Is human activity really causing Co2 increase in atmosph?

[shandcunt]

Thanks for posting the video, its really important that people get educated about the subject.

I think your experiment confirmed something we can all agree about which is that CO2 is released from the ocean as it gets hotter.

[DaveMcRae999]

OMG - no scientist picked this up before you - completely overlooked - you are truely the Galileo, the Einstein - I will be looking for your name as the next science Nobels are awarded. There is my government (Australia, we love coal) and dozens other hoping you will join them, or someone like you, to show that fossil fuels are fantastic and we need that export money.

[mbarrera47]

So this experiment shows that dissolved CO2 or other gas in a liquid escapes a lot more when it is heated up.

[Bigstubby1]

The pH of the ocean is decreasing (becoming more acidic). This is due to excess CO2 entering the ocean to make H2CO3. So the CO2 isn't coming from the ocean. The isotopic ratios of carbon is consistent with burning fossil fuels, rather than from biosphere respiration. Human emissions are about 7 Gt per year. That more than accounts for the extra CO2 in the atmosphere since 1850.

[gpetters]

Hi Bigstubby1!

How do you know measured Co2 increase in atmosphere are coming from man burning fossil fuel and not from other sources?

[Bigstubby1]

Isotopes of carbon (C12,C13, C14) was the key to determining the source of increasing CO2 in the atmosphere. Different material sources have different isotopic ratios that may vary over time. Measurement of carbon isotope ratios in materials that forms regular rings (tree rings) or layers (coral, sediment, arctic ice cores) over thousands to many millions of years compared to the last century gave us the clues that implicated the burning of fossil fuels as the source of CO2.

[Bigstubby1]

Key Observations: C13/C12 ratio and the C14/C12 ratio in the atmosphere, in tree rings, in coral & sediment layers & in arctic ice cores have been decreasing since the start of the human industrial era (1850) in parallel with the steady increase of CO2 in the atmosphere.

[Bigstubby1]

We know that atmospheric CO2 can come from various sources:

1) Volcanos?: Cant be derived solely from volcanos, because from 1850 to 2009, the six major volcano eruptions emitted only 0.17 Gt C/year compared to the 7 Gt c/year generated from human industry.

2) Animal vs plant respiration & photosynthesis? Must be plant-derived because plants are enriched in C12 vs C13. And the C13/C12 ratio has been decreasing since 1850.

[Bigstubby1]

3)Gas release from the oceans? Cant be oceans because ocean surface waters are enriched in C13 (because heavier isotopes are favored by precipitation). Not consistent with the decline of the C13/C12 ratio.

4) Burning of trees vs fossil fuels? CO2 cant be derived solely from burning trees because, in contrast to contemporary plants, fossil fuels are depleted in C14 due to its relatively short half-live (5700 years). This is consistent with observed decline in C14/C12 in atmospheric CO2.

[Bigstubby1]

In summary, unless there is a natural process that emits 7 billion tons per year of CO2 from material derived from old plants (fossil fuels), we conclude that the extra CO2 is coming from human processes consisting of burning fossil fuels.

[gpetters]

Hi Bugtubby! Thanks for your extensive answer. You seems to be well studied having very good knowledge about topic. Can you answer the following questions? :

What residence time in atmosphere does co2 have when co2 comes from the following sources: 1. "natural" co2 ('Animal respiration / plants outgassing co2 when they die/rotten/are burnt)? 2. man burning fossil-fuel? 3. co2 outgassing from earth crust?

[gpetters]

4. co2 outgassing from earth interior 4a. co2 outgasing through landbased volcanoes? 4b. co2 outgassing through underwater volcanoes? 5. co2 outgassing from oceans? 6. co2 released from underground coal fires burning world wide (burning 24/7 for many years now)?

Where do you think the major sink for atmospheric co2 is located?

[Bigstubby1]

Humankind is releasing CO2 at a rate of about 7 Gt C per year from fossil fuel combustion, with a further 2 Gton C per year from deforestation. In the last 129 years, volcanic eruptions account for 0.15 Gt/ year. The natural world is absorbing CO2 at a rate of about 2 or 2.5 Gt C per year into the land biosphere and into the oceans, for a total of about 5 Gt C per year. The CO2 concentration of the atmosphere is rising because of the 4 Gt C imbalance.

[Bigstubby1]

It appears that the term "residence time" has different meanings to different people. One definition describes residence time as the duration between a perturbation (rapid addition of CO2) and the reestablishment of equilbrium by CO2 uptake. The mechanisms for water vapor increase (evaporation) and decrease (precipitation) are simpler and quick (few months). For CO2, the mechanisms controlling CO2 release and uptake are varied and complex; but generally slower (200-800 years is one estimate).

[gpetters]

Hi Bigstubby1! You say general residence time of Co2 staying in atmosphere in average is say (200+800)/2=500 years. How can you explain oceans pH are decreasing nowadays due to co2 entering the oceans in the very slow rate of 500 years? Was there much co2 outgassing from mankind 500 years ago? .....and would'nt the sodapop industri be broke by now if they had to wait 500 years production time before they could sell their stuff?

[Bigstubby1]

What you are referring to as residence time is the estimated time it would take for natural processes to absorb the CO2 we added to the air to reach an equilibrium, IF WE CEASED adding CO2 to the atmosphere. In a short 125 years humans have added roughly 500 Gt of carbon into the air. This is faster than any natural process revealed by the ice-core data describing how CO2 varied in the atmosphere going back 650,000 years.

[Bigstubby1]

Thus it may take 200-800 years for the CO2 concentration to stabilize (reach equilibrium) and then begin to decrease. On the other hand the pH of the oceans is, in part, a function of the concentration of dissolved CO2. Over 125 year period, the rate of carbon release (9 Gt of carbon per year) exceeded the uptake (5 Gt of C/ year) by 4 Gt of C per year. The ocean is taking up 2.5 Gt of C per year which increases the concentration of dissolved CO2. That is why the pH is decreasing (more acidic).

[Bigstubby1]

CO2 + H2O is making H2CO3 (carbonic acid) and food chain organisms who survive by virtue of a carbonate shell are weakened by the low pH environment. Since we know the mass and density of the air, you can calculate for yourself the concentration of CO2 (ppmv) that would be generated by adding 500 Gt of carbon. It comes out to ~220 ppmv. In this short timeframe, wince we added more CO2 than is currently measured in the air, the extra CO2 must be being absorbed, not released.

[L571J]

@gpetters That is freaking hilarious.

[DLbrooks87]

@Bigstubby1 Exactly right. What the poster has discovered is the Van't Hoff transformation of the Henry's constant due to increasing temperature. What he is completely ignoring is the PRIMARY STATEMENT of Henry's law, that the concentration in the aqueous phase is proportional to the partial pressure in the atmosphere.

Not to mention that he is completely ignoring other independent lines of evidence for an anthropogenic CO2 source, such as C12/C13 ratio, fossil fuel estimates, O2 decline, etc

[OxAO]

@DLbrooks87

yes he does ignore Henry's constant but it still works out that the ocean becomes a HUGE sink for CO2

The heat capacity of the ocean overwhelms the trace concentration of CO2 in the air and makes the temperature the driver of this system.

ion chem usu edu/~sbialkow/Classes/3600/Ove­rheads/Carbonate/CO2 html

[DLbrooks87]

@OxAO By "system" what do you mean? Are you referring to ocean heating being the driving force to the 20th and 21st century trend in atmospheric carbon dioxide concentrations?

If so I'm afraid I'll need some proof beyond a link to basic carbonate chemistry.

[OxAO]

@DLbrooks87

said, "Are you referring to ocean heating...?"

No

in this case the exchange of CO2 between air and ocean

[DLbrooks87]

@OxAO Ok. But you said the ocean is "the driver of this system". Exactly what does that statement refer to? There are many 'systems'.

[Alfox64]

This demonstrates the relationship between the temperature of the water and the rate at which it releases the gas. It do not show that Human activity causes the raising of the Earths environment. I acknowledge that a Human boiled the water in that kettle though :-)