JoNova

A science presenter, writer, speaker & former TV host; author of The Skeptic's Handbook (over 200,000 copies distributed & available in 15 languages).



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Did an ice sheet collapse 120,000 years ago pushing sea levels up to 9m higher than today?

Proving that nature can outdo anything humans have done, a new paper shows that sea-levels off Western Australia may have risen as high as 9 m above the current level during the last warm period over a hundred thousand years ago. The authors (O’Leary et al) conclude that seas were 3-4 m higher for most of the last warm period (known as the Eemian) but towards the end of the period a large sudden rise occurred. They suggest that an ice shelf collapsed in Antarctica  or Greenland or both, causing a 5m rise (17 feet).

The point of the paper was this double spiked shape of the sea level rise during the last warm interglacial known as the Eemian.

The Age interviewed O’Leary who said “he was confident that the 17-foot jump happened in less than a thousand years – how much less, he cannot be sure.”

Figure 3 j Relative sea-level curve for Western Australia. Ageomorphically defined palaeoMSL datum of C2:5m 120 kyr ago (Fig. 1c) anchors a predicted relative sea-level curve at Red Bluff, which includes a GIA signal based on the test calculation (see Methods) plus the following ESL history: ESL jumps from 0 to 3.4m [...]

Hottest reefs on Earth make a nice home for corals?

If Earth warms by 2 degrees The Great Barrier Reef is a goner, or maybe not. Tropical reefs are generally about 28C but even a one degree rise above normal temperatures can bleach corals.

This latest paper by Hume et al, showed that some corals survive in the hottest reefs on  Earth which are in the Arabian/Persian Gulf and are a whopping 36 degrees C. In order to survive, corals do deals with symbiotic algae, but these are very sensitive to changes in temperature (or so we thought):

Reefs are made up of many species of coral, each of which have a mutually beneficial, or “symbiotic”, relationship with algae living in their tissue. These algae supply vital nutrition to the host but are sensitive to environmental changes including increases in seawater temperature.

Even a temperature rise of just one degree Celsius can harm the symbiotic algae, which in turn can increase mortality in corals. The associated loss of symbiotic algae is known as “coral bleaching” because the white skeletons of the corals become visible through the tissue depleted from the algal pigments.

Obviously those Gulf coral survive those wildly high temperatures with freak heat-loving-symbiotic-algae that can’t survive in normal oceans [...]

One vulnerable coral type adapts to ocean acidification in just 6 months

Credit: S. Ross et al., UNCW

We already know that pH varies naturally across the oceans of the world. In some sites, it varies more in a single day than global oceans are likely to face in a century.

But cold water corals live in deep water, are slow growing, and hard to study.

Six years ago, experts in cold water corals were telling us how they would be likely to fall victim to ocean acidification first, and that they believed this for good reasons but with little experimental data. But about a year ago data came out (by one of those same experts) showing that rather than being the badly affected, cold water corals adapted to effectively very high levels of CO2 and possibly even increased their calcification rates. Eight days after the pH was changed suddenly, the corals did worse. But when the experiment was continued for six months, the results turned right around. The researchers pointed out how useful longer studies are: “This is the first evidence of successful acclimation in a coral species to ocean acidification, emphasizing the general need for long-term incubations”. The paper is called “Acclimation to ocean acidification during long-term CO2 exposure in [...]

The debate continues: Dr Glikson v Joanne Nova

Dr Andrew Glikson (an Earth and paleoclimate scientist, at the Australian National University) contacted Quadrant offering to write about the evidence for man-made global warming. Quadrant approached me asking for my response. Dr Glikson replied to my reply, and I replied again to him (copied below). No money exchanged hands, but Dr Glikson is, I presume, writing in an employed capacity, while I write pro bono. Why is it that the unpaid self taught commentator needs to point out the evidence he doesn’t seem to be aware of? Why does a PhD need to be reminded of basic scientific principles (like, don’t argue from authority). Such is the vacuum of funding for other theories that a debate that ought to happen inside the university obviously hasn’t occurred. Such is the decrepit, anaemic state of university science that even a doctorate doesn’t guarantee a scientist can reason. Where is the rigor in the training, and the discipline in the analysis?

Credibility lies on evidence

by Joanne Nova

April 29, 2010

Reply to Andrew Glikson

Dr Andrew Glikson still misses the point, and backs his arguments with weak evidence and logical errors. Instead of empirical evidence, often [...]