Hi all.
Volcanos.
Hate to say this but "super" volcanos have not been responsible for ice ages. Multiple major volcanic eruptions have been present seven out of ten times at the end of interglacial period but that is a world of a different to ice ages. I believe that there is only one interglacial period in this current ice age that corresponded to a single volcanic eruption.
There is even the problem of whether the end of an interglacial period is the reason for the volcanic eruptions or the eruptions aid or cause the end of the interglacial period. It would well be that the glacial and snow and ice retreat and the heating of surfaces that were perma-frost etc actually induce volcanic activity. It sounds far fetched but the evidence is certainly not conclusive that it is the other way around.
Volcanos do cause cooling. Mt St Helens had a slight effect on the mid latitudes of the northern hemisphere for around three years. But I haven't seen any evidence that single volcanic eruptions cause ice ages. Ice ages are most commonly caused by plate tectonics. The balance of land to sea in the hemispheres tips to the point that an ice age is appropriate.
Polar Bears.
Yeah, sure, polar bears are going extinct because of global warming that is either 30 years old or maybe 80 if you really fudge the figures. Sorry, it just doesn't happen that way. Polar bears evolved to their modern form many hundreds of thousands of years ago and - without particular expertise in polar bears - I'm guessing they were not a great deal different for between 2 million and 10 million years.
As to seals, these are just part of a polar bears diet but a really important part. Less ice actually means more seals but I won't go into the reasons why warmer conditions mean more seals. Less ice means the seals will travel further north, not that there will be less of them. And actually from what I understand, polar bears need breaking pack ice to easily catch seals. They do not hunt in packs at all. Males are solitary. Females may have cubs but large groups only get together in areas of abundant food supply but not to hunt in any pack. I would suggest global warming is not at all relevant to how many seals individual polar bears are able to catch and eat.
Mammoths were pretty much the same for more than a million years. They went extinct during the last glacial period. It was actually the coldest period of the cycles between glaciations and interglacial periods. You certainly could not blame any type of warming for their extinction. Actually a great many large beasts went extinct in that 10,000 to 20,000 time frame, including a wombat like creature in Australia about 15 feet tall. (And that one really goes against climate change issues because Australia is very much immune to climate change of the extent that would threaten larger animals no matter whether it is a glaciation or interglacial period. It does not get covered with snow or ice nor does the climate dramatically change with world warming). None of these beasts went extinct because of warming.
Polar bears have managed to survive many periods of warm periods. Even in the middle of the warmest interglacial period, you still have ice over the Antarctic and over the North Pole and pack ice in the high northern latitudes. If it retreats so do the polar bears, and the seals. Indeed, if there is a late summer polar bears have real problems, food wise.
Polar bears, however, have the same problems that buffalos had. Man. More humans have entered their domain and for a while the only way that confrontation ended was with a gun shot. Now they are protected in most places and, at least from the Discovery program I saw about a month or so ago, their numbers have increased. Because of man's slaughter of their species, if there was further warming, they may actually go extinct but that would not be the fault of global warming. The effect of warming has happened to them many times before. It will be the fault of man killing too many of them previously for sufficient to survive the climate change.
With each climate change and movement of the plates, there are winners and losers. It is actually staggering just how many species of higher vertebrates have gone extinct over the last 40 to 50 million years. But it is also amazing just how many new species have evolved to fill the niche left behind by the extinctions.
Some species will get a reprieve from going towards extinction if there is a further period of warming before the next glaciation. So for many animals further warming will be a good thing.
Global warming - Not global!
I study the cycles of glaciations and interglacial periods. I have a pretty good understanding of the climate for major regions during both and during the transitions. Global warming is very much not a global thing just as global cooling with the current continental positions is a northern hemisphere phenomenon.
The tropics have a complex mechanism that limits the temperature ranges. Even at the most extreme of the interglacial periods, the tropics do not increase in temperature. Indeed, there is some evidence that they may cool a bit because of the warming actually creates a greater cloud cover for the tropics.
Global warming affects the mid latitudes but even then not uniformly. The oceans turn over. The currents running north or south from the equatorial areas have a massive effect on the climate of pretty much all countries in the world. Western Europe and Britain would be pretty bleak places but for such currents.
Major warming events will cause some areas to be much hotter, some areas to be a little hotter and most of the southern hemisphere to be not a great deal changed.
The biggest effect for humans is sea levels. This crap about a few millimetres average difference because of ocean expansion is just that, crap. The difference between ocean heights between a glacial period and an interglacial period as between 80 and 120 metres (about 240 to 380 feet). The average world temperature difference is only a few degrees. A three or four degree average increase in world temperatures would mean a major rise in sea levels.
Interesting range of topics currently. These are my two cents (which probably are not even worth that).
Regards
Richard
