Sea level measured by satellite altimeter (red with linear trend line; AVISO data from (Centre National d’Etudes Spatiales) and reconstructed from tide gauges (orange, monthly data from Church and White, 2011). Tide gauge data were aligned to give the same mean during 1993–2010 as the altimeter data. The scenarios of the IPCC are again shown in blue (third assessment) and green (fourth assessment); the former published starting in the 1990 and the latter from 2000. Graphic:

By dana1981
30 January 2013

A paper recently published in Global Environmental Change by Brysse, et al., (2012) examined a number of past predictions made by climate scientists, and found that that they have tended to be too conservative in their projections of the impacts of climate change.  The authors thus suggest that climate scientists are biased toward overly cautious estimates, erring on the side of less rather than more alarming predictions, which they call "erring on the side of least drama" (ESLD).

In this paper, Brysse et al. examined research evaluating past climate projections, and considered the pressures which might cause climate scientists to ESLD.

Conservative Climate Projections

While we have recently shown that the Intergovernmental Panel on Climate Change (IPCC) temperature projections have been exceptionally accurate, several other projections in the IPCC reports have been far too conservative. 

Sea Level Rise

For example, Rahmstorf (2007) and more recently Rahmstorf et al. (2012) showed that sea level is rising at a rate inconsistent with all but the highest IPCC scenarios (Figure 1).  Rahmstorf et al. (2012) concluded, “The satellite-based linear trend 1993–2011 is 3.2 ± 0.5 mm yr-1, which is 60% faster than the best IPCC estimate of 2.0 mm yr-1 for the same interval.”

The main reason these sea level rise projections have been too low and that the IPCC almost certainly underestimates future sea level rise is that their models do not include the effects of dynamic ice processes from chunks of ice breaking off into the ocean ("calving"), then melting.  The IPCC approach in attempting to account for these processes considers recent contributions to sea level rise from ice sheet melt, then "assume that this contribution will persist unchanged."  This is certainly a conservative approach, and the primary reason their sea level projections have been low. [more]

Climate Scientists Erring on the Side of Least Drama


  1. Anonymous said...

    Thank you Des, appreciate your consistent and faithful reporting of our unfolding planetary disaster(s).

    The IPCC only represents some of the science -- definitely not all of it -- and has consistently erred on the side of caution. Critical components have been entirely omitted however, leading to far more optimistic projects then reality dictates.

    Scientific reticence to raise the alarm adequately in light of ALL the data have been devastating for the political process and public awareness.

    Now, both science and the IPCC admit how far off they have been with their under projections. The end result of these combined failures is "catastrophic", because critical time has been wasted whereby necessary changes should have been made.

    Now we are undeniably committed to 4C+ warming in just a couple decades, which will make much of the country uninhabitable and unproductive (food crops and lack of water).

    These oversights are unforgivable, because they spell die-off, a death toll that will reach into the millions.

    Under any other scenario (war for example), this would be called genocide.

    But what we are really talking about here is speciescide, the extinction of uncountable number of species (plant, animal, insect, marine) that cannot either migrate or adapt fast enough.

    Wet-bulb temperatures will cause all things that cannot respirate fast enough to simply die out.

    Humans can move -- and will try to, en masse from too hot region (entire South from Florida to California), abandoning uninhabitable regions, drought, and lack of water, displacing over millions people. Coastal area throughout the entire world will also displace over a hundred million from rising seas. In the US, this means ALL coastal states including Alaska, Florida, California, the entire East coast and so forth as oceans rise, and aquifers are turned brackish or ruined and storms increase.

    New York city is "toast", probably the only good thing to come of this (punishment finally for Wall Street crimes). But to all the good people who live there - they will have to relocate.

    The complete failure to honestly address these issues in these reports is unforgivable. "Erring on the side of the least drama" is a gigantic understatement.  

  2. rpauli said...

    I consider Des to be part of my regular diet of climate news.

    And comments such as this above, to be the wise spice so necessary for insight.

    Thank you Anonymous.  


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