Man Based Global Warming....

[JSH]

Originally Posted by Alric

You are describing an effect of scale. Note how the scale gets larger and larger as go farther back in time. The issue is that temperature is increasing in a timescale that has not been documented for the past 2K years. It is also contrary to what climate scientists would expect in the absence of increased levels of C02.

It is not a matter if the climate has ever changed. The question is what happens if it is changing now, and if our civilization can weather it.

I am well aware that my graphs show a difference in scale; that was my point.

Why should we be concerned about a very rapid rise in temperature over the last 100 years? The timespan of our planet's climate is measured billions or years. We know temperature fluctuated greatly over that timespan.

"First, at many locations, there exist large temperature fluctuations on multi-centennial scales. Hence, climate change lasting for centuries appears to be a common feature of many regions."



The anomaly I see in this graph is the past 10,000 years. The earth's temperature has been abnormally stable and humans have flourished. Temperatures have been ~ 6 degrees warmer than normal. However, it is incredibly arrogant on our part to think that we can somehow break the natural cycles of the earth and force our will on the globe.

BTW, all my graphs have come from wikipedia.com / global warming

[Alric]

Originally Posted by jhinton

The timespan of our planet's climate is measured billions or years. We know temperature fluctuated greatly over that timespan.

However, it is incredibly arrogant on our part to think that we can somehow break the natural cycles of the earth and force our will on the globe.

Yes. However, the observation is that our emissions are warming the planet unnaturally and to levels not seen in the past couple of millenia. It is a logical fallacy to conclude that because the weather has changed in the past we could not be the cause of it now. Both statements can be true and it appears they are.

It is not arrogant. It is what the data bears.

I am linking a better written exposition:

Global warming and natural climate change in the past

Global warming and natural climate change in the past

The skeptic argument...
Earth's climate has changed long before we were pouring CO2 into the atmosphere. Europe was far warmer in the Middle Ages. During the 17th and 18th century, it was much colder, prompting the ‘The Little Ice Age’, when the Thames was frozen over months at a time. Further back, there were times when the Earth was several degrees hotter than current temperatures. Warming of several degrees often took only centuries or decades.

What the science says...
The usual drivers of natural climate change have shown little to no warming trend since the 70's.

It's a well established fact that climate changes naturally and sometimes dramatically. The pertinent question isn't "has climate changed in the past?" (of course it has) but "what is causing global warming now?" To begin to answer that, it's helpful to look at the major causes of natural climate change in the past.

Solar activity
Solar variations have been the major driver of climate change over the past 10,000 years. When sunspot activity was low during the Maunder Minimum in the 1600's or the Dalton Minimum in the 1800's, the earth went through 'Little Ice Ages'. Similarly, solar activity was higher during the Medieval Warm Period.

However, the correlation between solar activity and global temperatures ended around 1975. At that point, temperatures started rising while solar activity stayed level. This led a team of scientists from Finland and Germany to conclude "during these last 30 years the solar total irradiance, solar UV irradiance and cosmic ray flux has not shown any significant secular trend, so that at least this most recent warming episode must have another source." More on the sun & global warming...

Milankovitch cycles
Earth's climate undergoes 120,000 year cycles of ice ages broken by short warm periods called interglacials. The cycle is driven by Milankovitch cycles. Long term changes in the Earth's orbit trigger an initial warming which warms the oceans and melts ice sheets - this releases CO2. The extra CO2 in the atmosphere causes further warming leading to interglacials ending the ice ages.



For the past 12,000 years, we've been in an interglacial. The current trend of the Milankovitch cycle is a gradual cooling down towards an ice age.

Volcanoes
Volcanic eruptions spew sulfate aerosols into the atmosphere which has a cooling effect on global temperatures. These aerosols reflect incoming sunlight, causing a 'global dimming' effect. Usually, the cooling effect lasts several years until the aerosols are washed out of the atmosphere. In the case of large eruptions or a succession of eruptions such as in the early 1800's, the cooling effect can last several decades. Strong volcanic activity exacerbated the Little Ice Age in the 1800's.

Summary
The usual suspects in natural climate change - solar variations, volcanoes, Milankovitch cycles - are all conspicuous in their absence over the past 3 decades of warming. This doesn't mean by itself that CO2 is the main cause of current global warming - you don't prove anthropogenic warming by eliminating all other options. But the primary causes of commonly cited climate change in the past have played little part in the current warming trend.

As for CO2, empirical observations show that CO2 has a warming effect as a greenhouse gas, CO2 is increasing in the atmosphere and the expected warming you would get from greenhouse gases is occuring. Any alternative theory that found a different cause of global warming would also need to explain why the expected (and observed) warming from CO2 has not eventuated.

[FL_Prius_Driver]

Like all climate discussions (whether on PC or not), everybody virtually always centers on the "exciting" and "emotional" topic of Global Warming.

The boring aspect of dumping into the atmosphere every single carbon atom extracted from the ground and burned is apparently not a worthy issue in itself.

Boring questions to consider:
1) The ocean's pH is changing. Is this of any concern whatsoever?
2) Do we want the carbon burning to stop only due to running out of hydrocarbons to burn?
3) Where in history have we dumped megatons of pollution continually and not have had a problem occur? (I'm pretty surprised that this gets no airplay. Is the only possible impact on life of CO2 concentrations being increased dramatically some long term climate change?)

[JSH]

Originally Posted by Alric

Yes. However, the observation is that our emissions are warming the planet unnaturally and to levels not seen in the past couple of millenia. It is a logical fallacy to conclude that because the weather has changed in the past we could not be the cause of it now. Both statements can be true and it appears they are.

It is not arrogant. It is what the data bears.

30 years in a 10K year cycle is a rounding error. We will enter another ice age and it will be devastating to the human population. However life will go on. It is arrogant to assume that the human population is special in a timespan of billions of years.

Originally Posted by Alric

Milankovitch cycles
Earth's climate undergoes 120,000 year cycles of ice ages broken by short warm periods called interglacials. The cycle is driven by Milankovitch cycles. Long term changes in the Earth's orbit trigger an initial warming which warms the oceans and melts ice sheets - this releases CO2. The extra CO2 in the atmosphere causes further warming leading to interglacials ending the ice ages.

For the past 12,000 years, we've been in an interglacial. The current trend of the Milankovitch cycle is a gradual cooling down towards an ice age.

We should be VERY scared of entering another ice age. It seams that the natural temperature of the earth is 5 to 6 degrees C LOWER than it is now.

My concern with global warming is that it is consuming billions of dollars in research funds for something that may be a problem. However, we know we have huge global problems today that need to be fixed. Problems like disease, hunger, poverty, etc. These causes are being swept aside by the developed world to focus on CO2.

[TimBikes]

Originally Posted by Alric

Climate change in graphs:

Atmospheric CO2 concentrations:


Global temperature averages:



Any questions?

Yes ... a few questions:

- What caused the rapid 0.6 C temperature increase from 1910 to 1940 when CO2 levels were relatively low?
- Why did temperatures fall from the 1940s until around 1980, even as the amount of fossil fuels burned (and CO2 added to the atmosphere) increased dramatically?
- Why don't you clearly show the last 10 years - with ever increasing levels of CO2 and flat to cooling global temps?

I guess these observations run counter to the argument that temperature and CO2 are moving in "lockstep".

[darelldd]

My "feelings" on this subject are nicely summed up in this missive from a Starbuck's coffee cup:

So-called “global warming” is just a secret ploy by wacko tree-huggers to make America energy independent, clean our air and water, improve the fuel efficiency of our vehicles, kick-start 21st-century industries, and make our cities safer and more livable. Don’t let them get away with it!

Just ignore global warming and climate change if it upsets you or you don't "believe". There are PLENTY of reasons to change our ways even if we aren't causing global warming. Continuing to pollute at the same levels we have been because there's no proof that we're causing global climate change is... is... well, I have no word for it. Stupid doesn't do it justice.

[dbermanmd]

Originally Posted by jhinton

However, it is incredibly arrogant on our part to think that we can somehow break the natural cycles of the earth and force our will on the globe.

I agree totally,,, complete arrogance to think man has an influence on global climate -

And the leap of faith here is staggering,,, trust me,, i know what the worlds climate will be in 100 years yet we cant predict things 1/10 as complex with any degree of certainty....

Catch this one,,, global warming is causing the earth to cool down,,,, or,,, global warming is causing the most severe winter conditions ever seen over the past half century....

[dbermanmd]

Originally Posted by donee

Hi dbermandmd,
Looks like the evidence provided by Alric all goes against your hypothesis (that a few weeks of extra cold weather in North America disproves global warming), however.

Hi back to you too, and wishes for a Happy Holiday Season and New Year,,

And the evidence that any of the temperature variations we have seen are due to mankinds influence on the plantet?

Seems to me, the rocket scientists that are trying to prove their null hypothesis need to provide the jury with incontrovertible proof - still way too much doubt in this jurors mind,,, and more than enough doubt before i would create any more govt bodies to either tax or cap and trade carbon - especially given the potential for economic injury which imho would have greater negative impact on man and the environment.

mind you i believe we should treat the environment with respect,,, i for one heat my house with two wood pellet stoves,,, heat my house and pool water using the suns energy and own two hybrids (prius and camry)...

[icarus]

Darrell has it right,

As for waiting for incontrovirtible proof,,, What can I say? This just in to Week end update....Generalisimo Francisco Franco is still DEAD!

Get a clue folks!

Icarus

[Fibb222]

Originally Posted by dbermanmd

I agree totally,,, complete arrogance to think man has an influence on global climate -

I always surprised by this statement. Why wouldn't a doubling of CO2 in <300 years have an effect on the equilibrium of the climate? It's a known heat trapping gas. To say that there is no way we can or are affecting the climate, even though 99.9% of peer reviewed science says we can and we are, is what's truly and massively arrogant.

There comes a time when even the most stubborn person must come to the realization that that much denial, in the face of overwhelming evidence, is nothing short of a major psychological deficiency. That's not healthy skepticism, that's insanity. Nobody should be that arrogant.

With a little imagination it shouldn't be so hard to get past the denial stage.

Long term, what's going to happen to the climate and consequently our civilization if 10s of millions of people continue coming into the middle class every year? Our world wide emissions can only go up tremendously if we don't get off fossil fuels. Fortunately it looks like Obama is going to lead the world out of this malaise of in-action that's plagued us thus far.

So deny AGW all you want. Come late January you won't have like-minded people in power anymore. Nahhh!