Aerosol pollution impacts on climate projections

Lead Research Organisation: University of Leeds
Department Name: School of Earth and Environment

Abstract

Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.

Publications

10 25 50
publication icon
Peace A (2020) Effect of aerosol radiative forcing uncertainty on projected exceedance year of a 1.5 °C global temperature rise in Environmental Research Letters

Studentship Projects

Project Reference Relationship Related To Start End Student Name
NE/P010547/1 30/09/2017 30/03/2022
1935152 Studentship NE/P010547/1 30/09/2017 30/03/2022
 
Description Atmospheric aerosols have caused a net cooling of climate over the industrial period that has offset some of the warming of greenhouse gases. Globally aerosol emissions are predicted to decline in the coming decades in line with air quality and climate change mitigation policies. Reductions in aerosols will cause a near-term warming of climate and corresponding aerosol-driven climate responses. Hence, it is important we can accurately predict the impact of aerosols on climate. However, the interactions of aerosols with clouds and solar radiation remains one of the most uncertain aspects of climate modelling. In this project we have used an ensemble of climate model simulations alongside statistical techniques to first quantify the impact of uncertainty in the radiative effect of aerosols in near-term climate projections, and show this uncertainty can alter the projected year for exceedance of the 1.5? target set by the Paris Agreement by 4 years. Secondly, we have further investigated how the uncertainty in aerosol radiative can impact large-scale dynamical climate changes, such as shifts in tropical rainfall, based on our understanding of historical climate changes. We find accounting for single-model uncertainty and a greater influence from internal variability can obscure a relationship between anthropogenic aerosol forcing and tropical precipitation shifts over the 20th century. Yet, there is a clear influence of major volcanic eruptions on precipitation shifts. However, in the future, under a high greenhouse gas emission scenario, there is relationship between the magnitude of aerosol forcing and tropical precipitation shifts up to mid-21st century. This result, further illustrates how the uncertainty in aerosol radiative forcing limits the accuracy of future climate projections. Lastly, we have explored the use of trends in surface solar radiation over Europe as a measure of climate model performance and as a constraint on aeosol radaitive forcing. Our results suggest caution is needed when using surface solar radiation as a model constraint because model performance, model parameter influence and the relationship with aerosol radiative forcing varies between time periods when anthropogenic aerosol emissions increased compared to periods when emissions decreased, seasons, the degree of ocean coupling in the model, and the model ensemble size.
Exploitation Route Current emission reduction commitments suggest a global mean temperature rise of 1.5? since pre-industrial times will likely happen during the next two decades. This gives little time to put in place adaptation measures that limit the impact of the increased climate change. Our first paper has shown that when taking into account the parametric uncertainty in aerosol radiative forcing the timing of reaching 1.5? for for a middle of the road scenario is between 2034 and 2039. Our second paper shows that the magnitude of aerosol radiative forcing has a strong relationship with the strength in projected tropical precipitation shifts up to mid-21st century. The impact of aerosol radiative forcing uncertainty on temperature and precipitation projections illustrates the need for the continued effort in reducing aerosol radiative forcing uncertainty, in order for successful implementation of climate change mitigation and adaptation policies.
Sectors Environment