aerosols and climate - a crash course marianne t. lund cicero nove mesto 17/9-15

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Aerosols and climate - a crash course Marianne T. Lund CICERO Nove Mesto 17/9-15

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Page 1: Aerosols and climate - a crash course Marianne T. Lund CICERO Nove Mesto 17/9-15

Aerosols and climate- a crash course

Marianne T. Lund

CICERO

Nove Mesto 17/9-15

Page 2: Aerosols and climate - a crash course Marianne T. Lund CICERO Nove Mesto 17/9-15

Observed changes in the climate system

Page 3: Aerosols and climate - a crash course Marianne T. Lund CICERO Nove Mesto 17/9-15

IPCC 2013

We observe changes all across the climate system

"Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millenia."

Page 4: Aerosols and climate - a crash course Marianne T. Lund CICERO Nove Mesto 17/9-15

Global mean temperature

Global mean temperature anomaly

http://data.giss.nasa.gov

Page 5: Aerosols and climate - a crash course Marianne T. Lund CICERO Nove Mesto 17/9-15

IPCC 2013

Increasing energy in the climate system more than 90% of

accumuated energy between 1970 and 2010 stored in the oceans

Global mean ocean heat content

Efficient heat uptake by the global oceans

Global mean ocean temperature anomaly

Warming also of the deep ocean (below 700 m)

Page 8: Aerosols and climate - a crash course Marianne T. Lund CICERO Nove Mesto 17/9-15

What drives the changes?

Page 10: Aerosols and climate - a crash course Marianne T. Lund CICERO Nove Mesto 17/9-15

Natural and anthropogenic contributions

"(…) It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century. "

IPCC 2013

Page 11: Aerosols and climate - a crash course Marianne T. Lund CICERO Nove Mesto 17/9-15

A cocktail of emissions

Page 12: Aerosols and climate - a crash course Marianne T. Lund CICERO Nove Mesto 17/9-15

Warming and cooling contributions

CO2, O3, N2O …

Oppvarmende Avkjølende

AEROSOLS

Page 13: Aerosols and climate - a crash course Marianne T. Lund CICERO Nove Mesto 17/9-15

Radiative forcing 1750 to 2011

IPCC 2013

Page 14: Aerosols and climate - a crash course Marianne T. Lund CICERO Nove Mesto 17/9-15

Aerosols

Page 15: Aerosols and climate - a crash course Marianne T. Lund CICERO Nove Mesto 17/9-15

Definition

Main types of aerosols:• Dust• Sea salt• Sulfate • Soot (product of incomplete combutions)• Organic carbon• Products from biomass burning• Nitrate

“Aerosols are minute particles suspended in the atmosphere”

Page 16: Aerosols and climate - a crash course Marianne T. Lund CICERO Nove Mesto 17/9-15

Natural and anthropogenic sources

Myhre et al. 2013

Page 17: Aerosols and climate - a crash course Marianne T. Lund CICERO Nove Mesto 17/9-15

What do aerosols look like?

Heintzenberg et al. 2003

Aerosol sizes can vary from 1 nm to several 100 um

>10 um: giant aerosol

< 1 um: fine mode

Page 18: Aerosols and climate - a crash course Marianne T. Lund CICERO Nove Mesto 17/9-15

Atmospheric life cycle

www.pnl.gov/

Aerosols have short atmospheric lifetime and are not well mixed like CO2.

Their impacts can be strongly localized, but aerosols can also be transported over large distances.

Page 19: Aerosols and climate - a crash course Marianne T. Lund CICERO Nove Mesto 17/9-15

Aerosol distributions

Myhre et al. 2013

Aerosols are everywhere, but the amount and mixture of aerosols can be highly variable.

Page 20: Aerosols and climate - a crash course Marianne T. Lund CICERO Nove Mesto 17/9-15

Aerosol impacts

Air quality and visibility

Health

Climate

Atmospheric circulation and precipitation

Diffuse radiation and photosynthesis

Page 21: Aerosols and climate - a crash course Marianne T. Lund CICERO Nove Mesto 17/9-15

Air quality

Dehli Beijing

http://aqicn.org/map/

NY Times 14/2/2015

Page 22: Aerosols and climate - a crash course Marianne T. Lund CICERO Nove Mesto 17/9-15

Aerosol health impacts

WHO: “7 million people died - one in eight of total global deaths – as a result of air pollution exposure in 2012.”

Page 23: Aerosols and climate - a crash course Marianne T. Lund CICERO Nove Mesto 17/9-15

Aerosol climate impacts

Page 24: Aerosols and climate - a crash course Marianne T. Lund CICERO Nove Mesto 17/9-15

Absorption and scattering of solar radiation

Warming Cooling

• sulfate• dust• Sea salt• Nitrates• Organic carbon

• Soot (black carbon)• Brown carbon (?)

More details from Bjørn…

Page 25: Aerosols and climate - a crash course Marianne T. Lund CICERO Nove Mesto 17/9-15

Example: Volcanic sulfate

Mt. Pinatubo eruption

Page 26: Aerosols and climate - a crash course Marianne T. Lund CICERO Nove Mesto 17/9-15

Example: soot on snow

Soot deposited on snow/ice absorbs radiation snow melt enhanced warming

AMAP 2011

Page 27: Aerosols and climate - a crash course Marianne T. Lund CICERO Nove Mesto 17/9-15

Impact on clouds

More CCNs more, but smaller

droplets whiter cloud increased reflection

More CCNs more, but smaller

droplets longer cloud

lifetime

Local heating by soot Cloud burn-off

Low level clouds reflect solar radiation cooling

Myhre et al. 2013

Page 28: Aerosols and climate - a crash course Marianne T. Lund CICERO Nove Mesto 17/9-15

Aerosol climate impact

Our models struggle to accurately represent aerosols and their impacts

measurements

IPCC 2013

Page 29: Aerosols and climate - a crash course Marianne T. Lund CICERO Nove Mesto 17/9-15

How sensitive is the Earth’s climate to a doubling in CO2?

The stronger the aerosol effect until present, the higher the climate sensitivity

Reducing the uncertainties in aerosol climate forcing is crucial

Aerosols Greenhouse gases

1850 2015

+0.85o

Page 30: Aerosols and climate - a crash course Marianne T. Lund CICERO Nove Mesto 17/9-15

Aerosols as part of the solution? Climate engineering

Page 31: Aerosols and climate - a crash course Marianne T. Lund CICERO Nove Mesto 17/9-15

Summary

We observe changes all across the climate system consistent with a warming

It is extremely likely that human influence has been the dominant cause of the observed warming the last 60 years

Greenhouse gases (CO2) dominant warming impact, but important contributions from aerosols

Aerosols come in a number of types, shapes and sizes from numerous sources and have high spatial variability in the atmosphere

Aerosols influence climate through absorption and scattering of solar radiation and by making clouds whiter

Solving the challenges in aerosol science is a key priority

Reducing aerosols = co-benefits for air quality and human health