Chapter 2

Updated versions of Figs. 2.2, 2.4, 2.7, and 2.10 can be found here.  They have been updated to Jan. 2017.

State of the Climate

This is a nice explanation how global avg. temperatures are calculated.

Every year, NOAA puts out a summary of climate statistics and figures, entitled State of the Climate.  You can see the latest one here.  

If you're interested in looking at data yourself, NOAA also has a primer on climate data.

Check out NOAA's climate explorer and climate at a glance web pages to see what the climate in your area (or any area) looks like.

calculate the trend yourself

SkepticalScience has a nice web page where you can do your own temperature trend calculation. If your friend tells you the Earth is not warming, tell them to check it out for themselves.

Another neat way to visualize the climate is to look at maps of temperature anomalies.  NOAA has a cool website where you can do that.

history of warming

In 1938, Guy Stewart Callendar was the first to demonstrate that the Earth's land surface was warming. Callendar also suggested that the production of carbon dioxide by the combustion of fossil fuels was responsible for much of this modern change in climate. This short note analyzes Callendar's landmark study and demonstrates that his global land temperature estimates agree remarkably well with more recent analyses.

short-term variability

Understanding how short-term climate variability can mask long-term climate change is an important concept. This video is a very cute illustration of why the warming will occasionally pause, even when the climate is, on average, warming. Conclusion to remember: when you look at temperature data, you see the dog, but understanding climate change means trying to infer from the dog what the man is doing. For short periods of time, that can be hard because they can be going in opposite directions.

Watch a visualization of northern hemisphere temperatures and see how the distribution of temperatures shifted over the 2nd half of the 20th century to warmer temperatures. The x-axis is standard deviations, and it shows a dramatic increase in 3- and 4-sigma events.

Paleoclimate Variations

See this Annan and Hargreaves paper for estimates of the temperature of the last glacial maximum. They estimate that the LGM was 4°C cooler than today.

For a detailed summary of what the warmth of the Eocene and the abrupt warming of the PETM can tell us, see this great review paper by Richard Alley.

A view from the skeptical side ...

Dr. Fred Singer is a very well known climate contrarian who does not believe the Earth is warming. Watch dueling presentations from Prof. Dessler and Dr. Singer on this question.