“Almost every summer, there is a heat wave somewhere in the US that garners popular media attention.
During such hot spells, daily record high temperatures for various cities are routinely reported in local news reports.
A natural question arises: is global warming the cause of such heat waves or are they merely statistical fluctuations?
Intuitively, record-breaking temperature events should become less frequent with time if the average tem-
perature is stationary.
Thus it is natural to be concerned that global warming is playing a role when there is a proliferation of record-breaking temperature events. In this work, we investigate how systematic climatic changes, such as global warming, affect the magnitude and frequency of record-breaking temperatures.
We then assess the potential role of global warming by comparing our predictions both to record temperature data and to Monte Carlo simulation results…
Read the full article at Cornell University Library here: http://arxiv.org/PS_cache/physics/pdf/0509/0509088.pdf
Jennifer Marohasy BSc PhD is a critical thinker with expertise in the scientific method.
Jennifer: You may wish to catch up with Dr Mike Gagan from ANU and the latest reports on ABC, Canberra Times etc about the Indian Ocean Dipole
Thanks Jen for the advice on the record stats data. It looks very interesting in terms of methodology. It will be solace for statisticians and sceptics will pick out the wrong conclusion. They are simply showing not enough data to prove or disprove their is a trend in record temps. But they do note their have been significantly more max records (1,705) than mins (1,346). Their could be a problem in the crude north Americaan way they handle persistence. ENSO creates a seasonal pattern hwereas they only allowed for day to day. Interesting counter-intuitive or intuitive for some is the longer the period the less chance of a new record in a stationary series. ( the longer you live, the fewer the records you see – or perhaps care if you know the intuition)
Bazza: I can’t agree with your observation here “They are simply showing not enough data to prove or disprove…” what ever, see below.
At a glance: The most interesting bit for me is their statement towards the end on the increasing max min differential. It means to me a disturbance in drivers at least. Now let’s have some bright spark open up on that entire math before we bury their paradox; more hot days and more cold nights.
Dr Jeff Masters (who has the great blog at the Weather Underground that covers the Atlantic Hurricane season) has a recent post which discusses amongst other things the untypically warm December that was just experienced in the northern hemisphere. As always, Dr Masters is worth a read:
http://www.wunderground.com/blog/JeffMasters/show.html
Wrong Gav, not my observation – their conclusion “Our primary result is that we cannot yet distinguish between the effects of random fluctuations and long-term systematic trends on the frequency of record-breaking temperatures with 126 years of data. ” As with sporting data, their are infinite ways to anaylse for those who like to play the numbers, but they at least put up a hypothesis first. For a given length of record, it is of course a lot less powerful to test for changes in variability than it is for chnages in means – and their are more ways to do it so chance of false skill.
This is sceptic wishful thinking. And yes Masters is top notch and beta read my answer novel to Michael Crichton. He ravaged his for good reasons.
So tell us, Steve, what are we supposed to make of the record ice up in California and Texas in this record breaking cold January? Or is this more evidence of the selective green comprehension skills that ensure that inconvenient truths are not retained.
Tell us the pathway to follow Motty. Ignore the alleged threats and assume it’s not happening or if it is there’s nothing we can do so stop researching climate change? Do we spend on R&D for adaptive responses only or nothing at all?
Take a look at the link I posted above – the hot december spanned much of the north of the globe (not just California and Texas), and dr masters discusses why this seems to be unusual.
Why don’t you ask someone who knows Ian if you want answers, why not email Dr Masters for his take?
Unless of course you’ve decided that your trusty back-of-envelope and internal BS generator are sufficient to equip you to form your own formidible opinion.
Gavin and Bazza, the problem with the data sets showing both extreme hot days and extreme cold nights is that we have no data on what is happening in between.
As mentioned on other threads here, an increase in albedo from forest conversion to grassland will actually contribute to a net cooling but the daily mean temp based only on max/min temps will not be able to detect it.
This will only be detected in the changes to the rate of heating and cooling and the duration of plateaus and troughs. And that means hourly, if not half hourly, readings which do not exist back far enough to base any conclusions on.
What we do know is that vegetated landscapes operate at between 10% albedo for dense forest and 25% albedo for deserts or beaches. Oceans are only 3.5% with no cloud cover, absorbing 96.5% of insolation. Clouds boost the global albedo to about 30% while ice caps etc are much higher but represent a much lower proportion of the solar constant (1350w/m2) due to the reduced angle of incidence towards the poles.
And this means that permanent changes in albedo will have a far more significant long term effect on heat balances than the CO2 released in a single event from conversion of forest to pasture.
Ploughed paddocks waiting for rain before the sowing of crops, or freshly sprayed ones under minimum till regimes, will have the albedo of a desert. Pasture that has been fully grazed at the end of a seasonal rotation would also have albedo levels close to desert lands. And this means the night time capacity for cooling will be defined by the 75% of absorbed insolation during the day. (assuming no clouds)
Add water and a growing crop and the night time capacity to cool will be defined by the 85% of absorbed insolation exhibited by grassland. And, in theory, this would seem to mean that the night time minimum would be higher and be achieved at a slower rate of cooling.
The key point is that the range of variation in heat absorption capacity exhibited accross the modified landscape is as great as that exhibited by the natural landscape. And no attempt has been made to measure these effects.
Some of the delicious ironies in all this is that;
1 overgrazing reduces global warming,
2 deforestation reduces global warming in the long term,
3 the draining of wetlands reduces global warming,
4 land reclamation reduces global warming,
5 irrigation contributes to global warming, and
6 reforestation contributes to global warming once the forest has absorbed it’s carbon capacity.
All of these factors have been accounted for in the models. The contribution of CO2 by fossil fuels can’t be countered with tree planting. Just keep babbling about clouds, the sun, heat iskand index and everything else that has been covered at http://www,realclimate.org anything except addressing the source of the problem: climate forcing by CO2.
http://www.realclimate.org
Yorkie, everyone here is probably familiar with RealClimate. It contains every excuse and rationalization for holes in global warming claims. It’s propaganda disguised as science.
Here’s the extent to which gw worshippers are going:
http://epw.senate.gov/public/index.cfm?FuseAction=PressRoom.Blogs&ContentRecord_id=32abc0b0-802a-23ad-440a-88824bb8e528“
Weather Channel Climate Expert Calls for Decertifying Global Warming Skeptics
The Weather Channel’s (TWC) Heidi Cullen, who hosts the weekly global warming program “The Climate Code,” is advocating that the American Meteorological Society (AMS) revoke their “Seal of Approval” for any television weatherman who expresses skepticism that human activity is creating a climate catastrophe.
Masters guts Crichton and the sceptics.
http://www.wunderground.com/education/stateoffear.asp
Bollocks, York. How can there possibly be an inclusion of the impact of landuse change on albedo when there is no formal national reporting mechanism for these inputs and no way of recording the impacts when temp data only includes daily maxima and minima.
Please, either do us the courtesy of a link to a model that has incorporated this feature? Or take your rightfull place in the corner with Bugs Bunny.
The facts are that emitted carbon from vegetation change is a once-off event that eventually gets absorbed while a change in albedo is mostly permanent. So the longer a model that includes this factor is run, the more pronounced the mitigating effect on Global Warming will become.
The current models have no constraints on compounding the effects of emissions but clearly do not have room for the compounding and cumulative effect of albedo change.
“The facts are that emitted carbon from vegetation change is a once-off event that eventually gets absorbed”
ha, yeah the land covered in trees only stops absorbing CO2 at the time of land clearing and then continues absorption again afterward.
Ian, give us something of substance instead of obfuscated, flawed arguments and juvenile insults.
Mott says to Mark York:
“Please, either do us the courtesy of a link to a model that has incorporated this feature? Or take your rightfull place in the corner with Bugs Bunny.”
But earlier he made these claims without corroborating links or data:
“1 overgrazing reduces global warming,
2 deforestation reduces global warming in the long term,
3 the draining of wetlands reduces global warming,
4 land reclamation reduces global warming,
5 irrigation contributes to global warming, and
6 reforestation contributes to global warming once the forest has absorbed it’s carbon capacity.”
How about you educate us as to these claims? I’m all ears.
Steve – Ian’s having a love affair with albedo as he thinks it’s a work-around for AGW – he’s discovered Jacks’ beanstalk.
From above 1, 2 & 4 lighten albedo and reflect more radiation to space. 3 reduces methane and brightens albedo. 6 darkens albedo in temperature areas – forests being darker – (except in tropics where more clouds may form). Irrigation well that depends – maybe darker albedo, but more cooling evaporation, but need to do whole of life budget on the energy for pumping the water too.
So it’s all been beneficial really – Ian is starting to put his own system analysis together. He’s found there’s more than CO2 – there’s albedo.
What he has failed to Google is that we can add these features and assess their comparitive effects. There’s some evidence to support his view of his #6 in temperate regions – references in Climate Jen’s archive.
But gee the literature is full of this stuff – nothing new here. The IPCC aren’t going to say “Holy cow – why didn’t we think of that”
Anyway after albedo – he can tell us how surface roughness, stomatal conductance, LAI and surface wetness also cause further interactions. Boy he’s now got 2 factors of the energy balance under his belt. It’s impressive going.
http://climatesci.atmos.colostate.edu/2006/10/24/a-new-dataset-for-improved-land-surface-representation-for-climate-studies-by-dev-niyogi/
Oh yea – how do we know what’s happening with albedo – gee I wonder if remote sensing would help?
Ian better write the IPCC quick and tell them before they put the 4AR out – looks like a rewrite in the light of the above.
Oh back on the original topic – why would you bother looking for heatwaves in a global cooling hotpost like Phily (err coolspot) – see aerosol pollution.
Of course you could do a literature review and see if there are other views or statistical analyses but why bother?
The number of “record events” in a stochastic system increases as the log of the time over which obervations are made -even if there is no underlying trend.
Steve, they were conclusions based on the prior discussion on albedo. Is this another one of those situations where you are incapable of exercising reason without a web site to download common sense.
And Luke, it seems fair game for every second eurospiv to be producing horror stories based on a reduction in polar albedo due to receding ice so why do you have a problem with me highlighting the beneficial cooling effects of increasing albedo in more tropical climes?
Wouldn’t be a bias there by any chance?
And still the question remains, we know it has a cooling effect but how can it be detected if the temperature data is incapable of picking it up?
He’s sighs, exhales and tries to still his mind.
Ian – you might think they have albedo factored in. Sigh.
The temperature data does pick it up – the temperature data reflect a range of issues – solar flux, water vapour greenhouse, greenhouse CO2, aerosols, consequent changes in atmospheric circulations, albedo, surface roughness, stomatal conductance, surface wetness, LAI – yada yada – lotsa factors in the GCMs.
Do you think a temperature gauge measures just one of these factors?????
And if you change tree clearing or whatever – yes it makes differences. BUT – CO2 is still a big forcing. The climate models need and do to varying degrees of success integrate such diverse issues. That’s why you need a “model!”.
What we do not know though is the polar albedo changes are much more dramatic. White to dark !
So what if polar albedo changes are more dramatic, Luke? The change from white to dark is in relation to insolation with an angle of incidence greater than 65 degrees and diffused by a longer oblique passage through the atmosphere.
So in your infinite wisdom, Luke, can you assure us all that the cumulative impacts of permanent change in albedo from vegetation change has been incorporated into the models? If so how?
My suspicion is that this is not the case as there is no mechanism for reporting same and there certainly was no recognition of this beneficial impact when Kemp (the pathetic) was writing stupid letters to Qld Chief of Spivs.
And given your apparent assumption on polar albedo, can you assure us all that these models do adjust the solar constant, and hence insolation and albedo, according to latitude?
True, Annabelle, but if no trend then chance of a record declines every year. This paper was about records not climate change. A meteorologist would have at least checked the site and not just one site out of a context. ‘ Sorry, no science possible from isolated phenomenon eg what happened in Philidelphia. If you wish to extrapolate from one result, you are into religion.
Ian – instead of playing “guess what I can come up with next” – I suggest you do some background research on the subject then make a reasoned case for what’s not being handled well enough. So instead of going “but but but maybe it’s this ” – do some research – as I said elsewhere you wouldn’t accept anything I would say so you’ll have to find out yourself. You might find that climate modellers have considered a few issues including your tilt including a spatial radiation budget.
Try http://scholar.google.com
But be careful what you ask for – a win on albedo might give a negative on circulation system changes – it’s all inter-linked as a big system – land clearing probably has intensified the drying trend – but all work in progress. You might give the greenies more ammo by not considering all the ramifications. But now we’re out of climate change of course and into attribution of current climate.
P.S. I don’t think spiv-Chieftains know about albedo.
Woody – “Yorkie, everyone here is probably familiar with RealClimate. It contains every excuse and rationalization for holes in global warming claims. It’s propaganda disguised as science.”
Where of course CO2Science and the Marshall Institute, Climate Audit, and Tech Central Station are just propaganda without even the hint of science. At least Real Climate is written by working climate scientists that actually know what they are talking about and contribute with original work to the scientific knowledge base. Nothing like that can be said of Peiser, McIntyre et al who’s only contribution is to pick apart others work.
I would put my money on Real Climate for accurate information.