More than 2.5m Sea Level Rise by 2040?

More than 2.5m Sea Level Rise by 2040?

flood glaciers ice linear melt ocean polynomial rise sea level storm surge temperature trend water waves

Unknown 7/29/2014 Add Comment

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.

Has the descent begun?

Has the descent begun?

Arctic area earthquake El Nino extent Gakkel Ridge ice methane ocean sea sea surface temperatures

Unknown 3/12/2014 Add Comment

On March 9, 2014, Arctic sea ice area was at a record low for the time of the year, at only 12.88731 square kilometers.

Sea ice extent shows a similar descent, as illustrated by the NSIDC image below.

NSIDC update: The image below shows that Arctic sea ice extent was 14.583 square kilometers on March 11, 2014 (light green line), a record low for this time of the year and smaller than it was in 2006 (magenta line) and 2011 (orange line) at this time of the year.

The situation is dire, given that methane concentrations have risen strongly following an earthquake that hit the Gakkel Ridge on March 6, 2014, as illustrated by the image below.

[ click on image to enlarge ]

Huge amounts of methane have been released from the seafloor of the Arctic Ocean over the past half year, and the resulting high methane concentrations over the Arctic will contribute to local temperature rises.

The image below shows that sea surface temperatures are anomalously high in the Arctic Ocean and off the east coast of North America, from where warm water is carried by the Gulf Stream into the Arctic Ocean.

The prospect of an El Niño event makes the situation even more dire. NOAA recently issued an El Niño Watch. This follows a conclusion by an international research team that found a 75% likelyhood of an El Niño event in late 2014.

The consequences of sea ice collapse would be devastating, as all the heat that previously went into transforming ice into water will be asbsorbed by even darker water, from where less sunlight will be reflected back into space. The danger is that further warming of the Arctic Ocean will trigger massive methane releases is unacceptable and calls for comprehensive and effective action as discussed at the Climate Plan blog.



Related

- M4.5 Earthquake hits Gakkel Ridge
http://arctic-news.blogspot.com/2014/03/m45-earthquake-hits-gakkel-ridge.html

- Climate Plan blog
http://climateplan.blogspot.com

Post by Sam Carana.

M4.5 Earthquake hits Gakkel Ridge

M4.5 Earthquake hits Gakkel Ridge

Andy Lee Robinson Arctic area earthquake extent Gakkel Ridge ice methane ocean sea volume

Unknown 3/10/2014 Add Comment

The above image shows recent large methane release over the Gakkel Ridge, the faultline that crosses the Arctic Ocean between the northern tip of Greenland and the Laptev Sea (red line on map). Methane readings were as high as 2395 ppb at 586 mb, an altitude that often shows high methane readings originating from the Arctic Ocean.

An earthquake with a magnitude of 4.5 hit the Gakkel Ridge at a depth of 2 km on March 6, 2014, at 11:17.17.0 UTC. The location is shown on the map below.

[ click on image to enlarge ]

The image below shows more recent methane readings, around March 8, 2014.

The image below is a Naval Research Laboratory forecast of sea ice thickness for March 8, 2014, run on March 3, 2014.

Meanwhile, the sea ice is close to record lows (for the time of the year), as illustrated by the images below. The image directly below shows sea ice area.

The image below shows sea ice extent.

The image below, by Wipneus, shows sea ice volume.

The image below, by Andy Lee Robinson, offers a different way of looking at sea ice volume, the Arctic Death Spiral.

Post by Sam Carana.