Understanding the Direct and Ozone-Mediated Impacts of (CO2) and Ozone Depleting Substances (ODS) on the Climate System

了解 (CO2) 和消耗臭氧层物质 (ODS) 对气候系统的直接影响和臭氧介导的影响

• 批准号: 1914569
• 负责人: Lorenzo Polvani
• 金额: $ 99.93万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1914569&HistoricalAwards=false
• 关键词: Understanding; Direct; Ozone; Mediated; Impacts

The ozone hole and greenhouse gas-induced global warming are distinct environmental problems. The ozone hole matters because reductions in stratospheric ozone lead to increases in harmful ultraviolet radiation reaching the surface. The loss of ozone in the hole is caused by a small set of ozone depleting substances (ODS, primarily chlorofluorocarbons) used in a specific set of applications such as spray cans and cooling equipment. Global warming, on the other hand, is caused by the heat-trapping effect of greenhouse gases emitted throughout the world economy, principally the carbon dioxide (CO2) emitted in the burning of fossil fuels.Despite the clear distinction between global warming and the ozone hole there are important physical pathways that link the two. One is that most ODS are also greenhouse gases. ODS concentrations are minuscule compared to CO2 but they are thousands of times more effective as absorbers of infrared radiation, thus their heat-trapping effect is substantial. Another connection is that CO2 increases can change the amount and distribution of ozone in the stratosphere. Although CO2 warms the troposphere it cools the stratosphere, a difference caused by their opposite temperature profiles (cold aloft, warm below in the troposphere and vice versa in the stratosphere). Cooler stratospheric temperatures can increase ozone concentrations by reducing the reaction rates for ozone-depleting chemistry. But a CO2 increase can also cause a speed-up of the stratospheric overturning circulation, which in turn decreases the lifetime of stratospheric ozone.This work explores the climatic effects of CO2 and ODS, recognizing that they affect climate both directly and through their impact on stratospheric ozone. In addition to global temperature the study considers regional influences on sea surface temperature, sea level pressure, jet stream wind speed, and other variables. Preliminary work suggests, for example, that the greenhouse warming due to ODS is greatest in the subtropics of the North and South Pacific, presumably as a consequence of the uneven geographical distribution of ODS. A further consideration is that ODS can affect climate either directly, as a powerful greenhouse gas, or indirectly through the changes in climate induced by ozone loss. For example, previous work by the PI and others shows that the ozone hole has affected the winds, temperature, and precipitation of the Southern Hemisphere. The work also examines changes in stratospheric ozone due to CO2 increases. The primary research tool of the project is the Whole Atmosphere Community Climate Model developed at the National Center for Atmospheric Research.The work has broader impacts due to the societal impacts of ozone depletion and global warming. Efforts to address these impacts will benefit from a better physical understanding of the processes involved. The work also fosters international scientific collaboration given the participation of researchers at the Swiss Federal Institute of Technology in Zurich. The project also provides support and training to a graduate student and a postdoctoral research associate, thereby promoting the future workforce in this research area.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

臭氧层空洞和温室气体引起的全球变暖是两个截然不同的环境问题。 臭氧洞之所以重要，是因为平流层臭氧的减少导致到达地表的有害紫外线辐射增加。 臭氧空洞中的臭氧损失是由喷雾罐和冷却设备等特定应用中使用的一小部分臭氧消耗物质（ODS，主要是氯氟烃）造成的。 另一方面，全球变暖是由整个世界经济中排放的温室气体的吸热效应造成的，主要是燃烧化石燃料时排放的二氧化碳，尽管全球变暖和臭氧空洞之间有明显的区别，但两者之间有重要的物理途径。 其中之一是大多数耗氧物质也是温室气体。臭氧消耗物质的浓度与二氧化碳相比微不足道，但它们作为红外辐射吸收剂的有效性要高出数千倍，因此其吸热效果很大。另一个联系是，二氧化碳的增加会改变平流层中臭氧的数量和分布。虽然二氧化碳使对流层变暖，但它使平流层变冷，这是由它们相反的温度分布造成的差异（对流层高处冷，下方暖，平流层反之亦然）。较低的平流层温度可以通过降低臭氧消耗化学反应速率来增加臭氧浓度。但CO2的增加也会导致平流层翻转环流的加速，这反过来又会减少平流层臭氧的寿命。这项工作探讨了CO2和ODS的气候效应，认识到它们既直接影响气候，又通过对平流层臭氧的影响来影响气候。除了全球温度外，该研究还考虑了区域对海表温度、海平面气压、急流风速和其他变量的影响。 例如，初步工作表明，由耗氧物质造成的温室升温在北太平洋和南太平洋的亚热带地区最为严重，这大概是由于耗氧物质的地理分布不均造成的。 另一项考虑是，耗氧物质可作为一种强大的温室气体直接影响气候，或通过臭氧损失引起的气候变化间接影响气候。 例如，PI和其他人之前的工作表明，臭氧空洞已经影响了南半球的风、温度和降水。 这项工作还研究了由于二氧化碳增加而引起的平流层臭氧的变化。该项目的主要研究工具是国家大气研究中心开发的全大气社区气候模型，由于臭氧消耗和全球变暖的社会影响，这项工作具有更广泛的影响。 更好地了解所涉过程将有助于解决这些影响的努力。 由于苏黎世瑞士联邦技术研究所的研究人员参与了这项工作，这项工作还促进了国际科学合作。 该项目还为一名研究生和一名博士后研究助理提供支持和培训，从而促进该研究领域未来的劳动力。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。