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Posts by crandles

Posts by crandles

1) Message boards : News : Welcome to the News message board! (Message 56490)
Posted 30 Jun 2017 by crandles
Post:
'Very strong' climate change signal in record June heat

http://www.bbc.co.uk/news/science-environment-40449234

Now, researchers with World Weather Attribution have carried out a multi-method analysis to assess the role of warming connected to human activities in these record temperatures.
"We simulate what is the possible weather under the current climate and then we simulate what is the possible weather without anthropogenic climate change, and then we compare these two likelihoods which gives us the risk ratio," Dr Friederike Otto from the University of Oxford, one of the study's authors, told BBC News.
"We found a very strong signal."
That signal, according to the authors, made heat waves at least 10 times more likely in Spain and Portugal.
2) Message boards : Cafe CPDN : Trump (Message 55500)
Posted 17 Jan 2017 by crandles
Post:
No it is the Russians hacking everyone and causing everyone to believe everything is a hoax expounded by the Chinese, or was that the [censored]? ;)
3) Message boards : Cafe CPDN : Trump (Message 55493)
Posted 16 Jan 2017 by crandles
Post:
http://www.bbc.co.uk/news/science-environment-38640413

"Speaking to the media, UK climate experts said there were reasons for hope that the pro-active climate change agenda adopted by President Obama would survive under President Trump.

"It is clear that they actually accept a great deal more of the science of human influence on climate than they are prepared to let on," said Prof Myles Allen from the University of Oxford."

...

"For too long the climate change discussion has been about things that will happen in 100 years time," said Prof Allen.

"For economically insecure people, statements about what might happen in 100 years time they just don't care about, because they know these kind of predictions have been proved wrong in the past and will be in the future."
"Better science is not the crucial thing here. It's this realisation that the people primarily being affected by climate change are the poor and the people benefitting are the extremely wealthy."
4) Message boards : climateprediction.net Science : Climate change in the News (Message 55411)
Posted 28 Dec 2016 by crandles
Post:
Mention for weather@home - World Weather Attribution at

https://www.skepticalscience.com/record-breaking-arctic-warmth-extremely-unlikely-wo-cc.html

"The work, carried out by the World Weather Attribution (WWA) project, is the latest in what are known as “single event attribution” studies. Other recent studies by the same group found that climate change made torrential rains unleashed on south Louisiana in August twice as likely."

linking
https://www.carbonbrief.org/climate-change-doubled-odds-louisiana-heavy-rains
5) Message boards : climateprediction.net Science : Carbon emissions boosted 2014 January storm risk 'by 43%' (Message 53365)
Posted 1 Feb 2016 by crandles
Post:
See http://www.bbc.co.uk/news/science-environment-35444838

If you wish you can follow the link to the paper in Nature titled
Human influence on climate in the 2014 Southern England winter floods and their impacts

BBC reports
"Citizen scientists made key contributions to the study using their computers to run simulations of UK weather patterns."

together with Myles Allen being an author on the paper makes me suspect this is relevant.

More conclusively paper also says "The authors thank the climateprediction.net participants whose generous donation of their spare computer processing power has enabled...."
6) Message boards : climateprediction.net Science : New publications and articles from the science team (Message 51897)
Posted 27 Apr 2015 by crandles
Post:
7) Message boards : climateprediction.net Science : Antarctic Glaciers Retreat Unstopable (Message 49158)
Posted 18 May 2014 by crandles
Post:
http://www.bbc.co.uk/news/science-environment-27381010

Here is a nice Utube video:

https://www.youtube.com/watch?v=YQMtb1Pd07E
8) Message boards : climateprediction.net Science : Free MIT course in Climate Science (Message 48013)
Posted 20 Jan 2014 by crandles
Post:
MITx 12.340x Global warming Science

School: MITx
Course Code: 12.340x
Classes Start: 19 Feb 2014
Course Length: 12 weeks
Estimated effort: 8 hours/week

About this Course

12.340x introduces the basic science underpinning our knowledge of the climate system, how climate has changed in the past, and how it may change in the future. The course focuses on the fundamental energy balance in the climate system, between incoming solar radiation and outgoing infrared radiation, and how this balance is affected by greenhouse gases. We will also discuss physical processes that shape the climate, such as atmospheric and oceanic convection and large-scale circulation, solar variability, orbital mechanics, and aerosols, as well as the evidence for past and present climate change. We will discuss climate models of varying degrees of complexity, and you will be able to run a model of a single column of the Earth's atmosphere, which includes many of the important elements of simulating climate change. Together, this range of topics forms the scientific basis for our understanding of anthropogenic (human-influenced) climate change.

We will not cover issues regarding policy responses to climate change. Rather, Global Warming Science is designed to be a strictly scientific introduction to this important topic.

12.340x is geared toward students with some mathematical and scientific background, but does not require any prior knowledge of climate or atmospheric science. See the prerequisites section for more details.
9) Message boards : climateprediction.net Science : Prof Myles Allen looking for some funding (Message 47966)
Posted 13 Jan 2014 by crandles
Post:
Lack of research linking climate change and floods is a 'scandal'

BBC Lack of research linking climate change and floods is a 'scandal'
10) Message boards : climateprediction.net Science : Sherwood et al Climate Sensitivity at high end of range (Message 47921)
Posted 2 Jan 2014 by crandles
Post:
Realclimate now have a post up:

RealClimate
11) Message boards : climateprediction.net Science : Sherwood et al Climate Sensitivity at high end of range (Message 47913)
Posted 2 Jan 2014 by crandles
Post:
This paper seems potentially important:

Nature Sherwood et al Paper

further discussion and short video by an author of the paper at the climate state:

Climate State

Basically they find models with low sensitivity aren't mixing water vapour correctly so we won't get a lot of cooling low clouds as the climate warms.

I expect it will take a fair bit of reviewing now it is published before it should be considered a game changer but potentially it looks like it might be very important.

12) Message boards : climateprediction.net Science : Myles Allen views on 5th Assessment Report (Message 47824)
Posted 20 Dec 2013 by crandles
Post:
13) Message boards : Number crunching : News and Announcements (Message 39742)
Posted 19 May 2010 by crandles
Post:
On the science side, reasearch obviously continues.

There is a further paper on the topic of calculating Jeffreys\' Priors for climate models recently made available on Arxiv.

Objective Probabilistic Forecasts of Future Climate Based on Jeffreys’ Prior: the Case of Correlated Observables
Stephen Jewson, Dan Rowlands, Myles Allen
http://arxiv.org/PS_cache/arxiv/pdf/1005/1005.2354v1.pdf

The abstract of this and the earlier paper on which this is expanding are quoted below. The papers linked particularly the recent one may well be considered rather technical rather than interesting bedtime reading.


To attempt an introduction to what these papers are about:

A 2005 paper:
Constraining climate forecasts: The role of prior assumptions
http://climateprediction.net/science/pubs/2004GL022241.pdf

discussed the problem of how producing a probability from an ensembles of models is complicated by the way parameter space is sampled. Spacing the samples equally distanced in climate sensitivity will yield different probablities than if the samples are equally distanced apart in another plausible way such as feedback (proportional to 1/sensitivity).

The key feature of a Jeffreys_prior is that it is invariant under such reparameterizations.


Abstracts

To include parameter uncertainty into probabilistic climate forecasts one must first specify a prior.
We advocate the use of objective priors, and, in particular, the Jeffreys’ Prior. In previous work we
have derived expressions for the Jeffreys’ Prior for the case in which the observations are independent
and normally distributed. These expressions make the calculation of the prior much simpler than
evaluation directly from the definition. In this paper, we now relax the independence assumption and
derive expressions for the Jeffreys’ Prior for the case in which the observations are distributed with
a multivariate normal distribution with constant covariances. Again, these expressions simplify the
calculation of the prior: in this case they reduce it to the calculation of the differences between the
ensemble means of climate model ensembles based on different parameter settings. These calculations
are simple enough to be applied to even the most complex climate models.

The previous work was

A new method for making objective probabilistic climate forecasts from numerical climate models based on Jeffreys\' Prior
http://arxiv.org/abs/0908.4207
Stephen Jewson, Dan Rowlands, Myles Allen

We argue that it would be desirable to use Jeffreys’ priors in the construction of numerical model
based probabilistic climate forecasts, in order that those forecasts could be argued to be objective.
Hitherto, this has been considered computationally unfeasible. We propose an approximation that
we believe makes it feasible, and derive closed-form expressions for various simple cases.


If you want to discuss these Jeffreys\' priors papers, can I suggest this thread or create one on this board.
14) Questions and Answers : Macintosh : misconfigured BOINC crashing work units (Message 35496)
Posted 14 Nov 2008 by crandles
Post:
I got this email today as well, however all my work units appear to be fine, scanning through the stderr_um files, there all 0 bytes.

I\'m not sure what to do?

Here\'s my clientID

http://climateapps2.oucs.ox.ac.uk/cpdnboinc/results.php?hostid=924187


16 models downloaded to an 8 cpu computer does not sound too many especially when 8 of the models have credit granted. The email was supposed to have been sent to 80 troublesome hosts but my first reaction is that you shouldn\'t have been sent the email in repect of that computer. But it could easily be me misunderstanding. I\'ll try and find out.
15) Message boards : climateprediction.net Science : Climate is too complex for accurate predictions (Message 31197)
Posted 30 Oct 2007 by crandles
Post:
However this presentation
http://www.climateprediction.net/science/pubs/allen_NOC2007.pdf
may give you a flavour of what they are arguing. (Edit 14Mb download)



I think I got that completely wrong. Dave Frame has posted a quick summary which says:



Our basic point in the Perspectives piece is that it\'s probably a mistake to fix a concentration target now, based on some subjective estimate of climate sensitivity. As long as our policy people are allowed to bootstrap their targets occasionally we don\'t really ever need to know the exact value of climate sensitivity very well.

16) Message boards : climateprediction.net Science : Climate is too complex for accurate predictions (Message 31132)
Posted 26 Oct 2007 by crandles
Post:
There is more about this at

Real Climate

In essence, what Roe and Baker show is that this characteristic shape arises from the non-linear relationship between the strength of climate feedbacks (f) and the resulting temperature response (deltaT), which is proportional to 1/(1-f). They show that this places a strong constraint on our ability to determine a specific \"true\" value of climate sensitivity, S. These results could well be taken to suggest that climate sensitivity is so uncertain as to be effectively unknowable. This would be quite wrong.


This is similar to the non linear relationship between climate observables and sensitivity is something that Myles Allen and Dave Frame from this project have been saying.

I think it is worth pointing out that the forecasts of temperature rise for the next few decades are well constrained compared to climate sensitivity. Higher sensitivity (eventual effect of a doubling of CO2) means more committed warming but also that it will take longer to arrive.

http://www.sciencemag.org/cgi/content/summary/318/5850/582

Perspectives
ATMOSPHERE:
Call Off the Quest
Myles R. Allen and David J. Frame
Knowledge of the long-term response of Earth\'s climate to a doubling of atmospheric carbon doixide may be less useful for policy-makers than commonly assumed.


does not seem available without a subscription.

However this presentation
http://www.climateprediction.net/science/pubs/allen_NOC2007.pdf
may give you a flavour of what they are arguing. (Edit 14Mb download)

17) Message boards : Number crunching : Multiple Crunching of Same Thread (Message 31114)
Posted 25 Oct 2007 by crandles
Post:
Another thing to say is that at various times there have been changes to the number of models being sent out. This appears to me to indicate there is some management of the numbers being sent out to get the inintial condition ensemble sizes that they want.

More management in terms of aborting excess exact duplicates if they are getting more than they want might be possible but I imagine time consuming for the scientists who want to work on the science or preparing different models and so on.
18) Message boards : Number crunching : Multiple Crunching of Same Thread (Message 31113)
Posted 25 Oct 2007 by crandles
Post:
Yes there are different initial conditions in models. However your model, the two that have finished and the other models listed have initial condition parameter 0.05 so the listed models are all identical. Models with different initial conditions will be listed under a different work unit reference.

Just because the models handed out are identical does not mean the results will be identical. If the processor or operating system is different then a different maths library is likely to be in use and the results are likely to be fairly similar but slightly different.

There is a recent paper Knight et al (see climate science, publications, scientific papers for link) which examined the effects. The changes created were larger than changes caused by an initial condition but fairly similar (IIRC less than double the sizes of variations) This is much smaller than the differences caused by many parameters. The effect is that these different models can sensibly be used as an initial condition ensemble.

If you look very carefully at the graphs you may detect slight variations. If so your work is not quite a repeat and is useful to increase the initial condition ensemble size which is wanted.

If it is absolutely identical, then some of these are wanted. (Or at least before the Knight et al paper was published they were. I don\'t really know whether there are more papers like Knight et al planned or being prepared. But I would assume it is possible.)

Even if you are sure it is identical, I don\'t think this is enough reason to abort it.
19) Message boards : climateprediction.net Science : Met Office plans next five years in climate science (Message 30486)
Posted 11 Sep 2007 by crandles
Post:
I don\'t know anything about Met Office plans.

What is said there seems to fit in with NERC\'s new stratgy:

http://www.nerc.ac.uk/about/consult/strategy/documents/draft-strategy.pdf

BOINC isn\'t mentioned in there but I wouldn\'t expect it to be. Plans would be a more appropriate place than strategy.
20) Questions and Answers : Windows : No trickles on HadCM3 Coupled Model? (Message 28157)
Posted 26 Apr 2007 by crandles
Post:
I think that one is my fault. I wrote that for the wiki during beta testing when the trickle frequency was monthly. When the transient model was released the trickle frequency changed to yearly. It took me some time to spot the wiki needed changing and by the time it was brought to my attention, the wiki had been used as a basis for that faq. Sorry about that.

http://boinc-wiki.ath.cx/index.php?title=Climateprediction_FAQ#Why_are_the_work_units_so_big.3F

probably wants a bit of work again to put the transient model information first and archive the slab model information. (Though there may soon be some slab models again with better parameter values.)


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