[kpil]

Yes, interesting question.

(Other sources are what? Arctics? Heat expansion?)

Anyway, I particularly like that they are doing observations rather than just faffing around with models. Models are good, but data is better.

[baobabaobab]

The other sources are glacial melt, heat expansion, and water storage on land decreasing.

You need both the models and the data. Facts without theory answer only what happened, not why, you can't make projections without theory. Theory without facts... pretty obvious problem there.