Having now submitted a review of the empirical support for weakening of the Walker circulation to the Journal of Geophysical Research, I can get back to the “Is the sea level rise accelerating?” article. The abstract is below:
No Significant Basis for Acceleration in Sea level Rise Last Century
Abstract: Various authors have claimed that sea level rise is accelerating. This assumption is responsible for the high end projections for sea level by the year 2100. We evaluate three main datasets, and two studies, finding no support for an acceleration term in models fit to sea level over the 20th century, and a significant deceleration in satellite altimeter readings from 1993. The only empirical basis for sea-level acceleration arises from the inclusion of data prior to 1900, which cannot be attributed to the influence of greenhouse gases. Moreover, core references for projected sea level rise contain errors and imprecision that bias upward projections for sea level in 2100. We conclude that acceleration of sea level rise both in observations and the projections of climate models cannot be substantiated at this time. We find broad justification and agreement for empirical linear models, greatly reducing CI projections based on linear extrapolation.
It was interesting to find a reservation in the post at RealClimate today about projections for the future — something you won’t find in the published articles.
How do we know that the relationship between temperature rise and sea level rate is linear, also for the several degrees to be expected, when the 20th century has only given us a foretaste of 0.7 degrees? The short answer is: we donâ€™t.
In other words, this is an admission that the models are based on speculative assumptions. When we stick to the facts, it will become clear, there is no basis for belief in non-linearity (aka acceleration) either over temperature or time.
The other interesting admission below, identifies the RC team as advocates, and hence not the place to look for scientific objectivity. If one were equally cautious that would be objective, but Rahmstorf then goes on to justify a bias. It sounds like to them, erring on the high side is unbiased.
In our view, when presenting numbers to the public scientists need to be equally cautious about erring on the low as they are on the high side. For society, after all, under-estimating global warming is likely the greater danger.