Cold snap in North America – World Weather Attribution analysis
mercredi 17 janvier 2018 14:27

Over recent years (2014, 2016 and now), there have been a number of extreme cold events in North America, although in different regions and of different durations. Low temperatures have been observed over much of northeastern North America during the two weeks between December 26, 2017 through January 8, 2018, and these temperatures are unusually cold in a large region centered over the Great Lakes extending to the eastern seaboard.

To help us define this year’s event, we compare the coldest two weeks in the 2017/18 winter so far with the coldest two weeks in previous winters in North America. We chose this comparison, rather than using temperatures on the exact same dates in the past, because a cold wave can occur any time in winter and affects people similarly, regardless of the exact timing. We find that the coldest two weeks this winter have been 7ºF to 11ºF (4ºC to 6 ºC) colder than the coldest two weeks have been, on average, during the past “normal” period of 1981–2010 over most of the area affected by the cold wave.


To quantify the effect of warming on the coldest two-week period of the winter in the area, we fitted the series to a Generalised Extreme Value (GEV) distribution, indicating that the temperature of the coldest two-week period has increased about two times faster than the global mean temperature rise. This has been explained as a consequence of stronger warming trends in the Arctic, where the cold air originates. The fit also shows that these two weeks are very unusual in the current climate, with a return time of very roughly 250 years in this region.

The significant dependence of the GEV location on the values of global mean temperature allows us to ask what the return time of such an event was in the climate of a century ago. Our estimates indicate that a cold wave like this occurred on average every seventeen years. This means that cold waves like this have become approximately a factor fifteen less frequent due to global warming.

We conclude that this was an exceptional two-week cold wave in the area in the current climate. Cold outbreaks like this are getting warmer (less frequent) due to global warming, but cold waves still occur somewhere in North America almost every winter.

Full report

Geert Jan van Oldenborgh, Hylke de Vries (KNMI), Gabriel Vecchi (Princeton University), Friederike Otto (University of Oxford), Claudia Tebaldi (Climate Central and NCAR)

Project downtime on Tue Jan 23rd
Source:  Einstein@Home
mercredi 17 janvier 2018 10:30

Hi everyone,

We are going to shut down the project next Tuesday, Jan 23rd at around 10 AM CET for an upgrade of our database backend systems to make them ready for the years to come. We're going to upgrade hardware parts, operating systems as well the databases themselves, which is why we need to shut down the entire project, including the BOINC backend and this very website.

Generally you don't have to do anything at your end.

read more

Short interruptions Tuesday
Source:  LHC@Home Classic : SIXTRACK
mardi 16 janvier 2018 08:05

There will be a couple of short server outages while our BOINC service pass to fail-over nodes today, Tuesday 16th of January. Similar interruptions will happen next week, as we carry out security updates on our computing infrastructure.

Planned Maintenance on Monday, January 15 (Completed)
Source:  World Community Grid News and Updates
vendredi 12 janvier 2018 16:19

We are updating the database on our servers on Monday, January 15, beginning at 20:15 UTC.

GFN-262144 Mega Prime!
Source:  PrimeGrid
vendredi 12 janvier 2018 12:47

On 10 January 2018, 12:26:12 UTC, PrimeGrid’s Generalized Fermat Prime Search found the Generalized Fermat mega prime: 3853792^262144+1 The prime is 1,726,452 digits long and enters Chris Caldwell's The Largest Known Primes Database ranked 6th for Generalized Fermat primes and 55th overall. The discovery was made by Rod Skinner (rjs5) of the United States using an NVIDIA GeForce GTX 1080 in an Intel(R) Core(TM) i7-8700K CPU at 3.70GHz with 16GB RAM, running Linux. This GPU took about 18 minutes to probable prime (PRP) test with GeneferOCL3. Rod is a member of the Intel Corporation team. The PRP was confirmed prime by an Intel(R) Core(TM) i7-7700K CPU @ 4.20GHz with 16GB RAM, running Microsoft Windows 10 Professional. This computer took about 6 hours 59 minutes to complete the primality test using LLR. For more details, please see the official announcement.

Dr Friederike Otto presents to Chinese and Brazilian scientists at LOTUS workshop
lundi 8 janvier 2018 12:22‘s Dr Friederike Otto presented on climate attribution science to Chinese and Brazilian early career researchers today, as part of a week-long workshop for the LOTUS project being hosted by the Oxford e-Research Centre. The project is exploring why the climate in China is changing and what the implications could be for the country’s vulnerability to extremes such as drought.

Early career researchers from environmental research and monitoring institutions in China and Brazil have joined project participants Professor David Wallom and Dr Sarah Sparrow from the Oxford e-Research Centre, the University of Edinburgh’s Professor Simon Tett (LOTUS lead PI) and other researchers from UK institutions for the workshop.

The three-year LOTUS (Long Term Undulations versus secular change in Chinese Climate) project is funded by the Newton Fund through the Climate Science for Services Partnership (CSSP China) led in the UK by the Met Office.

CSSP China is a scientific research programme supported by the BEIS UK-China Research Innovation Partnership Fund that will help build the basis for services to support climate and weather resilient economic development and social welfare.

The three primary outcomes of CSSP China will be:

• A strong strategic partnership between UK and Chinese climate scientists;
• Accelerated and enhanced collaborative science R&D programmes;
• Climate services, developed in partnership, based on the climate science research & development programme.

As well as the presentation from Dr Otto, a series of breakout groups during the workshop will study two extreme events, one in China and one in Brazil, and attribute the occurrence of these to climate change.

The output of the workshop for early career researchers is to bring forward the next group of climate scientists who will have knowledge of this cutting edge area of research and its applications for societally relevant problems.

E&E News article explores how climate attribution science has developed in last 15 years
lundi 8 janvier 2018 11:14

A recent article in Environment and Energy News explores how the science of attributing the effects of climate change to individual extreme weather events has developed over the last 15 years.

The predominant view in the scientific community in 2003 was that, while it was evident that climate change had a significant event on the weather, it was impossible to attribute a particular event to past emissions of greenhouse gases.

But Professor Myles Allen, Principal Investigator of, was convinced it would become possible in the future.

In May 2004, he, Oxford colleague Daithi Stone and Peter Stott of the Met Office co-authored a report [1] which, E&E News claims, is now widely regarded as the world’s first extreme event attribution study. The paper examines the contribution of climate change to the European heatwave of 2003, which caused thousands of deaths across the continent and concludes that “it seems likely that past human influence has more than doubled the risk of European mean summer temperatures as hot as 2003”.

This breakthrough paper took existing science a little further, comparing real-world climate change simulations with scenarios with no human-induced climate change. The key to attribution of an individual event is in posing the right question – not whether climate change caused the event, but whether and by how much it increased the chances of it happening at all.

Extreme event attribution is not only possible now, but is one of the most rapidly expanding subfields of climate science, with a new paper published almost weekly. Two main approaches have emerged – those looking at the probability of an extreme event occurring, and those looking at the components that cause the events, and how changes to the climate system may affect them.

Dr Friederike Otto, who leads the World Weather Attribution project for, attributes the recent surge to the progression of technology — specifically, the improvement of climate models.

“Extremes are, by definition, rare,” she told E&E News. The development and improvement of climate ensembles — large groups of slightly different climate models — such as those carried out by volunteers, have improved scientists’ ability to simulate weather events under different conditions. The probability approach to event attribution also helps to identify the types of events that might become more common in the future, and where they may occur.

In future, the article suggests, climate attribution studies could apportion blame for extreme events caused by greenhouse gas emissions, and even provide evidence in cases against governments or private companies for failing to protect property or infrastructure against extreme weather.

In 2014, scientists from a number of different institutions including Myles Allen, Friederike Otto, William Ingram, Karsten Haustein and Sarah Sparrow at the University of Oxford, carried out an attribution study on the southern England winter floods of that year [2], which caused in the region of £451 million insured losses. This was the first attribution study following anthropogenic changes in atmospheric composition, through a meteorological extreme event and its hydrological impacts to an estimate of the value of those impacts in terms of flood damages.

“In the meantime, though”, concludes E&E News, “individual studies are expected to keep rolling out. This last summer alone, a wave of unusual events across the world — from Hurricane Harvey in the United States to devastating floods in Southeast Asia — sparked renewed interest in the link between extreme weather and climate change.”

Read the full article:


[1] Peter A. Stott, D.A. Stone, M.R. Allen, Human contribution to the European heatwave of 2003
[2] Schaller et al, Human Influence on climate in the 2014 southern England winter floods and their impacts


File upload issues
Source:  LHC@Home Classic : SIXTRACK
lundi 8 janvier 2018 10:25

Our NFS storage backend got saturated and hence uploads are failing intermittently.

The underlying cause is an issue with file deletion, we are trying to resolve that.

Sorry for the trouble and thanks for your patience with transfers to LHC@home.

Source:  Gerasim@home
samedi 6 janvier 2018 15:12

В проекте запущен тестовый подпроект, целью которого является тестирование возможностей поиска ОДЛК на NVidia GPU. Подробности обсуждаются тут:,


The project launches a test subproject aimed to testing of ODLS searching ability using NVidia GPUs. Detailed description here:,

Aliquot sequence 1164432 has terminated!!!
Source:  YAFU
samedi 6 janvier 2018 08:34