In Case You Missed It...

From the National Climatic Data Center at the Department of Commerce report State of the Climate in 2009, the opening paragraph of the Report at a Glance:

A comprehensive review of key climate indicators confirms the world is warming and the past decade was the warmest on record. More than 300 scientists from 48 countries analyzed data on 37 climate indicators, including sea ice, glaciers and air temperatures. A more detailed review of 10 of these indicators, selected because they are clearly and directly related to surface temperatures, all tell the same story: global warming is undeniable. [emphasis added]

Let's be honest, though. This is just the conclusion. Any (and I mean this sincerely) curious person has to ask some questions about that paragraph, if only to fill in the blanks. The report mentions 10 "key indicators." What sorts of "indicators" are we talking about? And what's the evidence for each?

The ten indicators are:

• Air Temperature Near Surface (Troposphere). Seven data sets.
• Humidity. Three data sets.
• Temperature Over Oceans. Five data sets.
• Sea Surface Temperatures. Six data sets.
• Sea Level. Six data sets.
• Ocean Heat Content. Seven data sets.
• Temperature Over Land. Four data sets.
• Sea Ice. Three data sets.
• Glaciers. Four data sets.
• Snow Cover. Two data sets.

If you click on the links you'll find a multi-colored graph that describes the data as well as a reference to the source of the data itself. The report goes on to say that the first seven of these are increasing and the last three are decreasing.

But isn't it possible for the data sets for each indicator to, you know, overlap? Because if six sets all copy the seventh and the seventh is flawed, then you really only have one flawed set masquerading as seven that all conveniently corroborate each other.

That's correct, my young Jedi, it is possible. Only in this case, the text on the page summarizing all the graphs reads:

The panels on this page show changes in climate indicators over several decades. Each of the different colored lines in each panel represents an independently analyzed set of data. The data come from many different technologies including weather stations, satellites, weather balloons, ships and buoys. [emphasis added]

Now before someone from the Trib screams Climategate!, let me quote something Chapter 2 of the full report, titled How Do We Know The World Has Warmed?

Although the IPCC AR4 concluded that “warming of the climate system is unequivocal,” public debate over the evidence for global warming continues. However, it is often confined to a small set of reiterated disputes about Land Surface Air Temperature (LSAT)records, diverting attention from the broader evidence basis.

The methods used to derive the principal estimates of global sur face temperature trends — HadCRUT3 (Brohan et al. 2006), NOA A (Smith et al. 2008), and NASA/GISS (Hansen et al. 2001)—are largely independent. So, the spread of the three estimates indicates the likely degree of uncertainty in the evolution of the global mean surface temperature.

And then a little bit later:

The IPCC conclusion (Alley et al. 2007) that “warming of the climate system is unequivocal” does not rest solely upon LSAT records. These constitute only one line of evidence among many, for example: uptake of heat by the oceans, melting of land ice such as glaciers, the associated rise in sea level, and increased atmospheric surface humidity. If the land surface records were systematically flawed and the globe had not really warmed, then it would be almost impossible to explain the concurrent changes in this wide range of indicators produced by many independent groups. The observed changes in a broad range of indicators provide a self-consistent story of a warming world. [emphasis added.]

Undeniable.