Observationally-constrained climate projections following the Paris Agreement

《巴黎协定》后受观测限制的气候预测

• 批准号: RGPIN-2017-04043
• 负责人: Gillett, Nathan
• 金额: $ 1.63万
• 依托单位: University of Victoria
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=750972
• 关键词: Observationally; constrained; climate; projections; following

The Paris Agreement, which recently came into force, commits signatories to holding the increase in global average temperature to well below 2C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5C above pre-industrial levels'. Since carbon dioxide is the dominant greenhouse gas, and since a certain total amount of carbon dioxide emissions gives the same amount of warming irrespective of whether it is emitted all at once or over a long period, a warming threshold of 1.5C can be associated with a particular total amount of carbon dioxide emissions, or carbon budget. Knowing the maximum amount of carbon dioxide which can be emitted while having a good chance of limiting global mean temperature to below the 1.5C and 2.0C thresholds is key to planning climate mitigation strategies and fulfilling the commitments made in the Paris Agreement. Carbon budgets presented in the last report of the United Nations Intergovernmental Panel on Climate Change (IPCC) were based directly on simulated emissions in all available climate models, and indicated that the best estimate of the 1.5C budget would be exceeded in less than ten years at current emissions levels, with a chance that this budget has already been exceeded. However, we know that historical carbon dioxide emissions, in conjunction with other climate drivers, have led to only about 1C global warming to date. Further, we know that on average the climate models considered in the last IPCC report on average warm more than observations. Can we use observations of past climate change to obtain better projections of future climate change? A number of ways of using observations to constrain projections have been proposed, including scaling simulated climate change up or down to best match observed changes, weighting models based on how well they agree with observations, or using observations to screen climate models in or out. This project will explore a range of approaches to observationally-constraining climate projections, with a focus on obtaining improved observationally-constrained carbon budgets and projections of global mean temperature. The application of observational constraints to other variables, such as regional temperature changes, rainfall changes and sea ice changes, will also be considered.

最近生效的《巴黎协定》承诺将全球平均温度的升高升至高于工业前水平以下的2C远低于2C，并追求将温度升高到前工业前水平以上的1.5℃的努力。由于二氧化碳是主要的温室气体，并且由于一定数量的总二氧化碳排放量会产生相同数量的变暖，无论是否一次或长时间发射，因此可以与1.5C的变暖阈值相关特定的总二氧化碳排放量或碳预算。知道可以发射的最大二氧化碳量，而在很有可能将全球平均温度限制在1.5C和2.0C阈值的情况下是计划气候缓解策略并履行巴黎协议中的承诺的关键。联合国政府间气候变化小组（IPCC）的最后一份报告中提出的碳预算直接基于所有可用气候模型中的模拟排放，并表明在不到十年的时间内，对1.5C预算的最佳估计值将超过在当前的排放水平上，有机会已经超过了该预算。但是，我们知道，历史二氧化碳的排放量与其他气候驱动因素结合使用，迄今仅导致了大约1C的全球变暖。此外，我们知道，在上次IPCC报告中平均考虑的气候模型平均比观察值更多。我们可以使用过去气候变化的观察来获得对未来气候变化的更好预测？已经提出了多种使用观测值来约束投影的方法，包括根据他们与观察值的同意或使用观察值来筛选气候模型，将模拟的气候变化向上或最佳匹配观察到的变化，加权模型。该项目将探索一系列观察到的气候预测的方法，重点是获得改进的观察到的碳预算和全球平均温度的预测。还将考虑将观察性约束应用于其他变量，例如区域温度变化，降雨变化和海冰变化。