Environmental Science 102
Global Warming

Weather vs. Climate

Weather – current state of the atmosphere
Climate – aggregate atmospheric conditions; long-term average weather


How do we measure global temperature?
Average of all temperature record measurements.

Proxy Temperature Records

Data from sources which do not give actual temp. – provide an inferred temperature
Biological Proxy Records: tree rings, pollen, floral and faunal distributions, fossils
Geological Proxy Records: sediment/glacial deposits, ice cores, minerals, geochemistry
Chemical Proxy Records: O18/O16 ratios (ice and foram shells)

Sea-Level Measurements

Sea level is not constant
Changes on a daily basis:
Changes on an annual basis:

Global Warming!!!

Is the world actually getting warmer?
“Warming of the climate system is unequivocal… The atmosphere and oceans have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentration of greenhouse gases have increased.” – IPCC 2013: Climate Change 2013: The Physical Science Basis.

The Evidence of Global Warming

Make note of each piece of evidence, and what that evidence shows:


What are the 4 main pieces of evidence for global warming?

Ten Signs of a Warming World - NOAA web site

Causes of Climate Change

Natural Causes or Human Induced Causes?

Solar Radiation:
Changes in amounts of incoming vs. outgoing radiation results in global warming or cooling.
Factors controlling amount of insolation:

Milankovitch Cycles

Cycles in amount of solar radiation received at surface due to orbital variations.

Greenhouse Gases

CO2 Carbon Dioxide
CH4 Methane

Future Predictions

Projected Future Global Temperature, Present to 2100
Projected Future Global Sea Level, Present to 2100
Average Projected Changes in Precipitation: 2080 to 2099

Additional Information

Global Warming: A Short Discourse