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

Three recent papers on long term sea level commitment:

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Sea level rise projections for Northern Europe under RCP8.5

Sea level rise poses a significant threat to coastal communities, infrastructure, and ecosystems. Sea level rise is not uniform globally but is affected by a range of regional factors. In this paper, we calculate regional projections of 21st century sea level rise in Northern Europe, focusing on the British Isles, the Baltic, and the North Sea.

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

BACCII chapter on Baltic sea level projections

Global warming is causing sea levels to rise, primarily due to loss of land-based ice masses and thermal (steric) expansion of the world oceans. Sea level does not rise in a globally uniform manner, but varies in complex spatial patterns. This chapter reviews projections of the individual contributions to sea-level rise. These are used to assemble a mid-range scenario of a 0.70 ± 0.30-m sea-level rise over the twenty-first century (based on the SRES A1B scenario) and a high-end scenario of 1.10 m.

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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

We use 1277 tide gauge records since 1807 to provide an improved global sea level reconstruction and analyse the evolution of sea level trend and acceleration. In particular we use new data from the polar regions and remote islands to improve data coverage and extend the reconstruction to 2009.

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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. 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.

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Ice sheet contributions to SLR from Bamber and 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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Image GeoRectification And Feature Tracking toolbox, ImGRAFT

The use of time-lapse camera systems is becoming an increasingly popular method for data acquisition. The camera setup is often cost-effective and simple, allowing for a large amount of data to be accumulated over a variety of environments for relatively minimal effort. The acquired data can, with the correct post-processing, result in a wide range of useful quantitative and qualitative information in remote and dangerous areas.

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Messerli, A. and Grinsted, A. (2015), Image GeoRectification And Feature Tracking toolbox: ImGRAFT, Geosci. Instrum. Method. Data Syst., 4, 23-34, 10.5194/gi-4-23-2015 Share

West Antarctic collapse in the IPCC reports

I have extracted some quotes from the IPCC reports since 1990 showing how West Antarctic Ice Sheet collapse has been discussed over time. It is not an exhaustive list.

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A Danish perspective on AR5WG2: Impacts, Adaptation, and Vulnerability

Analyse af IPCC delrapport 2 med et fokus på Danmark:

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Analyse af IPCC delrapport 2 - Effekter, klimatilpasning og sårbarhed : med særligt fokus på Danmark. / Christensen, Jen Hesselbjerg; Arnbjerg-Nielsen, Karsten; Grinsted, Aslak; Halsnæs, Kirsten; Jeppesen, Erik; Madsen, Henrik; Olesen, Jørgen Eivind; Porter, John Roy; Refsgaard, Jens Christian; Olesen, Martin.København : Miljøministeriet, Naturstyrelsen, 2014. 54 p. Share

Review of global glacier volume estimates

This is an updated version of the regularized global glacier volume estimates from Cogley (2012). I have included 2 new estimates: one by myself (G13) and another from Huss and Farinotti (HF12). These two papers are the first to use the new Randolph Glacier Inventory (they used v2).

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