Global Change

CHAPTER 19

Is this evidence of global warming?

Climate Change Debate?

• “The major scientific agencies of the United States — including the National Aeronautics and Space Administration (NASA) and the National Oceanic and Atmospheric Administration (NOAA) — agree that climate change is occurring and that humans are contributing to it.” - EPA

Questions Still Up For Debate

• Scientists are still researching a number of important questions:– Exactly how much will Earth warm?– How quickly will it warm?– What will the consequences of the warming be in

specific regions of the world?

Global Change

• Global change: any chemical, biological, or physical property change of the planet (ex: cold temperatures causing ice ages)

• Global climate change: changes in the climate of the Earth

• Global warming: one aspect of climate change, the warming of the oceans, landmasses, and atmosphere of the Earth

Greenhouse Effect

• When radiation from the sun hits the atmosphere, 1/3 is reflected back

• Some UV radiation is absorbed by the ozone layer• Some strikes the Earth and is converted into low-

energy infrared radiation• Infrared radiation then goes back toward the

atmosphere, where it’s absorbed by greenhouse gases that radiate most of it back to the Earth

Greenhouse Gases

• Water vapor (H2O)

• Carbon dioxide (CO2)

• Methane (CH4)

• Nitrous oxide (N2O)• Chlorofluorocarbons (CFCs)• Ozone (O3)

Global Warming Potential

• Certain GHGs are more effective at warming the Earth than others

• 2 most important factors:– How well the gas absorbs energy– How long the gas stays in the atmosphere

• Global Warming Potential (GWP) is a measure of the total energy that a gas absorbs over a particular period of time (usually 100 years), compared to CO2

U.S. Greenhouse Gas Emissions in 2010

Natural Sources of Greenhouse Gases

• Carbon dioxide from volcanic eruptions

• Methane from decomposition• Nitrous oxide from

denitrification• Water vapor

Anthropogenic Sources of Greenhouse Gases

• Burning of fossil fuels• Agricultural practices• Deforestation• Landfills• Industrial production (ex: CFCs)

U.S. Carbon Dioxide Emissions, By Source

Particulate Matter

• Aerosols are a subset of air pollution that refers to the tiny particles suspended in our atmosphere

• Particles can be both solid and liquid• Light-colored aerosol particles can reflect

incoming solar energy • Dark particles can absorb solar energy

Greenhouse Effect

• http://www.youtube.com/watch?v=ZzCA60WnoMk&list=PLi_1unC2AWvBgO2QcF9pfnWlyg4MemHAw

Radiative Forcing• Energy is constantly flowing into the

atmosphere and being absorbed by Earth• Some energy is always radiating back out into

space (infrared light)• If:

– Energy flowing out > energy flowing in = cooling– Energy flowing out < energy flowing in = warming– Energy flowing out = energy flowing in = no

change

Radiative Forcing• Energy is constantly flowing into the

atmosphere and being absorbed by Earth• Some energy is always radiating back out into

space (infrared light)• If:

– Energy flowing out > energy flowing in = cooling– Energy flowing out < energy flowing in = warming– Energy flowing out = energy flowing in = no

change

Radiative Forcing• Energy is constantly flowing into the

atmosphere and being absorbed by Earth• Some energy is always radiating back out into

space (infrared light)• If:

– Energy flowing out > energy flowing in = cooling– Energy flowing out < energy flowing in = warming– Energy flowing out = energy flowing in = no

change

Radiative Forcing

• Radiative forcing is a direct measure of the impact that human activities are having on changing the planet’s climate

• Measured in watts per square meter (W/m2) of surface

IPCC• The Intergovernmental Panel on Climate Change

(IPCC) is the leading international body for the assessment of climate change

• Established in 1988 by two United Nations organizations: the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP)

• Its mission is to provide the world with a clear scientific view on the current state of knowledge in climate change and its potential environmental and socio-economic impacts

• Thousands of scientists and other experts contribute (on a voluntary basis) to writing and reviewing reports, which are reviewed by representatives from all the governments

Increasing CO2 Concentrations

• David Keeling began measuring CO2 in 1958

Comparing Emissions

• Which country emits the most CO2?

• Which country emits the most CO2 per capita?

Comparing Emissions

CO2 Emissions Per Capita

• http://www.google.com/publicdata/explore?ds=d5bncppjof8f9_&met_y=en_atm_co2e_pc&idim=country:CHN&dl=en&hl=en&q=china%20co2%20emissions

What do you think?

• Should developing countries be held to the same CO2 emissions standards as developed countries?

• Things to consider:– How did developed countries become so wealthy?– Which countries are to blame for climate change?– Will strict CO2 standards inhibit growth in developing

countries?– Will developing countries be able to afford costly new

technology?

Global Temperature Change

• Since 1880, temperatures have increased 0.8°C

Global Temperature Change

• http://www.youtube.com/watch?v=SF5FxpedVlw&list=PLi_1unC2AWvBgO2QcF9pfnWlyg4MemHAw

Temperatures & Greenhouse Gas Concentrations in Past 400,000 Years

• No one was around thousands of years ago to measure temperatures, so we must use indirect measurements– Changes in species composition– Chemical analysis of ice

Ice Cores• Ice cores contain an abundance of climate

information – more so than any other natural recorder of climate like tree rings or sediment layers

• Although their record is short (in geologic terms), it can be highly detailed and extend back hundreds of thousands of years

• This record can include:– Temperature– Precipitation– Chemistry and gas composition of the lower atmosphere– Volcanic eruptions– Solar variability

http://nicl.usgs.gov/gif/timeline.gif

Ice Cores

• http://www.youtube.com/watch?v=NENZ6TSc1fo&feature=player_embedded

CO2 Concentration Throughout History

CO2 Heat Trapping

• http://www.youtube.com/watch?v=-RTLU4VTZ9o&list=PLi_1unC2AWvBgO2QcF9pfnWlyg4MemHAw

Sediment Cores• Rarely disturbed ocean sediment cores can provide records up

to 180 million years ago as new layers of sediment bury and preserve those of the past

• Fossilized specimens of microscopic foraminifera can provide clues to the climate conditions during their lives

• Some species are only found in certain environments, so we can reconstruct the sea level, ocean, and climate conditions of that period based on our knowledge of foraminifera species

Oxygen Isotopes

• Ocean water during warmer times has a lower 18O / 16O ratio than ocean water during colder times

• Foraminifera incorporate that oxygen into their shells (CaCO3), which accumulate on the ocean floor after they die

• We can estimate the water temperature by the ratio of 18O / 16O in fossilized shells

Climate Models

• Scientists use climate data gathered from the past to help predict the future

• Current models predict that average global temperatures will increase 1.8⁰ – 4.0⁰ C (3.2⁰ – 7.2⁰ F) by 2100

Battery Drive

• Bring in your old batteries to HR and put in the canisters this week

Feedback Loops

• What is a positive feedback loop?

• What is a negative feedback loop?

Positive Feedback Loop

Positive Feedback Loop

• We know that an increase in CO2 in the atmosphere causes a greater capacity for warming through the greenhouse effect

• Higher temperatures warmer oceans oceans release CO2 gas into atmosphere

Negative Feedback Loop

AP Practice Question• Which statement about feedback loops that occur

with climate change is true?a) All feedback loops are positive.b) All feedback loops are negative.c) Increased soil decomposition under warmer

temperatures represents a positive feedback loop.d) Increased evaporation under warmer temperatures

represents a negative feedback loop.e) Increased plant growth under higher CO2 concentrations

represents a positive feedback loop.

Consequences of Global Warming

• Melting of polar ice caps, Greenland, and Antarctica

• Melting of glaciers around the world• Melting of permafrost• Rising sea levels• Heat waves and droughts• Fewer cold spells• Greater frequency and intensity of storms

Melting Ice Caps

Melting Arctic Ice Cap

• http://www.youtube.com/watch?v=-8bHufxbxc8

Rising Sea Levels

Rising Sea Levels

• http://www.youtube.com/watch?v=aKoch_iEos8

Consequences to Living Organisms

• Changing growing season for plants can harm animals if they can’t move to better climates

• Humans may have to relocate• Diseases, like those carried by

mosquitoes, could increase • Economic consequences

Controversy of Climate Change

• The fundamental basis of climate change (that greenhouse gas concentrations are increasing and that this will lead to global warming) is not in dispute among the vast majority of scientists

• What is unclear is how much world temperatures will increase for a given change in greenhouse gases, because that depends on the different feedback loops

Kyoto Protocol

• In 1997, representatives of the nations of the world went to Kyoto, Japan to discuss how best to control the emissions contributing to global warming

• The agreement was that emissions of greenhouse gases from all industrialized countries will be reduced to 5.2% below their 1990 levels by 2012

• Developing nations did not have emission limits imposed by the protocol

• http://www.cbc.ca/news/politics/story/2012/12/20/pol-kyoto-protocol-part-one-ends.html

Climate Change Awareness

• The Nobel Peace Prize 2007 was awarded jointly to Intergovernmental Panel on Climate Change (IPCC) and Albert Arnold (Al) Gore Jr. "for their efforts to build up and disseminate greater knowledge about man-made climate change, and to lay the foundations for the measures that are needed to counteract such change"

Carbon Sequestration• An approach involving taking CO2 out of the

atmosphere• Some methods include storing carbon in agricultural

soils or retiring agricultural land and allowing it to become pasture or forest

• Researchers are looking at cost-effective ways of capturing CO2 from the air, from coal-burning power stations, and from other emission sources

• This captured CO2 would be compressed and pumped into abandoned oil wells or the deep ocean

• http://www.youtube.com/watch?v=ROEFaHKVmSs

Carbon Sequestration

AP Practice Question• Which statement regarding the Kyoto Protocol is

true?a) Developed and developing nations all agreed to reduce

their emission of greenhouse gasesb) All nations agreed to stop their emission of greenhouse

gasesc) The developed nations agreed to different levels of

emission reductionsd) Developing nations agreed to reduce their emission of

greenhouse gasese) Developing nations agreed to stop their emission of

greenhouse gases

What Do You Think?

• What is the best way to reduce CO2 emissions?– Force people and companies to be more energy

efficient and/or to use “green” technologiesOR

– Allow people and companies to pollute as much as they want, but tax them on how much CO2 they emit