Global Warming 5 Million Years Ago In Antarctic Drastically Raised Sea Levels 437
An anonymous reader writes "As temperatures rise, scientists continue to worry about the effects of melting Antarctic ice, which threatens to raise sea levels and swamp coastal communities. This event, though, isn't unprecedented. Researchers have uncovered evidence that reveals global warming five million years ago may have caused parts of Antarctica's ice sheets to melt, causing sea levels to rise by about 20 meters."
Re:More to the point... (Score:4, Interesting)
Re:More to the point... (Score:5, Interesting)
Not so sure (Score:4, Interesting)
A quick review of cities in the US at or around sea level where 20M rise would be a disaster include...
LA, SF, SD, SJ, Portland, Seattle, Honolulu, Houston, Miami, Jacksonville, DC, Baltimore, Phili, Newark, Boston. That is probably about 1/2 the US population. Insurance even if you have it will not be useful, the companies will default. Insurance is for sharing risk. If 50% of your policy owners experience disaster, the company will not have the resources to pay it out. Life will certainly adapt, but probably in a Mad Max kind of way. Although I am not sure I buy the 20M number by 2100. That implies close to 6in/year and we are running closer to 1in/year. Obviously the faster the rise the more difficult to adapt. Although faster might cause us to abandon places like New Orleans instead of moating it like the netherlands does.
Re:More to the point... (Score:5, Interesting)
Let's see....
According to Google, Antarctica is ~14 million square km, and has an average of about 1.6 km of ice on top of it.
So, call it 22.4 million cubic km of ice. With a density of about 0.92 g/cm^3. So ~20.6 million cubic km of water tied up in that ice sheet.
Surface area of the planet is ~510 milllion square km.
Which gives us ~40 meters of sea level rise as a MINIMUM if the entire ice sheet melts.
Of course, it's not all expected to melt, but hey....
Re:More to the point... (Score:5, Interesting)
It is well known that sea levels have been going up and down throughout the ages. The question now is whether or not we are acelerating these variations and whether life can adapt to them fast enough.
Life isn't threatened by anthropogenic global warming. Even the human specie, as a whole, isn't threatened. There is also a scientific consensus on the fact that global warming is happening and that we are responsible for it.
The real question is whether the costs of reducing greenhouse gases emissions outweigh the costs of global warming. The answer is that it's globally cheaper to reduce greenhouse gases, however every single country or individual, by being selfish, has interest to let the others pay the bill.
Re:More to the point... (Score:5, Interesting)
A couple of important points: Firstly, 5 million years ago, there weren't 7 billion people living on Earth, people whose food supply was dependent on an agricultural system tightly adapted to today's particular climatic conditons. I will always remember a lecture given by one of my geology professors. He drew a graph on the board, initially without a scale. On the left, the graph fluctuated wildly up and down, going from extreme highs to extreme lows. Then suddenly, the graph settled down to mild up and down variations, and became basically horizontal, continuing to the right. Then he labelled the axes. The vertical axis was local temperature for an area where most humans lived. The horizontal axis was time. The time when the temperature settled down to a relatively constant pattern was about 10 000 years ago, the time when the last ice age ended. Then he asked us what other important event occurred around 8000 to 10000 years ago. Of course, the answer was the dawn of human civilization. Human civilization appeared about 8000 years ago. Civilization can only exist because of agriculture. People begin to plant crops in one area. They grow more food than they can eat, so they can have more children. Not all members of society have to spend time farming; individuals can afford to spend time doing other things like making pottery to store extra food, building better houses, or posting on Slashdot.
The problem for cities comes when the conditions that allowed successful agriculture change. Three or four years of failed crops caused by drought or heat or cold or surplus precipitation will exhaust all stored food. The residents of the cities will have to abandon their cities to begin hunting and gathering again, thus largely shattering any nascent civilization. The lesson from this is that human civilization was not simply the result of the triumph of human intelligence over nature. Civilization appeared 8000 years ago because the climate conditions favored it. During the last ice age, the conditions did not favor the development of cities. Even in areas that were not covered in ice, the climate conditions would have been highly variable thanks to the huge persistent ice sheets to the north. One day the air would come from the warm south, another day, the air would come from the cold northern ice sheets. These unstable conditions would have made sustained agriculture impossible.
My second point is that the well known fact that the climate in the past has shifted from warm to cold to warm should not be comforting to us. In fact, it should be the opposite. The fact that the Earth's climate has shifted in the past indicates that our climate is highly sensitive to relatively small forcings. Tiny changes in the Earth's orbit that cause periodically the Northern hemisphere to get more sunlight, and then tens of thousands of years later less sunlight are thought to have forced the Earth into and then out of ice ages (Milankovic Cycles). The slow collision of the Indian sub-continent with Asia, and its resulting volcanism is thought to have caused a large spike in carbon dioxide concentrations, resulting in a climate where the conditions in the north were near tropical.
The fact that the climate has shifted in the past due to relatively small changes indicates that "relatively small" changes wrought by humans, such as the removal of carbon from under the ground and the dumping of it into the atmosphere are capable of pushing our climate into a very different state, one that is likely to reduce human agricultural output by enough to make our current large scale civilization a dubious proposition.
Re:More to the point... (Score:0, Interesting)
You will pick the "scientist" that deleted data after 3 years of ignoring FOIA requests were not going to work anymore because he feared what a peer review might find in his work.