims and sources as the article page.