Environmental Science 102
Global Warming

Is global warming real?
What is causing global warming?
What will happen in the near future?


Global temperature is an average of all temperature record measurements.
Historical records - municipal/state/federal records - amateur records and diaries
Limited span of time for which these records can be used. - first thermometer invented: 1611

Proxy Records

Proxy records are data from sources which do not give actual temperatures but provide information which can be used to infer the temperature.
Biologic, geologic, and chemical sources can be used.
Biological Proxy Records - tree rings, pollen, floral and faunal distributions
Geological Proxy Records - sediment deposits, minerals, geochemistry, glacial deposits
Chemical Proxy Records - O18/O16 ratios

Glacial Ice Mass Balance Measurements

Glaciers form from the long term accumulation of snow and ice.
Ocean water is the primary source of water found in glaciers
During climatic cold periods glaciers form:
During climatic warm periods glaciers melt:

Sea-Level Measurements

Sea level is not constant
Changes on a daily basis:
Changes on an annual basis:
Causes of eustatic changes in sea level:

The Causes of Climate Change

Natural Causes
Human Induced Causes

Solar Radiation

The sun is the main source of energy for processes at the Earth's surface
It is the driving force for life, atmospheric circulation, ocean circulation, weather, climate.
Changes in the amounts of incoming radiation vs. outgoing radiation will result in global warming or cooling.

Orbital Parameters

Variations in the amount of solar radiation received on Earth due to variations in three orbital parameters.

Greenhouse Effect

A system in which shortwave radiation is allowed to enter freely and is absorbed, then is re-radiated as longwave radiation. The longwave radiation is then retained within the system.
Important greenhouse gases:

Human Induced Causes

CO2 Trends

CH4 Trends

Future Predictions


Sea Level:




Additional Reading

Global Warming: A Short Discourse Answering Three Questions