Bell Ringer Glasgow is the largest city in Scotland. Glasgow sits at 58⁰N latitude, is about 39 meters above sea level, and is very close to the Atlantic Ocean. In addition, this city is supplied by a warm water current (the Gulf Stream). 1. Using this information, predict Glasgow’s climate, in terms of temperature and precipitation. 2. While Glasgow sits in the temperate zone, would you expect to see strong seasonal variance? Why or why not?

What is the ozone layer, and why is it important?

Our Ozone Shield  The ozone layer is found within the stratosphere. Ozone molecules (O 3 ) are found in very high concentrations here.  Ozone is vital because it absorbs a significant percentage of incoming ultraviolet (UV) radiation.  Why do we want to block UV radiation?

Our Ozone Shield

 Note from the diagram that UV radiation can be divided into UV-A, UV-B and UV-C radiation wavelengths.  The ozone layer effectively blocks UV-B and, while it is not shown, UV-C. These are the most harmful wavelengths by far.  UV-A has a longer wavelength, so it can bypass the ozone layer. However, it is also the least harmful UV radiation.

Our Ozone Shield OrganismHow is it harmed through UV radiation? HumansSkin cancer, premature aging, increased risk of cataracts, weakened immune system AmphibiansReduced chance of egg survival, increased risk of genetic mutations, increased vulnerability to other stresses and limiting factors Marine LifeDeath of phytoplankton (producers!), disruption of the local food networks Land PlantsInterference with normal photosynthesis, reduced crop yields

The Ozone Hole  Throughout the spring, the ozone layer thins out above the South Pole (Antarctica). This causes an ozone hole to appear.  This was first officially discovered in  While ozone levels vary throughout the year, a trend toward gradual thinning of the ozone layer was discovered as far back as Over time, ozone levels over the Artic (North Pole) have also dropped.  Why?

The Ozone Hole  Primarily, this was caused through the influence of chlorofluorocarbons (CFCs), a class of compounds once used as coolant, in aerosols, and as a foam additive.  They’re attractive because they are cheap, nontoxic, nonflammable, and noncorrosive.

The Ozone Hole  Close to the Earth’s surface, CFCs are quite inert and harmless.  However, CFCs that ascend to the stratosphere react with abundant UV radiation to form reactive molecules. This occurs in polar stratospheric clouds, high altitude clouds made of water and nitric acid.  These molecules can react with ozone in the ozone layer, depleting the ozone!

Defending Our Ozone  In 1987, the Montreal Protocol was first ratified in Canada. This was an agreement to limit the production of future CFCs.  Since its inception, it has been ratified by most of the world’s countries.  As a result, in 2012 the ozone hole reached its smallest reported size in the past decade!

Defending Our Ozone  Though the Montreal Protocol has been quite successful, scientists continue to monitor the ozone layer, as CFCs will still be present for many years to come.

Bell Ringer  Examine the graph and answer the questions: 1. Was 2007 an El Nino or La Nina year? 2. How do you know this? YearJanFebMarAprMayJunJulAugSepOctNovDecAnn  This graph shows monthly rainfall for Hawaii for the years (in inches)

How are we affecting both local and global climates?

The Greenhouse Effect  Greenhouse gases – gases that can absorb and radiate radiation from the sun – are needed to moderate Earth’s temperature. Without them, the Earth’s climates would be too extreme to support life as we know it.  Carbon dioxide, methane, nitrous dioxide and water vapor are the primary greenhouse gases.  This is known as the greenhouse effect.

The Greenhouse Effect  However, excessive amounts of greenhouse gases will trap an excessive level of thermal energy in the atmosphere.  The excess thermal energy can lead to changes in weather and climate patterns all over the world.  This is especially critical as it pertains to carbon dioxide; CO2 levels have risen dramatically in the past 50 years.

Climate Change  Both global warming and global cooling define changing trends in the Earth’s climate.  Scientists used to refer to the trend in increasing thermal energy as global warming. However, this is not an accurate picture of all of the effects of this phenomenon.  We now define this trend as climate change, since there are effects well beyond rising temperatures on Earth.

Climate Change  What could the localized effects of global climate change be?  Rising sea levels – trapped thermal energy warms the oceans, and melts terrestrial ice shelves. This could cause widespread flooding and salination of freshwater reservoirs.  Changing weather patterns – excess thermal energy can alter both wind and ocean currents, changing local climates.

Climate Change  What could the localized effects of global climate change be?  Mass extinction – climate change would change local ecosystems, prompting mass migrations and extinctions, and changing local food networks.  Health concerns – deaths due to adverse weather are a concern, as are an increase in disease vectors (e.g., mosquitoes or bats).  Agriculture – changing climates could disrupt local agriculture and stress local irrigation systems.