The rapid thinning, acceleration and retreat of Helheim, Jakobshavns and Kangerdlugssuaq glaciers in Greenland, all in close association with one another, suggests a common triggering mechanism, such as enhanced surface melting due to regional climate warming or a change in forces at the glacier front. The enhanced melting leading to lubrication of the glacier base has been observed to cause a small seasonal velocity increase and the release of meltwater lakes has also led to only small short term accelerations. The significant accelerations noted on the three largest glaciers began at the calving front and propagated inland and are not seasonal in nature. Thus, the primary source of outlet glacier acceleration widely observed on small and large calving glaciers in Greenland is driven by changes in dynamic forces at the glacier front, not enhanced meltwater lubrication. This was termed the "Jakobshavns Effect" by Terence Hughes at the University of Maine in 1986. Indeed, a study published in 2015 on glacial underwater topography at 3 sites found cavities, due to warm subglacial water intrusion, which has been identified as a possible dominant force for ablation (surface erosion). Thus, suggests ocean temperature controls ice sheet surface runoff at specific sites. These findings also show that models underestimate the sensitivity of Greenland glaciers to ocean warming and resulting ice sheet runoff. Hence, without better modelling, new observations suggest that past projections of sea level rise attribution from the Greenland Ice Sheet require upward revision.