Experts say the IPCC underestimated future sea level rise

[n2doc]

Posted on 4 December 2013 by John Abraham
It looks like past IPCC predictions of sea level rise were too conservative; things are worse than we thought. That is the takeaway message from a new study out in Quaternary Science Reviews and from updates to the IPCC report itself. The new study, which is also discussed in depth on RealClimate, tries to determine what our sea levels will be in the future. What they found isn't pretty.

Predicting of sea level rise is a challenging business. While we have good information about what has happened in the past, we still have trouble looking into the future. So, what do we know? Well it is clear that sea levels began to rise about 100 years ago. This rise coincided with increasing global temperatures.

What causes sea level to rise? Really three things. First, water expands as it heats. Second, glaciers melt and water flows to the oceans. Third, the large ice caps on Greenland and Antarctica can melt and the liquid water enters the ocean; often the water transfer is added by calving at the ice fronts which result in icebergs that float into the ocean. In the past, much of the sea level rise was related to the first cause (thermal expansion). Now, however, more and more sea level rise is being caused by melting ice.

But this is all the past. What we really want to know is, how much will sea level rise in the future? There are a number of ways to predict the future. First, we can look at the deep past and see how sea level changed with Earth temperature long ago.

A second way to predict the future is through computational models. These models are computer programs which create a virtual-reality of the Earth. These virtual reality models are very useful because they allow scientists to play "what if" scenarios; but, they have their weaknesses as well. One of their weaknesses is that they don't necessarily capture all of the phenomena which cause sea level rise. It is believed by most scientists that the computer programs are too conservative.

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http://skepticalscience.com/experts-IPCC-underestimated-sea-level-rise-Rahmstorf.html

[Bill USA]

1. interesting to note that the IPCC did not factor in any impacts due to thawing permafrost..(?!).

...methane has 34 times the heat trapping capacity of CO2 over a 100 yr period (75 times till it breaks down into CO2 in 20-30 yrs).

recommended.

[joshcryer]

2. IPCC is always way conservative.

They don't want to come off as "alarmist."

This admission is something we've known since AR4 and it's uncontroversial in environmentalist circles. If they don't even include Greenland or Antarctic melting in their calculations you know it's not going to be accurate.