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Aerosols in the Pre-industrial Atmosphere
- Source :
- Current Climate Change Reports
- Publication Year :
- 2020
-
Abstract
- Purpose of Review\ud \ud We assess the current understanding of the state and behaviour of aerosols under pre-industrial conditions and the importance for climate.\ud \ud \ud \ud Recent Findings\ud \ud Studies show that the magnitude of anthropogenic aerosol radiative forcing over the industrial period calculated by climate models is strongly affected by the abundance and properties of aerosols in the pre-industrial atmosphere. The low concentration of aerosol particles under relatively pristine conditions means that global mean cloud albedo may have been twice as sensitive to changes in natural aerosol emissions under pre-industrial conditions compared to present-day conditions. Consequently, the discovery of new aerosol formation processes and revisions to aerosol emissions have large effects on simulated historical aerosol radiative forcing.\ud \ud \ud \ud Summary\ud \ud We review what is known about the microphysical, chemical, and radiative properties of aerosols in the pre-industrial atmosphere and the processes that control them. Aerosol properties were controlled by a combination of natural emissions, modification of the natural emissions by human activities such as land-use change, and anthropogenic emissions from biofuel combustion and early industrial processes. Although aerosol concentrations were lower in the pre-industrial atmosphere than today, model simulations show that relatively high aerosol concentrations could have been maintained over continental regions due to biogenically controlled new particle formation and wildfires. Despite the importance of pre-industrial aerosols for historical climate change, the relevant processes and emissions are given relatively little consideration in climate models, and there have been very few attempts to evaluate them. Consequently, we have very low confidence in the ability of models to simulate the aerosol conditions that form the baseline for historical climate simulations. Nevertheless, it is clear that the 1850s should be regarded as an early industrial reference period, and the aerosol forcing calculated from this period is smaller than the forcing since 1750. Improvements in historical reconstructions of natural and early anthropogenic emissions, exploitation of new Earth system models, and a deeper understanding and evaluation of the controlling processes are key aspects to reducing uncertainties in future.
- Subjects :
- 0301 basic medicine
Biosphere model
Atmospheric Science
010504 meteorology & atmospheric sciences
Climate
Radiative forcing
Climate change
Atmospheric sciences
01 natural sciences
complex mixtures
Atmosphere
03 medical and health sciences
Biosphere
Aerosols and Climate (O Boucher, Section Editor)
Aerosol
0105 earth and related environmental sciences
Global and Planetary Change
15. Life on land
respiratory system
Climate sensitivity
Pollution
030104 developmental biology
13. Climate action
Climatology
Cloud albedo
Environmental science
Climate model
Subjects
Details
- ISSN :
- 21986061
- Volume :
- 3
- Issue :
- 1
- Database :
- OpenAIRE
- Journal :
- Current climate change reports
- Accession number :
- edsair.doi.dedup.....593ad1d08ff5aed460e7a3bef3c3f412