Question on climate change

[Indy Lurker]

First, let me say that I am fairly ignorant on the whole climate change thing, which is why I'm asking the question.

Second, It seems like everyone agrees the climate is getting warmer, and that many areas will suffer, especially coastal areas if this trend continues.

My question is how do we know the climate of the last 100 years is the "normal" climate for our planet?

On my last trip with my kids to the museum, I learned that we've had 7 ice ages, and I *thought* it said we were still in an ice age because there is ice on the planet.

How do we know we are not still climbing out of the last ice age, toward our "normal" climate?

Hope this question makes some sense.

[jaksavage]

1. the question is

are we accelerating this meltdown.

Yes climate change would happen without us.
The earth will survive our presence.

[unpossibles]

3. exactly. I look at it like this

if climate change is a hill, we are speeding down the hill with the throttle full on and non working brakes.

[Birthmark]

2. I'll answer your question with some questions

In how many of those previous ice ages and warm periods have there been advanced technological societies?

How many of those previous climate changes led to mass extinction events?

And since you say that you aren't familiar with the subject generally, I'll tell you rather than ask you that previous changes were MUCH slower on a global scale than the current warming. IOW, the ecosystems had some sort of time to adapt in the previous changes.

[tabatha]

4. Here are some links that may provide answers:

http://www.livescience.com/environment/070716_gw_notwrong.html

http://www.sciencedaily.com/releases/2007/03/070328155540.htm

http://www.globalwarmingart.com/wiki/Carbon_Dioxide_Gallery

http://scholarsandrogues.wordpress.com/2007/07/23/anti-global-heating-claims-a-reasonably-thorough-debunking/

http://www.pewclimate.org/state_of_fear.cfm

http://environment.newscientist.com/channel/earth/dn11462

http://www.climate.org/home.html

[Indy Lurker]

5. Thanks for the links

According to this chart: at http://www.globalwarmingart.com/wiki/Carbon_Dioxide_Gallery




we are roughly at 380 ppm compared to a historic high of 280 ppm or approximately 1.37 time higher that the historic top of the cycle, and about 2.0 times higher than the bottom of the CO2 cycle.


So in the past 200 years, we have added between 1.37 and 2.0 times as much CO2 has the historic cycle.

According to the second link: http://www.sciencedaily.com/releases/2007/03/070328155540.htm

"This study confirms that in the Earth's past 420 million years, each doubling of atmospheric CO2 translates to an average global temperature increase of about 3° Celsius, or 5° Fahrenheit."

This would appear to add between to 3.3°F - 5°F over the past 200 years, is this about right?


And according to: http://scholarsandrogues.wordpress.com/2007/07/23/anti-global-heating-claims-a-reasonably-thorough-debunking/

"average rate of change (in CO2) since 1995 has been about 0.68% per year."

This means that at the current rate, we will see another 5°F warming in the next 104 years (if my math is correct)


This of course would assume we do not increase our rate of CO2 Increase.



One thing I did notice is that in: http://scholarsandrogues.wordpress.com/2007/07/23/anti-global-heating-claims-a-reasonably-thorough-debunking/

it says "Scientists aren’t sure what happened in the late Ordovecian period, when the world plunged into an ice age while CO2 levels were still very high (8-20x current levels)."

Apparently it was left off the graph, but why were CO2 Levels 8-20x current levels 450 million years ago?

If CO2 levels were "naturally" 8-20x current levels 450 million years ago, why is assumed they aren't naturally occurring now?


ON EDIT:

I just looked at: http://environment.newscientist.com/channel/earth/climate-change/dn11657

and it says " About 120,000 years ago, when it was 1 to 2°C warmer, the sea level was 5 to 8 metres higher - more than enough to inundate many major cities around the world, including New York, London and Sydney."


I thought we were warmer now than any time in the last 400,000 years due to the record high CO2 levels?

ON SECOND EDIT:

Now I see, there's a time lag between CO2 increase and temp increase.

[Indy Lurker]

7. looks like the lag is 400-800 years

If the chart I found is correct.

[Indy Lurker]

10. I just found this chart

anybody see it before, or know if it's accurate



It looks like CO2 levels and Temperature have been all over the place in the last 600 million years!

[Viking12]

13. ..an answer and the best climate resource.

why were CO2 Levels 8-20x current levels 450 million years ago?

If CO2 levels were "naturally" 8-20x current levels 450 million years ago, why is assumed they aren't naturally occurring now?

The atmospheric carbon was sequestered through biological processes, re: compacted into fossil fuels. We are now reversing that sequestration. There is no doubt the current change in atmospheric chemsitry is the rsult of burning fossil fuels.

If you're truly interested, you can find the answer to nearly every climate related question in the Fourth Assesment Report (AR4) of the IPCC Working Group I:

http://www.ipcc.ch/ipccreports/ar4-wg1.htm

[kentauros]

6. Here's another good link

http://realclimate.org/

:)

[TheWraith]

8. Some answers.

"My question is how do we know the climate of the last 100 years is the "normal" climate for our planet?"

It depends on how you define a "normal" climate. Right now we have a mixed temperate/tropical climate, and we've stayed in a pretty close range for a very long time--ten thousand years, or thereabouts. However, if you check the graphs for long-term temperature, you'll find a very rapid increase in the last 100 years or so, tracking almost exactly with the increase in man-made CO2 in the atmosphere.

So the fact is that natural variations in climate aren't a significant factor in play here, because they move far, far slower than the man-made greenhouse effect. Even if the planet were still gradually warming up, our activities are vastly accelerating anything that's occurring naturally, and with highly destabilizing effects.

[phantom power]

9. Our activities may also be changing the destination.

We've been locked into a cycle of glaciation and warming for a while now. On balance, this has been a good climate for humans. If we jam enough GHG into the atmosphere fast enough, we may push the planet into a hot/dry regime.

Then there's the acidification of the oceans, also being driven by human CO2 release. Our current ocean ecologies are completely un-adapted to that.

[kristopher]

11. Here are my favorite climate sites

http://www.realclimate.org/
A climate change site provided by climatologists


Broad based, policy oriented, progressive advocacy research;
https://www.uspirg.org/

http://www.earthportal.org/
Science based environmental "encyclopedia"
Billed as "accurate, authoritative, accessible"

pew was already listed but what they hey, it's a terrific site:
http://www.pewclimate.org/global-warming-basics/

[OKIsItJustMe]

12. What is the "normal" climate for our planet?

My question is how do we know the climate of the last 100 years is the "normal" climate for our planet?

Actually, this is a misleading question. Our planet has had many climates in its life. IMHO no climate could really be considered "normal" for the Earth. The current climate suits us well. Other climates probably would not.


For example, before the anaerobic bacteria screwed up their environment, oxygen concentrations were much lower in the atmosphere. (For most of the time the Earth has existed, there was no "free oxygen" in the atmosphere at all!)

If the atmosphere went back to a complete lack of Oxygen, would you say, "Well, that's okay, things are just going back to 'normal?'"

We have a vested interest in maintaining the climate which we know as "normal."

[mihalevich]

14. Normal Climate is the climate

current life forms have evolved to. Change it slowly and life evolves with it. Change it fast and you get a mass extinction. We are currently going through a mass extinction event.

[Indy Lurker]

15. It seems we are fighting a losing battle

This chart is from the link you gave me:




It appears very little of the earth's history, like 5%, is down around the 400 ppm level or less.


Looking at the ice data www.realclimate.org




It looks like we have spiked up to around 290 ppm every 120,000 years, for the last 3 cycles.



This time around it looks like we are already up to 380 ppm.


Ah, so that's the problem, were 100ppm above previous CO2 levels for the last 400,000 years, and the hundred ppm is not so much the problem, as the trend suggesting it will continue to even higher levels.

And based on the lag time, we will see at least a 3 deg F even if the CO2 level does not increase.

And if we go to 800 ppm of CO2 we will see another 5 deg F temp increase in the next 800 years.

[OKIsItJustMe]

16. You're getting the idea

...

Ah, so that's the problem, were 100ppm above previous CO2 levels for the last 400,000 years, and the hundred ppm is not so much the problem, as the trend suggesting it will continue to even higher levels.

And based on the lag time, we will see at least a 3 deg F even if the CO2 level does not increase.

And if we go to 800 ppm of CO2 we will see another 5 deg F temp increase in the next 800 years.

You're beginning to grasp the enormity of the situation.

Here are a couple of key concepts (IMHO.):

• "Life as we know it," was made possible on this planet by life on this planet. (Go back and read that again a couple of times. If it doesn't bowl you over, you didn't really understand it.)
• The climate we know as "normal" was created by, and is—or perhaps, has been—maintained by living things.

These concepts are core to Lovelock's "Gaia Hypothesis" (AKA "Gaia theory.") I highly recommend his definitive book, http://www.amazon.com/Gaia-New-Look-Life-Earth/dp/0192862189/">Gaia: A New Look at Life on Earth. It's a fairly easy read, and I wish more people who throw the name "Gaia" about would take the time to sit down and read it.

Unfortunately the "Gaia hypothesis" has (IMHO) been widely misunderstood and consequently wildly misrepresented, perpetuating the problem.

...

The most extreme form of Gaia hypothesis is a non-scientific idea that the entire Earth is a single unified organism that is consciously manipulating the climate in order to make conditions more conducive to life. ...

Ah! If only it were so!


Okay, now another key concept:

• Some (most?) previous periods of warming were probably not initiated by increases of greenhouse gases — "GHG's." (This throws some people for a loop!) However, they were almost certainly amplified by them. (Some periods of warming may have been initiated by the natural releases of GHG's, for example, by massive amounts of volcanic activity.)

Something ("Milankvitch Cycles" perhaps?) kicks off a slight warming trend, which is reinforced by various feedbacks. (e.g. melting snow and ice means more sunlight is absorbed, which warms things up, which causes more snow and ice to melt etc.) Among the feedbacks appears to be a natural release of GHG's. (e.g. methane from thawing "permafrost.")

Okay, this is where the "tipping points" raise their ugly heads. We may have unknowingly initiated these feedback loops. If we have, then we have a real problem on our hands. We could stop all fossil fuel use tomorrow, and GHG levels would continue to climb.