Sea-level rise from glaciers and ice caps: A lower bound (min. 151mm—probably 373mm in 100 yr)

[OKIsItJustMe]

http://dx.doi.org/10.1029/2008GL036309

Sea-level rise from glaciers and ice caps: A lower bound

David B. Bahr
Department of Physics and Computational Science, Regis University, Denver, Colorado, USA

Mark Dyurgerov
Institute of Arctic and Alpine Research, University of Colorado, Boulder, Colorado, USA

Mark F. Meier
Institute of Arctic and Alpine Research, University of Colorado, Boulder, Colorado, USA

One of the most easily measured dimensions of a glacier, the accumulation area, is linked to future changes in glacier volume and consequent changes in sea level. Currently observed accumulation areas are too small, forcing glaciers to lose 27% of their volume to attain equilibrium with current climate. As a result, at least 184 ± 33 mm of sea-level rise are necessitated by mass wastage of the world's mountain glaciers and ice caps even if the climate does not continue to warm. If the climate continues to warm along current trends, a minimum of 373 ± 21 mm of sea-level rise over the next 100 years is expected from glaciers and ice caps. When compared to recent estimates from all other sources, melt water from glaciers must be considered as a particularly important fraction of the total sea-level rise expected this century.

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[NYC_SKP]

1. A related question re: sea level rise.

I've read that some believe that warming oceans might be a significant component of sea level rise.

I intuitively believe that the massive heat sink presented by the oceans would be resistant to the kind of temperature change that could cause enough expansion to become a concern.

What, if anything, have you read about this?

[muriel_volestrangler]

2. Tricky - fresh water is at its most dense at about 4 degrees C

http://www.lsbu.ac.uk/water/explan2.html#density

Which would mean that temperature rises in fresh water wouldn't necessarily mean expansion - it would depend at what temperature bits of it were at.

However, it's possible that seawater behaves differently.

On edit:

A summary of the 4th IPCC report on thermal expansion:

If radiative forcing were to be stabilized in 2100 at A1B levels, thermal expansion alone would lead to 0.3 to 0.8 m of sea level rise by 2300 (relative to 1980–1999). Thermal expansion would continue for many centuries, due to the time required to transport heat into the deep ocean. {10.7}
...
1. Thermal expansion (warmer ocean water takes up more space) is computed from coupled climate models. These include ocean circulation models and can thus estimate where and how fast the surface warming penetrates into the ocean depths.
...
As an example, take the A1FI scenario – this is the warmest and therefore defines the upper limits of the sea level range. The “best” estimates for this scenario are 28 cm for thermal expansion, 12 cm for glaciers and -3 cm for the ice sheet mass balance – note the IPCC still assumes that Antarctica gains more mass in this manner than Greenland loses. Added to this is a term according to (4) simply based on the assumption that the accelerated ice flow observed 1993-2003 remains constant ever after, adding another 3 cm by the year 2095.

http://www.realclimate.org/index.php/archives/2007/03/the-ipcc-sea-level-numbers/

This NASA article shows some of the work on this - they look at both deep ocean expansion and surface water (both of which are reckoned to be positive, so my remarks about density up above may be a red herring).