For those who don't know, scientific estimates - especially those that are high profile, such as, you know, predicting the demise of earth's climate and ecosystems - are conservative by nature. Scientists know complicated models are very difficult to predict accurately in terms of magnitude and timeline. So rather than predicting maximum severity outcome in the near future, they will predict minimum consequences by maximum year. What they predict will - in terms of climate - will be more severe at an earlier year.

In other words, it shouldn't surprise anyone that Greenland is melting faster than predicted. Everything is happening faster than predicted.