Alan Kendall & Paul Dennis

Thank you for your continued responses and explanations!

It amazes me that so much effort can go into calculations about how sea level has risen, when you can buy a 12"plastic ruler from a £1 shop.

I note Alan's reference to the disappearance of Inconvenient Trees, and have seen similar references before. The Marine Biology of rocky tidal coastlines, with photographs showing different bands/colours relating to flora and fauna is much more reliable than a photograph simply showing the level of the water. I appreciate the bands/colours may change with seasons.

I don't suppose there is much chance of me getting funding to sail around the Med for 5 years with scuba gear to photograph some of this stuff. The sailing would be very 'Renewable', the on board electrics could be wind and solar, but an air compressor rated to 3000psi would need diesel power.

Paul Dennis

It is over 40 years since I was involved in any research. I do calculations like today's to a much lower standard of thoroughness, but I find them a useful reality check. I am surprised that more sceptics do not try something similar. If AGW were wrong, it would show up very quickly in the energy accounting..

The satellite imbalance is quoted as 4.2W +/- 2.0; the surface based estimate at 0.7W +/-0.7W. Looking at the variation in thermal expansion with depth, my own value should probably be about 2.3W +/-1.3W.

We can set a lower bound of xero. Sea level rise, rising temperatures, ice melt and other secondary indicators all show warming and therefore net energy uptake. The question is not whether there is an imbalance, but how big it is and what is causing it.

I must read Shaviz.

EM "The question is not whether there is an imbalance, but how big it is and what is causing it."

Hooray - you finally got there!

Mike Jackson golf charlie

It is not the 20th century average you should consider, it is the trend. The 20th century began with sea level rise at 0.6mm/year and ended with 3.3mm/year. That is a doubling every 40 years.

Geometric or exponential processes are not friendly. They start slowly and end with rapid change. "We've been all right so far; there's no problem" is not a good attitude.

The UK is lucky. We are on the edge of the Greenland gravitational sea level bulge, so will suffer less than most.

You might like to consider the concerns of Florida mayors . You might also wonder why Miami is spending $400 million on pumps to keep the streets dry at high tide.

Martin A

You get a TOA imbalance when something has moved the climate out of equilibrium.

Over the last 20,000 years there has been a net uptake as the Holocene warmed, then 5000 years of stable temperature and no imbalance. There was then 5000 years of cooling and net energy loss into the 1800s.Finally temperatures are rising and the imbalance is favouring heat uptake again.

What caused the changes? I would say Milankovich cycles amplified by CO2, with the decline back to glacial conditions interrupted by the Industrial Revolution. Do you have evidence for an alternative?

Radical Rodent

The term is isostatic adjustment. The US East coast, including Miami, is sinking at 4.5mm/ year before you add in rising sea levels.

You sceptics tell me that this is too slow a change to worry about. Miami would seem to think that 4.5mm/year is a problem.

The climate was never in equilibrium.

Spectator

I've been there for a long time. The imbalance and temperature changes are following the pattern one would expect from AGW.

If you have an alternative, please make your case.

EM,

You would be hard pushed to demonstrate to me that the graph you linked to yesterday on sea level rise shows anything other than a long term linear rate of sea level rise of approximately 1.6mm per year since 1960. During this period there have been episodes of rapid rise and episodes of fall. There is nothing in the record that shows the present rate of rise is outwith this behaviour.

Your choice of data for radiation imbalances and errors are also very selective. I think Stephens et al (2012) suggest that the uncertainty in the surface energy balance is as high as 17W.m^-2. This is a very large number compared with your estimate of the surface of imbalance. I think Loeb et al (2012) also suggest that at TOA the range of possible values for the imbalance is from -2.1 to +6.7 W.m^-2.

I'm not putting these numbers up to suggest your calculations are wrong but to demonstrate that we actually don't have very precise measurement. In fact the lack of precision means we can't be very definite what either the surface or TOA imbalances are.

Paul,

Your choice of data for radiation imbalances and errors are also very selective. I think Stephens et al (2012) suggest that the uncertainty in the surface energy balance is as high as 17W.m^-2.

The surface energy imbalance isn't that relevant in this context. As far as energy accruing (or not) in the system is concerned, it's the top-of-the-atmosphere (TOA) imbalance that really matters, and the Stephens et al. TOA imbalance is 0.6 +- 0.4 W/m^2.

I may be wrong, but I also think that the +-17W/m^2 uncertainty in the surface imbalance is a combination of it being very hard to measure surface fluxes (the OHC data makes determining the TOA flux much easier than determining the surface fluxes) and the fact the surface warming can vary substantially (as we've seen in the last decade or so).

aTTP,

I agree that it is TOA we should really concern ourselves with and that the surface budget is very difficult to measure.

My understanding is that it isn't possible to measure the TOA budget with any degree of precision and that this is actually constrained by using the imbalance as determined by GCM's or the Argo data for ocean temperature/heat content. We don't actually have an independent measure of the TOA energy imbalance to compare with either modelled values, or values backed out from ocean heat content changes. There is a degree of circularity to the argument here. It might be correct but it is hardly satisfactory. The independent measure we have is neither accurate or precise.

Easter now beckons and chores are building up at home. I just want to say a happy Easter to everyone who has contribute to this discussion. It's been a good experience. I've learnt a lot and have some questions and thoughts I'd like to give time to thinking about.

Paul,

We don't actually have an independent measure of the TOA energy imbalance to compare with either modelled values, or values backed out from ocean heat content changes.

But the ocean has, by far, the largest heat capacity of any component of the climate system. Hence ocean heat content measurements are a pretty solid proxy for the TOA imbalance. Of course, some energy does go into other parts of the system, but the oceans account for about 93% of the imbalance. Unless you really think that there is some other component of the system that is somehow absorbing a significant fraction of the energy imbalance, the oceans are about all we need to consider.

aTTP,

sorry I was going to have a break. I don't disagree with you. I'm just saying that from a measurement point of view it isn't very satisfactory. If one is going to do a calculation of ocean heat balance and then say it agrees with TOA estimates this is a circular argument. It would be much more satisfactory if we could close this with independent measurements.

Paul,
I'll have a break after this too, but this certainly isn't what I was saying

If one is going to do a calculation of ocean heat balance and then say it agrees with TOA estimates this is a circular argument.

I was saying that OHC measurements - by themselves - provide an estimate for the TOA imbalance. Of course, it's better to have more than one single estimate, and we do (sea level rise, satellite measurements) but that doesn't change that the OHC measurements are, by themselves, an indication of a TOA imbalance.

Anyway, I'll stop there. Have a good easter break :-)

aTTP,

Sorry, I didn't mean to imply that was what you had said or done. My use of english was as imprecise as some of our emasurements. I am in full agreement that the ocean is a good calorimeter and measure of the energy imbalance and all for improving our measurement systems.

Likewise have a good holiday.

RR,

you will see that I have constantly said we need better measurements. The ocean is our best bet but measurement systems and coverage have a long way to go yet before we can have any degree of confidence in our estimates of energy gain or loss. Any notion that lots of measurements at a few locations is adequate is clearly wrong.

Now I really am signing off for Easter!