The document discusses the Copernicus Atmosphere Monitoring Service (CAMS) Climate Forcings project. CAMS provides estimates of radiative forcing from human-caused changes to atmospheric composition, like increases in greenhouse gases and aerosols. It uses modeling and observations to quantify forcings and uncertainties. Current products include aerosol radiative forcing estimates. Upcoming products in August will provide monthly average radiative forcings for various agents and conditions. The information supports climate research and policymaking.

1. Copernicus
Atmosphere
Monitoring
Service
CAMS General Assembly, Athens, 14-16 June 2016
Dr Nicolas Bellouin (University of Reading)
Climate Forcings

2. 2
CAMS Climate Forcings
• We are a climate-focused service based on the CAMS
Reanalysis of Atmospheric Composition.
• We provide estimates and uncertainties of radiative
forcing exerted by perturbations to atmospheric
composition caused by human activities.
• Our users are involved in the scientific and policy
aspects of climate change.

3. 3
The Earth’s energy budget
• The Earth gets its
energy from the Sun,
reflects a third of it,
absorbs the rest,
then emits longwave
radiation back to
space.
• The Earth’s surface
currently takes in
more energy than it
emits, and warms.
At the surface
Figure 2.11 of IPCC AR5, 2013

4. 4
Human activities perturb the composition of the
atmosphere, with consequences on the energy budget
• Increases in greenhouse
gases decrease the
longwave flux emitted to
space.
• Changes in stratospheric
and tropospheric ozone
perturb shortwave and
longwave fluxes.
• Pollution particles
(aerosols) increase
reflection of shortwave flux
to space.
Figure 1.01 of IPCC AR5, 2013

5. 5
Radiative forcing quantifies energy budget imbalances
Figure 8.15 of IPCC AR5, 2013
• Radiative forcing is
positive for changes that
lead to a gain in energy
in the Earth system.
• Radiative forcing is
negative for changes that
lead to a loss in energy in
the Earth system.
• Quantifying radiative
forcing components is a
crucial task for climate
researchers.

6. 6
How does the CAMS Reanalysis of atmospheric composition help?
• It is arguably the best
representation of
current atmospheric
composition.
• Combines the strengths
of modelling and
observations.
• Simulates the
distributions of many
radiative forcing agents
in a consistent way
Total columns for
July 2003 from
MACC Reanalysis.
CO2
CH4
O3
Aerosols

7. 7
How do we estimate radiative forcing?
• CAMS atmospheric
composition datasets are
used in radiative flux
calculations.
• We also use additional
observations, and
estimates of atmospheric
composition before they
were perturbed by human
activities.
• Strong focus on
uncertainties.

8. 8
Our expertise
• CAMS Climate Forcings
gathers top experts of
radiation, greenhouse
gases, aerosols, and
uncertainty quantification.
• Taken together, we have
contributed to every single
IPCC Assessment Report
since 1990!
Keith
Shine
Guy
Brasseur
Gunnar
Myhre
Olivier
Boucher
Piers
Forster
Johannes
Quaas
Nicolas
Bellouin
Ken
Carslaw
and Will Davies, Johannes Muelmenstaedt, Leighton
Regayre, Chris Smith, Natalia Sudarchikova

9. 9
Current products
www.gmes-atmosphere.eu/news/radiative_forcing/
• Identification of aerosol
origin
• Anthropogenic
• Natural
• Aerosol radiative forcing
• From increased
scattering/absorption
of shortwave radiation
• From modification of
cloud properties
Aerosol optical depth (2003—2012)
Aerosol radiative forcing (2003—2012)

10. 10
Current products: Uncertainties
• It is difficult to
identify aerosol origin
and quantify how
strongly aerosols
interact with
radiation and clouds
• We publish
uncertainty ranges
and make advanced
uncertainty analyses.

11. 11
Products coming in August 2016
• All forcings are monthly averages including stratospheric adjustment, at the
top of the atmosphere and surface, and for cloud-free and all-sky conditions.
• Also, 3-hourly distributions of aerosol radiative effects at surface to drive land-
surface models.
Forcing agent Shortwave Longwave
Carbon dioxide
Methane
Tropospheric ozone
Stratospheric ozone
Aerosol-radiation
interactions
Aerosol-cloud
interactions

12. 12
Climate forcings users
• Climate research
community
• National and international
policymaking via new sets
of CO2 equivalent
emission factors
• NGOs

13. 13
CAMS Climate Forcings
• We are a climate-focused service based on the CAMS
Reanalysis of Atmospheric Composition.
• We provide estimates and uncertainties of radiative
forcing exerted by perturbations to atmospheric
composition caused by human activities.
• Our users are involved in the scientific and policy
aspects of climate change.