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Mon 9 Aug, 2010 01:23 pm
Got questions about global warming?
I had four main ones and finally went looking for the answers.
My questions:
1. How do we make a significant statement about global climate based on 100 years worth of temperature data and 1500 years of proxy-models for temperature?
Answer: We don't. The impact of an increase in Co2 on global temperature was first examined 100 years ago by a Swedish chemist named Arrhenius. Over the decades since then, one revelation after another has altered perspectives in physical science.
Continental drift, Malinkovitch cycles, dinosaur extinction, oceanography, weather monitoring satellites, computer models... it's a lot. And in the year 2010, scientists believe Arrhenius was wrong: doubling the Co2 concentration wouldn't increase mean global temperature by 4--6 degrees C. It would be more like 2.5--4 degrees.
The graph of temperature data over the last 100 years doesn't change into a startling upward swing until about 1950. Various parties have examined the possible explanations for this upswing.. and there are numerous "climate forcers" to choose from... a climate forcer is anything that drives the climate one way or the other. At this point, while increased Co2 concentrations logically explain the increased temperature, any other climate forcer to explain it is lacking. People are free to conclude whatever they want based on that.
So I put that question on the shelf in my own mind by answering it this way: it doesn't really matter. The earth's climate over the last 60 years has been... fine. It's what it's going to to in the next couple thousand years that interests me because of longstanding curiosity about where humanity is headed in terms of population and globality.
So my next question: When I was about 20, I learned that we live in an interglacial period. The last glacial period, what most people, including Al Gore, call the Ice Age, ended about 10,000 years ago. That "Ice Age" was the latest glacial period in recurring alternation that goes back about 35 million years... the length of the present great ice age. Just from the appearance of the alternations, it looks like we could be heading back into a glacial period... well... right now. But definitely in the next three thousand years. Soo..... is that going to happen or not?
Answer: Probably not. We're at an interesting situation where it's possible that the next scheduled glacial period will be skipped and we won't have another one for 50,000 years.
The reason being: the earth's orbit is very circular right now. The cycles we've studied in the geological records have been during a time when the orbit was more elliptical. So we saw interglacials that always lasted about 10,000 years. The last time the earth's orbit was this circular, there was an interglacial that lasted 50,000 years, which means it missed its trigger to go glacial caused by the Milankovitch cycles (the axial wobble.)
So one computer model of the future (without anthropogenic warming) has us experiencing a "near miss" of the trigger. That's not definite though... it's like the coin is up in the air. Add in enhancement of the greenhouse effect right when the trigger is due and: it's not a near miss anymore. So personally, my outook has been altered. I always looked at the way the Great Lakes ecosystem is challenged by humans and thought: yea... that'll be fixed by a glacier. I'm still mentally digesting this new information: maybe no glacial period for another 50,000 years.
My last questions: tell me what's going to happen in the next 10,000 years with global warming... from best case to worst case scenarios, and what decrease in Co2 emission would be necessary to make any difference? I'm in the process of gathering the answer to those two questions. Tune in next time for an answer... if not the answer.
--most information taken from two books by David Archer, an oceanographer who works for the University of Chicago: Global Warming: Understanding the Forecast, and The Long Thaw.
@Arjuna,
AGW is the argument that is so political, and not the actual warming of the globe. The usual egomaniac suspects have planted it in minds of the masses that WE are the cause of global warming. I think humans tend to be arrogant at heart, and wealthy nations tend to lord their superiority over other nations. Those nations who are just now building up their infrastructure have zero desire to cut back on emissions. In speaking to leaders from these up-and-coming nations their comment to wealthy nations is, "You had your economic boom where you freely exploited natural resources, and now it's our turn." These same nations are all too happy to jump on idea of human CO2 emissions because from their perspective it's a free kick to the groin of industrialized nations in terms of world-side economics.
http://blogs.telegraph.co.uk/news/jamesdelingpole/100017393/climategate-the-final-nail-in-the-coffin-of-anthropogenic-global-warming/
http://www.nolanchart.com/article805.html
http://www.populartechnology.net/2009/10/peer-reviewed-papers-supporting.html
http://z4.invisionfree.com/Popular_Technology/index.php?showtopic=3570
@Pronounce,
Pronounce wrote:
AGW is the argument that is so political, and not the actual warming of the globe. The usual egomaniac suspects have planted it in minds of the masses that WE are the cause of global warming. I think humans tend to be arrogant at heart, and wealthy nations tend to lord their superiority over other nations.
I think politics only reflects something deeper... it's basically sensitivity to potential threats and cultural patterns in regard to seeking revelations about the future.
If you have a thought about the cause of the increase in global mean temperature since 1970, I'd be more curious than anything else. As I said, that issue is pretty much shelved for me. It's the forecast that interests me.
And a correction: it's not climate forcers... it's called climate forcing... a climate forcing has to do with mechanisms that affect the way energy is balanced into and out of the earth.
An interesting website:
http://realclimate.com/
@Arjuna,
Being recently from Fairbanks, AK, and looking into permafrost melt and the amount of released of greenhouse gases from these melts. I'm siding with the scientists who believe we've reached critical mass and global warming is being accelerated due to this process.
I theorize that as heating increases evaporation will increase. As evaporation increase a refrigeration effect will be noticed at sea level. This will produce a cooling effect in some areas.
So now we're in a warming trend, and in time we'll be in a cooling trend.
@Arjuna,
Is that what you were asking for?
@Pronounce,
Pronounce wrote:
Is that what you were asking for?
Yes, you're saying you agree that present warming could be explained by increased CO2 concentration in the atmosphere. You're suspicious that there are other factors to consider. Yea... there are so many factors that I've found it a tad confusing trying to keep it all straight.... which suggests a computer model or two (or 19... the number the IPCC examined) would be helpful.
I haven't seen the evaporation idea so far... wouldn't that be a transfer of heat from the ocean to the air? Then eventually the heat would escape from the atmosphere into space as infrared radiation.... earthshine. The way CO2 increases the temperature is that it acts as an obstruction to that escape. Surface temperatures increase until the obstruction is overcome and the balance between energy in from the sun and energy out as earthshine is reestablished.
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