June 25, 2012

Sea Level Rise Lags Change in Atmosphere Temperature

Even if ocean levels rose to similar heights as during the Last Interglacial, they would do so at a rate of up to three feet per century.

Therefore, any projected maximum global sealevel increase of 8.5 meters would take 850-1200 years to happen.

From now until 2040, if you want to have a 0.75 degree celsius increase instead of a possible 1.25 degree celsius temperature increase then soot mitigation should be targeted. Measure against CO2 would have an effect by around 2070.

Soot makes the ice darker and melt faster and increases the amount of heat that is absorbed instead of reflected.

"Even though the oceans are absorbing a good deal of the total global warming, the atmosphere is warming faster than the oceans," McKay added. "Moreover, ocean warming is lagging behind the warming of the atmosphere. The melting of large polar ice sheets lags even farther behind."

"As a result, even if we stopped greenhouse gas emissions right now, the Earth would keep warming, the oceans would keep warming, the ice sheets would keep shrinking, and sea levels would keep rising for a long time," he explained.

They are absorbing most of that heat, but they lag behind. Especially the large ice sheets are not in equilibrium with global climate," McKay added. "

Here is a site that is tracking the sea level rise at different points around the world.

The average sea level has been flat since late 2009.

There has been an average global sea level increase of 2 inches since the early 1990s.

Overpeck, who is McKay's doctoral advisor and a co-author of the study, added: "Unless we dramatically curb global warming, we are in for centuries of sea level rise at a rate of up to three feet per century, with the bulk of the water coming from the melting of the great polar ice sheets -- both the Greenland and Antarctic Ice Sheets."

According to the authors, the new results imply that 4.1 to 5.8 meters, or 13.5 to 19 feet, of sea level rise during the Last Interglacial period was derived from the Antarctic Ice Sheet, "reemphasizing the concern that both the Antarctic and Greenland Ice Sheets may be more sensitive to warming temperatures than widely thought."

"The central question we asked was, 'What are the warmest 5,000 years we can find for all these records, and what was the corresponding sea level rise during that time?'" McKay said.

There are engineering strategies for managing sea level rise.

* barrier(s) or tidal barrage(s) to manage tidal flows in and out of San Francisco Bay (at the Golden Gate or in smaller, strategic parts of the bay)

* coastal armoring with linear protection, such as levees and seawalls, to fix the shoreline in its current place

* elevated development in which the height of land or existing development is raised and protected with coastal armoring

* floating development on the surface of the water, or that which may be floated occasionally during a flood, making it largely invulnerable to changing tides

* floodable development designed to withstand flooding or to retain stormwater

* living shorelines with wetlands that absorb floods, slow erosion, and provide habitat

* managed retreat that safely removes settlement from encroaching shorelines, allowing the water to advance unimpeded, and bans new development in areas likely to be inundated

About 8 inches since 1916 when the Golden Gate was Built

There does not seem to have been much effect in terms of the cost or urgency in managing that level of sea level rise during the 20th century.

Projected Rise on the East Coast of the US

Boston has had a 12 inch rise in Sea level since 1920.

The seas along the East Coast from North Carolina to New England are rising three to four times faster than the global average, and coastal cities, utilities, beaches, and wetlands are increasingly vulnerable to flooding, especially from storm surges, according to the US Geological Survey study published Sunday.

The findings come as Boston and Massachusetts officials are taking the first of a range of responses to the threat of rising seas. The report did not project how much levels would rise in the Northeast, but globally, oceans are projected to increase between 2 feet and 6 feet by the end of the century, and as much as an additional 5 feet during the heaviest storms. Climate scientists say such storms are likely to increase in intensity and frequency over the coming decades.

In Boston, officials have begun mapping low-lying areas and critical systems that are most likely to be inundated. The maps show that if sea levels rise just 2.5 feet, it could take little more than a Nor’easter to put much of the Back Bay, East Boston, South Boston, Chelsea, Cambridge, and elsewhere underwater, including much of Logan International Airport and the financial district.

As a result, the Boston Water and Sewer Commission will begin inspecting hundreds of miles of sewers, storm drain connections, pumping stations, and other utility systems this summer to assess what needs to be done to protect them from rising seas. The Boston Redevelopment Authority, as part of its new climate adaptation plan, recently began requiring developers to fill out a questionnaire about their awareness of the potential impact of climate change and whether it is influencing their building plans.

The city, which now requires its departments to consider sea-level rise in planning decisions, has also launched a “green ribbon” commission to build support in the private sector for blunting climate change.

Global Sea Level Trends

NOAA sea level measurements around the world

Green - 0 to 1 foot per century
Yellow - 1 to 2 feet per century
Orange - 2 to 3 feet per century
Red - 3 to 4 feet per century
Blue - 0 to negative one foot per century
Purple - negative one to negative two feet per century

A study of China's vulnerability to sea level rises.

The costs are in RMB. So divide by 6.35 to get to US$.

Geoengineering is simple and cheap

The cost to construct a Stratospheric Shield with a pumping capacity of 100,000 tons a year of sulfur dioxide would be roughly $24 million, including transportation and assembly. Annual operating costs would run approximately $10 million. The system would use only technologies and materials that already exist—although some improvements may be needed to existing atomizer technology in order to achieve wide sprays of nanometer-scale sulfur dioxide particles and to prevent the particles from coalescing into larger droplets. Even if these cost estimates are off by a factor of 10 (and we think that is unlikely), this work appears to remove cost as an obstacle to cooling an overheated planet by technological means.

HIGH-FLYING BLIMPS, based on existing protoypes, could support a hose no thicker than a fire hose (above) to carry sulfur dioxide as a clear liquid up to the stratosphere, where one or more nozzles (below) would atomize it into a fine mist of nanometer-scale aerosol particles.

The UK performed geoengineering tests in 2011.

If you liked this article, please give it a quick review on ycombinator or StumbleUpon. Thanks
blog comments powered by Disqus