1. Climate Forcings
Dr Nicolas Bellouin (University of Reading)

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. 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. 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. Radiative forcing quantifies energy budget imbalances
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.
Figure 8.15 of IPCC AR5, 2013

6. How does the CAMS Reanalysis of atmospheric composition help?
Total columns for July 2003 from MACC Reanalysis.
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
CO2
CH4
MACC reanalysis: 9 product classes from 11 satellite instruments O3
Aerosols

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. 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. 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. 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. Products coming in August 2016
Forcing agent
Shortwave
Longwave
Carbon dioxide
Methane
Tropospheric ozone
Stratospheric ozone
Aerosol-radiation interactions
Aerosol-cloud interactions
IMPROVED
IMPROVED
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.

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

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.