Ozone Depletion vs. Greenhouse Effect

The Ozone Layer• Ultraviolet radiation is a part of the

solar radiation spectrum. It causes sun-burn and is deadly to living organisms, including humans.

• Ozone can absorb the most lethal type of ultraviolet rays and is therefore crucial to life on Earth.

• Since 1980, the ozone in the atmosphere has been depleting because of pollutants emitted by human manufacture e.g. CFCs.

• The issue of ozone depletion is an entirely different process to the greenhouse effect

• The two are commonly confused, but they are two distinct processes

Thinning of the Ozone Layer

The Montreal Protocol

• In 1987, many international governments signed an agreement to stop the production and use of CFCs

• The Montreal Protocol was a success as the ozone layer is beginning to recover.

• However, scientists estimate that it will take at least 50 more years to return to its original thickness

Scientific Evidence of Climate Change

Modelling Climate Change• There is lots of evidence showing

us that Earth’s climate has always been changing

• However, most scientists agree that the recent changes in Earth’s climate is because of anthropogenic factors

• Ideally, if we had 2 Earths we could conduct a controlled experiment to isolate the effect of humans

• This is impossible, so instead we must use evidence from the past and present as well as future models

• There are many tools that scientists can use to study past climate events.

• Scientists examine the long term geological record to see whether the climate change events since the industrial revolution are normal or unusual.

• This helps to determine how big a role humans have on climate change.

Ice Cores

• The ice in Greenland & Antarctica contains air pockets that have been trapped for 1000’s of centuries

• Ice cores provide the longest record of conditions in the atmosphere

• Scientists drill deep into the ice then cut small sections to analyse the air pockets

Ice Cores• Tests can give information about:

– The amount and type of greenhouse gases present

– The air temperature– Precipitation levels– Volcanic activity

Tree Rings• Some trees live for 1000’s of years• Scientists use evidence from both

living and dead trees• Rings are thickest in years with good

growing conditions (warm and wet)• Can also indicate forest fires and

other events

Sedimentary Layers

• Layers of soil and rock build up over time

• Can give clues about the movement of tectonic plates and erosion

• Fossils provide clues about climate conditions based on the types of species present

Melting Glaciers and Ice Caps• Increased global temperatures are already

associated with:– A reduction in polar ice– Melting of glaciers– Thawing of permanently frozen

ground

Rising Sea Levels• The increase in ocean temperatures will not only melt polar

ice and glaciers, it will also make the volume of water in oceans expand.

• As waters rise, there is a greater risk of the edges of ice shelves and coastal glaciers collapsing into the sea, thereby causing further sea level rise.

Extreme Events• It is anticipated that the number of very hot days

will increase with fewer colder and frosty days. • Intense summer heat could result in more violent

storms as the oceans warm and more energy is stored in our warming atmosphere.

• This could cause greater flooding, mud/land slides, and damage to buildings, roads and bridges.

• In contrast, in the mid latitudes, particularly in inland regions, more frequent and prolonged drought could be associated with reduced water supply, lost productivity and possibly famine.

• In addition, drier conditions will cause more frequent and higher intensity bushfires.

Climate ModelsClimate ModelsScientists use climate data (such as that collected Scientists use climate data (such as that collected

from ice cores) as inputs in quantitative models from ice cores) as inputs in quantitative models that simulate the interactions of the Earth’s that simulate the interactions of the Earth’s systems.systems.

Confidence LevelConfidence LevelEach prediction can be given a confidence rating, Each prediction can be given a confidence rating,

based on the amount and accuracy of data based on the amount and accuracy of data measurements and scientists’ understanding of measurements and scientists’ understanding of climate interactions.climate interactions.

Questions1. What are 3 pieces of evidence that

scientists can use to study past climate events?

2. What are some examples of current extreme weather conditions?

3. In your opinion, should we wait until predictions of climate change are more accurate before taking action to prepare for the impacts of climate change? Defend your choice.