Biology 141 Lewis & Clark College

Atmospheric pollution and global warming

K.E. Clifton

Pollutants in the atmosphere can have global impacts

Industrial pollutants and acid rain

CFC emissions and Ozone depletion

Greenhouse gasses and climate change

 

First, a bit about the atmosphere:

It is mostly Nitrogen, with about 20 % Oxygen and very little of lots of other elements.

Much of the planet's temperature profile is linked to the composition of our atmosphere

Like water, it is stratified, with patterns of thermal structure

In addition to providing the gas needed for respiration (O₂), the atmosphere plays a critical role in regulating Earth's climate.

 

Acid Rain: Industrial emissions change the pH of rainfall

The worst offender: sulfer dioxide (SO₂)

Other relevant pollutants nitric oxide (NO), nitrogen dioxide (NO₂), chloride (Cl ^-)

These combine to form Sulfuric Acid (H₂SO₄) and Nitric Acid (HNO₃)

Emmission controls have worked to reduce the impact of acid rain in regions like the American Northeast

Ozone in the atmosphere absorbs UV radiation

The EPA provides a great deal of information on the topic.

Ozone depleting substances: chloroflourocarbons (CFCs)

Bans on CFC emmissions have been implemented to reduce ozone depletion... but is it working?

Nasa's Ozone Watch site

Now, more on climate, the atmosphere, and global warming

Reflection (albedo) and absorption of light energy in the atmosphere and on the surface dictate patterns of warming and cooling

The planet goes through natural cycles of warming and cooling:

Ice ages

Global Warming

There is clear evidence that the planet is currently in a period of warming

This is recent.... what about more historical patterns?

Where do such data come from?

Projections for the future vary, depending on the model used

Why does warming occur?

Thank goodness for the "greenhouse effect"

 

The burning of fossil fuels contributes to global warming and climate change

And the levels of CO₂ are rising

What are the potential consequences of global warming/climate change?

On land

Biome shifts

Shifts in patterns of primary productivity (good for agriculture in some places... bad in others)

More variance in local weather patterns and associated ecological impacts

Changing phenology (timing and amount) of reproduction by different species.

 

In the oceans

Temperature changes

Sea level rise

Thermal expansion

Ice melt

Shifts in global circulation patterns

Acidification - Here is a link to a whole lecture on this topic

pH influences the relative proportions of carbonate and bicarbonate

What does this mean for marine organisms like corals that use calcium carbonate (CaCO₃) for support structures?

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