Beautiful satellite image of Mauna Loa at NASA's Earth Observatory site, with contours drawn in. Look at those lovely flows! But what's particularly interesting about this post is the discussion of why the Mauna Loa Observatory is such a good location for measuring the CO2 content of the atmosphere, and how emissions of that gas are filtered out of the data accumulated there. Essentially, the prevailing winds only rarely carry emissions from the summit to the observatory, and when they do, it's obvious what's happening. Those data points are simply not counted; what they're looking for is long-term averages and trends, not spikes.