THE GREENHOUSE EFFECT

GLOBAL CLIMATE CHANGE

THE OZONE LAYER

Learning Goal

• Compare and contrast greenhouse effect and global climate change.

The Earth would be about 60oF colder without the Greenhouse Effect.

What is the Greenhouse Effect?

The greenhouse effect is • the name applied to the process which causes

the surface of the Earth to be warmer than it would have been in the absence of an atmosphere

• it describes the retention of heat in the Earth’s atmosphere.

• During the day, heat enters the Earth’s atmosphere and heats up the Earth’s surface

• At night, heat is radiated into space as the Earth cools

• CO2 gas reflects some of the heat causing the atmosphere and the Earth to remain slightly warm

HOW IT WORKS

The Main Greenhouse Gases:

• CO2 (Carbon dioxide) is the most important greenhouse gas

• CO (Carbon monoxide)

• methane

• water vapor

• CFC (Chlorofluorocarbons)

• Nitrous oxides (NOx) are also involved

GLOBAL CLIMATE CHANGE

Is the temperature of the Earth and Atmosphere increasing?

Is the global climate change just a trend?

Does Global Warming really exist?

Are humans to blame?

Is the global climate change related to the greenhouse effect?

Scientists have spent years trying to answer these questions...and are still working on

them!

• A term used to describe the overall warming of the planet surface and atmosphere

• “11 of the 12 warmest years on record have occurred in the past 12 years”

• “Scientists have found that over the past 100 years, the global climate has gotten between 1-1.6oF warmer.”

• Some areas are effected more than others, “temperatures in the Arctic have risen significantly more than in the rest of the world”

GLOBAL CLIMATE CHANGE

Global Warming Report: UN Warms up to Climate Change. Sales, Adam. Feb 2007.

What’s wrong with a little heat?

• Arctic ice seems to be melting, the ice has shrunk by about 2.7% every decade since 1978

• Warmer temps affect precipitation. Some areas of the world have experienced more rain and snow recently along with more intense storms, while other areas have dried up with more frequent and intense droughts

Global Warming Report: UN Warms up to Climate Change. Sales, Adam. Feb 2007.

In November 2002, an iceberg broke off from the Antarctic icecap and drifted north in the Atlantic Ocean. Some experts contend that the growing number of icebergs off Antarctica's coast can be attributed to global warming.

Global Warming Report: UN Warms up to Climate Change. Sales, Adam. Feb 2007.

A major new report released by the Intergovernmental Panel on Climate Change called global warming "unequivocal," and said that it was "very likely" that humans are to blame.

Global Warming Report: UN Warms up to Climate Change. Sales, Adam. Feb 2007.

The blue regions = temperature change if there were not human contribution to global warming

The pink regions = temp change taking into account human activity

The fact that the simulations that take pollution into account agree much better with the data indicates to scientists that humans are probably causing global warming.

So…What do YOU think?

Are humans to blame for the increase in our global

temperatures?

OZONE DEPLETION

• A term used to describe the thinning of the natural protective ozone layer in the stratosphere

• It is caused by the addition of chlorofluorocarbons (CFC) in the atmosphere

• The CFC’s breaks the ozone molecule (O3) apart

• CFC has many sources but has been very restricted in their use by law

Is the hole in the Ozone getting larger?

Replenished Ozone.,  By: Choi, Charles Q., Scientific American, 00368733, Nov2005, Vol. 293, Issue 5

A report published in Scientific American magazine in 2005 states:

The ozone layer is no longer disappearing. Depletion of stratospheric ozone, which defends the planet from harmful levels of ultraviolet rays, was first detected 25 years ago and stems mostly from industrial pollutants, especially chlorofluorocarbons. Atmospheric scientists analyzed data on the entire ozone layer from satellites and ground stations and found ozone level decline plateaud between 1996 and 2002.

The ozone layer has even increased a small amount in parts of the Northern Hemisphere, including much of the area over North America, Europe and Asia.

Overall, however, ozone will remain seriously depleted worldwide, especially at the poles, because ozone-destroying chemicals persist in the atmosphere for decades.