At what level will atmospheric CO2 matter?

Wangler

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Wangler
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Some folks say current global warming is due (entirely or in part) to anthropogenic release of CO2, a known greenhouse gas. It is a problem worth dealing with now. Call this group Camp 1.

Some folks say current global warming is not due to man's release of CO2, and dealing with CO2 is not worth it at the present time. Hello, Camp 2.


Currently, CO2 is ~385 ppm in the atmosphere, and there are many who would like it to stay there (it won't).

Others would like it to eventually get lower (long time to wait for that).

However, my question is primarily for Camp 2:

At what level (ppm) will atmospheric CO2 matter?

By matter, I mean at what level will it be a problem worth dealing with? 1,000ppm? 2,500ppm? 250,000ppm?
 
I think the big problem with this way of thinking is that it dichotomises the dilemma. It defines it as a 'problem' versus 'no problem', as if there is a sudden limit at which the Earth with spontaneously go boom.

It doesn't seem to matter which what a person's position is on AGW - alarmists and denialists alike seem to see things as being defined in a black-and-white manner. The truth is, with the exception of perhaps trigger events, global warming is not (in its literal meaning) a dilemma. Climate change cannot be switched off by not driving your car, and there isn't a sudden mark where carbon dioxide will roast us alive.

It is a spectrum, and a complicated one at that. Nobody asks how many times you have to spin the wheel to win it big on a game of roulette. Obviously, it depends. But the more times you spin it (given unlimited funds) the greater the chance that at some point you will win.

AGW and climate change education suffers big time from oversimplification and alarmism more than it does from GW skeptics and denialists, in my view.

Athon
 
The science is complex, but how do you explain that to the general public? The possibilities are quite alarming, do you not tell people what the possibilities are?

It involves a global change to the climate. Most the habitat that we live in and depend on, depends on the climate. It is changing, and at a rate that is very fast in geological terms, and in adaptation terms. It is a global phenomenon, that will impinge on most life. There is a good reason to be alarmed.

The science has been studied intensively, and has been developed over the course of a century.

http://www.aip.org/history/climate/
 
a_unique_person said:
The science is complex, but how do you explain that to the general public? The possibilities are quite alarming, do you not tell people what the possibilities are?
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Damn good question, and one that is pretty much the question of the hour amongst science communicators. There are a number of positions on this, and there is no clearly defined 'how to guide'. At least that we all agree on.

For my money, based on having worked on an educational program on this very topic for the past few months, it depends on the focus. By all means, people should understand the possibilities.

However people are really bad with understanding risk and risk analysis. While decisions are indeed dichotomous actions (either you act or don't act), the decision on which it is based is far more complex.

So, with kids at least, I've found it works much better to feed their optimism rather than their fears, providing examples of things that work well and concentrate on discussing the idea of sustainability providing good things (savings in costs, helping the next generation, increasing biodiversity etc.) rather than the bad things that might result from not acting (poverty, increasing chance of death, decrease in biodiversity).

It involves a global change to the climate. Most the habitat that we live in and depend on, depends on the climate. It is changing, and at a rate that is very fast in geological terms, and in adaptation terms. It is a global phenomenon, that will impinge on most life. There is a good reason to be alarmed.
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The problem with being alarmed is that it has a paralysing effect. People either feel the problem is too big, too late or too inevitable. Kids especially don't respond as well to things they can't quite grasp. Oddly, it was realised even back during the cold war that science communication based on fear is less likely to promote effective action, and yet people still use it with current climate education.

The science has been studied intensively, and has been developed over the course of a century.

http://www.aip.org/history/climate/
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I don't think the science is in doubt, or is being questioned on that level. Some events will, by their nature, alarm people as a possibility. Those same events won't cause others much concern at all.

What I'm referring to is the communication of these changes, and how to best encourage behaviours that promote sustainable living.

Athon
 
At 1% by volume of the atmosphere (100,000 PPM) toxic effects begin to be noticed with drowsiness. 3-4% is fatally toxic over months of constant exposure.

One data point.
 
Thanks for the responses, JREFers.

What I was hoping was to get a response from someone who thinks that our current levels of CO2 are not a concern in the short term.

Alright, I would say, if you don't consider it a problem now, when would you consider it a problem? Never?
 
If I remember correctly, OSHA allows workers to put in eight hour days with co2 concentrations of up to 5000 ppm.
 
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There is a very good short article in November's Scientific American on page 13. Heading Still Hotter Than Ever. If says the temperature has gone up in the 20th century.

The "hockey stick" graph has been both a linchpin and target in the climate change debate. As a plot of average Northern Hemisphere temperature from two millennia ago to the present, it stays relatively flat until the 20th century, when it rises up sharply, like the blade of an upturned hockey stick.
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So CO2 matters now. We should reduce the level to what it was at the start of the 20th century. But we will never do that.
 
shadron said:
At 1% by volume of the atmosphere (100,000 PPM) toxic effects begin to be noticed with drowsiness. 3-4% is fatally toxic over months of constant exposure.

One data point.
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Wouldn't 1% be 10,000 PPM?
 
Wangler said:
At what level (ppm) will atmospheric CO2 matter?

By matter, I mean at what level will it be a problem worth dealing with? 1,000ppm? 2,500ppm? 250,000ppm?
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To answer that you need to answer two other questions:

1. How does increase in atmospheric CO2 relate to increase in temperature?

2. How much can the temperature increase before it results in significant human suffering?

You also have to take into account the speed of the increases: the slower the increase in temperature the more likely it is that we will be able to adapt to it without significant human suffering.

There are reasonable estimates for question 1, but question 2 is much harder to answer.
 
What we should really be worried about is the almost hundreds of billions of tons of clathrates under Siberia.
 
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