Tuesday, June 15, 2010

Is the common brown butterfly emerging 10 days earlier than it did 65 years ago because of climate change?

The answer actually appears to be that nobody really knows!

More misleading warmy bullshit revealed and, my God!, is that an urban heat island effect there?

And warmies cherry picking data to get the "right" result? Surely not!

Mr Bolt reports:

The Age was very excited in March by the latest research of climate alarmist David Karoly:

Researchers have found that because of a rise in temperature, caused by an increase in greenhouse gas emissions by humans, the common brown butterfly now emerges from its cocoon 10 days earlier than it did 65 years ago.

Professor Karoly seized on the study as proof of man-made global warming:

This new work has tied the earlier emergence of butterflies directly to a regional temperature increase, and has tied the temperature increase very strongly to increases in greenhouse gas concentrations caused by humans...

I was immediately suspicious, noting the glaring evidence of an urban heat island effect at Laverton that could have explained plenty.

In fact, the study that so pleased The Age was so dodgy that some PhD student, Marc Hendrix, now comes along and blows it to pieces with a quick letter that the Royal Society considers so convincing that it’s obliged to publish. The main charge is cherry picking. Some extracts:

I have obtained the same data used in this study as Kearney et al. and am unable to confirm the results for the historical observation data. I count 239 observations made in Oct-Dec from 1942 to 2009. The annual data show a wide range of earliest observation dates (Figure 1), and at face value the use of 5 year or 10 year averages appears to be a convenient statistical method that hides the very wide spread of observation dates. Applying a linear regression to a graph of the earliest observation date for each year indicates a trend of -0.7 days per decade. However, with an R2 of 0.0091 the trend has no statistical significance....

Indeed the caption for Figure 1a is incorrect and misleading. The graph is in fact a measure of earliest “observance” times, not emergence… The historical trends identified simply reflect variation in the time collectors have ventured out to observe and collect butterflies. The databases in question do not record a single observation of natural emergence of H.Merope. Indeed no work has been published that records natural emergence times for the butterfly concerned…

There is also a considerable bias in observation locations, with the vast majority collected in Melbourne’s east and none in the vicinity of Laverton, the weather station that was used to characterise temperature change over the whole of the study area (Figure 2).

The other issue relates to the use of this Laverton weather station to characterise temperature over the very large and geographically diverse study area, amounting to approximately 12,000km2 (37.60-38.54 S, 144.17-145.48 E). The paper does not mention well documented Urban Heat Island effects over Melbourne that encompasses Laverton that have clearly affected temperature at this station over the period of study (see Morri and Simmonds, 2000 and Torok et al., 2001)… It seems the authors have chosen one station that favours their theory without adequately explaining why others should be rejected…

Trends for other stations (eg Durdidwarrah) fall well within the limits of natural temperature change indicted by Kearney’s Figure 1d and provide an indication that observed temperature trends over parts of the study area can be adequately explained by natural factors without recourse to warming through increased green house gases.

Based on these points, I believe that the authors’ conclusions remain unsupported by the data presented.

Buit, of course, the correction will receive none of media publicity that Karoly’s original scare did.

Posted via email from Garth's posterous

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