Originally posted by llmaurice
Thats fine then , now we know we have NO control over the environment , Blair doesn't need to waste his breath trying to Get George W to do anything about Americas emissions.
The good news I guess is that we can all go back to burning coal and wood plus all our rubbish .
Back to the original thread , we may as well bring pack our razor sharp 2 strokes as well as a bit of HC can't do any harm -only to California ?
That is basically correct. The Earth is basically a greenhouse planet. The default condition for the past 1.8 billion years has been no polar ice caps. Sea levels have been up to 80 metres higher than at present (the major control on this is rate of sea floor spreading, not the melting of ice stored on land). With a lower temperature differential between equator and poles, the atmosphere would have been calmer. Humid temperate conditions would have prevailed.
This condition has been episodically upset by ice ages. There have been in the order of ten since the Proterozoic, with two probable major events in the Pecambrian, and one in the Permian. They last for a few to tens of millions of years. The ice age we live in started about 15 million years ago, with the formation of the Antarctic ice cap, but has only fully developed in the past 2-4 million years.
The Quaternary ice age has been characterised by a number (20-40) of glacial/interglacial cycles, of which the last four are reasonably well recorded in the sedimentary record. These cycles comprise about 110,000 years of glacial alternating with 10-20,000 years of interglacial. Right now we are about 13,000 years into the current interglacial.
During glacial periods at higher latitudes, the normal conditions that prevail are cold and dry. Temperatures in central North America drop 5-10C below current averages of around 15C. While some areas may be wetter than at present (Some African and North American lakes were larger), in general desert areas expand. Increased aridity and higher wind speeds cause dune fields to replace scrubby desert. The last glacial maximum, when ice caps were developed in North America, Europe as well as high areas into the tropics, and sea level dropped by 140 metres, lasted about 20,000 years.
The current interglacial (presumptuously named the Holocene) has seen at least 3 warm periods, at about 7, 4, and 1.5 thousand years BP, alternating with cooler periods. The range of variation is in the order of 2-3 degrees C. During the last warm period, the Vikings were able to colonise Greenland. During the "Little Ice Age" that followed, the colonists were abandoned and integrated with the Inuit or died. The Little Ice Age peaked at about 1700 AD, as anyone familiar with Breughal's work will know, and since then temperatures have typically increased by about 1 degree C.
We have a very nice correlation between Quaternary glacial/interglacial events and Milankovich cycles, although these do not explain the greenhouse/ice house episodes. We understand that the disposition of continents and mountains influences atmospheric and marine circulation, and therefore heat transfer. We know that elevated levels of greenhouse gasses coincide with warm periods, but not whether they cause them. These sytems are complex, and may work in counter intuitive ways. Water vapour is much more important greenhouse gas than CO2, but when it condenses into cloud, the albedo rises and the area under cloud cools. Cold conditions are generally dry: precipitation is a more critical parameter for the growth of ice sheets than cold. And of course, when we have an ice cap, the high albedo helps maintain the staus quo in a nice feedback loop.
Nothing in the summary above is controversial. It is based on a wealth of detailed and robust observation and scientific evidence. What are we to make of it? The absolute certainties are that climate is dynamic, climate change will continue to occur, and that claims of "...hottest/mostest on record" are false.
Our best guess for the future is that the current interglacial will get warmer before we enter the, possibly delayed, next glacial. The current ice age is likely to continue thus for a few million years before we enter the next prolonged greenhouse age. No power on Earth can resist climate change. The widely known curve showing steadily increasing global temperatures since the nineteenth century is simply a section of the trace showing an increase, and of which there are many which are larger, faster and more sustained. We may be able to alter the route, but the destination remains the same. I am not arguing against conservation, but it is important to understand that the aim of the Greenhouse Industry is stasis, and this is not possible. So fire up the barbie, light up that Havana, and enjoy the ride.