Climate Change Today

1. Is it Really Changing?

2. If so, are Humans the Cause?

Temperature Change in the Last 1000 Years

Figure 12.30

World Temperature Anomaly for 2009Temperature increase is not evenly distributed.

Minimum Arctic Sea Ice Sept. 1979

Minimum Arctic Sea Ice Sept. 2005

CERES UC Boulder

What Did the Snowy/Cold Winter of 2010 in the Eastern U. S. Mean?

Is carbon dioxide an effective greenhouse gas?

http://www.youtube.com/watch?v=kGaV3PiobYk&feature=related

Is the level of atmospheric CO2 increasing?

• Atmospheric CO2 has ranged between 180 parts per million (ppm) and 300 ppm over the past 800,000 years.

• Today, CO2 levels are around 390 ppm.

The Keeling Curve and CO2 levels since 1958

Where is the carbon dioxide coming from?

Table 12.5

HUMAN-INDUCED INCREASES IN ATMOSPHERIC CARBON DIOXIDE AND METHANE

Carbon dioxide1. Burning of fossil fuels – oil, coal, and natural

gas2. Clearing rainforests and burning the wood

MethaneMethane is mostly produced by anaerobic

decomposition of organic material.1. Rice paddies2.Cattle raising3.Burning of fossil fuels

• http://climate.jpl.nasa.gov/ClimateTimeMachine/climateTimeMachine.cfm

The Vostok Ice Core and how temperature, carbon dioxide, and methane work together.

• As an ice age ends, temperature starts to rise before either carbon dioxide or methane. Cause: Milankovitch cycles.

• As ocean temperatures rises, its ability to absorb CO2 decreases. Then, CO2 begins to increase in the atmosphere. A positive feedback loop is produced.

• Methane hydrate in ocean floor sediments begins to melt, releasing CH4 into the ocean and then into the atmosphere.

• Another positive feedback loop occurs.

Is there agreement among climate scientists about global warming and its cause?

One study found that 97% of climate research scientists agree that…

1. Climate is warming, and 2. Human activities are a significant factor in that warming.

http://tigger.uic.edu/~pdoran/012009_Doran_final.pdf