Checking a climate prediction from 1981

In Now This Is Interesting: A Climate Prediction From 1981 James Fallows looks at a climate prediction made by James Hansen in 1981:

It is very much worth checking out an item on Real Climate, from two Dutch scientists. They have found a paper by James Hansen and others from 1981, before climate change was even an occasion for political disagreement.

Hansen is now famous in the world of climate studies, and infamous to the world of the right wing, but back then he was a 40-year-old researcher who came up with a projection of how rising CO2 levels might affect global temperatures. Science lives for the "falsifiable hypothesis" -- a claim that can be tested against the evidence -- and that is what the paper by Hansen and his colleagues offered up. Three decades later, his worst-case projections were matched against what has happened since then. You should read their full findings, but this gives you the idea.

Basically, actual observations show an increase on 30% over what Hansen predicted. Read the article to see a graph showing the increase.