Predicting rainfall: climate models flawed

13 September, 2012 by

More likely over drier soils

A new paper in Nature reveals that afternoon storms are more likely over dry soils as opposed to soils that were moist, calling into question climate models that predict increasing drought with rising temperatures.

The paper provides evidence that rather than drier soil increasing drought, by having less moisture available for evaporation and precipitation, it actually increases the likelihood of convective rainfall.

The abstract highlights the fact that current climate models incorrectly represent this relationship:

We find no evidence in our analysis of a positive feedback—that is, a preference for rain over wetter soils—at the spatial scale (50–100 kilometres) studied. In contrast, we find that a positive feedback of soil moisture on simulated precipitation does dominate in six state-of-the-art global weather and climate models—a difference that may contribute to excessive simulated droughts in large-scale models. (source)

Associate Professor Stewart Franks, a hydrologist at the University of Newcastle and president of the International Commission on the Coupled Land Atmosphere System (ICCLAS), comments on the paper:

“The study is important in that it demonstrates yet again that when we scrutinise the models against the observations, the models fail to simulate reality. The climate models represent the interactions between the land surface and the atmosphere in only a very crude way. The exchange of moisture and energy between the land and the atmosphere is represented by a single ‘big leaf’ over areas the size of 400x400kms. What this means is that the small-scale physics of rainfall generation, especially by well-known convective processes, are entirely missed.

The models fail to represent the large-scale drivers of global climate variability such as the El Nino – Southern Oscillation (ENSO). The models fail to represent the regional scale rainfall processes.  Given this, no-one can have any confidence in any prediction of future rainfall regimes when using climate models. Climate modellers argue that they are the best we have – that might be right, but if they don’t work, they don’t work.”

Filed Under: Climate Tagged With: ,

Flannery out of his depth as flooding rains return

8 March, 2012 by

Stewart Franks

Tim Flannery is little short of a national joke. Appointed by the Labor government as “Climate Commissioner” (whatever that is) on a juicy $180k salary for a 3 day week, his string of failed predictions would make even the most hopeless astrologers blush.

He has spread relentless alarmism about climate change, including rising sea levels (despite owning a waterfront property), and now had embarrassed himself yet further by claiming that even if it rained again, it wouldn’t fill the dams, as I sit here in Sydney with an east coast low sitting just offshore dumping widespread rain over the region (nearly 50mm in the last 12 hours at my station), Warragamba spills for the first time in 14 years, and dams across the eastern states are full.

Professor Stewart Franks, from Newcastle University, writing in The Australian, twists the knife:

TIM Flannery, Australia’s Chief Climate Commissioner, once declared that “even the rain that falls will not fill up the dams”.

This was back in 2007 at the height of the protracted drought that afflicted eastern Australia. Now, for the second year in a row, we see the effects of El Nino’s twin sister — La Nina — bringing extreme rainfall across great swaths of Australia. This is hardly the climate change future envisaged by Flannery.

Flannery has recently been the target of growing criticism for his wildly speculative claims, in particular from Andrew Bolt and Alan Jones.

Perhaps of even greater significance, Flannery is being publicly criticised by prominent meteorologists. Indeed, The Weather Channel’s Dick Whitaker recently stated: “People ideally suited to (weather forecasting) are meteorologists. From what I can see on Tim Flannery, meteorology wasn’t one of his specialties.”

In response to this growing criticism, Flannery has declared that the recent “big wet” cannot be taken as evidence that climate change is not happening — it is merely an interlude before we continue with the drying of the continent.

In a statement of extreme chutzpah, he also has declared that interpreting the recent wet is merely confusing weather with climate.

But as Franks explains, Flannery himself is confusing climate variability with climate change:

Despite our uncertainty about the PDO-IPO, one thing should be abundantly clear: to look at simple trends across a relatively short 40-year period is meaningless. If one looks at the trends in eastern Australian climate from 1950 to the present, one can see a marked, statistically significant decline in rainfall and flood risk.

However, if one looks at a similar length of records from, say, 1925 to 1975, we see a statistically significant trend, but in the opposite direction: upward. If Flannery were hawking his climate change message back in 1975, he would probably be claiming that the carbon climate future would be one of permanent flood.

Relatively short trends are clearly irrelevant given the multidecadal variability of eastern Australian climate driven by El Nino-La Nina Southern Oscillation and the PDO-IPO.

Flannery in his opinion piece has also stated: “Some commentators jump on any cold spell or rainy period to claim climate change is not happening. This cherry-picking is irresponsible and misleading.”

It is also true that some commentators jumped on the recent drought to claim climate change was happening. This cherry-picking is indeed irresponsible and entirely misleading.

Read it here.

Filed Under: Climate Tagged With: , ,

Professor Stewart Franks writes at The Conversation

6 March, 2012 by

Flannery and Combet in the good old days…

Congratulations to Stewart on getting this piece, highly critical of Tim Flannery and other alarmist doomsayers, published at The Conversation (which, let’s face it, until now has been more like The [Warmist] Lecture). In particular, the article focusses on the recent severe drought in Australia:

Farmers struggled through very desperate times. The conditions were so bad that Tim Flannery, now Australia’s Chief Climate Commissioner, declared that cities such as Brisbane would never again have dam-filling rains. Rather bizarrely, in 2007 he stated that hotter soils meant that “even the rain that falls isn’t actually going to fill our dams and river systems”.

Fast forward to 2012 and we see widespread drenching rains, flooded towns and cities, and dams full to the brim and overtopping. Indeed, the rainfall that we had last year not only filled Brisbane City’s Wivenhoe Dam water supply storage, but also all of its flood mitigation capacity. The resultant releases of water required to prevent a truly catastrophic dam failure contributed to the inundation of large parts of metropolitan Brisbane.

How is it that Tim Flannery could have got it so spectacularly wrong? The most obvious factor could well be Flannery’s lack of background in a climate science. He is an academic, however his background is mammalogy – he studied the evolution of mammals.

Flannery obviously has a great interest in climate change and no doubt has read some of the scientific literature and no doubts consults with other climate commissioners. I have no doubt either that he by and large understands what he reads.

The one thing he cannot do without a solid education in climate science is critique what he reads; without the background surely he cannot perceive the underlying and often unstated assumptions associated with what he reads or is told. He is perhaps best described as an amateur enthusiast, in which case I could actually have a little sympathy for him for getting it so wrong.

As I speak, the comments are pretty fair, much to my amazement.

A step in the right direction – towards sensible dialogue.

Read it here.

Filed Under: Climate Tagged With: ,
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