2015 Global Sea Level Thread

[AvantHiatus]

Indeed this AMOC event coupled with possible Antarctica WAIS collapse is a recipe for rapid regional SLR and in some cases global SLR depending on various factors.

 

Here is the recent global SLA.

 

 

[AvantHiatus]

[chubbs]

New study in Science (behind a pay wall) indicates we are approaching temperatures that caused more than 6m of sea level rise in recent warm periods. Haven't read article but from Figure in Abstract looks like both WAIS  and Greenland contributed.

 

http://www.sciencemag.org/content/349/6244/aaa4019.abstract

 

 

[wolfpackmet]

CU updated their Global Mean Sea Level (seasonal signals removed) yesterday.  +ENSO will continue to keep values above the long term trend.  Data goes through May 10th.  

 

 

 

 

 

[A-L-E-K]

up up up we go

[chubbs]

This talk will be published as a written paper this fall.

 

 Geophysical Research Abstracts
Vol. 17, EGU2015-8104, 2015
EGU General Assembly 2015

Modeling Antarctica’s contribution to sea-level rise during the Last Interglacial and the future: differing roles of oceanic versus atmospheric warming

 

Rob DeConto (1) and David Pollard (2)

 

(1) Climate System Research Center, Univ. of Massachusetts, Amherst, MA, USA 

(2) EMS Earth/and Environmental Systems Institute, Pennsylvania State University, State College, PA, USA

 

A hybrid ice sheet-shelf model with freely migrating grounding lines is extended by accounting for surface meltwater enhancement of ice shelf calving; and the structural stability of thick, marine-terminating (tidewater) grounding lines. The ice model is coupled to a high-resolution atmospheric model with imposed and simulated ocean temperatures, and applied to past and future climate scenarios. When forced by greenhouse gas and orbital forcing representing the Last Interglacial (LIG; 130 to 115ka), the model simulates an Antarctic global mean sea-level contribution of up to +5m, in agreement with observed estimates. Most of the ice sheet response is driven by circum-Antarctic oceanic warming, rather than atmospheric warming, implying meridional overturning ocean dynamics were an important factor in the timing of Antarctic ice sheet retreat. A long, coupled climate-ice sheet simulation through the entire LIG shows that two peaks in sea level (early and late in the interglacial) are possible, but depend on the timing of Southern Ocean warming relative to local insolation maxima.

 

Using the same atmosphere and ice-model physics used in the LIG simulations, future simulations are run following RCP2.6, 4.5, and 8.5 greenhouse-gas scenarios extended to the year 2500 CE. Ocean temperatures in each scenario are prescribed from offline simulations using the NCAR CCSM4 with 0.5º ocean resolution. As expected, the magnitude and rate of Antarctic ice sheet retreat are highly dependent on which future greenhouse gas scenario is followed, but even the lower emission scenarios produce an Antarctic contribution of several meters within the next several centuries. Once atmospheric CO2 concentrations exceed 2x preindustrial levels, we find that hydrofracturing by surface melt on ice shelves can trigger large-scale ice sheet retreat, regardless of circum-Antarctic ocean warming. Hence, unlike the LIG, atmospheric (not ocean) warming has the potential to become the primary mechanism driving future retreat of the Antarctic ice sheet. In simulations without atmospheric warming, we find small amounts of ocean warming can still produce large-scale retreat of the West Antarctic Ice Sheet, although the timescale of ocean-driven retreat is slower than atmospherically driven retreat.

 

In sum, these results suggest past Pleistocene episodes of Antarctic ice loss were primarily driven by Southern Ocean warming, which in itself has serious implications for future commitment to sea-level rise given current rates of ocean heat uptake. However, we also find that atmospheric warming and surface melt on ice shelves (driving hydrofracturing and ice shelf breakup) will take over as the dominant driver of future Antarctic ice loss if greenhouse gas emissions continue unabated, making the LIG and other Pleistocene interglacials poor mechanistic analogues for future sea-level rise.

 

http://meetingorganizer.copernicus.org/EGU2015/EGU2015-8104.pdf

[AvantHiatus]

Two-pronged attacked via bottom melt and surface hydrofracturing. This can only imply faster rises than which occured in the Eemian, but primarily post-2100 to the best of my knowledge. Hansen's range of 3-7m by 2100 seems reasonable at this point.

[HailMan06]

Two-pronged attacked via bottom melt and surface hydrofracturing. This can only imply faster rises than which occured in the Eemian, but primarily post-2100 to the best of my knowledge. Hansen's range of 3-7m by 2100 seems reasonable at this point.

You think we could have a 7 meter sea level rise in 85 years? That's nearly 23 feet.

[AvantHiatus]

You think we could have a 7 meter sea level rise in 85 years? That's nearly 23 feet.

You're killing me bro, 7m would be on the tail uncertainty range, aka highly unlikely. I'm thinking approx. 4.5m in 85 years.

 

As you may have surmised, we are in for some crazy stuff in even the next 30 years.

[chubbs]

Aviso sea level plot updated through May. Still running above the trendline in this warm ENSO phase. 

 

http://www.aviso.altimetry.fr/en/data/products/ocean-indicators-products/mean-sea-level.html

 

 

 

[The_Global_Warmer]

And seasons peak isn't until November.

I'm guessing that's related to snow and rivers freezing locking water in.

[chubbs]

And seasons peak isn't until November.

I'm guessing that's related to snow and rivers freezing locking water in.

 

The chart above is seasonally adjusted. There was an unusually small sea level decrease during the 2014-15 NH cool season minimum. Too early to say much about this summer's melt season.

[chubbs]

Increased threat of tropical cyclones and coastal flooding to New York City during the anthropogenic era

 

Andra J. Reed^a,¹,Michael E. Mann^a,^b,Kerry A. Emanuel^c,Ning Lin^d,Benjamin P. Horton^e,^f, Andrew C. Kemp^g, and Jeffrey P. Donnelly^h

 

Abstract

In a changing climate, future inundation of the United States’ Atlantic coast will depend on both storm surges during tropical cyclones and the rising relative sea levels on which those surges occur. However, the observational record of tropical cyclones in the North Atlantic basin is too short (A.D. 1851 to present) to accurately assess long-term trends in storm activity. To overcome this limitation, we use proxy sea level records, and downscale three CMIP5 models to generate large synthetic tropical cyclone data sets for the North Atlantic basin; driving climate conditions span from A.D. 850 to A.D. 2005. We compare pre-anthropogenic era (A.D. 850–1800) and anthropogenic era (A.D.1970–2005) storm surge model results for New York City, exposing links between increased rates of sea level rise and storm flood heights. We find that mean flood heights increased by ∼1.24 m (due mainly to sea level rise) from ∼A.D. 850 to the anthropogenic era, a result that is significant at the 99% confidence level. Additionally, changes in tropical cyclone characteristics have led to increases in the extremes of the types of storms that create the largest storm surges for New York City. As a result, flood risk has greatly increased for the region; for example, the 500-y return period for a ∼2.25-m flood height during the pre-anthropogenic era has decreased to ∼24.4 y in the anthropogenic era. Our results indicate the impacts of climate change on coastal inundation, and call for advanced risk management strategies.

 

http://www.pnas.org/content/early/2015/09/24/1513127112

 

 

 

[AvantHiatus]

[chubbs]

Seasonally adjusted sea level from UColorado through July. Continues to increase faster than the trend line with ENSO likely enhancing.

 

[skierinvermont]

Seasonally adjusted sea level from UColorado through July. Continues to increase faster than the trend line with ENSO likely enhancing.

 

CU_sealevel.png

 

OHC and sea level should increase more during La Ninas than El Ninos. Higher trade winds during La Ninas mix warm surface water deeper and bring cold water to the surface which radiates less energy to space.

[nflwxman]

OHC and sea level should increase more during La Ninas than El Ninos. Higher trade winds during La Ninas mix warm surface water deeper and bring cold water to the surface which radiates less energy to space.

That's not entirely true. La Niña events actually redistribute a lot of water into the water tables of continents which inherently removes additional volume from the ocean (albeit, a small amount). El Ninos are the opposite, in which the heaviest precipitation is usually found over the ocean.

http://www.cgd.ucar.edu/cas/Staff/Fasullo/my_pubs/Boening2012etalGRL.pdf

[AvantHiatus]

Either way there are ominous signals in the system, perhaps presenting as a polynomial curve.

[ORH_wxman]

That's not entirely true. La Niña events actually redistribute a lot of water into the water tables of continents which inherently removes additional volume from the ocean (albeit, a small amount). El Ninos are the opposite, in which the heaviest precipitation is usually found over the ocean.

http://www.cgd.ucar.edu/cas/Staff/Fasullo/my_pubs/Boening2012etalGRL.pdf

 

Yep, El Ninos have historically seen larger SLR than La Ninas because of this.

[salbers]

El Nino correlates pretty well with Sea Level as can be seen here:

 

 

The latest CU Sea Level data are here:

 

http://sealevel.colorado.edu/

 

 

[Mallow]

El Nino correlates pretty well with Sea Level as can be seen here:

 

sl_mei.png

 

The latest CU Sea Level data are here:

 

http://sealevel.colorado.edu/

 

With detrended sea level.

[AvantHiatus]

The 1992-2010 era is a bad analog for what's ahead. I often feel like a broken record but I am very confident about this, especially considering the doubling period for SLR is about 15 years currently. 

 

Thanks Mallow.

 

Sea level has increased 3.4" in about 22 years. That's substantial almost alarming when you consider the doubling period.

[salbers]

Thanks for the clarification. Indeed the plot 3 posts up (and my intent) is to show detrended sea level.

 

As for the doubling period of sea level rise, the trend shown in the CU data is pretty linear so far. Hard to consider this as evidence of acceleration over the past 20 years or so. A linear trend equates to an infinite doubling period.

[Jonger]

I actually think sea level rise has been underwhelming compared to how much the earth has warmed.

 

The rate is nearly the same as before CO2 really started impacting anything.

 

[salbers]

Looks like the tide gauges show a slow acceleration.

 

It seems the expansion of the oceans has so far been dominant and roughly linear. The ice melt may have a more rapid doubling and as it becomes a greater share of the overall sea level rise, we'll see this accelerate more. Thus relatively large sea level rises by 2100 are still possible.

[wolfpackmet]

A little more noticeable acceleration from this Columbia graphic which uses C.C Hay, et al. approach.  

http://www.columbia.edu/~mhs119/SeaLevel/

 

[chubbs]

El Nino correlates pretty well with Sea Level as can be seen here:

 

 

The latest CU Sea Level data are here:

 

http://sealevel.colorado.edu/

 

Nice chart. Note that in 1997 and 2009 SLR lagged the ENSO metric slightly but appears to be leading ENSO slightly this year. Would be interesting to look at the timing of tropical rainfall shifts this year.

[The_Global_Warmer]

Global sea level rise is accelerating.

Going back to 2008 we get about a 4-5MM/yr trend.

Going back to 2011 that jumps to about 7-8mm/yr.

And that's with trmming 5MM off from enso warming.

But OHC isn't going to drop much so a big reason for the acceleration is global land ice loss.

[chubbs]

Article on living with nuisance flooding along Jersey shore.

 

http://www.app.com/story/news/local/land-environment/enviroguy/2015/11/24/residents-resist-tidal-flooding-increasing-threat-jersey-shore/75893620/

 

[AvantHiatus]

Article on living with nuisance flooding along Jersey shore.

 

http://www.app.com/story/news/local/land-environment/enviroguy/2015/11/24/residents-resist-tidal-flooding-increasing-threat-jersey-shore/75893620/

 

floodingNJnuisance.jpg

If you look closely, you can see disinformation or a kind of reassurance in these articles. Down here, there is a large subset of conservative people who won't accept the reality of what's coming. You can see it most strongly in local newspapers.

 

In addition, we know the Mid-Atlantic is a SLR hotspot due to various factors. 1-2ft was the amount of SLR pedicted by IPCC in the 21st century globally less than a decade ago. We can see how this is highly misguided and that Hansen and the latest SLR research has a better handle on where we are going.

 

Perhaps I'm looking too deeply into this, but there should be more emphasis on climate change rather than natural factors such as el nino and storminess which no doubt multiply the anthropogenic signal.

 

 

Sea levels have risen about 1.3 feet in the past 100 years, typical for the mid-Atlantic region