The Naked Scientists

The Naked Scientists Forum

Author Topic: Overheated oceans and methane rising to the surface and combustion?  (Read 3744 times)

Offline Europan Ocean

  • Sr. Member
  • ****
  • Posts: 153
  • Thanked: 3 times
    • View Profile
Are the oceans overheating? If they are, could this mean methane will rise to the surface? And if that happens, could it be ignited by bouys or lasers or masers from satellites?


 

Offline CliffordK

  • Neilep Level Member
  • ******
  • Posts: 6321
  • Thanked: 3 times
  • Site Moderator
    • View Profile
Most flammable gases will have a LEL and UEL (lower explosive limit, and upper explosive limit).
If the concentration of the gas in Air is below the LEL, or above the UEL, it won't burn.

It is possible that some places will have bubbles of methane, but short of igniting each bubble as it pops, it would be difficult to ignite.  Once the bubble pops, the methane would be diluted to below the LEL almost immediately.

I find it doubtful that one could efficiently harvest methane from the sea water, or sea surface. 

One option might be to mine the methyl hydrates in at-risk places before they melt.  That is if we could efficiently extract the methyl hydrates from the sea floor.
 

Offline evan_au

  • Neilep Level Member
  • ******
  • Posts: 4103
  • Thanked: 245 times
    • View Profile
It is thought that some undersea drilling operations are already tapping into methyl hydrates.
If you pump out the material in a borehole, the reduced pressure causes the methane to pop out of its clathrate cage, allowing you to pump methane out of the undersea deposits.

There is some fear that such mining operations could destabilise the seafloor, causing undersea landslides, and releasing large quantities of methane. But it's probably better to pump it out under controlled conditions than to allow uncontrolled release at a later date.

Buoys, Lasers & masers are unlikely to ignite methane, even if it were at the right concentration. A flare on a gas platform could ignite it, but as noted above, the right concentration is unlikely to be achieved (methane is lighter than air, and so won't hang around at sea level).
 

Post by MoreCarbonOK click to view.

Offline MoreCarbonOK

  • Sr. Member
  • ****
  • Posts: 164
    • View Profile
Shrunk
Since the world has been cooling for at least the past 11 years, I would not worry about.
http://www.thenakedscientists.com/forum/index.php?topic=47181.0
 

Offline yor_on

  • Naked Science Forum GOD!
  • *******
  • Posts: 11978
  • Thanked: 4 times
  • (Ah, yes:) *a table is always good to hide under*
    • View Profile
You are thinking of they are becoming saturated by CO2, right? The southern oceans may, or rather is, already be saturated (cold oceans) with the warmer oceans still acting as a sink. It has to do with stratification, or 'layers''. The ocean mix the atmospheric CO2 with sea water, using winds and natural slow circulation to stir up those layers, to  then subsequently transport the CO2 down into its depth for long time storage.

I would recommend reading the oceans carbon balance. for a better description of how it works.

The point though, is that it won't matter how deep a ocean is for its storage, as it is layered. What seem to matter is the oceans (vertical/up down) circulation, what winds there are mixing it, and the heat of the ocean.
 

Offline yor_on

  • Naked Science Forum GOD!
  • *******
  • Posts: 11978
  • Thanked: 4 times
  • (Ah, yes:) *a table is always good to hide under*
    • View Profile
The methane won't get free from the deep oceans in any foreseeable time as I would expect. What seem to happen is that you get methane from former tundra, together with CO2, and for shallow cold oceans as measured in arctic. If it is accelerating I don't know. Even if it is, it will be broken down in one year about, with the major part of CO2 staying in the atmosphere for at least a couple of hundred years. So even if Methane can 'store' more heat than CO2 ,it breaks down fairly quickly, whereas CO2 tail (rest part) stays for thousand of years.
=

Just a question,  some 'deniers' seem to get a awful lot of 'hits' on the site? As soon as they have opened their mouths. Now, is this just a coincidence, or a arrangement? Eh, not by TNS :) of course..
« Last Edit: 06/04/2013 02:42:30 by yor_on »
 

Offline yor_on

  • Naked Science Forum GOD!
  • *******
  • Posts: 11978
  • Thanked: 4 times
  • (Ah, yes:) *a table is always good to hide under*
    • View Profile
--Quote—Lisa Moore, Ph.D., scientist in the Climate and Air program at Environmental Defense.--

Here's a table showing a selection of greenhouse gases, their global warming potential (GWP), and their lifetimes:

Greenhouse Gas . . . . . . . .  .Lifetime years . . (100-Year GWP)
Carbon Dioxide (CO2) . . …. . . . hundreds .. .. . .1
Methane (CH4) . . . . . . …. . . .. . . 1 . . .  . . . .25
Nitrous Oxide (N2O) . . . . . . . . . .114 . . . . . . .298
Hydrofluorocarbon-23 (CHF3) . . . .264 . . . .. . .14,800
Sulphur hexafluoride (SF6) . . . . ..3,200.  . . . .22,800
PFC-14 (CF4) . . . . . . . .. . . . . .50,000 . . . . .7,390

Notice that the carbon dioxide lifetime is "hundreds of years", rather than a specific number. The IPCC ‘Third Assessment Report’ defines a gas's lifetime as the amount of the gas in the atmosphere divided by the rate at which it is removed from the atmosphere. That sounds simple enough, except that not all gases are removed by just one (or mainly one) process. Ironically, the gas that accounts for the greatest proportion of global warming, carbon dioxide (CO2), is the hardest to pin down. When CO2 is released into the atmosphere, about three-quarters of it dissolves into the ocean over a few decades (- Acidity -). The rest is neutralized by a variety of longer-term geological processes, which can take thousands of years.

From IPCC Fourth Assessment Report:  About 50% of a CO2 increase will be removed from the atmosphere within 30 years, and a further 30% will be removed within a few centuries. The remaining 20% may stay in the atmosphere for many thousands of years.

From U.S Greenhouse Gas Inventory Reports: (CO2) Atmospheric lifetime: 50-200 years. No single lifetime can be defined for CO2 because of the different rates of uptake by different removal processes.

From RealClimate: “My model indicates that about 7% of carbon released today will still be in the atmosphere in 100,000 years. I calculate a mean lifetime, from the sum of all the processes, of about 30,000 years. That's a deceptive number, because it is so strongly influenced by the immense longevity of that long tail. If one is forced to simplify reality into a single number for popular discussion, several hundred years is a sensible number to choose, because it tells three-quarters of the story, and the part of the story which applies to our own lifetimes.” ("How long will global warming last?")

For other gases, a meaningful lifetime is easier to calculate because one process dominates their removal from the atmosphere:

    * Methane is mostly scrubbed from the atmosphere by hydroxyl radicals (a chemical reaction).
    * Nitrous oxide is destroyed by photolytic reactions (chemical reactions involving photons or light) in the stratosphere.

As you can see from the chart, some gases have extraordinarily long lifetimes. Because emission rates are vastly higher than removal rates, greenhouse gases are accumulating in the atmosphere and will affect climate for generations to come.

----End of Quote----

http://www.thenakedscientists.com/forum/index.php?topic=35899.0;nowap
« Last Edit: 06/04/2013 02:22:15 by yor_on »
 

The Naked Scientists Forum


 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums