Global warming changes natural event: first causal link

[ibis]

For the first time, a causal link has been established between climate change and the timing of a natural event – the emergence of the common brown butterfly.

Although there have been strong correlations between global warming and changes in the timing of events such as animal migration and flowering, it has been hard to show a cause-and-effect link. This is what Michael Kearney and Natalie Briscoe of the University of Melbourne, Australia, have now done.

The researchers compared temperature changes in Melbourne – where the butterfly is common – with recorded observations of the first brown butterfly to be seen in the spring since the 1940s.

With each decade, the butterflies emerged 1.6 days earlier and Melbourne heated by 0.14 °C. Overall, the butterfly now emerges on average 10.4 days before it did in the 1940s, says Kearney. "And we know the rise in air temperature links to butterfly emergence in a cause-and-effect pattern."

Full article is here.

This may well set off a rash of such studies, which will be roundly shouted at by the usual people without being disproven. It will be interesting to see which one of them becomes climate science's equivalent of the 'peppered moth study'.

[toxic avenger]

To be fair, the article does quote a couple of quibbles (albeit from an entomologist and not a climate scientist):

Myron Zalucki, an entomologist at the University of Queensland in Brisbane, Australia, calls this "an interesting piece of work". But he questions the accuracy of the butterfly emergence dates in Kearney and Briscoe's model, saying that there are discrepancies between what the model predicts and what is actually observed.
Zalucki also queries whether the butterflies are indeed emerging earlier or Melbourne's growing population has more people on the lookout.

I'd also wonder how accurate the emergence dates for the 1940s or 1950s were, though I wouldn't doubt they're probably correct in their general assessment, given the experiments under climate-controlled conditions they performed.

[ibis]

To be fair, the article does quote a couple of quibbles (albeit from an entomologist and not a climate scientist):

I'd also wonder how accurate the emergence dates for the 1940s or 1950s were, though I wouldn't doubt they're probably correct in their general assessment, given the experiments under climate-controlled conditions they performed.

New Scientist always include a couple of quibbles - often, it has to be said, from people whose first introduction to the work is on being rung by the New Scientist journalist. That doesn't detract from the quibbles themselves, but one is never sure whether they were actually addressed by the study or not (in a couple of cases authors have written in afterwards to say that they had addressed such issues in their work).

As to the earlier recording dates - earlier naturalists weren't any less obsessive than modern ones.

Zalucki also queries whether the butterflies are indeed emerging earlier or Melbourne's growing population has more people on the lookout.

That's a fair point, being the sort of thing that bedevils studies of things like incidence rates in medicine.

[toxic avenger]

New Scientist always include a couple of quibbles - often, it has to be said, from people whose first introduction to the work is on being rung by the New Scientist journalist. That doesn't detract from the quibbles themselves, but one is never sure whether they were actually addressed by the study or not (in a couple of cases authors have written in afterwards to say that they had addressed such issues in their work).

As to the earlier recording dates - earlier naturalists weren't any less obsessive than modern ones.

Thank God for obsessive amateurs. I'll say this much for the British, whatever else they did they were meticulous measurers and recorders. Perhaps that spirit was evident in Melbourne in the 1940s...

[odie1kanobe]

Building big cities changes the environment around it........doh.

One only has to look at cities where the urban fox has developed in huge numbers versus the fox population in the countryside.

A big city generates massive amounts of heat so why would there be a shock that areas within it would not change.

[ibis]

Building big cities changes the environment around it........doh.

One only has to look at cities where the urban fox has developed in huge numbers versus the fox population in the countryside.

A big city generates massive amounts of heat so why would there be a shock that areas within it would not change.

The urban heat island effect in Melbourne applies to the central business district and the industrial suburbs rather than the area of the study - see here, here. It's pretty well studied, and naturally enough the researchers took it into account:

The final step taken by the researchers was to link the regional temperature changes with human-induced global warming.

Team member and climatologist Professor David Karoly applied global circulation models to the Melbourne region, taking into account local factors that influenced climate.

This suggested that the regional temperature changes observed over the decade were unlikely to be observed without the influence of human greenhouse emissions, Dr Kearney said.

He and the team used temperature records from the Laverton weather station, located on Melbourne's outer edge.

This weather station was used to avoid the "urban heat island" effect of the city of Melbourne on temperature records.

[COLOR="White"]Jaysus, what a limited number of tools there are in the climate opposition's mental toolbox! It's the sun...it's an urban heat island...it's a plot...ad infinitum.[/COLOR]

[wombat]

The urban heat island effect in Melbourne applies to the central business district and the industrial suburbs rather than the area of the study - see here, here. It's pretty well studied, and naturally enough the researchers took it into account:

This sounds very dodgy, two events are linked because we say so.

[ibis]

This sounds very dodgy, two events are linked because we say so.

Hm.

1. butterfly life cycle timing is known to be responsive to temperature changes

2. butterfly life cycle timing in a locale has changed by exactly amount that it should have changed given the recorded increase in temperature of locale.

Sure, it could be completely accidental - after all, that's the null hypothesis in every experiment. It could also be the Hand of God. The causal link between two events is only ever statistical...which is why we have statistical confidence levels in the first place.

[Almanac]

Full article is here.

This may well set off a rash of such studies, which will be roundly shouted at by the usual people without being disproven. It will be interesting to see which one of them becomes climate science's equivalent of the 'peppered moth study'.

Who knows what the reprecussions could be. The butterfly effect and all that.

[wombat]

The causal link between two events is only ever statistical...which is why we have statistical confidence levels in the first place.

But you know the danger of seeing with our minds rather than our eyes. Climate change is quite trendy in Oz., its a lot easier to save the planet than the Murray. In fairness, their study may be a lot more rigorous than the outline implies, just because I'm sceptical doesn't mean they're wrong