Global Environmental Change Climate Change, Global Warming, Ozone Depletion… …what’s going on?

Stratospheric Ozone Depletion

What are Halogen Gases?

Where do CFC’s come from?

Where else can we find Ozone depleting chemicals?

What are the key sources of Ozone depleting chemicals?

How has Ozone Changed over Antarctica?

What does Ozone thinning look like in the ArticWhat does Ozone thinning look like in the Artic. What does Ozone thinning look like in the Artic. What does Ozone thinning look like in the Artic

How long do CFC’s last??? The chlorine atoms can break down tens of thousands of ozone molecules before being removed from the stratosphere. Given the longevity of CFC molecules, recovery times are measured in decades. It is calculated that a CFC molecule takes an average of 15 years to go from the ground level up to the upper atmosphere, and it can stay there for about a century, destroying up to one hundred thousand ozone molecules during that time. The chlorine atoms can break down tens of thousands of ozone molecules before being removed from the stratosphere. Given the longevity of CFC molecules, recovery times are measured in decades. It is calculated that a CFC molecule takes an average of 15 years to go from the ground level up to the upper atmosphere, and it can stay there for about a century, destroying up to one hundred thousand ozone molecules during that time.

Montreal Protocol After a series of rigorous meetings and negotiations, the Montreal Protocol on Substances that Deplete the Ozone Layer was finally agreed upon on 16 September 1987 at the Headquarters of the International Civil Aviation Organization in Montreal. The Montreal Protocol stipulates that the production and consumption of compounds that deplete ozone in the stratosphere--chlorofluorocarbons (CFCs), halons, carbon tetrachloride, and methyl chloroform--are to be phased out by 2000 (2005 for methyl chloroform). Scientific theory and evidence suggest that, once emitted to the atmosphere, these compounds could significantly deplete the stratospheric ozone layer that shields the planet from damaging UV-B radiation.

Back to the Troposphere

What is Climate? Climate = the average and variations of weather over a long period of time (~30 years) Climate = the average and variations of weather over a long period of time (~30 years) Above: Global average for atmospheric water vapor.

What is Weather? Weather = all natural phenonmena within the atmosphere at a given time (hours to days) Weather = all natural phenonmena within the atmosphere at a given time (hours to days)

Modern Climate Systems Atmospheric circulation Atmospheric circulation

Modern Climate Systems Atmospheric circulation Atmospheric circulation Sunlight

The Earth has many different systems that interact with each other in different ways. The Earth has many different systems that interact with each other in different ways. Land OceansAtmosphere Biosphere Ice The Climate System

Modern Climate Systems Ocean circulation Ocean circulation The Great Ocean Conveyor Sinking cool water, rising warm water and wind help to form global ocean current systems.

Atmosphere and Greenhouse Effect Atmosphere and Greenhouse Effect The Earth’s atmosphere keeps it around 30°C warmer than it would otherwise be. The Earth’s atmosphere keeps it around 30°C warmer than it would otherwise be. This is the Greenhouse Effect This is the Greenhouse Effect Modern Climate Systems

What is the Greenhouse Effect? cc. Robert A. Rohde (Global Warming Art) The temperature of the Earth depends on the amount of energy we receive from the sun versus the amount of energy lost back out to space.

Past Climate Systems How do we know about climate systems in the past? How do we know about climate systems in the past?

Past Climate Systems 1. Early human record Tourism NT Rock paintings provide evidence of fertile Sahara region (now desert) 6,000 years ago. cc. W.V. Bailey

Past Climate Systems 2. Geomorphology Above: A “U” shaped valley shows that it was formed by a glacier. River deltas show where rivers entered the ocean or a lake.

Past Climate Systems 3. Geological record Drilling into the ground can recover rock layers that record what conditions were like when the rock was deposited. Fossils preserve evidence of past life.

Past Climate Systems 4. Ice cores GISP2 ice core at 1837m depth with clearly visible annual layers. Ice cores can preserve seasonal layering. Studying the chemistry of each layer can give clues about climate change.

Is the Climate Changing?

What are the current climate trends? cc. Robert A. Rohde Global temperature for the last 150 years

What are the current climate trends? cc. Robert A. Rohde

Looking further into the past… cc. Robert A. Rohde Global temperature for the last 1000 years

What causes it? *CO2 *methane *nitrous oxide *fluorinated compounds Greenhouse Gases: Human Impacts-

Anthropogenic Influence Fossil fuel Fossil fuel Aerosols Aerosols Cement manufacture Cement manufacture Land use Land use Livestock Livestock cc. Robert A. Rohde

Who’s Responsible? Burning of fossil fuels is main cause Burning of fossil fuels is main cause U.S. is leader in greenhouse gasses Human impacts are changing the composition of the atmosphere

What causes it? Natural Impacts: Natural Impacts: *Volcanoes *Water vapor *clouds *Change in sun’s energy output

The Carbon Cycle

Future predictions… Based on no changes in emissions (“business as usual”) Based on no changes in emissions (“business as usual”) The U.S. would be °C hotter on average. The U.S. would be °C hotter on average. cc. Robert A. Rohde

What does it all mean? Sea level rise Sea level rise More extreme weather More extreme weather Changes in precipitation Changes in precipitation Spread of disease Spread of disease cc. Robert A. Rohde

What’s all this talk about Arctic Ice increasing? nimumpr.html nimumpr.html nimumpr.html nimumpr.html

Questions to be answered… How fast will the sea level rise? How fast will the sea level rise? How much warmer will it get? How much warmer will it get? When will the Arctic Ocean be ice-free? When will the Arctic Ocean be ice-free? Will the water cycle accelerate? Will the water cycle accelerate? Are climate extremes increasing? Are climate extremes increasing? Will there be abrupt changes? Will there be abrupt changes?

Boiling Frog Syndrome

Science can provide knowledge… …We all have to provide the solutions.