GREENHOUSE GASES:“THICKENING THE EARTH’S BLANKET”

Climate Alteration & Global Warming

What are Greenhouse gases? Greenhouse gases are gases that trap

heat in the atmosphere. Main Greenhouse Gases

Carbon Dioxide, CO2

Methane, CH4

Nitrous Oxide, N2O Fluorinated Gases

Carbon Dioxide

How can carbon dioxide enter the atmosphere? Burning fossil fuels coal, natural gas and oil Burning solid waste, trees and wood products As a result of certain chemical reactions

For example: manufacture of cement How is carbon dioxide removed

(sequestered) from the atmosphere? When absorbed by plants

Part of the biological carbon cycle

Methane

How can methane enter the atmosphere? During production of coal, natural gas, and

oil During transport of coal, natural gas, and

oil Result from livestock and other agricultural

practices Decay of organic waste in municipal solid

waste landfills How is methane removed from the

atmosphere? See Hand-out

Nitrous Oxide & Fluorinated Gases How can nitrous oxide enter the atmosphere?

During agricultural activities During industrial activities During combustion of fossil fuels and solid waste

What are fluorinated gases? Synthetic, potent, powerful greenhouse gases that are

emitted from a variety of industrial processes Hydrofluorocarbons, perfluorocarbons, sulfur hexafluoride

Sometimes used as substitutes for stratospheric ozone-depleting substances

Emitted in small quantities, as they are categorized “High Global Warming Potential gases”

What factors determine each gases effect on climate change?

How much of each is present in the atmosphere? Concentrations measured in parts per million, billion, or

trillion One part per million : one drop of a substance diluted into

about 13 gallons of another substance How long do they remain in the atmosphere?

Range: a few years to 1000s of years Long enough to become well mixed Amount measured of a particular gas in the atmosphere is

the same all over the globe Regardless of source of emmisions

What is their impact on global temperatures? Gases that absorb more energy per pound contribute more

to global warming

http://www.epa.gov/climatechange/ghgemissions/gases.html

THE SUN-EARTH HEATING SYSTEM

What makes our planet warm?

- Heating System

1. The Sun The Sun radiates energy

Visible radiation aka Visible light high energy Ultraviolet radiation aka UV light

The Sun’s energy strikes the Earth Result: The planet warms

2. The Earth The planet radiates energy

Infrared radiation aka Infrared light lower energy Radiation you can’t see, but can feel

For example: the heat you feel being radiated from the hot asphalt This radiation of lower energy is radiated because Earth is not as hot

as the Sun.

How does infrared radiation have an effect on the planet’s warmth?

Note: Infrared radiation doesn’t pass through the atmosphere as easily as UV and visible radiation

Infrared radiation is ABSORBED by greenhouse gases This warms the greenhouse gases The greenhouse gases emit infrared radiation

Some of this emitted infrared radiation goes into space and the rest goes back toward Earth

*The Greenhouse Effect

Greenhouse Gases, continued Review: Greenhouse gases are gases that trap heat in the

atmosphere. Gases N2 and O2 compromise 99% of the atmosphere; they don’t

absorb infrared radiation; they are not greenhouse gases, therefore they don’t contribute to the warming of the Earth

Greenhouse gases make up a small fraction of the atmosphere. Most common greenhouse gas is water vapor (H2O)

Water vapor absorbs more infrared radiation from Earth than any other compound.

Water vapor does not persist as long as other greenhouse gases. Certain greenhouse gases have been apart of the atmosphere for

millions of years, and have kept Earth warm enough so that it could remain inhabitable. Water vapor, carbon dioxide, methane, nitrous oxide, ozone Without any greenhouse gases the average temperature would be 0°F

So what’s the problem?

The Danger of Greenhouse Gases There is a growing concern that an increase in

concentration of these gases may cause the planet to warm even more.

Example: CFCs don’t exist naturally and occur in the atmosphere due to synthesis by humans.

Each gas has a greenhouse warming potential. Estimates how much a molecule of any compound can

contribute to global warming over 100 years relative to 1 molecule of CO2

CONSEQUENCES OF GLOBAL WARMING TO THE ENVIRONMENT & ORGANISMS

Chapter 14 continued

How is global warming expected to affect the environment?

Effects already happening to the Environment due to warming temperatures

Melting of polar ice caps Melting of glaciers Melting of permafrost Rising sea levels

Effects predicted to occur in the future An increased frequency of heat waves Reduced cold spells Altered precipitation patterns and storm intensity Shifting ocean currents

How is global warming expected to affect the organisms living on Earth?

Global warming affects wild plants and animals. Intergovernmental Panel on Climate Change, IPCC,

reviewed 2,500 scientific papers on the effects of warmer temperatures of plants and animals. Growing season for plants lengthened in Northern Hemisphere Many of species of plants flower earlier Birds arrive at their breeding grounds earlier Insects emerge earlier in the Northern Hemisphere Corals are sensitive to global warming their range of

temperature tolerance is very small Causes of coral bleaching are warming oceans, pollution, and

sedimentation More coral bleaching is expected from global warming even if the

climate changes are kept small

Consequences to Humans

Global warming could affect humans in the following ways…

Habitation Some people will have to relocate from such vulnerable areas

as coastal communities and some ocean islands. Rebuild communities close to or along coastlines on

higher ground Will face severe consequences from flooding and

saltwater intrusion if they can’t relocate financial difficulty?

Water availability might limit an areas habitability The alternative: some areas might become more hospitable if

they become warmer Health Tourism

EXAMINING THE FEEDBACK CYCLES: THE WAY THEY INFLUENCE TEMPERATURES ON EARTH

Climate Alteration & Global Warming

The Complexity in Predicting Global Warming & Climate Change

Positive and Negative feedback loops make predicting global warming and climate change complex.

What is a feedback? A feedback is an adjustment in input or output rates

caused by changes to a system. They are diagrammed as loops/cycles.

What are positive and negative feedback loops? A positive feedback loop is a feedback loop in which

change in a system is amplified. A negative feedback loop is a feedback loop in which a

system responds to a change by returning to its original state, or by decreasing the rate at which the change is occurring.

Examples of Feedback Loops Positive Feedback Loop

Example: warmer soils increasing their rates of decomposition and thereby increasing their emission of carbon dioxide

Negative Feedback Loop Example: plants being able to increase their

growth under elevated carbon dioxide environments, thereby reducing some of the carbon dioxide in the atmosphere

Positive Feedbacks

A rise in temperature could create a positive feedback. Higher temperatures are expected to biological activity of

decomposers in soils rich in carbon dioxide; decomposition leads to the release of additional carbon dioxide from soil to atmosphere

More Carbon dioxide in the atmosphere means temperature change will be amplified more

A More Troubling Example: In Tundra biomes containing permafrost- as carbon dioxide

concentrations from anthropogenic sources, the region warms and the frozen tundra thaws; areas of standing water with little oxygen beneath the water develop; organic layers decompose (anerobic decomposition) which produces methane leading to even more global warming

Methane is a stronger greenhouse gas than carbon dioxide

Negative Feedback Loops

A rise in temperature could create a negative feedback. An increase in carbon dioxide can stimulate

plant growth (Review: Carbon dioxide is needed for plant growth.) More plants = more carbon dioxide removed from the atmosphere; carbon dioxide and temperature increases are smaller than they would have been. This feedback may be one important reason why

only ½ of carbon dioxide emissions from anthropogenic sources have remained in the atmosphere

Feedbacks can be limited by features of the systems in which they take place. Carbon-soil feedback limited by amount of

carbon in soils Eventually soil stocks will become low

Enhanced carbon dioxide uptake by plants is limited because only some plants benefit from carbon dioxide fertilization; also enhancement happens only until another factor becomes limiting- water and nutrient limiting

GLOBAL CHANGE NEEDS TO BE ADDRESSED AT THE INTERNATIONAL LEVEL.

Climate Alteration and Global Warming

Global change needs to be addressed at the international level.

Why? The scale of impact is very large, and people and ecosystems affected can be distant from the cause.

Review: What is global change? Change that occurs in the chemical, biological, physical properties of the planet

Kyoto Protocol

The nations of the world must work together to address the problem of global warming.

The Kyoto Protocol – an international agreement to reduce global emissions of greenhouse gases from all industrialized countries to 5.2 percent or below their 1990 levels by 2012

As of 2010, 190 countries had ratified (sign or give formal consent to) the Kyoto Protocol – The U.S. is the ONLY developed country that has not yet ratified the agreement

Kyoto Protocol cont.

Who?: Representatives of the nations of the world What?: Addressing Climate Change Internationally

Meeting was to discuss how best to control the emissions contributing to global warming

An agreement that global emissions of greenhouse gases from all industrialized countries would be reduced by 2012

Developing nations didn’t have emission limits imposed by the protocol –i.e. India, China. Why?

Developing countries are unfairly exposed to consequences of global warming that mostly come from developed nations –i.e. U.S. (7% reduction), countries of the European Union (8% reduction).

Having countries who emit the most emissions pay most of the cost of reducing emissions seemed fair.

Where?: Kyoto, Japan When?: 1997

Kyoto Protocol cont.

Why?: There is sufficient evidence to suggest human activities are altering the global climate. Therefore, there is a need to stabilize

greenhouse gases by…Reducing emisionsOr removing gases from the atmosphere

Kyoto Protocol cont.

How?: How can we reducing emmisions?

Increase fuel efficiency or switch from coal and oil to energy sources (natural gas, solar energy, wind-powered energy, nuclear energy) that emit less or no carbon dioxide

How can we removing gases from the atmosphere? Carbon sequestration

Involves taking carbon dioxide out of the atmosphere Methods to do this include storing carbon n soils, retiring

agriculture land by allowing it to become pasture or forest (storage in plant biomass or soil carbon)

New science: capturing carbon dioxide from air, compressing it, and pumping it into oil wells or the deep ocean

We don’t know yet how this exactly effects the environment

What has the U.S. done?

The U.S. Supreme Court required that the EPA had to regulate emissions of greenhouse gases as part of the CLEAN AIR ACT. EPA proposed increase in fuel efficiency

requirements for cars (would bring a 30% reduction in carbon dioxide and other gases by 2016, and REDUCE U.S. CONSUMPTION OF FOSSIL FUELS).

But has still not ratified the Kyoto Protocol.