1. Chapter 19
Global Change

2. Global Climate Change and the Greenhouse Effect
Module 62
Global Climate Change and the Greenhouse Effect
Learning Objectives
After this module, you should be able to:
distinguish among global change, global climate change, and global warming.
explain the process underlying the greenhouse effect.
identify the natural and anthropogenic sources of greenhouse gases.

3. Weather vs. Climate
Weather: a local area’s short-term physical conditions such as temperature and precipitation.
Climate: a region’s average weather conditions over a long period of time (at least 30 years).
“Climate is what we expect, weather is what we get.”
-- Mark Twain
“If you don’t like the weather, wait 5 minutes;
If you don’t like the climate…MOVE.”
-- Paraphrased Mark Twain

4. Climate
Climate variability: variations in climate from season to season or year to year.
Explains why one winter may be warmer to colder than last year to next year.
Influenced by large scale natural processes like El Niño
Averaged out over longer periods of time

5. Climate
Climatology: the study of Earth’s climate and the factors that cause past, present, and future climate changes
Over the Earth’s history the climate has been altered by:
Volcanic emissions
Changes in solar input
Movement of the continents
Impacts by meteors

6. Global Warming vs. Climate Change
Important distinction:
Global Warming vs. Climate Change
Global warming = the warming of the troposphere and the oceans as a result of an increase in the natural greenhouse effect
Global climate change = a broader term referring to any changes in the Earth’s climate over a period of decades

7. Global Warming vs. Climate Change
More detailed definitions:
Global warming: Rise in global temperatures because of the trapping of more heat in the lower atmosphere.
Average temp. of Earth has already risen by 1.4°F since 1880
Predicted to rise another 2.5°F during this century (IPCC 2015)
Global climate change: Long-term change in average weather conditions in an area. Changes may include:
Temperature – warmer or cooler
Rainfall – more or less
Wind patterns

8. Global Change
Global change: Change that occurs in the chemical, biological, and physical properties of the planet.
Global change includes a wide variety of factors that are changing over time.

9.  The Greenhouse Effect
At our distance from the Sun, the Earth should have an average global temp. of around -2º F (-19º C).
Instead, the Earth’s average temp is 57º F (14º C)
WHY??
The Earth’s natural greenhouse effect

10. The Greenhouse Effect
The Greenhouse Effect (GHE): Absorption of infrared radiation by atmospheric gases and re-radiation of the energy back toward Earth.
As solar energy reaches Earth’s surface, a small amount of it is reflected; most of it is absorbed.
The absorbed energy warms the earth, which radiates heat back towards space as infrared energy (heat).
Greenhouse gases absorb some of the outgoing infrared energy.
Heat energy remains trapped near earth’s surface, keeping it warmer.

11.  The Greenhouse Effect

12. Greenhouse Effect vs. Global Warming
The greenhouse effect is a natural process and without it, Earth would be too cold to support life.
However, the natural GHE can be “enhanced” by too many greenhouse gases in the atmosphere
Too much energy trapped means rising temperatures on earth = GLOBAL WARMING

13. The Gases That Cause the Greenhouse Effect
The major greenhouse gases are:
Water Vapor (H2O): the most abundant greenhouse gas, warmer air holds more water vapor (positive feedback)
Carbon Dioxide (CO2): enters the atmosphere through the burning of fossil fuels, solid waste, trees and wood products, etc. It is removed from the atmosphere or “sequestered” when it is absorbed by plants as part of the carbon cycle.
Methane (CH4): emitted during the production and transport of fossil fuels, from livestock and other agricultural practices, and by the decay of organic waste in municipal solid waste landfills.
Nitrous Oxide (N2O): emitted during agricultural and industrial activities and during combustion of fossil fuels and solid waste.

14. The Gases That Cause the Greenhouse Effect
Other greenhouse gases:
Tropospheric Ozone (O3): A secondary pollutant created at ground level that absorbs infrared energy.
Chlorofluorocarbons (CFCs):
Do not exist naturally.
In the troposphere, they
absorb infrared energy.
We know what they do
in the stratosphere…

15. Greenhouse Gases
Greenhouse warming potential: How much a GHG molecule can contribute to global warming over a period of 100 years relative to a molecule of CO2.
The contribution of each gas to global warming depends on its greenhouse warming potential and its concentration.

16. Natural Sources of Greenhouse Gases
Volcanic eruptions
Ash: reflects sunlight; short-term cooling effect
Carbon dioxide: significant amounts added over time
Decomposition and digestion
Carbon dioxide: high oxygen conditions
Methane: low oxygen conditions (under water or in guts)
Denitrification
Nitrous oxide: low oxygen wet soils
Evaporation and evapotranspiration
Water vapor: evaporation from land or bodies or water; transpiration from plants.

17. Anthropogenic Sources of Greenhouse Gases
Anthropogenic sources of greenhouse gasses:
Burning of fossil fuels
Carbon dioxide: burning coal produces the most CO2, following by gasoline. Natural gas produces the least.
Particulates: reflects sunlight, but also coats snow/ice lowering albedo so it melts faster.
Agricultural practices
Nitrous oxide: excess nitrates in the soil
Methane: livestock manure lagoons
Deforestation
Carbon dioxide: loss of trees decreases CO2 taken out of atmosphere; if trees are burned, excess CO2 is put into atmosphere

18. Anthropogenic Sources of Greenhouse Gases
Anthropogenic sources of greenhouse gasses:
Landfills
Methane: decomposition of organic matter
Industrial production
CFCs: refrigerant, coolant, propellant
Hydrochlorofluorocarbons (HCFCs): CFC substitutes that do not harm the ozone layer, but act as greenhouse gases.
Phased out by 2030

19. Anthropogenic Causes of Greenhouse Gases
Can you name the greenhouse gases emitted by the following human activities?

20. Anthropogenic Causes of Greenhouse Gases
Methane
Bacteria that breakdown livestock manure
Landfill decomposition
Leaks from production, storage, and transport of natural gas and petroleum products.
Nitrous oxide
Nitrogen from applied fertilizers
Combustion of fossil fuels
Industrial production of fertilizers
Carbon dioxide
Burning of fossil fuels in different forms

21. 63 The Evidence for Global Warming Module Learning Objectives
After this module, you should be able to:
explain how CO2 concentrations have changed over the past 6 decades and how emissions compare among the nations of the world.
explain how temperatures have increased since records began in 1880.
discuss how we estimate temperatures and levels of greenhouse gases over the past 500,000 years and into the future.
explain the role of feedbacks on the impacts of climate change.

22. The Consequences of Global Climate Change
Module 64
The Consequences of Global Climate Change
Learning Objectives
After this module, you should be able to:
discuss how global climate change has affected the environment.
explain how global climate change has affected organisms.
identify the future changes predicted to occur with global climate change.
explain the global climate change goals of the Kyoto Protocol.