1. Short-Lived Climate Forcers
Department of Meteorology
Short-Lived Climate Forcers
Ideas for a SPARC Activity

2. Motivation SLCFs are currently barely addressed in WCRP
There was a placeholder in the Biogeochemical Cycle Grand Challenge.
- ended up being entirely carbon-cycle.
Given importance of SLCFs there should be a place for them in WCRP.
The most obvious WCRP project is SPARC
→ SPARC activity?

3. Climate impacts AerChemMIP/PDRMIP CCMI /Aerocom Evaporation / runoff
Emissions
CH4
NOX CO
VOC
NH3
SO2
OCaer
BCaer
Atmospheric Chemistry & Microphysics
Evaporation / runoff
ERF
ΔCH4
ΔO3
S +
N +
SOA +
OC +
BC aerosols
Surface Temperature
Biosphere Interactions
Feedbacks
Cloud Interactions
Additional ERF
ΔBio
ΔCH4
ΔCO2
ΔN2O
Δclouds
Precipitation
From Michael Prather
AerChemMIP/PDRMIP
CCMI /Aerocom

4. Chain of effects Complex chain from SLCF emission to climate response
Decades of research on first two steps
Recent individual studies on the rapid and slow responses
Few coordinated studies (PDRMIP)
There is a community need to coordinate this.
Emissions
Chemistry
transport
Composition
Absorption
scattering
Cloud physics
Radiative effect
Meteorology
adjustments
Rapid response
Climate
feedbacks
Slow response

5. Science Questions
1) How does the atmosphere adjust to changes in SLCFs, and what is the effect of these rapid adjustments on the ERFs?
2) How does the climate respond to different patterns of these ERFs
globally, spatially, temporally
temperature, precipitation,…

6. Experimental structure
Shindell and Faluvegi (2009) used GISS slab model
ΔF in 4 latitude bands →ΔT in 4 latitude bands
4×4 matrix, 4 species
This needs to be updated with range of models and extended beyond temperature to precipitation…
Extend the AerChemMIP/PDRMIP protocols
Prescribe concentrations, and aerosol radiative properties?
by region N. Amer, S. Amer, Europe, S. Asia, E. Asia, Africa
or latitude bands?
Fixed-SST runs – year simulations
Coupled-ocean runs – need years to see signal

7. Timeline HTAP2 PDRMIP AerChemMIP SLCF Activity Design Experiments
Analysis
2017
2018
2019
2020

8. Grand Challenges Societal benefits
Clouds, circulation and climate sensitivity
Some mention of aerosol-cloud interactions in this
Carbon feedbacks in the climate system
Some mention of short-lived species in biogeochemical cycles
Regionality of SLCF climate impacts important for C-cycle
Near-term climate prediction
SLCFs crucial to near-term climate prediction. Scope for interactions here.
Near-term climate change – particularly regional
Climate impacts of air quality policies
Societal benefits

9. Summary
There already exist coordinated projects on the chemistry and physical processing of SLCFs
Research into their climate impacts is ready for coordinated activities
Rapid adjustments in meteorology to changes in SLCFs
Surface temperature (and precipitation) responses to heterogeneous forcing
Great opportunity for WCRP/SPARC activity