|2010-12-13 04:10:59||Abrupt Climate Change|
|Folks, I'm not sure if this is the correct place to discuss a technical question that I have so if it isn't please let me know. Also, I thought I had just posted this but I don't see it. If it is posted twice, my apologies. The more reading that I do, the more I believe that climates do not change gradually. Abrupt changes are the norm. I just read that about 5000 or so years ago, the Sahara was a lush area with a lot of rain and vegetation. Then, within about a hundred years, it dried out and never recovered. Is it true that most climate changes are abrupt? If so, I would say that, considering the current situation, things are much worse than most believe. Bob|
Bob, you're correct. the climate is a highly non-linear system|
|Bob, that's very much what we're seeing around the world now isn't it?, abrupt change. Oh, and by the way, large portions of the continental US were desert when the Sahara was flourishing.|
This makes our argument against the skeptics a tad more difficult.
I used to argue that the rate of temperature increase in recent years is indicative of the seriousness of the problem. Of course, this is true but the contrarians can say that the climate reacted abruptly in the past so this is nothing new. This abrupt rise in temperature is caused by some natural phenomenon and not man.
I now say that because of the abrupt changes of the past, we do not know exactly what we are dealing with. We know that CO2 has caused the temperature to increase but as far as how serious it's going to get, who really knows.
Some very prominent climatologist referred to the climate system as a "drunk". Totally unpredictable and scary (my words).
|2010-12-14 15:28:07||Great article in Climate Progress today|
Lonnie Thompson on why climatologists are speaking out: “Virtually all of us are now convinced that global warming poses a clear and present danger to civilization”
Found at Climate Progress here.
Lonnie's source paper here.
Graphic found here: http://www.skepticalscience.com/pics/2100Temperatures-IPCCFARandMeehletal2007.png.
Abrupt Climate Change Possible
We know that very rapid change in climate is possible because it has occurred in the past….
One way that rapid climate change can occur is through positive feedback. In the physical sciences, positive feedback means that an event has an effect which, in turn, produces more of the initial event. The best way to understand this phenomenon as it relates to climate change is through some very plausible examples:
Higher global temperatures mean dryer forests in some areas, which means more forest fires, which means more CO2 and ash in the air, which raises global temperature, which means more forest fires, which means.…
Higher global temperatures mean melting ice, which exposes darker areas (dirt, rock, water) that reflect less solar energy than ice, which means higher global temperatures, which means more melting ice, which means…
Higher global temperatures mean tundra permafrost melts, releasing CO2 and methane from rotted organic material, which means higher global temperature, which means more permafrost melting, which means.…
Positive feedback increases the rate of change. Eventually a tipping point may be reached, after which it could be impossible to restore normal conditions. Think of a very large boulder rolling down a hill: When it first starts to move, we might stop it by pushing against it or wedging chocks under it or building a barrier, but once it has reached a certain velocity, there is no stopping it. We do not know if there is a tipping point for global warming, but the possibility cannot be dismissed, and it has ominous implications. Global warming is a very, very large boulder.