Last Time Earth Hit 400 ppm, Temps Were 8C Warmer, Sea Levels 40 M Higher, Sediment Records Show

[hatrack]

The future of a globally warmed world has been revealed in a remote meteorite crater in Siberia, where lake sediments recorded the strikingly balmy climate of the Arctic during the last period when greenhouse gas levels were as high as today.

Unchecked burning of fossil fuels has driven carbon dioxide to levels not seen for 3m years when, the sediments show, temperatures were 8C higher than today, lush forests covered the tundra and sea levels were up to 40m higher than today.

"It's like deja vu," said Prof Julie Brigham-Grette, at the University of Massachusetts Amherst, who led the new research analysing a core of sediment to see what temperatures in the region were between 3.6 and 2.2m years ago. "We have seen these warm periods before. Many people now agree this is where we are heading."

"It shows a huge warming – unprecedented in human history," said Prof Scott Elias, at Royal Holloway University of London, and not involved in the work. "It is a frightening experiment we are conducting with our climate."

EDIT

http://news.mongabay.com/2013/0512-gen-lake-el-gygytgyn.html

[aristocles]

1. 65 million years ago 3/4ths of species became extinct

http://en.wikipedia.org/wiki/Cretaceous–Tertiary_extinction_event

Some day the human species will become extinct, to be replaced by intelligent CO2-breathing cockroaches, or immortal intelligent machines. My guess it will be the latter, within 200 years.

[Geoff R. Casavant]

2. Just curious . . .

Does anyone know how the past temperature can be inferred from the present sediment?

[aristocles]

3. Ice cores provide temperture and gas data from up to 800,000 years ago

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

[hatrack]

4. Lots of the really old data are from isotope balances in different elements associated with oceans

You can infer temperatures, evaporation rates, salinity, much more from these kinds of core samples.

[Yo_Mama]

5. Assuming CO2 is the only climate driver

which we know is not true.

[OKIsItJustMe]

12. No, that is not an assumption being made here

There is an association here between CO[font size="1"]₂[/font] concentrations and temperature.

The last time CO[font size="1"]₂[/font] levels were about this high, the temperatures (in this part of the Arctic) were about 8°C warmer.

[pscot]

6. That would put the Capitol under 80 feet of water

So you can't say there's no upside.

[aristocles]

7. +1

[CRH]

8. + another one, (1)

[truebrit71]

9. ROFL

[happyslug]

10. White House is on ground ground with a 20 METER increase in water levels, the Capital can take 40m

http://geology.com/sea-level-rise/washington.shtml

Sorry, much of the Capital is still above sea level even at an 80 METERS increase in world wide sea levels (80 meters increase is what is expected if the East Antarctic Ice Sheets melts).

The White house becomes sea front property if the West Antarctic Ice Sheets melts (or the Greenland Ice Sheets Melts).

I mention the East Antarctic Ice Sheet (EAIS), the West Antarctic Ice Sheet (WAIS) and the Greenland Ice sheets, for these are the three largest Ice Sheets in the world and each will have an effect on World Wide Sea Levels (on the other hand, the Arctic Ocean is one huge Ice Shelf).

The difference between an ice Sheet and an Ice Shelf is an Ice Shelt FLOATS onto of water, and thus displaces the water it would be when melted (and this when melted has no net effect on world wide sea levels, through can prevent warmer water from reaching any Ice Sheet). An ice Sheet is grounded on LAND and thus when it melts or floats, only then will it displace the water equal to the water in the Ice Sheet.

Thus while there is concern about Ice Shevles, the big concern is Ice Sheets. East Antarctic Ice Sheet (EAIS) which contains 60% of world wide fresh water, West Antarctic Ice Sheet (WAIS) just Over 10% of world wide fresh water, and the Greenland Ice Sheets with just under 10% of wold wide Fresh water (The remaining 30% of FRESH water is held in various Ice Sheets, lakes, ponds, rivers, creeks and other fresh water sources).

Right now, under present theory, the East Antarctic Ice Sheet (EAIS) is actually expected to EXPAND, due to increase water coming with the warmer air from the Equator. Then 50-100 years from now, that will reverse and the EAIS will start a slow but steady decline in size due to increase loss due to increase heat.

The Greenland Ice Sheets is melting as I write, but again a slow but steady decline over the next 50 years, till it is all gone.

The big concern is the below sea level grounded West Antarctic Ice Sheet (WAIS), which could break up any March or April and increase world wide sea levels over night. Being below Sea level, the WAIS can be undermined by warm waters from the Equator. It is possible for the WAIS to break up and float in any spring (March or April is when the WAIS is at its lowest level of Ice Shelves protecting the Ice Sheet from the warm waters of the Pacific and Indian oceans).

Such a situation would make the White House Ocean Front Property, but NOT under water. To get the White House under water you would need the Greenland Ice Sheet to melt AND some of the East Antarctic Ice Sheet (EAIS) to melt in addition to the break up of the West Antarctic Ice Sheet (WAIS). Such a situation is at least 50-100 years away (and most theories make it longer). Thus there is no way the Capital can be under 80 Feet of Water (about 16-20 meters) UNTIL the East Antarctic Ice Sheet (EAIS) melts.

[pscot]

13. According to Google Earth

The elevation at the foot of the Capitol steps is 52 feet.

[OKIsItJustMe]

11. For more, see here

http://www.democraticunderground.com/112743279