Scientists here are concerned about data. In Africa, we heard yesterday, the amount of data from river gauges being sent to international databases has decreased by some 90% since 1990 – not a promising statistic given the vast importance of water flow to that continent. And today Kevin Trenberth of NCAR hammered home the potential upcoming problems with earth-observing satellite data.

Many such satellites, including ones monitoring solar radiation for example, aren’t accurate enough to produce absolute numbers. Instead scientists can really only trust the trend in the data. But that confidence dissolves as we switch from one satellite to another. Unless the satellites overlap, in which case you can reasonably compare one to another and carry the data set forwards, it’s difficult or impossible to compare the new data with the old.

Observations typically do overlap. But it isn’t guaranteed. Recent cuts may mean a gap in satellite records sometime around 2013 or so, he says. But they’re petitioning hard to fill that, and will hopefully succeed.