Climate Change The Move to Action AOSS 480

Climate Change: The Move to Action (AOSS 480 // NRE 480) Richard B. Rood Cell: 301 -526 -8572 2525 Space Research Building (North Campus) rbrood@umich. edu http: //aoss. engin. umich. edu/people/rbrood Winter 2014 February 6, 2014

Class News • Ctools site: AOSS_SNRE_480_001_W 14 • Reading: The World Four Degrees Warmer – New et al. 2011 • Something I am playing with – http: //openclimate. tumblr. com/ Politics of Dismissal Entry Model Uncertainty Description

First Reading Response • The World Four Degrees Warmer – New et al. 2011 • Reading responses of roughly one page (single-spaced). The responses do not need to be elaborate, but they should also not simply summarize the reading. They should be used by you to refine your questions and to improve your insight into climate change. • They should be submitted via CTools by next Tuesday and we will use them to guide discussion in class on Thursday. Assignment posted with some questions to guide responses.

This lecture: • Projects? – Tuesday work on teams and specifics • Energy – Absorption – Reflection • Aerosols

Let’s focus on the balance of the energy at the Earth’s surface

The sun-earth system (What is the balance at the surface of Earth? ) SUN Based on conservation of energy: If the Earth did NOT have an atmosphere, then, the temperature at the surface of the Earth would be about -18 C ( ~ 0 F). Radiative Balance. This is conservation of energy. Energy is present in electromagnetic radiation. Earth But the Earth’s surface temperature is observed to be, on average, about 15 C (~59 F).

Let’s build up this picture • Follow the energy through the Earth’s climate. • As we go into the climate we will see that energy is transferred around. – From out in space we could reduce it to just some effective temperature, but on Earth we have to worry about transfer of energy between thermal energy and motion of wind and water.

Building the Radiative Balance What happens to the energy coming from the Sun? Top of Atmosphere / Edge of Space Energy is coming from the sun. Two things can happen at the surface. In can be: Reflected Or Absorbed

Building the Radiative Balance What happens to the energy coming from the Sun? Top of Atmosphere / Edge of Space We also have the atmosphere. Like the surface, the atmosphere can: Reflect or Absorb

Building the Radiative Balance What happens to the energy coming from the Sun? Top of Atmosphere / Edge of Space In the atmosphere, there are clouds which : Reflect a lot Absorb some

Building the Radiative Balance What happens to the energy coming from the Sun? RS Top of Atmosphere / Edge of Space For convenience “hide” the sunbeam and reflected solar over in “RS”

Building the Radiative Balance What happens to the energy coming from the Sun? RS Top of Atmosphere / Edge of Space Consider only the energy that has been absorbed. What happens to it?

Building the Radiative Balance Conversion to terrestrial thermal energy. RS Top of Atmosphere / Edge of Space 1) It is converted from solar radiative energy to terrestrial thermal energy. (Like a transfer between accounts)

Building the Radiative Balance Redistribution by atmosphere, ocean, etc. RS Top of Atmosphere / Edge of Space 2) It is redistributed by the atmosphere, ocean, land, ice, life. (Another transfer between accounts)

Building the Radiative Balance Terrestrial energy is converted/partitioned into three sorts Top of Atmosphere / Edge of Space RS It takes heat to • Turn ice to water • And water to “steam; ” that is, vapor 3) Terrestrial energy ends up in three reservoirs (Yet another transfer ) CLOUD ATMOSPHERE PHASE TRANSITION OF WATER RADIATIVE ENERGY (infrared or thermal) (LATENT HEAT) SURFACE WARM AIR (THERMALS)

Building the Radiative Balance Which is transmitted from surface to atmosphere Top of Atmosphere / Edge of Space RS 3) Terrestrial energy ends up in three reservoirs CLOUD (LATENT HEAT) (infrared or thermal) SURFACE ATMOSPHERE (THERMALS)

Building the Radiative Balance And then the infrared radiation gets complicated Top of Atmosphere / Edge of Space RS 1) Some goes straight to space 2) Some is absorbed by atmosphere and re-emitted downwards 3) Some is absorbed by clouds and re -emitted downwards CLOUD (LATENT HEAT) (infrared or thermal) SURFACE 4) Some is absorbed by clouds and atmosphere and re-emitted upwards ATMOSPHERE (THERMALS)

Want to consider one more detail • What happens if I make the blanket thicker?

Thinking about the greenhouse A thought experiment of a simple system. Top of Atmosphere / Edge of Space 1) Let’s think JUST about the infrared radiation • Forget about clouds for a while 3) Less energy is up here because it is being held near the surface. • It is “cooler” ATMOSPHERE (infrared or thermal) 2) More energy is held down here because of the atmosphere • It is “warmer” SURFACE

Thinking about the greenhouse A thought experiment of a simple system. Top of Atmosphere / Edge of Space 1) Remember we had this old idea of a temperature the Earth would have with no atmosphere. • • This was ~0 F. Call it the effective temperature. Let’s imagine this at some atmospheric height. 3) Up here it is cooler than T effective ATMOSPHERE 2) Down here it is warmer than T effective (infrared or thermal) SURFACE T < T effective T > T effective

Thinking about the greenhouse Why does it get cooler up high? Top of Atmosphere / Edge of Space 1) If we add more atmosphere, make it thicker, then 3) The part going to space gets a little smaller • It gets cooler still. ATMOSPHERE 2) The part coming down gets a little larger. • It gets warmer still. (infrared or thermal) SURFACE The real problem is complicated by clouds, ozone, ….

Think about that warmer-cooler thing. • Addition of greenhouse gas to the atmosphere causes it to get warmer near the surface and colder in the upper atmosphere. • This is part of a “fingerprint” of greenhouse gas warming. • Compare to other sources of warming, for example, more energy from the Sun.

Think about a couple of details of emission. • There is an atmospheric window, through which infrared or thermal radiation goes straight to space. – Water vapor window • Carbon dioxide window is saturated – This does not mean that CO 2 is no longer able to absorb. – It means that it takes longer to make it to space.

Thinking about the greenhouse Why does it get cooler up high? Top of Atmosphere / Edge of Space 1) Atmospheric Window 2) New greenhouse gases like N 20, CFCs, Methane CH 4 close windows ATMOSPHERE 3) Additional CO 2 makes the insulation around the window tighter. (infrared or thermal) SURFACE The real problem is complicated by clouds, ozone, ….

Changes in the sun So what matters? THIS IS WHAT WE ARE DOING Things that change reflection Things that change absorption If something can transport energy DOWN from the surface.

Think about the link to models • energy reflected = (fraction of total energy reflected) X (total energy) • energy absorbed = total energy - energy reflected = (1 fraction of total energy reflected) X (total energy) • fraction of total energy reflected – – – Clouds Ice Ocean Trees Etc.

Radiation Balance Figure In this figure out = in

Radiative Balance (Trenberth et al. 2009) In this figure out does not = in

This lecture: • Energy – Absorption – Reflection • Aerosols

The Earth System SUN CLOUD-WORLD ATMOSPHERE ICE (cryosphere) OCEAN LAND

The Earth System SUN CLOUD-WORLD ATMOSPHERE Where absorption is important ICE (cryosphere) OCEAN LAND

The Earth System Where reflection is important SUN CLOUD-WORLD ATMOSPHERE ICE (cryosphere) OCEAN LAND

The Earth System Solar Variability SUN CLOUD-WORLD ATMOSPHERE ICE (cryosphere) OCEAN LAND

The Earth System SUN CLOUD-WORLD ATMOSPHERE ICE (cryosphere) OCEAN LAND Possibility of transport of energy down from the surface

Earth System: Sun SUN Lean, J. , Physics Today, 2005 SUN: • Source of energy • Generally viewed as stable • Variability does have discernable signal on Earth • Impact slow and small relative to other changes Lean: Living with a Variable Sun CLOUD-WORLD ATMOSPHERE OCEAN LAND ICE (cryosphere)

SUN What are the most important greenhouse gasses? • Water (H 2 O) • Carbon Dioxide (CO 2) • Methane (CH 4) Earth System: Atmosphere The Atmosphere: • Where CO 2 is increasing from our emissions • Absorption and reflection of radiative energy • Transport of heat between equator and pole • Weather: Determines temperature and rain CLOUD-WORLD ATMOSPHERE Change CO 2 Here OCEAN LAND ICE (cryosphere)

Cloudy Earth

SUN Most uncertain part of the climate system. Earth System: Cloud World: • Very important to reflection of solar radiation • Very important to absorption of infrared radiation • Acts like a greenhouse gas • Precipitation, latent heat • Related to motion in the atmosphere • Reflecting Solar Cools • Largest reflector • Absorbing infrared Heats CLOUD-WORLD ATMOSPHERE OCEAN LAND ICE (cryosphere)

Earth System: Land SUN Land where consequences are, first and foremost, realized for people. • What happens to atmospheric composition if permafrost thaws? • Can we store CO 2 in plants? • Adaptability and sustainability? OCEAN Land: • Absorption of solar radiation • Reflection of solar radiation • Absorption and emission of infrared radiation • Plant and animal life • Impacts H 2 O, CO 2 and CH 4 • Storage of moisture in soil • CO 2 and CH 4 in permafrost CLOUD-WORLD ATMOSPHERE LAND Change Land Use Here ICE (cryosphere)

SUN What will the ocean really do? • Will it absorb all of our extra CO 2? • Will it move heat into the sub-surface ocean? • Changes in circulation? Earth System: Ocean: • Absorption of solar radiation • Takes CO 2 out of the atmosphere • Plant and animal life • Impacts CO 2 and CH 4 • Takes heat out away from surface • Transport of heat between equator and pole • Weather regimes: Temperature and rain CLOUD-WORLD ATMOSPHERE Does it buy us time? Does this ruin the ocean? Acidification OCEAN Doney: Ocean Acidification LAND ICE (cryosphere)

Today • Scientific investigation of the Earth’s climate: Foundational information – Radiative Balance – Earth System – Aerosols

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 particulate matter in the atmosphere. – They impact the radiative budget. – They impact cloud formation and growth.

Aerosols: Particles in the Atmosphere Aerosols: Particles in the atmosphere. • Water droplets – (CLOUDS) • “Pure” water • Sulfuric acid • Nitric acid • Smog • … • Ice • Dust AEROSOLS CAN: • Soot REFLECT RADIATION • Salt ABSORB RADIATION • Organic hazes CHANGE CLOUD DROPLETS

Earth’s aerosols

Dust and fires in Mediterranean

Forest Fires in US

The Earth System Aerosols (and clouds) Clouds are difficult to predict or to figure out the sign of their impact Top of Atmosphere / Edge of Space • Warmer more water more clouds • More clouds mean more reflection of solar cooler • More clouds mean more infrared to surface warmer • More or less clouds? • Does this stabilize? • Water in all three phases essential to “stable” climate CLOUD ATMOSPHERE (infrared) SURFACE

The Earth System: Aerosols Top of Atmosphere / Edge of Space Aerosols directly impact radiative balance • Aerosols can mean more reflection of solar cooler • Aerosols can absorb more solar radiation in the atmosphere heat the atmosphere • In very polluted air they almost act like a “second” surface. They warm the atmosphere, cool the earth’s surface. AEROSOLS ATMOSPHERE ? (infrared) SURFACE Composition of aerosols matters. • This figure is simplified. • Infrared effects are not well quantified

South Asia “Brown Cloud” • But don’t forget – Europe and the US in the 1950 s and 1960 s • Change from coal to oil economy

Asian Brown Cloud (But don’t forget history. ) • Coal emits sulfur and smoke particulates • “Great London smog” of 1952 led to thousands of casualties. – Caused by cold inversion layer 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

Current Anthropogenic Aerosol Extreme • South Asian Brown Cloud

Aerosol: South & East Asia http: //earthobservatory. nasa. gov/Newsroom/Nasa. News/200108135050. html

Reflection of Radiation due to Aerosol http: //earthobservatory. nasa. gov/Newsroom/Nasa. News/200108135050. html

Atmospheric Warming: South & East Asia WARMING IN ATMOSPHERE, DUE TO SOOT (BLACK CARBON) http: //earthobservatory. nasa. gov/Newsroom/Nasa. News/200108135050. html

Surface Cooling Under the Aerosol http: //earthobservatory. nasa. gov/Newsroom/Nasa. News/200108135050. html

Natural Aerosol

Earth’s aerosols

Volcanoes and Climate • Alan Robock: Volcanoes and Climate Change (36 MB!) Alan Robock Department of Environmental Sciences

More Reflected Solar Flux Stratospheric aerosols (Lifetime » 1 -3 years) Less Upward IR Flux backscatter absorption (near IR) H 2 S ® H SO 2 4 SO 2 CO 2 H 2 O ve osi l Exp Solar Heating Heterogeneous ® Less O 3 depletion Solar Heating NG Heating ATI IR HE NET Q absorption (IR) emission Reduced Direct Flux Enhanced Diffuse Flux Tropospheric aerosols (Lifetime » 1 -3 weeks) ent IR Cooling forward scatter Ash sc uie emission Less Total Solar Flux SO 2 ® H 2 SO 4 Indirect Effects on Clouds Alan Robock Department of Environmental Sciences Effects on cirrus clouds N ING L O O ET C More Downward IR Flux

Superposed epoch analysis of six largest eruptions of past 120 years Significant cooling follows sun for two years Robock and Mao (1995) Year of eruption Alan Robock Department of Environmental Sciences

The Earth System Aerosols (and clouds) Aerosols impact clouds and hence indirectly impact radiative budget through clouds Top of Atmosphere / Edge of Space • Change their height • Change their reflectivity • Change their ability to rain • Change the size of the droplets CLOUD ATMOSPHERE (infrared) SURFACE

Aerosols and Clouds and Rain

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 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

Iconic and Fundamental Figures

Scientific investigation of Earth’s climate SUN: ENERGY, HEAT EARTH: ABSORBS ENERGY EARTH: EMITS ENERGY TO SPACE BALANCE

Sun-Earth System in Balance SUN EARTH PLACE AN INSULATING BLANKET AROUND EARTH The addition to the blanket is CO 2 FOCUS ON WHAT IS HAPPENING AT THE SURFACE EARTH: EMITS ENERGY TO SPACE BALANCE

Increase of Atmospheric Carbon Dioxide (CO 2) Primary increase comes from burning fossil fuels – coal, oil, natural gas Data and more information

Temperature and CO 2: The last 1000 years Surface temperature and CO 2 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” q Temperature starts to follow CO 2 as CO 2 increases beyond approximately 300 ppm, the value seen in the previous graph as the upper range of variability in the past 350, 000 years.

The Earth System SUN CLOUD-WORLD ATMOSPHERE ICE (cryosphere) OCEAN LAND

Radiation Balance Figure

Radiative Balance (Trenberth et al. 2009)