Update (Jul 28, 2008): On Jan 18, 2008, two days after this article was posted, RSS issued a revised version of their data set. The graphics below are based on RSS versions as of Jan 16, 2008, the date of this article, and, contrary to some allegations on the internet, I did not “erroneously” use an obsolete data set. I used a then current data set, which was later adjusted, slightly reducing the downtick in observations. On Jan 23, 2008, I updated the graphic comparing Hansen projections using the revised RSS version. Today I re-visited this data, posting a further update of this data including the most recent months. While some commentators have criticized this post because the RSS adjustment reduced the downtick slightly, the downtick based on the most recent data as of July 28, 2008 is larger than the RSS adjustment as of Jan 2008.)

In 1988…