Copernicus Atmosphere Monitoring Service

CAMS General Assembly, Athens, 14-16 June 2016

Dr Nicolas Bellouin (University of Reading)

Climate Forcings

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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.

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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

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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

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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.

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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

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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.

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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!

KeithShine

GuyBrasseur

GunnarMyhre

OlivierBoucher

PiersForster

JohannesQuaas

NicolasBellouin

KenCarslaw

and Will Davies, Johannes Muelmenstaedt, Leighton Regayre, Chris Smith, Natalia Sudarchikova

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Current productswww.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)

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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.

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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 LongwaveCarbon dioxideMethaneTropospheric ozoneStratospheric ozoneAerosol-radiation interactions

Aerosol-cloud interactions

IMPROVED

IMPROVED

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Climate forcings users

• Climate research community

• National and international policymaking via new sets of CO2 equivalent emission factors

• NGOs

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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.