Physical Geography 101
Global Warming


Global Warming

Is the world actually getting warmer?

“Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air[1] and ocean[2] temperatures, widespread melting of snow and ice[3], and rising global average sea level[4]” – IPCC 2007: Climate Change 2007: The Physical Science Basis.

"The instrumental temperature record shows that surface warming has taken place across the oceans and land, and that the rate of warming has accelerated over the most recent decades." Michael E. Mann and Lee R. Kump, 2009. Dire Predictions: Understanding Global Warming. Grove Weidenfeld, New York, 283 p.

"No credible climate scientist now doubts that humans have had an effect on Earth's climate during the last two centuries, primarily by causing increases in the concentrations of greenhouse gases like carbon dioxide and methane in the atmosphere...[T]he so-called global warming debate is not about whether humans are warming climate or whether we will warm climate in future decades - we are warming it." William F. Ruddiman, 2005. Plows, Plagues & Petroleum: How Humans Took Control of Climate. Princeton University Press, New Jersey, 202 p.

"The world is getting warmer." John Gribbin, 1990. Hothouse Earth: The Greenhouse Effect and Gaia. Grove Weidenfeld, New York, 283 p.

"Since 1900 a careful study of world temperature records shows that the average temperature has been increasing..." Gilbert N. Plass, July, 1956. Carbon Dioxide and the Climate. in American Scientist, vol. 44.

The Evidence

Temperature Graph: 1880 to 2010

Benthic Foraminiferal Stable Isotope Data Graph: 1 million b.p. to Present

Entire Earth History Temperature Graph: 4.6 billion b.p. to Present

Glacier Mass Balance Graph: 1960 to 2000

Sea Level Change Graph: 1880 to Present

Ocean Surface Temperature Graph: 1880 to 2010

The Causes of Climate Change

Natural Causes or Human Induced Causes?

Solar Radiation:
– Main source of energy at Earth's surface.
Driving force for: life, atmospheric/oceanic circulation, weather, climate
Changes in amounts of incoming vs. outgoing radiation will result in global warming or cooling. [simplest climate model]

Orbital Parameters

Surface insolation variations due to orbital parameter variations.
1) Axial tilt
2) Precession
3) Orbital Eccentricity

Human Induced Causes: CO2 Trends

"[G]lobal greenhouse gases are now under human control...Humans, by rapidly burning fossil fuels, have caused global warming that overwhelms the natural tendency towards the next ice age." Hansen, James, 2009. Storms of My Grandchildren. Bloomsbury USA, New York, 304 p.

Carbon Dioxide from Vostok Ice Core Data; 0 to 500,000 B.P.

Carbon Dioxide from Vostok Ice Core Data; 0 to 100,000 B.P.

Carbon Dioxide from Vostok Ice Core Data; 0 to 100,000 B.P., with projected trend

Trends in CO2: 1958 to 2006

Human Induced Causes: CH4 Trends

Methane from Vostok Ice Core Data; 0 to 500,000 B.P.

Methane from Vostok Ice Core Data; 0 to 100,000 B.P.

Methane from Vostok Ice Core Data; 0 to 100,000 B.P., with projected trend

Trends in CH4: 1986 to 2007

Future Predictions

"I've come to conclude that if we burn all reserves of oil, gas and coal, there is a substantial chance we will initiate the runaway greenhouse."
"[T]he strength of the strongest storms will increase as global warming increases."
"[W]hen large sea level change will begin is during the lifetime of my grandchildren - or perhaps your children."
Hansen, James, 2009. Storms of My Grandchildren. Bloomsbury USA, New York, 304 p.

IPCC Temperature Forecast

IPCC Sea Level Forecast

IPCC Precipitation Forecast

Storm Forecast

Additional Reading

Global Warming: A Short Discourse Answering Three Questions