This talk about the government (some agency of it anyway) declaring “Global Warming Is Here” makes me wonder:
What are the chances that we’re just still “on the way up” out of the last Ice Age? It didn’t end all that long ago.
Has anyone postulated this? I have little trouble believing that we (humans) can mess up the world pretty significantly, but is this even a possible alternative explaination?
My life was saved by rock and roll. --Lou Reed
Back about twenty years ago, we in the Midwest suffered through two consecutive HORRIBLE winters. As I recall, during one winter we in Ohio had to get used to referring to snow in ‘feet’ rather than ‘inches,’ a mighty rare occurrence here. The next winter had plenty of snow too, and temperatures as low as -30F. (That was the only time I recall seeing the Ohio River completely frozen over, bank to bank.)
‘Global warming’ hadn’t been invented yet, so the scientific types squawked about the coming of the next Ice Age instead. I distinctly recall one white-coat pontificating that we were ‘overdue’ for the next ‘big freeze,’ a thing, he said, that occurs on a fairly regular cycle of about 10,000 years.
I don’t know why fortune smiles on some and lets the rest go free…
T
I remember reading somewhere that for most of its geological history the Earth has had no ice caps and the fact that they exist today was given as an indication that we are still on the trailing end of the last glaciation period (or Ice Age). In this scenario global warming is part of a natural, long term trend.
I have also heard the argument that we are overdue for another glacial period (as was mentioned above) and that human-caused global warming prevented it from occuring (and the cooling period associated with the missed Ice Age has disguised the magnitude of the global warming problem).
Unfortunately, environmental discussions tend to polarize fairly quickly and decend through Great Debates and into the Pit.
“Drink your coffee! Remember, there are people sleeping in China.”
Dennis Matheson — dennis@mountaindiver.com
Hike, Dive, Ski, Climb — www.mountaindiver.com
I’m of the theory that we’re just warming up from the last ice age.
The Earth has been much hotter and colder in the past, long before us people have been around. During the last Ice Age, the oceans were much shallower, so much so that the Chesapeake Bay was still just the Susquehanna River. Now, it’s backflooded for about 200 miles. Who’s to say that it wasn’t fated to flood up to Harrisburg or Scranton?
The record of CO[SUB]2[/sub] levels for the last century has been going up, but at a linear rate. One would think that if the Industrial Age has had such a negative impact that the levels would have gone up geometrically. This leads me to think that this increase is mostly natural.
Judges 14:9 - So [Samson] scraped the honey into his hands and went on, eating as he went. When he came to his father and mother, he gave some to them and they ate it; but he did not tell them that he had scraped the honey out of the body of the lion.
I read an article that strongly correlated this warm spell to the 11 year solar cycle, which we are sitting right at the top of the hump. http://www.sunspotcycle.com/
I have also read articles that talk of a neutating patchy dust cloud between the earth and the sun that causes radiation we get to fluctuate over extended periods suspiciously close to 10,000 years.
I have also read that that the energy reflecting pollutants are, to a large extent, offsetting the effect of the energy trapping pollutant.
And finally that the “greenhouse effect” of actually greenhouses did not depend on whether the glass used was tranparent to IR or not, but was actually caused by the lack of convection.
In any event the rapid disaperance of anarctic ice sheets seems to indicate that something is up, but I dont think its worth eco-freaking about.
We all seem to have been lulled into the misconception that humans are the source of all the ecological woes of the planet, and if there were no humans, the earth would remain some sort of paradise for all the other animals, forever. This is simple not true. The earth has heated up in the past, and it has cooled down in the past without human help. The ugly side earths corrective feature doesn’t seem to be too nice for the inhabitants.
I’ve often wondered, if we found out conclusively that the warming is a natural event, would people still feel we had to change our civilization and lifestyle to prevent it?
Too many unknowns to start making blanket statements about how we have to combat this scourge. What if we make a massive effort to reduce global warming and trigger a new ice age? Imagine the law suits.
I too am of the conviction that the earth is cooling. Some evidence:
(1) the fact that oranges used to be cultivated in the US, as far north as Tennesee (up til the 1880s)
(2) the Vikings lived in Greenland from ca970 AD till ca 1450 AD. They were able to grow wheat and barley, two crops that CANNOT be grown in Greenland today
(3)ancient trees have been found in the interior of Ellesmere Island, in the canadian artic (about 800 miles south of the pole). These trees are around 200,000 years old.
I am not convinced either way.
We’ve had between 18 and 24 glaciations in the past two and a half million years. They seem to be on about a 100-thousand year cycle. The Wurm started about 35 thousand years ago and “ended” about twelve thousand years ago. If we are still shaking off the last Ice Age, global temperatures should be going up for at least another 12 thousand years or so.
I feel that projections of global temperatures based upon a hundred years worth of measurements at a few locations is insufficient data to warrant the more scare-mongering extrapolations.
Dr. Fidelius, Charlatan
Associate Curator Anomalous Paleontology, Miskatonic University
“You cannot reason a man out of a position he did not reach through reason.”
The key to this is to think in terms of Geological Time. The trend we are observing is only, at most, a few decades older. Inter-glacial periods can last tens to hundred of thousans of years. In light of all the talk of Global Warming, Vancouver is getting snow every other day. We usually see snow MAYBE once a year. Maybe… Scientists can only guess as to where we are in the cycle.
Keep in mind that ice ages can be triggered (theoretically) by sustained drops in temperature of 1 degree…
kylen
According to the geologists at Chicago’s Field Museum, tanstaafl is correct – the fact that we have polar ice caps means we are still in an ice age.
But Dr. Fidelus makes an important point as well. Whatever the Earth may be doing “naturally,” there’s no excuse for humans to think we’re free to mess everything up. There are no controls on this experiment, so we need to err on the side of caution.
And I’d just like to cloase by saying “pornography,” because the web blocker on my grilfriend’s computer seems to block every SD page that contains that word, and I just want to see how well it works. I thank you all for your indulgence.
“The dawn of a new era is felt and not measured.” Walter Lord
The Earth experiences variability in climate trends on a range of timescales from one year to millions of years, with some intervals warmer than present and others far colder, as tanstaafl, AWB and DrFidelius pointed out. The potential range of natural climate variability, and the forcings responsible for that variability, are not fully understood. So when you read the papers and it looks as though no one really knows what’s happening, it’s true - to a point.
Because we don’t know exactly what will happen in near future (say, the next 100,000 years or so), we have to assume for the moment that we are in fact still living in an ice age; we just happen to be living during a slighlty warmer period of time, called an interglacial, between periods of major ice sheet development (glacials). The oscillation between cold and warm intervals is referred to as the glacial-interglacial cycle.
The present interglacial (i.e., the Holocene Epoch, 10,000 BP to present) has itself been marked by shorter-term climate fluctuations including intervals as warm as (or warmer) than today (the Holocene Climatic Optimum [9,000-7,000 BP] and the Secondary Optimum [1000-1200 AD]), as well as colder times (the Iron Age cold epoch [2900-2300 BP] and the Little Ice Age [1400-1700 AD]). Our current climatic conditions are part of a naturally warmer phase that began around 1700.
What many scientists have finally reached a consensus upon is that at least SOME of the present global warming trend can be accounted for by anthropogenic activity, e.g., burning of fossil fuels, use of CFC’s and HCFC’s. The level of carbon dioxide in the atmosphere has increased from about 280 ppm in 1800 (the “pre-industrial value”) to about 315 ppm in 160, to roughly 360 ppm today - so the increase is NOT linear.
Contrary to popular belief, “global warming” doesn’t mean that every spot on the Earth will get warmer - the average global temperature will rise because the difference between daytime maximum temperatures and nighttime minimum temperatures will diminish. However, regional variability can still result in some areas getting somewhat cooler than the are now, and precipitation patterns ought to change noticeably.
Although there continue to be debates about whether or not the warming trend will continue (or whether any anthropogenic interference will contribute to longer-term cliamtic change), I have to agree with DrFidelius that we shouldn’t continue to burn fossil fuels just because we can. This is our first (and maybe only) home - we ought to take care of it better.
A few more quick points:
kylen, continental ice sheet buildup begins when winter snow precipitation is high and summer temperatures are not warm enough to completely melt all the snow. (We’ll assume here that ice sheet buildup begins at high latitudes to make the process a bit easier.) Putting an exact number on the required drop in global average termperature that would permit this scenario is tricky business, because the present computer models (from which such estimates are often derived) aren’t perfect. That’s not to say, though, that a drop of 1 or 2 degrees in global avg. temp wouldn’t have an impact on climatic patterns at all. The current global avg. temp. has increased by 0.5 degrees since last century.
falcon2, annual to decadal climate variability is likely connected to short-term solar variability (e.g., the sunspot cycle), but it is not yet clear that the decades-long warming trend in the 20th century be explained entirely in this way. The present data also do not suggest that anthropogenic negative climate feedbacks (such as sulfur dioxide) are balancing out the positive feedbacks (carbon dioxide and CFCs), else we wouldn’t see a warming trend. BTW, if you live in a coastal area you should care very much if the East Antarctic ice sheet shows signs of collapsing, because the melting of all that ice into the ocean may raise global sea level by as much as several tens of meters.
DrFidelius, while atmospheric temps have been measured in realtime by reliable instruments for only the last century or so, we can still determine reliable temperature measurements for the last several thousand years through a variety of proxies, including gases dissolved in groundwater, tree-ring data, and lake sediments. Individual methods may not be absolutely perfect, but the combined data yield a pretty good picture of cliamte in the recent past.
Fillet - Very interesting.
These periods are very confusing and it helped when I has some graphs so put some below. For a completely useless addition, there is a larger period cycle not in the graphs at 540, 240 and 3 millions of years.
Had these kicking around from some work I had done.
http://users.rcn.com/trouts1/sd/ice1.jpg
http://users.rcn.com/trouts1/sd/ice2.jpg
falcon2, nice term eco-freaking
trouts1, excellent graphs for showing climate variability on different time scales! - thanks for posting them.
BTW, I just noticed a typo in my last post - atmospheric CO2 levels reached 315 ppm in 1960 (sorry for any confusion).
(thank you very much)