Climate Change: An Inter-disciplinary Approach to Problem Solving
(AOSS 480 // NRE 480) Richard B. Rood
Cell: 301-526-8572 2525 Space Research Building (North Campus)
[email protected] http://aoss.engin.umich.edu/people/rbrood
Winter 2015
January 27, 2015
Class Information and News
• Ctools site: AOSS_SNRE_480_001_W15
– Record of course
• Rood’s Class MediaWiki Site – http://climateknowledge.org/classes/index.php/Climate_Change:_The_Move_to_Action
• A tumbler site to help me remember – http://openclimate.tumblr.com/
Resources and Recommended Reading
• NASA Resources – Aerosols: What and Why Important – NASA/EO: Smoke and Clouds – NASA/EO: Dust and Desertification – NASA/EO: Volcanoes and Climate Change – NASA/EO: Big Effects of Aerosols
• Aerosols: Open Source Systems, Science, Solution – NASA – Realclimate
• Aerosols Wikipedia • Miller et al. Onset of Little Ice Age
Outline: Class 7, Winter 2015
• Basics of aerosols • South and East Asian brown cloud • Aerosol relation to clouds • Volcanoes and climate
– Models and Little Ice Age • Earth system summary • Changes in radiative balance
So what matters?
Things that change
reflection Things that
change absorption
Changes in the sun
Accumulation, transport and storage of energy in ocean, ice, land
THIS IS WHAT WE ARE DOING
Following Energy through the Atmosphere
• We have been concerned about, almost exclusively, greenhouse gases. – Need to introduce aerosols
• Continuing to think about – Things that absorb – Things that reflect
Aerosols
• Aerosols are fine, airborne particles consisting at least in part of solid material – They impact the radiative budget.
• Absorb • Reflect
– They impact cloud formation and growth.
Particles in the Atmosphere
Clouds and Aerosols: Particles in the atmosphere. • Water (and other) droplets and ice particles – (CLOUDS)
• “Pure” water • Sulfuric acid • Nitric acid • Smog • …
• Dust • Soot / Black Carbon • Salt • Organic hazes
AEROSOLS CAN: REFLECT RADIATION ABSORB RADIATION CHANGE CLOUD DROPLETS
Earth’s aerosols
Earth’s Aerosols http://www-das.uwyo.edu/~geerts/cwx/notes/chap02/aerosol&climate.html
Dust and fires in Mediterranean
Forest Fires in US
The Earth System: Clouds
SURFACE
Top of Atmosphere / Edge of Space
ATMOSPHERE
(infrared)
Clouds are difficult to predict or to figure out the sign of their impact • Warmer à more water à more clouds • More clouds mean more reflection of solar à cooler • More clouds mean more infrared to surface à warmer • More or less clouds?
• Does this stabilize? • Water in all three phases essential to “stable” climate
CLOUD
The Earth System: Aerosols
SURFACE
Top of Atmosphere / Edge of Space
ATMOSPHERE
(infrared)
Aerosols directly impact radiative balance • Aerosols can mean more reflection of solar à cooler • Aerosols can absorb more solar radiation in the atmosphere à heat the atmosphere
• In very polluted air they almost act like a “second” surface. They warm the atmosphere, cool the earth’s surface.
AEROSOLS
?
Composition of aerosols matters. • This figure is simplified. • Infrared effects are not well quantified
South & East Asia “Brown Cloud”
• But don’t forget – Europe and the US in the 1950s and 1960s
• Change from coal to oil economy
• Coal emits sulfur and smoke particulates
• “Great London smog” of 1952 led to thousands of casualties. – Caused by cold inversion layer
à pollutants didn’t disperse + Londoners burned large amounts of coal for heating
• Demonstrated impact of pollutants and played role in passage of “Clean Air Acts” in the US and Western Europe
Asian Brown Cloud (But don’t forget history.)
Aerosol: South & East Asia
http://earthobservatory.nasa.gov/Newsroom/NasaNews/2001/200108135050.html
Reflection of Radiation due to Aerosol
http://earthobservatory.nasa.gov/Newsroom/NasaNews/2001/200108135050.html
Atmospheric Warming: South & East Asia
http://earthobservatory.nasa.gov/Newsroom/NasaNews/2001/200108135050.html WARMING IN ATMOSPHERE, DUE TO SOOT (BLACK CARBON)
Surface Cooling Under the Aerosol
http://earthobservatory.nasa.gov/Newsroom/NasaNews/2001/200108135050.html
Aerosol relation to clouds
The Earth System Aerosols and Clouds Interactions
SURFACE
Top of Atmosphere / Edge of Space
ATMOSPHERE
(infrared)
Aerosols impact clouds and hence indirectly impact radiative budget through clouds • Change their height • Change their reflectivity • Change their ability to rain • Change the size of the droplets
CLOUD
Aerosols and Clouds and Rain
Less
Volcanoes and Climate
• Alan Robock: Volcanoes and Climate Change (36 MB)
Alan Robock Department of Environmental Sciences
NET COOLING
Stratospheric aerosols (Lifetime ≈ 1-3 years)
Ash
Effects on cirrus clouds
absorption (IR)
IR Heating
emission
emission
IR Cooling
More Downward
IR Flux
Less Upward IR Flux
forward scatter
Enhanced Diffuse Flux Reduced
Direct Flux
Less Total Solar Flux
Heterogeneous → Less O3 depletion Solar Heating
H2S SO2
NET HEATING
Tropospheric aerosols (Lifetime ≈ 1-3 weeks)
SO2 → H2SO4
→ H2SO4
CO2
H2O
backscatter absorption (near IR)
Solar Heating
More Reflected Solar Flux
Indirect Effects on Clouds
Alan Robock Department of Environmental Sciences
Robock and Mao (1995)
Superposed epoch
analysis of six largest
eruptions of past 120
years
Year of eruption
Significant cooling follows
sun for two years
Alan Robock Department of Environmental Sciences
Some important things to know about aerosols
• They can directly impact radiative budget through both reflection and absorption.
• They can indirectly impact radiative budget through their effects on clouds à both reflection and absorption.
• They have many different compositions, and the composition matters to what they do.
• They have many different, often episodic sources. • They generally fall out or rainout of the atmosphere; they don’t stay
there very long compared with greenhouse gases. • They often have large regional effects. • They are an indicator of dirty air, which brings its own set of
problems. • They are often at the core of discussions of geo-engineering
Models and Little Ice Age
Temperature and CO2: The last 1000 years
Surface temperature and CO2 data from the past 1000 years. Temperature is a northern hemisphere average. Temperature from several types of measurements are consistent in temporal behavior.
q Medieval warm period
q “Little ice age”
Schematic of a model experiment.
T
T Start model prediction
Model prediction without forcing
Model prediction with forcing
Model prediction with forcing and source of internal variability
Observations or “truth”
Eat+Δt = Ea
t + Δt((Pa – LaEa) + (Traßàoil + Ma ))
Little Ice Age
• Miller et al. Onset of Little Ice Age – Numerical Experiment based on observational
evidence of decades long period of high volcanic activity
• 50 years 4 major eruptions • Sea-ice/ocean feedbacks • No requirement of large changes solar energy
Earth-system Summary
CLOUD-WORLD
The Earth System
ATMOSPHERE
LAND
OCEAN ICE (cryosphere)
SUN
CLOUD-WORLD
The Earth System
ATMOSPHERE
LAND
OCEAN ICE (cryosphere)
SUN Where
absorption is important
CLOUD-WORLD
The Earth System
ATMOSPHERE
LAND
OCEAN ICE (cryosphere)
SUN Where reflection
is important
CLOUD-WORLD
The Earth System
ATMOSPHERE
LAND
OCEAN ICE (cryosphere)
SUN Solar Variability
CLOUD-WORLD
The Earth System
ATMOSPHERE
LAND
OCEAN ICE (cryosphere)
SUN
Storage and transport of energy. Influences
surface air temperature
The Earth System
ATMOSPHERE
LAND
OCEAN ICE
SUN Solar
variability
Water vapor feedback accelerates warming
Ice-albedo feedback accelerates warming
Increase greenhouse gases reduces cooling rate à Warming
Changes in land use impact absorption and reflection
Cloud feedback?
Aerosols cool?
Cloud feedback?
Changes in Radiative Forcing
Radiative forcing: Changes to absorption and reflection
• Earth's most abundant greenhouse gases – water vapor (H2O) – carbon dioxide (CO2) – methane (CH4) – nitrous oxide (N2O), commonly known as "laughing gas" – ozone (O3) – chlorofluorocarbons (CFCs)
• Long-lived, well mixed • Short-lived, regional variability • Aerosols, short-lived and regional
Radiative Forcing Changes
Interesting History of This Plot at RealClimate
Summary: Class 7, Winter 2015
• Aerosols – Absorb – Reflect – Human and natural – Regional – Short lived
• Asian brown cloud demonstrate aerosol effects – Likely “masking” warming
Summary: Class 7, Winter 2015
• Aerosols change clouds – Precipitation – Characteristics of absorption and reflection
• Volcanoes – Important natural drivers of climate variability – Provide one of our best “controlled” experiments
• Considering all source of radiative forcing – Warming from greenhouse gases – Aerosols in net cooling à black carbon
management – Cloud-aerosol effects are cooling
Outline: Class 7, Winter 2015
• Basics of aerosols • South and East Asian brown cloud • Aerosol relation to clouds • Volcanoes
– Models and Little Ice Age • Earth system summary • Changes in radiative balance
