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>> At some point a significant proportion of the people who have been ridiculing climate change ... will shift their beliefs to accept moderate action to tackle

>> At some point a significant proportion of the people who have been ridiculing climate change ... will shift their beliefs to accept moderate action to tackle climate change... what makes you so sure of that (assuming by 'climate change' you mean 'anthropogenic global warming') ?

Brakenshire 9y ago
Because a significant percentage of anthropogenic warming is down to the direct heating effect of CO2, and the positive feedback of that direct heating raising evaporation of water, and the direct heating effect of water. i.e. it's based on simple calculations from core scientific principles. If there's going to be no effect, it requires some negative feedback effect which is not adequately described. So there is a baseline of warming which is very likely to occur, and over time that kind of evidence of rising temperatures becomes undeniable.
- ChemicalWarfare 9y ago
  >> anthropogenic warming is down to the direct heating effect of CO2... OK, let's say this was the case. First question - what percentage of CO2 in the atmosphere is attributed to human activity?
  - Brakenshire 9y ago
    We've increased it by about 50% since the industrial revolution, from about 280ppm to 410ppm. You can tell both from isotope analysis and inventory studies most of the ongoing excess is down to humans. Also, I'm not sure what in that statement is even up for debate, does anyone question that a concentration of CO2 in a volume of space absorbs light at particular wavelengths? It's core science, and a straightforward calculation.
    - ChemicalWarfare 9y ago
      That's not what I asked. If total CO2 in the atmosphere is 100%, what portion of that number is attributed to human activity? Also, CO2 itself - out of all of the greenhouse gases in the atmosphere - what percentage belongs to CO2?
      - mikeash 9y ago
        How is that not what you asked? If we've increased the amount by 50% over preindustrial levels, then the current portion attributable to us is about 33%.
        ChemicalWarfare 9y ago
        ...except that figure is less than 4%. about 8 gigatons are attributed to humans out of ~220 gigatons injected into the atmosphere overall on a yearly basis. the kicker is - the percentage of CO2 in the overall greenhouse pool is also in the single digits, the most significant (volume-wise) greenhouse gas which comprises about 95% of the greenhouse gases in the atmosphere is water vapor. so if you factor that in - if humanity ceases to exist tomorrow, there is a potential for a .3% change in greenhouse gas volumes.
        Brakenshire 9y ago
        > ...except that figure is less than 4%. about 8 gigatons are attributed to humans out of ~220 gigatons injected into the atmosphere overall on a yearly basis. This is like the difference between profit and savings. Accumulated CO2 is a savings accounts, and the pre-industrial climate in the short term acts like a business which has zero profit, balanced revenues and expenditure. If you come into the business, and hold expenditure the same, but increase revenues by 4%, and yield a 4% profit, which every year you put in the bank account, that is going to accumulate over time. And the warming is created by the accumulation. You talk about a 4% yearly excess as if that was a small amount! Also, your point about water vapour ties into what I said in the earlier comment, a lot of the warming is exactly that secondary effect - CO2 has a direct heating effect, that raises temperature, which then raises the partial pressure of water vapour, which increases concentrations of water vapour in the atmosphere, which as you say is a very important greenhouse gas. It's the combination of these two effects, of direct CO2 warming, causing increased water vapour concentration, which accounts for the baseline warming which everyone who is sceptical of computer models should believe in. This very well-established baseline warming accounts for about half of the climate sensitivity proposed by the IPCC, if you think computer models are junk, that discounts many of the positive feedbacks proposed, but also the negative feedbacks which would have to exist, to lead to zero warming.

Brakenshire 9y ago

Because a significant percentage of anthropogenic warming is down to the direct heating effect of CO2, and the positive feedback of that direct heating raising evaporation of water, and the direct heating effect of water. i.e. it's based on simple calculations from core scientific principles. If there's going to be no effect, it requires some negative feedback effect which is not adequately described. So there is a baseline of warming which is very likely to occur, and over time that kind of evidence of rising temperatures becomes undeniable.

ChemicalWarfare 9y ago
>> anthropogenic warming is down to the direct heating effect of CO2... OK, let's say this was the case. First question - what percentage of CO2 in the atmosphere is attributed to human activity?
- Brakenshire 9y ago
  We've increased it by about 50% since the industrial revolution, from about 280ppm to 410ppm. You can tell both from isotope analysis and inventory studies most of the ongoing excess is down to humans. Also, I'm not sure what in that statement is even up for debate, does anyone question that a concentration of CO2 in a volume of space absorbs light at particular wavelengths? It's core science, and a straightforward calculation.
  - ChemicalWarfare 9y ago
    That's not what I asked. If total CO2 in the atmosphere is 100%, what portion of that number is attributed to human activity? Also, CO2 itself - out of all of the greenhouse gases in the atmosphere - what percentage belongs to CO2?
    - mikeash 9y ago
      How is that not what you asked? If we've increased the amount by 50% over preindustrial levels, then the current portion attributable to us is about 33%.
      - ChemicalWarfare 9y ago
        ...except that figure is less than 4%. about 8 gigatons are attributed to humans out of ~220 gigatons injected into the atmosphere overall on a yearly basis. the kicker is - the percentage of CO2 in the overall greenhouse pool is also in the single digits, the most significant (volume-wise) greenhouse gas which comprises about 95% of the greenhouse gases in the atmosphere is water vapor. so if you factor that in - if humanity ceases to exist tomorrow, there is a potential for a .3% change in greenhouse gas volumes.
        Brakenshire 9y ago
        > ...except that figure is less than 4%. about 8 gigatons are attributed to humans out of ~220 gigatons injected into the atmosphere overall on a yearly basis. This is like the difference between profit and savings. Accumulated CO2 is a savings accounts, and the pre-industrial climate in the short term acts like a business which has zero profit, balanced revenues and expenditure. If you come into the business, and hold expenditure the same, but increase revenues by 4%, and yield a 4% profit, which every year you put in the bank account, that is going to accumulate over time. And the warming is created by the accumulation. You talk about a 4% yearly excess as if that was a small amount! Also, your point about water vapour ties into what I said in the earlier comment, a lot of the warming is exactly that secondary effect - CO2 has a direct heating effect, that raises temperature, which then raises the partial pressure of water vapour, which increases concentrations of water vapour in the atmosphere, which as you say is a very important greenhouse gas. It's the combination of these two effects, of direct CO2 warming, causing increased water vapour concentration, which accounts for the baseline warming which everyone who is sceptical of computer models should believe in. This very well-established baseline warming accounts for about half of the climate sensitivity proposed by the IPCC, if you think computer models are junk, that discounts many of the positive feedbacks proposed, but also the negative feedbacks which would have to exist, to lead to zero warming.