Comment by Construct | Hacker News Reader

Comment by Construct | Hacker News Reader

The proposed solution for cooling the Earth in the article is questionable at best. Furthermore, even if you lower global temperatures through stratosphere manipulation, there are many other scary unknowns in the field of climate change. Take ocean acidification for example:

http://en.wikipedia.org/wiki/Ocean_acidification

The ocean is a substantial sink for atmospheric CO2. Our best guess is that 1/3 of the CO2 we produced is absorbed by the ocean. As the ocean absorbs CO2, however, the pH of ocean water drops. Unfortunately, we don't know how this will affect all of the different species of marine life that live in the ocean, but early experiments show that shellfish in particular do not tolerate more acidic waters very well. Furthermore, there is reason to believe that the ocean's CO2 absorbing capabilities will decrease as the pH decreases, leaving us with even more CO2 in the atmosphere.

Basically, there are a whole lot of unknowns in the whole debate, many of which could have unpleasant (to say the least) consequences. Brushing the entire field of climate science aside and declaring that all of our problems can be solved by pumping sulfur dioxide into the atmosphere is wildly irresponsible.

But the climate models say that we can do this. The models are so accurate and trustworthy that we can totally predict what global climate will be 100 years in the future depending on whether or not we adopt Kyoto. We can also predict what they would be now if humans didn't emit CO2.

Why are you denying the consensus and being anti-science? You must also be a creationist.

</snark>

This is an interesting topic, because it really forces us to evaluate how much we actually know about climate. To draw conclusions like "the modern warming trend is anthropogenic in origin", we need to believe that our climate models are really good. So good, in fact, that they can accurately model virtually the entire climate, which is what allows us to pinpoint CO2 emissions and rule out all other forcings as the cause of modern warming.

We do this by running the models with those other forcings, but without CO2, and observe less warming. But then, we turn around and say "we can't model $geoengineering_scheme". Why not? Are our models simply incapable of predicting the response of climate to various forcings?

Geoengineering schemes are entirely novel new forcings, while the impact of atmospheric CO2 can be studied historically.

This weakens your contention, but I still think you're pointing out an interesting bit of hypocrisy in the public debate (often these hypocrisies cease to exist in debates among experts).

We have historical data on SO2 - basically every volcanic eruption ever.

That's actually not a lot of data, but it's considerably more than we know about exogenous inputs of CO2 - we have only one data point on CO2, but a handful on SO2 (Pinatubo, Krakatoa, a few more).

The models don't enter into it.

You just need to observe the relative carbon isotope levels in the CO2 of the atmosphere. If the CO2 is natural, there'll be a large proportion of C-14 (it's created by interactions with cosmic rays in the upper atmosphere). If it's man made, there'll be a lot of C-12 and 13, since that comes from oil, which has been nowhere near the upper atmosphere for millions of years.

Oh, and there's now enough man-made CO2 in the air that carbon dating is inaccurate for recent things (it tests as really old).

How does measuring CO2 levels answer the question of "what would have happened if there were less CO2 in the atmosphere?"

Can we do the same thing with sulfur dioxide after a volcano? If so, all we need to do is wait for the next big volcano to prove geoengineering is viable.

Sulphur dioxide will lower temperatures, sure - but at what cost? The oceans are acidic enough already.

The models certainly do enter into it if you want to predict what the consequences will be of having higher CO2 concentrations. Knowing that we belch a lot of carbon dioxide into the atmosphere may tell us the cause, but not the effect. That has to be done with modeling or educated guesses.

Most of yummyfajitas' post seemed to be name-calling; I was responding to this point:

> To draw conclusions like "the modern warming trend is anthropogenic in origin", we need to believe that our climate models are really good.

Which is entirely wrong. There are plenty of other sources of data which support that conclusion.

I'll ask you again: without using models, how do we know what the earth's temperature would have been without anthropogenic CO2?

Without knowing that, we can not draw any conclusions as to whether the modern warming trend is caused by human-emitted CO2 or not.

Incidentally, I devoted precisely one line of my post to name-calling, namely reversing a common ad-hominem levied against skeptics of climate modelling.

Increased CO2 is the only reasonable forcing so far; water vapour, methane, etc. have too short a half life in the atmosphere. The bulk of the CO2 increase is anthropogenic in origin, ergo the warming is caused by humans - no models necessary.

there are a whole lot of unknowns in the whole debate, many of which could have unpleasant (to say the least) consequences. Brushing the entire field of climate science aside and declaring that all of our problems can be solved by pumping sulfur dioxide into the atmosphere is wildly irresponsible.

I think the article says just that:

Myhrvold is not arguing for an immediate deployment of the sulphur shield but, rather, that technologies like it be researched and tested so they are ready to use if the worst climate predictions come true.

It seems to me that any objection to this reasoning is really in favor of what we're doing now, which to run around in circles crying that the sky is falling, and claiming that the only possible solution is to pretty much destroy our way of life.

I certainly prefer the Myhrvold approach, of thinking outside the box and challenging others to react, than the Gore fear-mongering.

>claiming that the only possible solution is to pretty much destroy our way of life.

That is what many climate warming deniers like to claim will happen. Doesn't have to be so, Sweden for instance has increased its wealth steadily while at the same time reduced its environmental impact.

>I certainly prefer the Myhrvold approach, of thinking outside the box and challenging others to react, than the Gore fear-mongering.

What Al Gore does is also challenging people to react.

> That is what many climate warming deniers like to claim will happen. Doesn't have to be so, Sweden for instance has increased its wealth steadily while at the same time reduced its environmental impact.

It does actually have to be so, especially for developing nations like China and India. If they were forced to stop using even 20% of their coal plants it would devastate their growing economies. It would take thousands of Swedens and their (frankly) mediocre efforts to reduce their carbon footprints to offset China and India's contribution to global warming.

I think that's a point made in this article too, that even if we are destroying the planet that there really is very little we can do to stop it without encroaching on the human rights of every person on the planet.

>It does actually have to be so, especially for developing nations like China and India

No, it doesn't actually have to be so. Knowledge and technology transfer, more efficient markets, and alternative energy sources combined can ensure continued growth without increased emissions. It is fascinating that some free-market proponents believe in the amazing ability of human imagination and drive to surmount any dificulty (as I do). But as soon as we make any attempt to include environmental externalities when calculating the cost of something, the whole market will appearently collapse and billions die!

>thousands of Swedens and their (frankly) mediocre efforts

It is of course impossible for Sweden to offset the emissions of everyone else. The point is that everyone else can learn from Sweden and do the same. A 9% decrease in carbon emissions over 20 years combined wth healthy growth and high living standards? What would you consider not mediocre?

>destroying the planet that there really is very little we can do to stop it without encroaching on the human rights of every person on the planet.

So destroying the planet is not encroaching on their rights in any way then?

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