OT of an OT: Ethanol

[Phoenix-D]

"Life becoming extinct" is a pretty severe standard. There have been periods where 80-90% of all life on the planet died. You'd consider that pretty nasty, and it'd likely take *us* out, but it wouldn't fit that standard.

Read your statements again. "We don't have records beyond a few decades ago" and "There have been times when it was warmer than now" DON'T fit together.

The answer there is we do have records, care of trapped air bubbles in ice sheets and the like.

More to the point, global warming is a problem regardless of the cause. There are countries that will *cease to exist* if the sea level rises too much, and most of the human population lies close to a coast. Beyond that you have increased storm power, desertifcation of previous cropland, all sorts of unpleasant crap.

[Will]

We have precise temperature records dating back to sometime around the turn of the 19th century. And there's also things like core samples of ice in Antarcica that gives us a very good estimate of concentrations of atmospheric gasses and a reasonably good estimate on what temperatures were (varying amounts of gas would be trapped based on the temperature at the time it was frozen, and crystal structure of the ice will vary based on the conditions when the water froze).

Data from around 1900 back is going to be a lot more coarse than data that we have today, so that does affect estimates of the impact of the greenhouse gasses, since more detailed analysis is not possible. All we really have is aggregate data averages; the temperature in a certain approximately 10 year range in the past, in the area the ice was formed, averaged X degrees. Correlate to percentages of greenhouse gasses trapped. Studies have found a correlation to the calculated levels of gasses and the calculated temperature.

The naysayers for global warming point out that the estimated release of greenhouse gasses by human actions (including farmed livestock, vehicles, factories, etc.) is calculated to be only a modest percentage of the natural release. The only problem with this criticism is what Phoenix-D pointed out: large portions of the population of the world is in danger if sea levels rise even a little. Even the modest percentage accelerates the temperature increase, which accelerates the melting of ice at the polar caps, which accelerates the rising of sea levels and the rising of sea temperatures. Higher ocean temperatures mean bigger more powerful storms (see this year's hurricane season). Higher sea levels mean more danger from those storms and flooding, tsunamis, etc. There are lots of costal areas that are technically below sea level, and only have essentially a small ridge holding back the ocean.

So, the point is, do we want to accelerate the cycle and make sure the peak temperature is even higher than it would have been? Or do we want to cut back on our emissions and make sure that the damage is minimized?

[Renegade 13]

Read your statements again. "We don't have records beyond a few decades ago" and "There have been times when it was warmer than now" DON'T fit together.

My fault. I should have said "We don't have detailed, in depth records beyond a few decades ago". We do, however, have estimates based on ice cores, etc, that give estimates of past climates.

Some of the mass extictinctions in the past may have wiped out as many as 90% of the species. Yes life recovered, after millions of years.

The climate shift I was talking about, when temps. were a few degrees warmer than now was only about 140,000 years ago. There was no massive extinction event around that time (as far as I know), so this is why I doubt a climate 'shift' of a few degrees can wipe out many species on a global scale.

OK, another couple questions. Is there actually enough ice in glaciers, polar ice caps, icebergs, etc. to raise ocean levels beyond a few feet over what they are today, if they all melted? Lets say a meter of water was added to todays ocean levels. A meter wouldn't cause any significant damage to coastlines beyond making a few seawalls necessary. The area of the worlds oceans is ~361 Million square km. So, to raise ocean levels by a meter, you'd need an additional 361,000,000 x .001 = 361,000 cubic kilometers of water! Is there even that much ice in the polar caps/glaciers?

Another question: Is it possible to slow significantly the amount of CO2 that is emitted into the atmosphere without cutting back so much that we might as well be in the stone age again?

[geoschmo]

Renegade 13 said:
So, to raise ocean levels by a meter, you'd need an additional 361,000,000 x .001 = 361,000 cubic kilometers of water! Is there even that much ice in the polar caps/glaciers?

There is ten times that much ice just in Greenland. And another ten times that at the south pole. linky
The north pole ice is sea ice so as it melts it won't have much net change in sea level.

[Renegade 13]

On the subject of Ethanol, I agree with your assessment Will. It may work as a supplement to gasoline, but I doubt it's up to the task of full replacement. For that, we need something else. Hopefully we can find that something else relatively soon, with the way fuel prices are going...