Surface air and sea temperatures of today’s global warming are typically compared to past global temperatures, and the comparison is then used to judge how severe current warming is. The commonly held view is that 100 million years ago, the world’s oceans were about 15 degrees C warmer than they are today. That figure has been produced by looking at a particular oxygen isotope present in fossils and extrapolating from the abundance of that isotope to arrive at an estimate for past temperatures. So far, so good.
Except it’s not.
Very recent research has demonstrated that the proxy for temperature (the oxygen isotope in fossils) varies over time and so can’t be used as a straight forward indicator of temperature after all. In other words, the temperature estimates for deep time that have been calculated from the presence of a particular oxygen isotope in fossils are too high.
The scientists behind the study claim that the apparent cooling of the oceans was actually just the effect of the process they’ve seen. The changes in the amount of oxygen in the shells isn’t a reflection of changing temperatures – just a consequence of the fact that the amount of oxygen seen changes over time anyway.
Is that a big deal? Well yes it is. Here’s a chart for global temperature going back 500 million years. (Link to full size here)
The temperatures given in panels one two and three all rely on the supposedly “stable oxygen isotope measurements from the shells of macroscopic marine organisms” – ie, the “stable oxygen isotope” that isn’t stable at all. (Scroll down to “Data” through the link)
No-one knows how much of a ‘bump’ has been given to temperature estimates because of the assumption that the oxygen isotope was stable. But there has most definitely been a bump and the estimates are wrong.
Look. I’m no scientist, and I’m aware that by recalibrating and recalculating from existing samples and data (if that can be done) that more accurate temperature estimates might be produced. So not being scientific at all about this, but the more or less steady drop in temperatures through panels 2 and 3 of that graph (Panel 1 doesn’t estimate global temp) would suggest to me the possibility that the ‘bump’ amounts to most, if not all, of the heightened temperature of the deep past.
So look at the far right hand axis of the graph where current warming is plotted. Then come back along to 1 million years ago where the panel includes temperature estimates extrapolated from ice core samples (hydrogen isotopes) that, being polar samples, were manipulated to yield a global temperature estimate. And perhaps quite reasonably entertain the idea of that data having been manipulated so that the results aligned with the accepted and “known” temperature estimates arrived at via that stable oxygen isotope in fossils…
Go back to 7, 70 and 500 million years ago with all the bags of salt you can drag along with you – because those estimates are wrong and probably increasingly so the further back through time we go.
“Yesterday” we could have said that current global temperatures are at levels unknown in the past 4 or 5 million years. And bad as that was, we can’t even say that today. Today we need to look further back in time, but don’t have any reliable estimates that might help us determine at what point in the deep past the world was this warm.
So where to from here?
Well, we know the perspective of politicians and policy makers. They’re happy enough to keep us mainlining on fossil for now because it’s good for the economy. And we know they’re contentedly throwing all our eggs into what might be described as the ‘economy preservation jars’ labelled “trade”, “tax” and “tech magic”.
Now, are you happy about that? Because I’m not happy about that.
It’s essentially ‘madness in a jar’ sitting against the knowledge that the changes coming with AGW are going to be as sledgehammer blows. Sanity might dictate we switch off fossil today (all of it and without exception) – cop the fallout – and urgently cast around for avenues that might allow us to escape further consequences of our current fossil dependent socio/economic set-up.
The unfortunate catch is, that much as you or I might feel compelled to act, this socio/economic system has us shackled – we can’t move. Maybe it could be likened to being stuck on the Titanic with the knowledge that if the captain had headed straight for the ice-berg instead of trying to avoid it, then the ship wouldn’t be about to go down. The answer then, is simple enough, but seemingly impossible to action.
So what’s the solution?
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