Climate news doesn’t just turn up in an RSS feed; sometimes it jumps right into your lap. A day or two ago, I discovered that a new paper about sea temperatures around New Zealand during the Eocene (50 million years ago) has significant implications for climate modelling and is based on fieldwork done very close to my home. Stuff reports:
Using sedimentary rocks from the bed of the Waipara River in North Canterbury, an international research group led by GNS Science palaeontologist Chris Hollis has reconstructed ancient sea temperatures. They found surface sea water exceeded 30 degrees Celsius, and water at the sea floor hovered around 20ºC during an episode of greenhouse gas-induced global warming that lasted for between two million and three million years. “These temperatures are at the extreme end of modern tropical water masses,” Dr Hollis said. Year-round sea surface temperatures of 25ºC to 30ºC are today found only at the equator.
The Eocene and the associated Palaeocene Eocene Thermal Maximum (PETM) are interesting to climate scientists because at the time the world was in a warm greenhouse phase, and the PETM saw a burst of rapid additional warming associated with the injection of massive amounts of carbon into the atmosphere (possibly methane from hydrates). Modeling the climate of the time poses a few problems, however. Temperature reconstructions show that the Arctic was very warm (ice free, with crocodiles) but it’s difficult to get the models to reproduce that without driving tropical temperatures up to over 40ºC — and that should have caused a massive die-off that is not (yet) seen in the fossil record. New Scientist had a very good article discussing Eocene climate reconstructions earlier this year (not behind a paywall, thankfully).
The new NZ work confirms that Eocene NZ was much warmer than previously thought, so Hollis and his co-authors make the following point:
To us, this suggests that the earth’s climate is much more sensitive to changes in greenhouse gas levels than is allowed for in climate models, which appear to be underestimating the degree of warming. Extreme greenhouse warming either caused high latitudes to warm far more than low latitudes or equatorial regions warmed beyond the limits of life: above 40ºC.
Another piece in the jigsaw puzzle of climate reconstructions for the period, made the more interesting by coming from my back yard.
I live on a small farm above1 the Waipara River where Hollis and his team conducted their fieldwork. This section of the Waipara is world famous in New Zealand (to palaeontologists and geologists, at least) because of the fossils found here — marine dinosaurs, penguins, sharks and concretions much like the Moeraki boulders (click on the thumbnail to see “God’s Marbles”, a few km upstream from us) — as well as the extensive faulting2. Generations of geologists from the University of Canterbury have done fieldwork or enjoyed field trips here. It’s also scenically beautiful, and I’ve become involved in efforts to protect and enhance the whole river environment.
The Hollis et al paper was given advance publicity to draw attention to a conference, Climatic and biotic events of the Paleogene in Wellington, which includes a public Greenhouse Earth Symposium at Te Papa on Jan 14th. I’d love to be there, but when I contacted Chris to discuss the paper, I stumbled on the next best thing: the pre-conference field trip is visiting my neck of the woods on Tuesday. My chance to meet the experts, while they examine “the siliciclastic mid-Waipara section, containing a bioturbated K/T boundary and an Early Eocene record of tropical conditions”. I’m looking forward to it (thanks for the invite, Chris).
Finally, while poking around on the conference web site, I stumbled on the following fine example of geological humour in the guidelines for formatting abstract submissions:
What I did in my holidays
A. Geologist and W.E.T. Field-assistant
We went out in the pouring rain and freezing wind, dodging mad sheep, to find some rocks. When we did, I hit them with my big hammer. From this we deduced that we needed more money for a big expensive machine that goes ‘ping’ in order to obtain some real data. The rest of the year was spent writing (unsuccessful) grant proposals.
Every geologist needs a big hammer3.
- Literally above. Our house is on top of a 40m limestone cliff above the river. [↩]
- The cliff is the result of the Boby’s Stream fault, a large active fault that ruptures roughly every 900 years, generating movement of up to 2.5m and quakes large enough to cause severe damage to our nearest city, Christchurch. The last quake was about 300 years ago. Our vineyard straddles the fault – hence our wine being called The Faultline Pinot Noir (first production to be bottled in February). [↩]
- Which reminds me of a Freddy Trueman joke. During commentary on a test match, someone made mention of the ample proportions of the backside of a fast bowler. Freddy offered, in his broad Yorkshire accent, “Aye, a big nail needs a big hammer”. [↩]