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David Hone
Climate Change Adviser, Shell Group

David Hone

David Hone is the climate change adviser for the Shell Group and vice chairman of the International Emissions Trading Association. He also works closely with the World Business Council for Sustainable Development. ALL POSTS

Physics rules (well it should)

With the recent discovery that methane is bubbling out of the Arctic faster than expected, how worried should we be about abrupt changes in climate such as this one? Are there precautions we should be taking that both the political and scientific communities have been overlooking?

No doubt this will be argued from both sides -- from those that say it is just a natural phenomena to those who argue it is yet another worrying sign of a tipping point. Arguments over temperature records, sea level rise, urban heat island effects and more are becoming the norm as the pressure mounts to address the level of greenhouse gas emissions from anthropogenic sources. This doesn't seem like a useful way forward or even a practical way to decide how best to address the issue.

Perhaps it is time to revisit the basic physics around the issue and look at the sobering realities of this issue. We know that over the last million years (at least) the world has flipped in and out of ice ages and we know that this is due to very small shifts in the orbit and wobble of the planet as it moves around the sun. We can calculate that the change in energy intensity reaching the earth because of this is less than 1 Watt/m2 and when combined with various feedback effects, causes the ice sheets to advance and retreat many thousands of miles. We also know that as a result of this sea level shifts by many tens of meters over hundreds and thousands of years.

So now, turning to the rising level of greenhouse gases in the atmosphere, we can calculate that the increase in forcing as a result of current levels of CO2 and other gases is already over 2 Watt/m2. This isn't a difficult calculation and uses some very fundamental physics laws such as those developed by German physicist Max Planck and Swedish chemist Svante Arrhenius. So we are already at more than double the natural variation due to orbital change that has taken us in and out of ice ages over many millennia.

Of course the story isn't this simple and many other factors come into play as a result. It is the combination of factors that matters. It may in the end turn out that various factors cancel out or it may be that the warming is even worse than currently anticipated. The fact that we don't know all the answers isn't a reason not to act. What we do know is that we are operating above a range that has previously changed the face of the planet dramatically. Why should we somehow expect that not to be the case this time?

By David Hone  |  March 9, 2010; 6:57 AM ET Save & Share:  Send E-mail   Facebook   Twitter   Digg   Yahoo Buzz   Del.icio.us   StumbleUpon   Technorati  
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It's not particularly good science to imply that, because a 1 Watt/M2 change is what it takes to trigger the growth or retreat of snowfields on a land mass distributed as it is in the northern hemisphere, there is anything special about a 1 Watt/M2 change generally.

The day the story of the methane discovery broke in the news, the Canadian papers quoted a leading permafrost expert thus:

"In my view, it's much more likely to be a persistent continuing phenomenon than the beginning of some catastrophe," says Chris Burn, at Carleton University in Ottawa, who has been monitoring permafrost in Canada's Western Arctic since 1982.

Burn says the Siberian shelf has probably been emitting large amounts of methane for thousands of years, as organic matter under the sea floor decomposes, but the emissions went unnoticed because the region is so remote.

If anything, this discovery casts doubt on the theory that there is a tipping point towards greater warming associated with the release of additional permafrost methane.

Posted by: unwashed_brain | March 15, 2010 8:18 AM
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In the midst of all the fearful comments, it seems one fact is not being explained to us.
The planet has, in the past, been quite a bit hotter than it is now, with amazing luxuriant vegetation and life, enough to feed the plethora of gigantic dinosaurs.
Please explain what the dangers are.

Posted by: eogord | March 14, 2010 8:56 PM
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Hmm. Interesting. I ask for causation of the Milankovitch cycles, and the Gorebal Whiner accuses me of being an ostrich.

Riddle me this BO squared: How can CO2 cause Gorebal whining when the Ice Core data clearly shows that temperature rises 800 years BEFORE CO2 levels increase. Or since water vapor has 10x the partial pressure of CO2, how can CO2 possibly have any major effect???

What the truth is is that all you Gorebal Whiners out there have an anti-capitalist, anti-Demicratic cult religion that you want to replace our gov't with a left wing elitist oligarchy the uses fiats like the EPA to foist your religion down our throats. Not on my watch, Bucko!!!

You know, you losers remind me of the flaggilants. You go around whipping yourself trying to atone for the "sins" of mankind. If you want to go around whipping yourself, knock yourself out. I'm not going to stop you. Just don't expect me to join you.

TICK TICK TICK TICK TICK TICK!!!

MENE MENE TEKEL UPHARSIN!!!

The clock IS ticking, the writing IS on the wall, and in November you Dumbocrats' time IS up!!! YOU GOIN' DOWN!!!

VOTE REPUBLICAN!!!

Posted by: A1965bigdog | March 14, 2010 12:18 AM
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Put fairly simply, this particular component of the warming threat is a natural phenomenon set into motion by a dangerously irresponsible human process.

That we still have head-in-sand (to put it nicely) people like A1965bigdog above (who cannot get past his obsessive resentment of a former presidential candidate far enough to act responsibly) - who somehow think that Malankovitch cycles are now controversial - does not bode very well for this species. Let us hope the responsible voices win out over the know-nothing anti-intellectuals, hmm?

Posted by: B2O2 | March 13, 2010 9:58 PM
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Dude, you really believe in the Milankovich cycles??? You must believe in the tooth fairy.

Give me a break. It's the worst form of curve fitting I've ever seen.

Let's see. The cycle that revolves around precession. I'll give that one a pass. The Earth is a big gyro. It precesses. I'll take that one at face value.

Periodic changes in the angle of inclination. Hmm. Do you have a cause for that? Did some magic fairy cause this??? We need causation. With out causation, it's a fairy tale.

Periodic changes in the eccentricity of the Earth's orbit. That's a riot. Dude, what causes it? Does Merlin the Magician wave his magic wand and cause it to happen? I'm just dying to hear the explaination, other than that Milankovich said it happened.

You Gorebal Whiners really need to get a life. You also need to start thinking for yourself.

Posted by: A1965bigdog | March 13, 2010 3:32 PM
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are not ice ages "natural changes"/ duh

Posted by: coolgolf | March 13, 2010 12:48 PM
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Mr Hone: you seem to have ignored the question and cut and pasted generic text from some briefing document.

Does this panel need 2 members from the oil industry?

Posted by: mikemclennan | March 13, 2010 4:53 AM
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Er... David: You really did not answer the question you were given.

Posted by: billSWS | March 13, 2010 12:54 AM
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