Earth’s outgoing longwave radiation linear due to H 2 O greenhouse effect
All rights reserved. Satellite measurements and radiative calculations show that Earth's outgoing longwave radiation (OLR) is an essentially linear function of surface temperature over a wide range of temperatures (≳60 K). Linearity implies that radiative forcing has the same impact in warmer a...
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| Format: | Article |
| Language: | English |
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Proceedings of the National Academy of Sciences
2020
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| Online Access: | https://hdl.handle.net/1721.1/125085 |
| _version_ | 1826213682596544512 |
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| author | Koll, Daniel D. B. Cronin, Timothy Wallace |
| author2 | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences |
| author_facet | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Koll, Daniel D. B. Cronin, Timothy Wallace |
| author_sort | Koll, Daniel D. B. |
| collection | MIT |
| description | All rights reserved. Satellite measurements and radiative calculations show that Earth's outgoing longwave radiation (OLR) is an essentially linear function of surface temperature over a wide range of temperatures (≳60 K). Linearity implies that radiative forcing has the same impact in warmer as in colder climates and is thus of fundamental importance for understanding past and future climate change. Although the evidence for a nearly linear relation was first pointed out more than 50 y ago, it is still unclear why this relation is valid and when it breaks down. Here we present a simple semianalytical model that explains Earth's linear OLR as an emergent property of an atmosphere whose greenhouse effect is dominated by a condensable gas. Linearity arises from a competition between the surface's increasing thermal emission and the narrowing of spectral window regions with warming and breaks down at high temperatures once continuum absorption cuts off spectral windows. Our model provides a way of understanding the longwave contribution to Earth's climate sensitivity and suggests that extrasolar planets with other condensable greenhouse gases could have climate dynamics similar to Earth's. ©2018 National Academy of Sciences. |
| first_indexed | 2024-09-23T15:53:09Z |
| format | Article |
| id | mit-1721.1/125085 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T15:53:09Z |
| publishDate | 2020 |
| publisher | Proceedings of the National Academy of Sciences |
| record_format | dspace |
| spelling | mit-1721.1/1250852022-10-02T04:51:50Z Earth’s outgoing longwave radiation linear due to H 2 O greenhouse effect Koll, Daniel D. B. Cronin, Timothy Wallace Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences All rights reserved. Satellite measurements and radiative calculations show that Earth's outgoing longwave radiation (OLR) is an essentially linear function of surface temperature over a wide range of temperatures (≳60 K). Linearity implies that radiative forcing has the same impact in warmer as in colder climates and is thus of fundamental importance for understanding past and future climate change. Although the evidence for a nearly linear relation was first pointed out more than 50 y ago, it is still unclear why this relation is valid and when it breaks down. Here we present a simple semianalytical model that explains Earth's linear OLR as an emergent property of an atmosphere whose greenhouse effect is dominated by a condensable gas. Linearity arises from a competition between the surface's increasing thermal emission and the narrowing of spectral window regions with warming and breaks down at high temperatures once continuum absorption cuts off spectral windows. Our model provides a way of understanding the longwave contribution to Earth's climate sensitivity and suggests that extrasolar planets with other condensable greenhouse gases could have climate dynamics similar to Earth's. ©2018 National Academy of Sciences. NSF (Grant no. AGS-1623218) James McDonnell Foundation Postdoctoral fellowship 2020-05-06T20:41:07Z 2020-05-06T20:41:07Z 2018-09 2018-06 2020-04-15T16:59:07Z Article http://purl.org/eprint/type/JournalArticle 1091-6490 https://hdl.handle.net/1721.1/125085 Koll, Daniel D. B. and Timothy W. Cronin, "Earth’s outgoing longwave radiation linear due to H 2 O greenhouse effect." Proceedings of the National Academy of Sciences of the United States of America 115, 41 (September 2018): 10293-10298 doi. 10.1073/PNAS.1809868115 ©2018 Authors en 10.1073/PNAS.1809868115 Proceedings of the National Academy of Sciences of the United States of America Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf Proceedings of the National Academy of Sciences PNAS |
| spellingShingle | Koll, Daniel D. B. Cronin, Timothy Wallace Earth’s outgoing longwave radiation linear due to H 2 O greenhouse effect |
| title | Earth’s outgoing longwave radiation linear due to H 2 O greenhouse effect |
| title_full | Earth’s outgoing longwave radiation linear due to H 2 O greenhouse effect |
| title_fullStr | Earth’s outgoing longwave radiation linear due to H 2 O greenhouse effect |
| title_full_unstemmed | Earth’s outgoing longwave radiation linear due to H 2 O greenhouse effect |
| title_short | Earth’s outgoing longwave radiation linear due to H 2 O greenhouse effect |
| title_sort | earth s outgoing longwave radiation linear due to h 2 o greenhouse effect |
| url | https://hdl.handle.net/1721.1/125085 |
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