Atlantic hurricane surge response to geoengineering

Devastating floods due to Atlantic hurricanes are relatively rare events. However, the frequency of the most intense storms is likely to increase with rises in sea surface temperatures. Geoengineering by stratospheric sulfate aerosol injection cools the tropics relative to the polar regions, including the hurricane Main Development Region in the Atlantic, suggesting that geoengineering may mitigate hurricanes. We examine this hypothesis using eight earth system model simulations of climate under the Geoengineering Model Intercomparison Project (GeoMIP) G3 and G4 schemes that use stratospheric aerosols to reduce the radiative forcing under the Representative Concentration Pathway (RCP) 4.

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Moore J. C., A. Grinsted, X. Guo, X. Yu, S. Jevrejeva, A. Rinke, X. Cui, B. Kravitz, A. Lenton, S. Watanabe, D. Ji (2015) Atlantic hurricane surge response to geoengineering, Proceedings of the National Academy of Sciences, doi:10.1073/pnas.1510530112 Share

Optimistic & over-confident ice sheet projections in AR5

Take away message: The graph on the right shows that AR5 process based ice sheet projections are optimistic and over confident when compared to views of ice sheet experts. To be fair they do mention a possible collapse scenario which could close the gap.

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More and Stronger Hurricane surges

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Digitizing pdf figures using inkscape

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Sea level, the moon, and Frankenstein

Jens Morten Hansen (JMH) and co-authors have recently published a study where they use sine-regression to fit 5 oscillations plus a linear trend to a 160-year sea level record from waters near Denmark (a stack of local GIA corrected tide gauge records). They then observe that the sines-plus-trend model correlates highly with the record it was fitted to, after applying a 19-year moving average. This should be unsurprising as the procedure guarantees high correlation, regardless of input data (see figure). This result is clearly not significant in any meaningful sense of the word.

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Three views on sea level commitment

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Sea level rise projections for Northern Europe under RCP8.5

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Grinsted, Jevrejeva, Riva, Dahl-Jensen (2015), Sea level rise projections for Northern Europe under RCP8.5, Clim. Res., doi:10.3354/cr01309 Share

BACCII chapter on Baltic sea level projections

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Grinsted, A. (2015). Projected Change—Sea Level. In Second Assessment of Climate Change for the Baltic Sea Basin (pp. 253-263). Springer International Publishing. Share

Trends and acceleration in global and regional sea levels since 1807

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Jevrejeva, S., Moore, J. C., Grinsted, A., Matthews, A. P., & Spada, G. (2014). Trends and acceleration in global and regional sea levels since 1807. Global and Planetary Change, 113, 11-22. doi:10.1016/j.gloplacha.2013.12.004 Share

Finnish Antarctic expedition 2006-2007 blog

In the austral summer 2006⁄07 i was part of an ~100 day expedition to Scharffenbergbotnen, Heimefrontfjella, Antarctica with FINNARP. There we collected a ~2.5km long horizontal ice core. We kept a blog of our field work.

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Ice sheet pessimists are not outliers

Bamber and Aspinall 2013 published a formal expert elicitation on the future of our two ice sheets, and found a large spread between individual expert answers. It has been argued by them,  and others that there are outlier experts in the data, and that they drive the long-tails of the pooled uncertainty distribution. I wonder if that is really true or whether it could be a visual artifact from drawing samples from a long tailed distribution. When you plot samples from a long tailed distribution then of course the tail values will appear to stand out, but that does not necessarily make them outliers. The question is really whether there are two groups of experts optimists vs. pessimists or whether they all have been sampled from a continuum of experts.

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Ice sheet contributions to SLR from Bamber & Aspinall

Bamber and Aspinall (2013) carried out an expert elicitation of ice sheet experts. From this they could derive uncertainty ranges of the rate of mass loss from each ice sheet in 2100. In order to calculate the total 21st century contribution to sea level rise we need to integrate the rates. This is what I do in the two tables in the results section below.**

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