Climate Change: The Move to Action (AOSS 480 // NRE 480) Richard B. Rood Cell: Space Research Building (North Campus) Winter 2014 February 11, 2014

Class News Ctools site: AOSS_SNRE_480_001_W14AOSS_SNRE_480_001_W14 Reading: The World Four Degrees Warmer –New et al. 2011New et al Something I am playing with – Politics of Dismissal Entry Model Uncertainty Description

First Reading Response The World Four Degrees Warmer –New et al. 2011New et al 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.

Projects Fracking –Emissions –Bridging fuel in U.S. –Pipeline and climate change Agricultural –Emissions associated with meat production –Local, organic, sustainable –No till, water, temperature, Low-cost / Low-impact technology –Stoves in India / Short-term management strategies Abrupt Climate Change –Placing this into context Midwest Warming Hole –Regional changes impact decision making

Today Scientific investigation of the Earth’s climate: Foundational information –Aerosols –Feedbacks

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

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 Soot Salt Organic hazes AEROSOLS CAN: REFLECT RADIATION ABSORB RADIATION CHANGE CLOUD DROPLETS

Earth’s aerosols

Dust and fires in Mediterranean

Forest Fires in US

The Earth System Aerosols (and 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  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

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  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 ? 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 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  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.)

Current Anthropogenic Aerosol Extreme South Asian Brown Cloud

Aerosol: South & East Asia earthobservatory.nasa.gov/Newsroom/NasaNews/2001/ html

Reflection of Radiation due to Aerosol earthobservatory.nasa.gov/Newsroom/NasaNews/2001/ html

Atmospheric Warming: South & East Asia earthobservatory.nasa.gov/Newsroom/NasaNews/2001/ html WARMING IN ATMOSPHERE, DUE TO SOOT (BLACK CARBON)

Surface Cooling Under the Aerosol earthobservatory.nasa.gov/Newsroom/NasaNews/2001/ html

Natural Aerosol

Earth’s aerosols

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

Explosive NET COOLING Stratospheric aerosols (Lifetime  1-3 years) Ash Effects on cirrus clouds absorption (IR) IR Heating 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 O 3 depletion Solar Heating H 2 S SO 2 NET HEATING Tropospheric aerosols (Lifetime  1-3 weeks) Quiescent SO 2  H 2 SO 4  H 2 SO 4 CO 2 H 2 O 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

The Earth System Aerosols (and clouds) 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

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

Today Scientific investigation of the Earth’s climate: Foundational information –Aerosols –Feedbacks

More consideration of radiative energy in the atmosphere FEEDBACKS.... –The idea that one thing causes a second thing to happen. That second thing then does something to the first thing –It damps it, negative feedback –It amplifies it, positive feedback –Technical Reference: Soden and HeldSoden and Held

We perturb the system – how does it respond? What happens when we perturb the system? Is it stable or unstable? Feedbacks – are they positive or negative?

The Earth System: Feedbacks 1 Infrared Proportional to Temperature SURFACE Top of Atmosphere / Edge of Space ATMOSPHERE (infrared) Assume that greenhouse gases remain the same Infrared emission is proportional to temperature Temperature increases  emission increases

The Earth System: Feedbacks 2 Water Vapor When it gets warmer more water, a greenhouse gas, will be in the atmosphere Higher temperature increases evaporation from land and ocean Higher temperature allows air to hold more water Increase of water increases thickness of blanket – increases temperature more This could runaway! Natural limit because of condensation  clouds, rain? Compensating circulation changes? Think deserts … SURFACE Top of Atmosphere / Edge of Space ATMOSPHERE (infrared)

The Earth System: Feedbacks 3 Ice - Albedo ICE Top of Atmosphere / Edge of Space When it gets warmer less ice Less ice means less reflection  warmer Warmer means less ice This could runaway! Cooler works the other way  ice-covered

The Earth System: Feedbacks 4 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  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

The Earth System: Feedbacks 5 Something with the Ocean? Is there something with the ocean and ice? Land ice melting decreases ocean salinity (density) Sea-ice impacts heat exchange between ocean and atmosphere Sea-ice impacts solar absorption of ocean North Atlantic sea-ice and ocean interaction very important to the climate Think Gulf Stream Think climate and people and economy Is there a natural feedback that stabilizes climate? Even if there is, it would be very disruptive, perhaps not stable from a societal point of view.

Cloud-Ice-Atmosphere Feedback Some carry away messages –This is where much of the discussion about scientific uncertainty resides. –The Earth is at a complex balance point That balance relies on water to exist in all three phases. –Too warm could run away to “greenhouse” vapor –Too cold run away to “snowball” ice –How clouds change is not much argued. The Iris Effect?The Iris Effect –Is there something in all of this that changes the sign; namely, that CO 2 warming will be compensated by more cooling?

CLOUD-WORLD Earth System: Ice ATMOSPHERE LANDOCEAN ICE (cryosphere) SUN ICE: Very important to reflection of solar radiation Holds a lot of water (sea-level rise) Insulates ocean from atmosphere (sea-ice) Ice impacts both radiative balance and water – oceans and water resources on land.. Large “local” effects at pole. Large global effects through ocean circulation and permafrost melting. Might change very quickly.

The Earth System: ICE (Think a little more about ice) non-polar glaciers and snow polar glaciers (Greenland) (Antarctica) sea-ice Impacts regional water supply, agriculture, etc. Solar reflection, Ocean density, Sea-level rise Solar reflection, Ocean-atmosphere heat exchange (Tour of the cryosphere, Goddard Scientific Visualization Studio)

Feedbacks Ice-albedo, water vapor feedback are positive and definitive. Feedbacks associated with melting in the Arctic are largely positive. –(WWF, Literature Assessment, 2009)WWF, Literature Assessment, 2009 The only potentially negative feedback is associated with clouds, which is observed. Complex role of particles in the atmosphere. Theoretical and observational investigation concludes that feedbacks are substantially linear and positive. –(Roe and Baker, Science, 2007)Roe and Baker, Science, 2007

The Cryosphere TOUR OF CRYOSPHERE: MAIN NASA SITETOUR OF CRYOSPHERE: MAIN NASA SITE

Let’s think about the Arctic for a while WWF: Arctic Feedbacks Assessment

Projected Global Temperature Trends: temperatures relative to Special Report on Emissions Scenarios Storyline B2 (middle of the road warming). IPCC 2001

The Thermohaline Circulation (THC) (Global, organized circulation in the ocean) (The “conveyer belt”, “rivers” within the ocean) Where there is localized exchange of water between the surface and the deep ocean (convection) From Jianjun Yin, GFDL, see J. Geophysical Research, 2006 Warm, surface currents. Cold, bottom currents. Green shading, high salt Blue shading, low salt

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  Warming Changes in land use impact absorption and reflection Cloud feedback? Aerosols cool? Cloud feedback?

Iconic and Fundamental Figures

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

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

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

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.  Medieval warm period  “Little ice age”  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.

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

Radiation Balance Figure

Radiative Balance (Trenberth et al. 2009)Trenberth et al. 2009