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jshell wrote: The cow-phart thing I always took with a pinch of salt
The cow flatulence thing is actually an issue (it seems it's burps more than farts, incidentally). Methane is a greenhouse gas 25 times stronger than CO2. (That's 25 times over a century, the standard comparison).
[Source: IPCC, Table 2.14 on page 212 of this report].
It's not just the flatulence, but the fact that cattle take a lot of land to raise (meaning forests are cleared) and a lot of land to grow feed on (they retain very little of the food we give them - why are we feeding half the world's grain harvest to animals that shit 95% of it out when we could eat that grain ourselves?).
More fodder means more forest clearance, plus oil-derived fertilisers are used on the feed crops. These decay into nitrous oxide, a greenhouse gas 298 times stronger than CO2. This is one of the most compelling arguments for eating organic, as it doesn't use artificial nitrate fertilisers.
I wrote a thing about the carbon cost of meat here.
jshell wrote: the volcano contribution seems to be much more serious
No, it's not.
After the slew of lies in the documentary the Great Global Warming Swindle, the university of Cambridge got experts in the relevant fields to explain the errors and establish the truth. It's reproduced in the U-Know Features
http://www.headheritage.co.uk/uknow/features/?id=82
In response to the idea that volcano eruptions dwarf human carbon emissions, Professor Chris Rapley said:
"This is untrue: current annual emissions from fossil fuel burning and cement production are estimated to be around 100 times greater than average annual volcanic emissions of CO2. That large volcanoes cannot significantly perturb the CO2 concentration of the atmosphere is apparent from the ice core and atmospheric record of CO2 concentrations, which shows a steady rise during the industrial period, with no unusual changes after large eruptions."
A survey of papers published in the world's premier peer-reviewed scientific journal Science found that, of all the 928 that dealt with climate change, none doubted that anthropogenic climate change was happening.
The doubt comes in small part from non peer-reviewed science, and in the most part from non-scientists with a personal political slant.
jshell wrote: Any disbelief that I may have or foster in future would be related to how much we as man effect the cycle of warming.
That's easily established by the 4 questions I mentioned earlier in this thread. The only reason the planet is warm enough to live on is because greenhouse gases trap solar radiation. The more of them there are, the greater the amount of heat retained. This stuff is uncontroversial basic climate science, as described long before anyone talked much about climate change, and indeed we can prove it in a laboratory.
Most of the gases that make up the atmosphere have no greenhouse effect - those that do are measured in parts per million of the total atmosphere. So with it being so small a part, it's easy to change the balance. Think of it like how small a part of your meal is salt, but double or treble the amount and, even though it's still a small percentage, your meal is changed.
Perhaps more apt is to think of heating your house. There are natural cycles that affect the temperature of your house. But you also have a heating system. Double the amount of radiators and you will find the place gets stifling.
jshell wrote: can we do anything about it?
Just as we can make it worse, so we can stop. What we've emitted since we started burning fossil fuels in earnest has already committed us to a great deal of change. But the more we burn, the worse it will be. Some lands and species are already doomed, but many more hang in the balance.
most importantly, there is a 'tipping point' where natural cycles kick in to make it worse. For instance, the colossal West Siberian peat bog is defrosting. Peat is undecayed moss. As it warms and dries, it decomposes, releasing its vast store of carbon. This creates more climate change. Forests dry out and burn, releasing their carbon. Ice caps shrink, reflecting less sunlight. The dark ocean beds beneath them release their methane.
There are many such examples. Basically, after a certain point the bioshpere takes over as the major emitter and we will just be spectators and victims.
It is impossible to put a precise point on when that happens. The more we emit, the greater the chance we have of reaching it. It's generally held to be about 2 degrees of global warming above pre-industrial temperatures. To have a good chance of staying within that, the IPCC say global emissions need to peak around 2015. It's this generation that decides.
so yes, we still have time, but not for long.
jshell wrote: Suggestions are that it'd cost the destruction of every economy on Earth to make and noticeable change.
The UK government commissioned the Stern Review to look at precisely that. It said that the global cost of a high level of warming this century would be 5-20 percent of global spending power, while preventing it would cost about 1 percent.
But beyond the cost is the social justice. Stern found that a rise above 2 degrees would mean 1-4 billion people face water shortages. Food production would plummet. Those with wealth would buy the scarce resources, the poor would go without. It is, of course, the poor who bear least responsibility for the problem, whilst the rich accrued their wealth largely through high-carbon activity.
And then, Stern says, 15-40 percent of all species would face extinction. How do we put a price on that? What happens to the ecosystems when we remove those species? What knock-on effects does that have on us?
Such a magnitude of risk is absurd and obscene when we have an alternative available. There are other ways of growing food, getting around, keeping warm and having fun that don't involve such huge emissions. We have to stop seeing economic growth (the consumption of more and more stuff) as the point of society. We can sustain life very well, but many things have to change.
If we leave it until we see the worst effects of climate change, it will be like trying to avoid a car crash at the point of hitting the brick wall. We still have time to slow down and go round. But that time is running out, and the later we leave it the more drastic and uncomfortable the remedy will be.
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