Week One: Climate Change: Challenges and Solutions 1-13-2014

Week One: Climate Change: Challenges and Solutions              1-13-2014 

 This is a transcript of my notes from Week One of University of Exeter's Massive Open Online Course (MOOC) on Climate Change.
 Offered via: www.futurelearn.com Course beginning date: Jan. 13, 2014   [I started 1/23.]
 Professor: Tim Lenton  (all sections are presented by Dr. Lenton unless otherwise noted.)

1.1 Reflective Learning 

Guest presenter, Dr. Damien Mansell, suggests that the participants use social media to enhance “reflective learning;” specifically, set up a blog using a blog hosting site such as Word Press or Blogger to record your insights, case studies, examples, and so on. Students may then post their documents on the discussion boards and invite others to comment. At the end of the course, you can create a summary post.

 1.2 Key Principles of Climate Change

GREENHOUSE EFFECT: Short wave radiation comes in from the sun, strikes objects on the Earth, and re-emits heat radiation at long wavelengths that are invisible to us. 

• SUNLIGHT is visible, short wave radiation.  We see it as light.
• Long wave radiation is "infrared heat" and is not visible to us.
• The "Greenhouse Effect" doesn't really work exactly like a greenhouse.  A greenhouse works mostly by trapping air.  The sunlight passes through the glass, strikes the ground or plants or objects in the greenhouse, which warms them up, which in turn warms some of the air in the greenhouse, and then the air is kept within the greenhouse by the glass. The glass itself only traps a little bit of the heat radiation on the way out.  But in the atmosphere, the greenhouse gases absorb some of the radiation bouncing back from the earth, and become warmer, and some of that heat radiates back to earth as long-wave radiation.
• Short-wave radiation (sunlight) is either absorbed by or reflected from the surface according to how high its albedo is.  Albedo is a measure of "shinyness" or reflectiveness.  The higher the albedo, the more light is reflected.  The average albedo of the Earth is 0.3, which means 30% of the light is reflected (and in turn means 70% of the sunlight radiation reaching earth is absorbed.)
• If the absorption of 70% of the sun's energy were the only factor, Earth's temperature would be -18 degrees Celsius (-19 C per the I.P.C.C.), which is right about zero Fahrenheit (-0.4 F to -2.2 F).
• But, Earth's average temperature is about 15 degrees Celsius (59 F) because of our atmosphere.  Certain gases absorb some of the radiation, and some of that comes back to the surface.   That's a total difference of 33 C (59.4 degrees F) warmer because of our greenhouse gases.

THE GREENHOUSE GASES:
        These are the important greenhouse gases in our atmosphere:  Water vapor, methane, ozone, nitrous oxide, and CO2.  The last four exist in much smaller amounts than water vapor. These are Earth's "thermal blanket."

1.3 Blanket Earth - more information, from NASA's website

NASA says most scientists agree that :

"... the main cause of the current global warming trend is human expansion of the "greenhouse effect"-- warming that results when the atmosphere traps heat radiating from Earth toward space."

Greenhouse gases are those which trap some of the heat being radiated back from the Earth.  Those which are long-lived and do not react physically or chemically to temperature changes are considered to be "forcing" climate change; those which do respond physically or chemically to temperature changes are considered feedbacks to the system.

• Water Vapor:  This is the most abundant greenhouse gas.  Because it responds physically or chemically, increasing with warmth but then carrying more clouds and rain, it is considered an important feedback in the climate system.
• Carbon Dioxide (CO2):  Minor [in amount] but important component of the greenhouse effect.  It has increased by one third since the industrial revolution began.  It creates a "forcing" of climate change because it is long-lived, semi-permanent in the atmosphere, and does not respond physically or chemically to changes in temperature.
• Methane:  Comes from natural and human sources.  It is a hydrocarbon.  Sources are: decomposition of wastes, e.g. from landfills, also from ruminants and rice cultivation.  It is less abundant than CO2 but more potent.
• Nitrous Oxide:  Very powerful.  Comes especially from fertilizers, and burning fossil fuels or biomass.
• Chlorofluorocarbons (CFCs): Human origin; now regulated.

The NASA article also contains a good disputation about Solar Irradiance factors in global warming.  Some data shows that global warming increases cannot be from increases in solar irradiance, because the irradiance has been decreasing lately.  Or, some sources believe it cannot account for more than 10% of global warming.
 This is a link to the NASA article:  http://climate.nasa.gov/causes

1.4  What Is Climate?

An Introduction to the Climate System, especially defining the difference between climate and weather, via a video from the U.K. Met [Meteorological] Office:

WEATHER:  Temperature, wind and precipitation, changing by the hour and by the day.
CLIMATE:  How weather changes over a long period, typically at least 30 years.

A CLIMATE SYSTEM is comprised of many interactions and factors, such as oceans, ice sheets, land masses, vegetation, sunlight, and atmosphere.  Atmosphere affects world climate greatly.  The greenhouse effect was discovered 150 years ago.

1.5 DISCUSSION:  What is the difference between Weather and Climate?  Give examples. 

(Please see the January 26, 2014 blog post, titled "Assignment: Weather vs. Climate")

1.6  The Climate System, Feedbacks, Cycles and Self-Regulation

Components of the climate system:

1. Atmosphere

1. Hydrosphere 

1. Biosphere

1. Cryosphere  (ice)

1. Lithosphere   (surface of Earth's crust)

LINKS:  We will see that there are a whole series of cycles that act as the active links--the interactions between components that power the climate system.  For example, in the hydrologic cycle, water can re-enter the hydrosphere or the cryosphere.

The Hydrologic Cycle (Water Cycle)--illustrates the coupling between components of the climate system:

• Water vapor rises

• then condenses (forms clouds)

• falls as rain or snow

• rain enters ground or aquifers, or rivers and lakes, then oceans; or

• plants

• snow or ice can evaporate directly into atmosphere

At many points, humans can influence the system.

FEEDBACKS:   "Feedback Loops" are "closed loops of cause and effect."  Cycles also create feedback loops.  There are three key feedbacks:  1.  Water Vapor feedback. 2. Ice Albedo feedback. 3. Radiation feedback.










(MORE TO BE ADDED LATER...  )