Effects of ozone levels on climate through Earth history
| dc.contributor.author | Deitrick, Russell | |
| dc.contributor.author | Goldblatt, Colin | |
| dc.date.accessioned | 2024-07-08T15:16:53Z | |
| dc.date.available | 2024-07-08T15:16:53Z | |
| dc.date.issued | 2023 | |
| dc.description | We thank Eric Wolf for guidance in running CESM, Brandon Smith for further guidance in running CESM and for providing CAM model output, and Daniel Garduño Ruiz for photochemical model output. We also thank Victoria McDonald, whose documentation and code helped immensely with running CESM and with our analysis. | |
| dc.description.abstract | Molecular oxygen in our atmosphere has increased from less than a part per million in the Archean Eon to a fraction of a percent in the Proterozoic and finally to modern levels during the Phanerozoic. The ozone layer formed with the early Proterozoic oxygenation. While oxygen itself has only minor radiative and climatic effects, the accompanying ozone has important consequences for Earth climate. Using the Community Earth System Model (CESM), a 3-D general circulation model (GCM), we test the effects of various levels of ozone on Earth's climate. When CO2 is held constant, the global-mean surface temperature decreases with decreasing ozone, with a maximum drop of ∼3.5 K at near total ozone removal. By supplementing our GCM results with 1-D radiative flux calculations, we are able to test which changes to the atmosphere are responsible for this temperature change. We find that the surface temperature change is caused mostly by the stratosphere being much colder when ozone is absent; this makes it drier, substantially weakening the greenhouse effect. We also examine the effect of the structure of the upper troposphere and lower stratosphere on the formation of clouds and on the global circulation. At low ozone, both high and low clouds become more abundant due to changes in the tropospheric stability. These generate opposing shortwave and longwave radiative forcings that are nearly equal. The Hadley circulation and tropospheric jet streams are strengthened, while the stratospheric polar jets are weakened, the latter being a direct consequence of the change in stratospheric temperatures. This work identifies the major climatic impacts of ozone, an important piece of the evolution of Earth's atmosphere. | |
| dc.description.reviewstatus | Reviewed | |
| dc.description.scholarlevel | Faculty | |
| dc.description.sponsorship | his research was enabled in part by support provided by the BC DRI Group and the Digital Research Alliance of Canada (https://alliancecan.ca, last access: 9 June 2023) and via NSERC Research Tools and Instruments grant RTI-2020-00277. The CESM project is supported primarily by the National Science Foundation (NSF). Administration of the CESM is maintained by the Climate and Global Dynamics Laboratory (CGD) at the National Center for Atmospheric Research (NCAR). Financial support was provided by the Natural Sciences and Engineering Research Council of Canada (NSERC; Discovery Grant RGPIN-2018-05929) and the Canadian Space Agency (grant 18FAVICB21). | |
| dc.identifier.citation | Deitrick, R., & Goldblatt, C. (2023b). Effects of ozone levels on climate through Earth history. Climate of the Past, 19(6), 1201–1218. https://doi.org/10.5194/cp-19-1201-2023 | |
| dc.identifier.uri | https://doi.org/10.5194/cp-19-1201-2023 | |
| dc.identifier.uri | https://hdl.handle.net/1828/16724 | |
| dc.language.iso | en | |
| dc.publisher | Climate of the Past | |
| dc.rights | Attribution 4.0 International | en |
| dc.rights.uri | http://creativecommons.org/licenses/by/4.0/ | |
| dc.subject.department | School of Earth and Ocean Sciences | |
| dc.title | Effects of ozone levels on climate through Earth history | |
| dc.type | Article |