More than 2.5m Sea Level Rise by 2040?

A warming period more than 400,000 years ago pushed the Greenland ice sheet past its stability threshold (which may have been no more than several degrees above pre-industrial temperatures). This resulted in a nearly complete deglaciation of southern Greenland, raising global sea levels some 4.5-6 meters, found a recent study by Reyes et al. Due to melting elsewhere, global mean sea level then was 6 to 13 metres above the present level. Indeed, melting of the entire West Antarctic Ice Sheet can add a further 6-meter rise in sea levels. If the East Antarctic Ice Sheet (EAIS) were to melt as well, sea levels would rise by around 70 metres.

Sea level is now rising by 3.1mm (0.122 inch) per year. Much of this rise is due to rising temperatures, but there are also other factors. One quarter of the rise results from groundwater depletion, while run off from melting ice and glaciers adds another quarter and the remainder is attributed to thermal expansion of sea water. Furthermore, as temperatures rise, feedbacks start to kick in, e.g. the kinetic energy from stronger waves and more intense storms can speed things up.

Clearly, a rapid multi-meter rise would be devastating as it would flood many coastal cities, as well as much of the land now used to grow food. By how much have sea levels been rising recently and how fast can they be expected to rise in the near future?

NASA image, data by the JPL PODAAC, in support of the NASA's MEaSUREs program.

Sea levels have risen by some 60 mm over the past 20 years, as above NASA image shows, which has a linear trendline added. The question is whether a linear trendline is the most appropriate trendline, given that it suggests that a similar rise could be expected over the next 20 years. A polynomial trendline appears to fit the data better, as the animation below shows.

Such a polynomial trendline, however, points at a similar rise (of some 50 mm) in just four years time, with an even more steeper rise to follow, as illustrated by the image below.

And indeed, such a rise doesn't slow down there. A polynomial trendline applied to the data points at a sea level rise of more than 2.5 m (8.2 ft) by the year 2040.

The image below gives an idea of what a sea level rise of six feet (1.829 m) would do to the City of New York. Of course, this is only the sea level rise. Storm surge would come on top of this, as discussed at Ten Dangers of Global Warming.

So, what would be more appropriate, to expect sea levels to continue to rise in a linear way, or to take into account feedbacks that could speed things up? Where such feedbacks could lead to is illustrated by the image below.

[ from: How many deaths could result from failure to act on climate change? click on image to enlarge ]

This calls for comprehensive and effective action, as discussed at the Climate Plan blog.


References

- South Greenland ice-sheet collapse during Marine Isotope Stage 11, Reyes et al. (2014)
http://www.nature.com/nature/journal/v510/n7506/full/nature13456.html

- Nonsustainable groundwater sustaining irrigation: A global assessment, Yoshihide Wada et al. (2012)
http://onlinelibrary.wiley.com/doi/10.1029/2011WR010562/abstract

- Groundwater Depletion Linked to Rising Sea Levels
http://www.waterworld.com/articles/2010/11/groundwater-depletion-linked-to-rising.html

- Assessment of the Jason-2 Extension to the TOPEX/Poseidon, Jason-1 Sea-Surface Height Time Series for Global Mean Sea Level Monitoring, Beckley et al. (2010)
http://www.tandfonline.com/doi/abs/10.1080/01490419.2010.491029

- Feedbacks in the Arctic
http://climateplan.blogspot.com/p/feedbacks.html

- How many deaths could result from failure to act on climate change? (2014)
http://arctic-news.blogspot.com/2014/05/how-many-deaths-could-result-from-failure-to-act-on-climate-change.html

Post by Sam Carana.

The Growing Threat of Catastrophic Storm Surge in the Next 30 Years on a Fast, Global Warming Induced, Sea Level Rise and its Consequences for Coastal Cities and Humanity

By Malcolm P.R. Light
November 11, 2012

Abstract

Methane is erupting as widespread torches and fountains in the Arctic ocean up to 1 km across and is exponentially increasing in concentration in the Arctic atmosphere (Shakova et al. 2008 and 2010; Light and Carana 2012; Light 2012). The Arctic atmospheric methane is mostly derived from Arctic subsea shelf and slope methane hydrates due to their destabilization by globally warmed Gulf Stream currents which enter the Arctic west of Svalbard and through the Barents Sea. In the North Atlantic, the surface of the Gulf Stream is heated in the summer and is marked by excessive evaporation due to the global warming effects of pollution clouds emanating from North America (Figure 5; IPCC Working Group 1. Fig. 10.12 Lavatus Prodeo, 2012).

The exponential increase in Arctic atmospheric methane has caused an exponential decrease in the volume of Arctic sea ice and in the continent wide reflectivity (albedo) of the Greenland ice cap (Light 2012; NASA Mod 10A1 data, from Carana, 2012). The atmospheric Arctic methane which is almost half the density of air is rising like hydrogen into the Stratosphere where it is forming and all encompassing global warming veil further aggravating the global warming of the lower level greenhouse gas clouds.

The ice melt back curves from the oldest lower 5* year old ice to the youngest shallowest 2 and 1 year old ice are caused by the progressive increase in temperature of the Gulf Stream “Atlantic Waters” which are entering the Arctic beneath the ice and melting it from the bottom up. The heating of the Gulf Stream waters is directly linked to the global warming of the North Atlantic caused by green house gas pollution blowing east off North America.

Above summary diagram (Figure 15, click on image to enlarge) shows all the determined global warming temperature curves and the latest "Sandy" storm surge curve based on a mean storm surge of 14 feet added to the mean latent heat of ice melting curve (Light 2012; Fichetti, 2012). All the global warming curves converge on a region between 2034 and 2052 where the mean atmospheric temperature anomaly will be greater than 8°C and all of the Earth's ice caps will have melted with a consequent sea level rise of 68.3 m (224 feet) above mean sea level (Wales, 2012). In particular the accelerated global warming curve from Carana (2012) and the "Sandy" storm surge curve converge on the mean atmospheric temperature extinction point derived from 20 estimates (Light 2012). This gives great confidence in the interpretation that we can expect catastrophic climate change from methane induced global warming between 2034 and 2052 unless humanity sharply cuts back some 90 to 95% on global greenhouse gas emissions and converts all its energy resources to renewable energy/ nuclear power.

A series of progressive extinction zones have been determined (after Parry et al. 2007) and include:-

• Bleaching of most corals when the atmospheric temperature anomaly is between 1 and 2°C
• Extreme droughts will extend over 1 - 30% of the land area when the atmospheric temperature anomaly exceeds 2°C which will make more than 1.8 billion people water stressed.
• Widespread coral mortality will occur when the mean atmospheric temperature anomaly is between 2.5°C and 3.5°C and will be associated with a massive increase in the ferocity of tropical cyclones/hurricanes far in excess of the Sandy super storm.
• Complete deglaciation and coastal inundation is expected when the mean atmospheric temperature anomaly increases from 4 to 8°C with a consequent sea level rise of some 68.3 metres (224 feet) above sea level. There will be major global extinction over this temperature interval as cereal production sharply decreases outside of the tropics.

Super storm Sandy has shown that Manhattan is already open to storm surge flooding and by 2016 when the Arctic Ocean begins to be free of ice, we can expect more violent hurricanes bearing down on the eastern coastline of the United States and increasing catastrophic damage to the coastal cities there.

The Alamo Project is a call for United States scientists and engineers to volunteer to develop a system of destroying the fast growing methane clouds in the atmosphere by radio/laser means or other processes before they destroy us. See this page:-
http://www.facebook.com/AlamoProject

Immediate and concerted action must be taken by governments and oil companies to depressurize the Arctic subsea methane reserves by extracting the methane, liquefying it and selling it as a green house gas energy source (see the ANGELS Project). See this post:-
http://arctic-news.blogspot.com/2012/06/angels-proposal.html

If greenhouse gas emissions are not sharply curtailed by 90% to 95% and the Arctic subsea and atmospheric methane extracted and destroyed, mean rising sea levels will breach the Thames Barrier by 2029 flooding London and the proposed Verrazano Narrows barrier in New York by 2030. The base of the Washington Monument (D.C.) will be inundated by 2031. By 2051, total global deglaciation will finally cause the sea level to rise up the lower 35% of the Washington Monument and humanity will have been eliminated by worldwide flooding and firestorms.