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Attributing impacts of external climate drivers on extreme weather in Africa

外部气候驱动因素对非洲极端天气的影响

基本信息

批准号：
NE/K005472/1
负责人：
Rosalind Cornforth
金额：
$ 16.72万
依托单位：
University of Reading
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2013
资助国家：
英国
起止时间：
2013 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FK005472%2F1
关键词：
Attributing impacts external climate drivers

项目摘要

Given limited progress in reducing greenhouse gas emissions and uncertain potential for adaptation to many impacts, attention in vulnerable regions and sectors is turning to the question of "loss and damage". Who should bear the costs of human influence on climate that cannot be neutralized by adaptation? This debate is impeded by lack of robust estimates of what these costs are. Despite concerted efforts to compile inventories of emissions, we still have no agreed method of establishing how countries, companies or individuals are being adversely affected by anthropogenic climate change in the context of other drivers of regional environmental change.Many of the most important impacts of climate change are related in some way to high-impact weather events (HIWEs), such as floods, storms, and droughts. Compiling an impact inventory requires documenting the impacts of individual events and how these events are affected by multiple climate drivers and internal climate variability. We will build on research into HIWEs and their impacts under THORPEX-Africa.Studies assessing the link between climate change and extreme weather have so far focused primarily on mid-latitude phenomena and the impact of rising greenhouse gases. Yet in many tropical regions, short-lived climate forcings (SLCFs) such as sulphate, mineral and black carbon aerosols and tropospheric ozone may have played a larger role in changing patterns of weather risk to date. Substantial reductions in anthropogenic SLCFs could be achieved in only 20 years. Including measures already planned to reduce emissions of sulphate aerosol precursors, SLCFs may dominate near-term changes in weather risk. Climate impact assessments used for adaptation planning typically focus on net multi-decadal anthropogenic change, dominated by greenhouse-induced warming. Few address uncertainty in SLCF forcing and response. Hence relying on these and extrapolation of recent trends risks "adapting to yesterday's problem" as key drivers of regional weather are reversed.Assessing the influence of external drivers on extreme weather is challenging because the most important events are typically rare. The only solution is to rely on simulation models, whose reliability can be tested and if necessary re-calibrated using well-established procedures developed for seasonal forecasting. We will also use the land-surface model JULES for indirect validation in regions with sparse meteorological data. Large ensembles of climate model simulations at relatively high resolution are required for robust statistics of extreme weather events, allowing for uncertainty in both external drivers and simulation models.This project makes use of the climateprediction.net weatherathome worldwide volunteer computing project. We will quantify the role of various external climate drivers on changing risks of extreme weather in Africa by implementing a regional climate model over the CORDEX-Africa domain and simulate observed weather statistics over recent decades using multi-thousand-member ensembles, systematically excluding the influence of different climate drivers to quantify their effects.Attribution studies of HIWEs to date have typically focussed on hydrometeorological events themselves, rather than modelling all the way through to their impacts. This can lead to "over-attribution": if a record-breaking weather event occurs that has been made more likely by some external driver, people tend to blame most of the impact of that event on that driver. But much of this impact might also have been caused by a lesser, non-record-breaking, event. Hence accurate assessment requires explicit modelling of changing impact risk, not simply weather risk, so a major focus of this project will using JULES to investigate various impacts and working with impact modellers across Africa to assess the implications of our weather simulations for changing impact risk in other sectors.

鉴于在减少温室气体排放方面的进展有限，以及适应许多影响的潜力不确定，脆弱地区和部门的注意力正转向“损失和损害”问题。人类对气候的影响无法通过适应来抵消，谁应该承担这些代价？由于缺乏对这些成本的可靠估计，这场辩论受到了阻碍。尽管各方共同努力汇编排放清单，但我们仍然没有商定的方法来确定在其他区域环境变化驱动因素的背景下，国家、公司或个人是如何受到人为气候变化的不利影响的。气候变化的许多最重要的影响在某种程度上与高影响天气事件（HIWEs）有关，如洪水、风暴和干旱。编制影响清单需要记录单个事件的影响，以及这些事件如何受到多种气候驱动因素和内部气候变率的影响。我们将在THORPEX-Africa项目下进一步研究低卫生指标及其影响。迄今为止，评估气候变化与极端天气之间联系的研究主要集中在中纬度现象和温室气体增加的影响上。然而，在许多热带地区，硫酸盐、矿物和黑碳气溶胶以及对流层臭氧等短期气候强迫（SLCFs）迄今可能在改变天气风险模式方面发挥了更大的作用。在短短20年内，就可以大幅度减少人为的长链碳排放。包括已经计划的减少硫酸盐气溶胶前体排放的措施在内，slcf可能会主导天气风险的近期变化。用于适应规划的气候影响评估通常侧重于以温室气体引起的变暖为主的多年人为净变化。很少涉及SLCF强制和响应的不确定性。因此，依赖这些和对近期趋势的推断，有可能“适应昨天的问题”，因为区域天气的主要驱动因素被逆转了。评估外部驱动因素对极端天气的影响是具有挑战性的，因为最重要的事件通常是罕见的。唯一的解决办法是依靠模拟模型，这些模型的可靠性可以进行测试，必要时可以使用为季节预报开发的成熟程序重新校准。我们还将在气象数据稀疏的地区使用陆面模型JULES进行间接验证。极端天气事件的可靠统计需要相对高分辨率的气候模式模拟的大集合，这考虑到外部驱动因素和模拟模式的不确定性。这个项目利用了climateprediction.net weatherathome全球志愿计算项目。我们将通过在CORDEX-Africa域实施区域气候模式，量化各种外部气候驱动因素对非洲极端天气变化风险的作用，并使用数千成员集合模拟近几十年来观测到的天气统计数据，系统地排除不同气候驱动因素的影响，以量化其影响。迄今为止，HIWEs的归因研究通常集中在水文气象事件本身，而不是对其影响进行建模。这可能会导致“过度归因”：如果一个破纪录的天气事件的发生更有可能是由某些外部驱动因素造成的，人们倾向于将该事件的大部分影响归咎于该驱动因素。但这种影响很大程度上也可能是由一个较小的、没有破纪录的事件造成的。因此，准确的评估需要对不断变化的影响风险进行明确的建模，而不仅仅是对天气风险进行建模。因此，本项目的一个主要重点将是利用JULES调查各种影响，并与非洲各地的影响建模者合作，评估我们的天气模拟对其他部门不断变化的影响风险的影响。