What America will look like once global warming melts the polar ice caps

[Uncle Joe]

62. Your post doesn't take methane in to account along with other feedbacks and tipping points,ie:

loss of white reflective snow and ice with an increasing amount of dark heat absorbing land/water mass, increasing deforestation with an adverse affect on carbon dioxide absorption, acidification and warming of the oceans destroying coral reefs which also serve to absorb carbon dioxide, not to mention wiping out vast numbers of ecosystems.

The Antarctic will not melt at a constant rate but is accelerating and will have major events in the process.

http://en.wikipedia.org/wiki/Global_warming

Human activity since the Industrial Revolution has increased the amount of greenhouse gases in the atmosphere, leading to increased radiative forcing from CO2, methane, tropospheric ozone, CFCs and nitrous oxide. According to work published in 2007, the concentrations of CO2 and methane have increased by 36% and 148% respectively since 1750.[65] These levels are much higher than at any time during the last 800,000 years, the period for which reliable data has been extracted from ice cores.[66][67][68][69] Less direct geological evidence indicates that CO2 values higher than this were last seen about 20 million years ago.[70] Fossil fuel burning has produced about three-quarters of the increase in CO2 from human activity over the past 20 years. The rest of this increase is caused mostly by changes in land-use, particularly deforestation.[71] Estimates of global CO2 emissions in 2011 from fossil fuel combustion, including cement production and gas flaring, was 34.8 billion tonnes (9.5 ± 0.5 PgC), an increase of 54% above emissions in 1990. Coal burning was responsible for 43% of the total emissions, oil 34%, gas 18%, cement 4.9% and gas flaring 0.7%[72] In May 2013, it was reported that readings for CO2 taken at the world's primary benchmark site in Mauna Loa surpassed 400 ppm. According to professor Brian Hoskins, this is likely the first time CO2 levels have been this high for about 4.5 million years.[73][74]

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Emissions scenarios, estimates of changes in future emission levels of greenhouse gases, have been projected that depend upon uncertain economic, sociological, technological, and natural developments.[80] In most scenarios, emissions continue to rise over the century, while in a few, emissions are reduced.[81][82] Fossil fuel reserves are abundant, and will not limit carbon emissions in the 21st century.[83] Emission scenarios, combined with modelling of the carbon cycle, have been used to produce estimates of how atmospheric concentrations of greenhouse gases might change in the future. Using the six IPCC SRES "marker" scenarios, models suggest that by the year 2100, the atmospheric concentration of CO2 could range between 541 and 970 ppm.[84] This is an increase of 90–250% above the concentration in the year 1750.

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Global dimming, a gradual reduction in the amount of global direct irradiance at the Earth's surface, was observed from 1961 until at least 1990.[88] The main cause of this dimming is particulates produced by volcanoes and human made pollutants, which exerts a cooling effect by increasing the reflection of incoming sunlight. The effects of the products of fossil fuel combustion – CO2 and aerosols – have largely offset one another in recent decades, so that net warming has been due to the increase in non-CO2 greenhouse gases such as methane.[89] Radiative forcing due to particulates is temporally limited due to wet deposition which causes them to have an atmospheric lifetime of one week. Carbon dioxide has a lifetime of a century or more, and as such, changes in particulate concentrations will only delay climate changes due to carbon dioxide.[90]

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In terrestrial ecosystems, the earlier timing of spring events, and poleward and upward shifts in plant and animal ranges, have been linked with high confidence to recent warming.[134] Future climate change is expected to particularly affect certain ecosystems, including tundra, mangroves, and coral reefs.[140] It is expected that most ecosystems will be affected by higher atmospheric CO2 levels, combined with higher global temperatures.[148] Overall, it is expected that climate change will result in the extinction of many species and reduced diversity of ecosystems.[149]

The Antarctic will not melt at a constant rate but is accelerating, and is becoming more unstable.

http://en.wikipedia.org/wiki/Antarctic_ice_sheet

The Antarctic ice sheet is one of the two polar ice caps of the Earth. It covers about 98% of the Antarctic continent and is the largest single mass of ice on Earth. It covers an area of almost 14 million square km (5.4 million sq. miles) and contains 26.5 million cubic km of ice[2] (6.36 million cubic miles). That is, approximately 61 percent of all fresh water on the Earth is held in the Antarctic ice sheet, an amount equivalent to 70 m of water in the world's oceans. In East Antarctica, the ice sheet rests on a major land mass, but in West Antarctica the bed can extend to more than 2,500 m below sea level. Much of the land in this area would be seabed if the ice sheet were not there.

In contrast to the melting of the Arctic sea ice, sea ice around Antarctica has expanded in recent years.[3] The reasons for this are not fully understood, but suggestions include the climatic effects on ocean and atmospheric circulation of the ozone hole,[3] and/or cooler ocean surface temperatures as the warming deep waters melt the ice shelves.[4]

If the transfer of the ice from the land to the sea is balanced by snow falling back on the land then there will be no net contribution to global sea levels. A 2002 analysis of NASA satellite data from 1979–1999 showed that while overall the land ice is decreasing, areas of Antarctica where sea ice was increasing outnumbered areas of decreasing sea ice roughly 2:1.[15] The general trend shows that a warming climate in the southern hemisphere would transport more moisture to Antarctica, causing the interior ice sheets to grow, while calving events along the coast will increase, causing these areas to shrink. A 2006 paper derived from satellite data, measures changes in the gravity of the ice mass, suggests that the total amount of ice in Antarctica has begun decreasing in the past few years.[16] Another recent study compared the ice leaving the ice sheet, by measuring the ice velocity and thickness along the coast, to the amount of snow accumulation over the continent. This found that the East Antarctic Ice Sheet was in balance but the West Antarctic Ice Sheet was losing mass. This was largely due to acceleration of ice streams such as Pine Island Glacier. These results agree closely with the gravity changes.[17][18] The estimate published in November 2012 and based on the GRACE data as well as on an improved glacial isostatic adjustment model indicates that an average yearly mass loss was 69 ± 18 Gt/y from 2002 to 2010. The West Antarctic Ice Sheet was approximately in balance while the East Antarctic Ice Sheet gained mass. The mass loss was mainly concentrated along the Amundsen Sea coast.[19]

Antarctic sea ice anomalies have roughly followed the pattern of warming, with the greatest declines occurring off the coast of West Antarctica. East Antarctica sea ice has been increasing since 1978, though not at a statistically significant rate[citation needed]. The atmospheric warming has been directly linked to the recent mass losses in West Antarctica. This mass loss is more likely to be due to increased melting of the ice shelves because of changes in ocean circulation patterns (which themselves may be linked to atmospheric circulation changes that may also explain the warming trends in West Antarctica). Melting of the ice shelves in turn causes the ice streams to speed up.[20] The melting and disappearance of the floating ice shelves will only have a small effect on sea level, which is due to salinity differences.[21][22][23] The most important consequence of their increased melting is the speed up of the ice streams on land which are buttressed by these ice shelves.

As the Arctic and Greenland Glacier's melt, the oceans will rise and this in turn will put more land based glaciers in Antarctic in danger of melting even sooner.