But as I said, we have to wait and see.

(The quantum of the increase in methane conc may be small in terms of total atmospheric forcing, but it is the sudden increase after near ten years of more or less stasis that catches the eye) – The sudden decrease in temp catches the eye

( – especially when that uptick is set alongside reports of methane releases from Arctic permafrost, lakes and ocean floor hydrates.) Especially when the down tick is set along side solar minimum and when 2008 showed the early stages of a cool phase of the basin-wide Pacific Decadal Oscillation.

(With respect to temperature, we’re dealing with climate — average weather – and so it makes no sense to talk sbout short term “trends” because they’re the weather we have to average to talk meaningfully about climate. As I’ve said before, wiggles on an underlying trend.) The methane “spike” is not beyond the normal wiggles of the last 25 years. The last two times methane rose by more than 10ppb in a single year it was followed by a negative movement within 2 years. If you think OH has changed, it makes no sense to talk about single years that may be affected by natural events.

My point is you apply two different forms of logic to methane data and temperature data. I am not saying we are DEFIANTLY cooling, only that your logic is unbalanced.

If I can read between the lines… There is no “doublethink” involved. If the recent couple of years uptick in methane conc continues, then it will be a matter for increasing concern because it means (as it said in the post I referred to originally) either the sources of methane are increasing (which we suspect they are based on direct observation), or that the sinks (OH principally) are becoming saturated, or both. But we’ll have to wait and see…

Climate, on the other hand, is not measured on a few years data. I confidently expect a new global average temperature record in the next five years. I wouldn’t bet on methane, because the underlying mechanisms are nowhere near as well understood.

With respect to temperature, we’re dealing with climate — average weather – and so it makes no sense to talk sbout short term “trends” because they’re the weather we have to average to talk meaningfully about climate.

As I’ve said before, wiggles on an underlying trend. The same rationale does not apply GHG emissions, whether caused by warming or man.

The quantum of the increase in methane conc may be small in terms of total atmospheric forcing

but it is the sudden increase after near ten years of more or less stasis that catches the eye

specially when that uptick is set alongside reports of methane releases from Arctic permafrost, lakes and ocean floor hydrates.

The concern is straightforward enough.

How is this logic (that you ridicule on a daily basis), any different to your own?

Doublethink: The power of holding two contradictory beliefs in one’s mind simultaneously, and accepting both of them.

You appear to be a master!

Or maybe you can explain how one and maybe a second year is now a trend for methane concentrations but not for temperature.

There you go again… Two years do not make a trend, and neither I nor anyone else is claiming that it does. The quantum of the increase in methane conc may be small in terms of total atmospheric forcing, but it is the sudden increase after near ten years of more or less stasis that catches the eye – especially when that uptick is set alongside reports of methane releases from Arctic permafrost, lakes and ocean floor hydrates. The concern is straightforward enough. Arctic methane emissions have the potential to be a significant and dangerous positive feedback (more warming, more methane), so it’s a situation we need to watch very closely.

If you read back through the posts tagged methane you’ll get the picture…

With respect to temperature, we’re dealing with climate — average weather – and so it makes no sense to talk sbout short term “trends” because they’re the weather we have to average to talk meaningfully about climate. As I’ve said before, wiggles on an underlying trend. The same rationale does not apply GHG emissions, whether caused by warming or man.

Even if 2008 does rise, that does not change the fact that this is a small (0.5%) increase in the forcing from methane. Less if the relationship is non-linear. And it does not change the fact there is no established change in long term trend of OH, so we not expect a change in atmospheric lifetime. Are you aware of research since 2005 that shows OH is decreasing? Because I am not (and this would still not be a long term trend, as it decreased from 79-89 and then recovered).

“With respect to the recent rise, no-one is making claims about a new trend, just that after years of relative stability we see a significant increase.”

Right, statistically significant (greater than 95% chance it did increase), but not as dramatic as you imply, 10ppb. We have had other years increase this much (1998), and were then followed by decreasing atmospheric levels 2 years later.

Why is the change in OH potentially worrying? The 10ppb change is well with in the normal range. The change in OH is probably well within the normal range.

This statement by nature: “Although atmospheric levels of methane have increased in the past they are not currently increasing according to IPCC AR4 [2007].”, drew criticism, and comments such as “Methane is currently increasing again (see p11)” were posted. But I don’t think this has been proven. Perhaps a retract is in order Gareth? Or maybe you can explain how one and maybe a second year is now a trend for methane concentrations but not for temperature.

And Steve Bloom, you insult me by calling me stupid and accusing me of lifting my comments. I find this approach degrades the whole AGW community. When someone uses IPCC documents to question your own beliefs you turn to insult – not earning my respect, others can make their own minds up.

Always nice to meet another Steve . I think we may be talking about different papers here. The one I was referring to was http://pubs.giss.nasa.gov/abstracts/2007/Chylek_etal.html.

The paper doesn’t really state that CO2′s feedback is zero or negative it just states that because the Aerosol Optical Depth (AOD) has been decreasing aerosols can’t really explain the “missing” temperature rise that should have occurred from the increases in atmospheric CO2. The models have mean 2CO2 forcing around a 3 degree rise in global temperatures.

The conclusion Christy makes from Chylek et al is that is either 2CO2 forces at most a 1 degree rise in global temperatures or some other forcing is counteracting the effects of the CO2 increase. One possibility he mentions are changes in the ENSO or PDO which could influence low cloud cover over the oceans. There could be others too.

Sadly there doesn’t seem to be any really reliable scientific measurements of variability in cloud cover, as there is for the PDO and ENSO indexes, and they still remain one of the biggest uncertainties in the models.

I guess the optimist in me hopes they’re right but I also have that nagging fear they could be wrong. Anyway I still think there is a lot of interesting science to be done in this area.