Atmosphere Monitoring

Climate ForcingsDr William H. Davies, University of Readingand the CAMS 74 teamCAMS 4th General Assembly, Budapest, 17-18 September 2019

AtmosphereMonitoring

C A M S C l i m a t e F o r c i n g s

• We are a climate-focused service based on the CAMS Reanalysis of Atmospheric Composition.

• We provide estimates and uncertainties of radiative forcing exerted by changes in atmospheric composition caused by human activities.

• Our users are involved in the scientific and policy aspects of climate change.

AtmosphereMonitoring Radiative forcing

quantifies energy budget imbalances

Positive radiative forcing means a gain in energy in the Earth system. Negative means a loss of energy.

Current estimates come from a variety of methods depending on the forcing agent. CAMS Climate Forcing brings consistency.

R a d i a t i v e f o r c i n g

Figure 8.15 of IPCC AR5, 2013

AtmosphereMonitoring

V e r s i o n 1 p r o d u c t s

2003—2016

Carbon dioxide +20% per decadeMethane +3% per decade

AtmosphereMonitoring

V e r s i o n 1 p r o d u c t e v a l u a t i o n

Comparison to IPCC AR5 (Chris Smith, Leeds)

Time series and envelope: CAMS version 1, uncertainties from a Perturbed Parameter EnsembleError bars: IPCC AR5 ranges (for methane, dashed bar accounts for Etminan’s correction)

Ozone will be evaluated in the Autumn 2019.

AtmosphereMonitoring • In the process of estimating radiative forcing, we derive useful

distributions out of the CAMS Reanalysis, like anthropogenic aerosol optical thickness or profiles of cloud condensation nuclei.

A d d i t i o n a l p r o d u c t s

Cloud condensation nuclei concentrations

at 200 hPa [CCN, cm−3]

150

100

50

0

AtmosphereMonitoring • Current work covers:

– Use of carbon dioxide and methane concentrations from CAMS73.• Accounts for the first time for daily/horizontal/vertical variations.

• Challenge: Find the best way to obtain a preindustrial state compatible with those distributions.

– Revision of aerosol optical properties, with CAMS43• Improvements to carbonaceous aerosol optical properties.

– Estimates of preindustrial ozone distributions, with CAMS42• Again, need to find the best way to obtain a preindustrial state compatible

with present-day distributions simulated in the CAMS Reanalysis.

• Challenge: Pushing the ECMWF C-IFS into new territory.

C u r r e n t w o r k a n d c h a l l e n g e s

AtmosphereMonitoring

P r e i n d u s t r i a l o z o n e

First attempts were based on Cariolle simulations (left), which have important discrepancies compared to CMIP6 modelling (right):• Much larger industrial-era

increases in tropospheric concentrations

• Lack of an ozone hole

Thankfully, progress made by CAMS42 with BASCOE are very promising and will allow us to be fully CAMS-based for our ozone radiative forcing estimates.

AtmosphereMonitoring

W h e r e t o f i n d o u r p r o d u c t s ?

http://apps.ecmwf.int/datasets/data/cams-climate-forcings/

Products will be updated to latest

version in the coming months.

AtmosphereMonitoring

C A M S C l i m a t e F o r c i n g s

• We are a climate-focused service based on the CAMS Reanalysis of Atmospheric Composition.

• We provide estimates and uncertainties of radiative forcing exerted by changes in atmospheric composition caused by human activities.

• Our users are involved in the scientific and policy aspects of climate change.

• CAMS Climate Forcing is:– University of Reading

• Nicolas Bellouin, Will Davies, Keith Shine

– University of Leipzig• Johannes Quaas, Johannes

Muelmenstaedt

– University of Leeds• Piers Forster, Chris Smith

– MPI-Meteorologie Hamburg• Guy Brasseur, Natalia

Sudarchikova

– LMD, UPMC, Paris• Olivier Boucher

– CICERO Oslo• Gunnar Myhre