[Arragonis]

Originally Posted by jamesqf

I don't quite get it. The "big melt" described in that article does show up on the reconstruction graph, and it's only a fraction of the melting observed today.

There's a wiggle but its all be smoothed out.

Originally Posted by jamesqf

Seems obvious to me. There is a period of time for which they have both satellite observations and the data from which the reconstruction was done. The satellite observations are overlaid on the graph to show that for that period, the reconstruction is a very good match to satellite data.

Satelites starts in 1979, observations start well before that on that graph. Observations pre-war would not include Aircraft (much), or radar (still a military secret) or satelites. Just ships and observations from people in the area.

And they should match because those observations are used to calibrate the "models" - remember, measure x vs y, create relationship, verify against another period of x vs y... Tapping of which

Originally Posted by NeilBlanchard

We have a way to measure the extent of ice, and as I understand it, it has to do with the different way sediments on the ocean bottom collect under the ice and under open water.

The melting now is unprecedented in recorded history. If all the ice melts in the summer, then that is the first time in like a million years or more that this has happened.

Edit: here's the Danish map from August 1923: http://brunnur.vedur.is/pub/trausti/...23/1923_08.pdf.

The captions on the top, right of the map show how it was done - over time. Today a satelite can do a snapshot which is how we get day by day charts and figures. This map was made up of observations probably over a whole season - look at the day to day stats from last years melt - how fast the measurements went down when the ice broke up from the storm, and how fast it recovered when the broken ice refroze into detectable pieces. All inside of a single season.

We can detect this today, it was much harder then.

So we have 3 sets of figures
- Modern satelites
- "Observations" pre satelites - probably aircraft and radar post WW2, pre WW2 ships and reports (the red spots on the map above)
- Reconstructions beforehand

Originally Posted by NeilBlanchard

If the drought continues or reoccurs soon, it will be due to climate change. This may be a matter of semantics, though.

ThinkProgress say "WE'RE DOOMED", NOAA says "Nothing to do AGW".