I would be very happy to be helpful, Mike, if I thought there were a genuine chance that RT would allow himself to understand the basics of the science. Sadly, his reply above contains so many errors and misunderstandings that it would take me many, many hours to unpack them all – and, frankly, I have far better things to do with my time…

You have a duty to educate yourself – not continually demand answers from other people. Simply repeating contrarian talking points that have been debunked over and over again wins you no friends.

“However, you are making some very strange assumptions about the accumulated emissions of CO2 in the atmosphere.”

Yes, on checking, this could be incorrect. I took the figure from WryHeat, who got the data from the IPCC. But it’s headed “Sources and absorption of greenhouse gases in the 1990s”. I took it to mean the accumulated anthro contribution, which it might be, but now I’m unsure.

So our contribution could be larger, but I must stand by the assertion that temperature rises to cause CO2 outgassing, not the other way around. That’s not to say we don’t contribute to the increase in CO2, just that any temperature increase is trivial (as evidenced so far!).

You say thinking of heating caused by DLR as “reduced cooling” explains “why you don’t find much written on the subject.” But that doesn’t follow at all. I don’t know what you mean.

You say “the net effect is fairly obvious”, but everyone says that and it’s not true.

You then muddy the waters by adding: “even if an exact explanation of what’s going on is complex.” You reckon what’s obvious is complex? I don’t think so. Anyway, the exact explanation isn’t complex, it’s missing. It’s absent. No such description exists. No paper has been written on it. I’ve found a preliminary tutor, no more than that. The quest goes on.

You say we now have 400 ppm atmospheric CO2; I agree. For the sake of discussion, I accept your figures on the conditions during glaciation. But you imply humans have added the 120 ppm since the Industrial Revolution, and assert that the “extra CO2” was responsible for SLR of 120 m during the last thaw.

These are unjustified assertions unless there’s evidence that increasing CO2 precedes temperature rise. The evidence so far is the reverse.

You say the planet is warming when it has not warmed significantly since the 1980s. The most accurate and comprehensive global mean surface temperature datasets are from the two satellite-based teams, which show little warming since the 1990s. You may have noticed that in the last few days the May records have been released, showing a steep drop from the peak of the El Nino. Apparently there might be a cooling La Nina later this year, though I have learned to take climate forecasts with a grain of salt.

“We’ve added an extra 120 ppm, and we see the planet warming.” Probably better expressed as: “An extra 120 ppm has been added, and we see the planet warming.” But that still shows mere correlation, not causation; and it’s still the wrong way around, because what warming we’ve had has come before the CO2 increase.

But thanks for your comments.

I am glad that you have found a source you’re prepared to trust re ocean warming. The key point, as Arthur Smith points out in the comments, is:

The effect of the absorption of downwelling radiation is best viewed as, the same as for land surface, a *reduction in the rate of cooling* via radiation.

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This is not mysterious at all, and goes a long to explain why you don’t find much written on the subject. To (real) physicists the net effect is fairly obvious – even if an exact explanation of what’s going on is complex.

However, you are making some very strange assumptions about the accumulated emissions of CO2 in the atmosphere. The sum is a simple one: before humanity started adding large amounts of CO2 to the atmosphere, there was about 280 ppm of the gas in the atmosphere. We now have 400 ppm. The difference between those two is 120 ppm, or a little over 40% of the starting amount. We know (by doing sums) that the total amount of carbon emissions over that time are greater than the amount we see in the atmosphere, but we observe the oceans becoming more acidic and see evidence of some “greening” of the biosphere, which shows that the planet is doing us a big favour by absorbing some of our excess carbon.

How important is that 40% increase? It might be helpful to think of the difference between the depths of an ice age, when the planet is on average about 5ºC cooler than 150 years ago and CO2 was about 180 ppm, and an interglacial period such as the current one, when CO2 is (before we mucked it up) usually around 280-300 ppm. That difference caused by the extra CO2 is enough to radically transform the planet, raising sea levels by 120 meters.

We’ve added an extra 120 ppm, and we see the planet warming. Sea level rise is a certainty as the great ice sheets of Greenland and Antarctica respond to that warming. Once again, we can learn a lot from the climate history of the planet. The last time CO2 stood at 400 ppm, the sea level was around 20 m higher than now.

It might take a few hundred years to get the full 20 meters, but that’s where we are inevitably heading, unless we can both stop emitting CO2 and get levels back down under 300 ppm.