For such a small population, Australia seems to have it’s share of climate change skeptics.

Just this morning Bob Carter (an adjacent research fellow at JCU) writes in an op-ed in the Australian “global temperature warmed slightly in the late 20th century and has been cooling since 2002. Neither the warming nor the cooling were of unusual rate or magnitude”.

And Andrew Bolt asks on his blog “just how anyone can detect a human signal in the “warming” of the Great Barrier Reef” in regard to this graph, purportedly based on NOAA satellite imagery (which I assume he thinks proves his point):

My guess is that Bolt’s confusion lies in his misunderstanding of the causes of coral bleaching and the patterns of ocean warming.  Most of the public and many climate skeptics envision ocean warming as a gradual, linear increase, like water in a pot on the stove.  If they don’t see an increasing average trend line, they conclude the warming described by scientists hasn’t occurred.  Yet this GBR temperature graphic shows exactly what all the reef scientists I know have been saying; most summers over the last decade have seen especially high maximum temps, generally above 29C.  Whereas before 1998, this was quite rare and the anomalies lasted for only a few days, rather than a few weeks.

Some of the many comments in response to Bolt’s post are even more telling (and really emphasize how much work we have to do educating the public):

At this time with absolutely no evidence of global warming, or of carbons effect upon climate, we have environmental and green dupes hysterically demanding the closure of power stations, and even higher carbon taxes on industries.

RAI Italian TV news on SBS Thursday morning showed Alpine towns near Turin under metres of snow with one local (young) saying…never seen snow like this…

I think you will find that if you inspect an uncontaminated source of temperature data such as the satellite record, that 2008 was actually the coldest year since 1980.

Other peer reviewed studies have shown that by analysing raw data numbers from some weather reporting stations, they find a slight cooling trend operating over the last 100+ years, rather than the supposed warming trend of 0.6 C.

The graph below is based on the four major global compilations of temperature records: NASA’s GISStemp, the Hadley Center’s HadCRU, Remote Sensing Systems’ RSS, and the University of Alabama, Huntsville’s UAH.  (See an article about the concordance of these analyses here)

This graph essentially represents the state of our knowledge about recent anthropogenic climate change.  The world is clearly warming, not cooling.  Unless you spuriously compare the last 8 years with 1998.  The first half of 2008 was relatively cool (but as noted by Andrew Revkin, 2008 was between the 7th and 12th warmest since meteorological record keeping began in 1880 and  the 9 warmest years in the record have occurred since 1998).  Nobody said that EVERY year is going to be progressively warmer.  The argument is that over the next several decades and centuries we will see a general warming trend (but certainly not ever year or everywhere).

This morning, one of the world’s leading coral reef scientists, Dr. Terry Hughes, spoke on the AM about the threats to the reef this summer with warmer than usual temperatures:

JENNIFER MACEY: It’s only the start of summer but satellite images show sea surface temperatures in the Coral Sea are already higher than average. The Bureau of Meteorology and the American National Oceanic and Atmospheric Administration have both forecast a high risk of coral bleaching this summer.

Dr Russell Reichelt is the chairman of the Great Barrier Reef Marine Park Authority.

RUSSELL REICHELT: They’re likening the conditions that we’re looking at this summer now to be same as they were in 1998 when a very large global event occurred where 16 per cent of world’s coral reefs died from coral bleaching.

JENNIFER MACEY: Ten years ago, half of the Great Barrier Reef was affected by coral bleaching but only five per cent suffered permanent damage.   Dr Reichelt says reefs can recover from bleaching if they don’t face further stresses from pollution, over-fishing or repeated hot weather events.

JENNIFER MACEY: Professor Terry Hughes is the director of the Australian Research Council Centre for Excellence for Coral Reef Studies. He says if the warmer temperatures last for more than two months there’s a serious risk of coral dying.

TERRY HUGHES: If you lose the structure that the corals provide through their skeleton then fish populations inevitably decline as well.  It’s important to remember that for coral reefs, global warming is not some distant threat that might or might not happen in the future. It’s already happening. So the Great Barrier Reef has already bleached twice and there’s a very good chance that this year will be the third major bleaching event to impact on the Great Barrier Reef.

See a related post on current GBR temperature here