Further supplementary memorandum submitted
by the Government Office for Science and the Cabinet Office (SAGE
00b)
RECORD OF THE SEVERE SPACE WEATHER WORKSHOP
Meeting held in Room 35 Great Smith Street,
London on 21 September 2010 at 1000.
Representation from Government: Cabinet Office,
Ministry of Defence, Her Majesty's Treasury, Department for Transport,
Department of Energy and Climate Change, Centre for the Protection
of National Infrastructure, Government Office for Science, Department
of Health.
Representation from the science community: The
Rutherford Appleton Laboratory, The British Geological Survey,
The Electrical Infrastructure Security Council, The Meteorological
Office.
Representation from the Energy, Communication
and Transport Sectors.
(1) Introducing the meeting, the Chair said
that the purpose of the meeting was to hold an initial exchange
of views on the likelihood of severe space weather and possible
impacts. The discussion would contribute to the process Government
uses to understand risks in this area.
THE REASONABLE
WORST CASE
SCENARIO
(2) The selection of the Carrington Event
as the basis for a reasonable worse case solar scenario was discussed.
Although much work has been done on the scaling of this event
compared to other historical events, the data on which this has
been based are limited. A full analysis and use of the Carrington
event as a reasonable worst case scenario requires the use of
"extreme value statistics" and the currently available
data allow only rough and preliminary estimates using this technique.
Discussion also centred on different scaling factors used between
the UK and the US, because of differences in magnetic latitude.
Given these uncertainties, the view of most was that the duration
and magnitude of a Carrington event scenario cannot at present
be used with high levels of confidence.
(3) It was reported that there was a 1%
chance of a Carrington-like event occurring during a solar maxima
year. The Carrington Event was 150 years ago but the intervening
years contain about 30 strong geomagnetic storms of a similar
but slightly lower intensity, notably the 1921 storm which damaged
telephone networks in Sweden. It was also reported that large
geomagnetic storms can be caused by a rapid succession of flare/Coronal
Mass Ejections and this has been the case in several important
storms. Discussions were held on the increase or decrease in the
probability of a severe event in relation to solar maxima and
minima years respectively. It was reported that strong solar events
can happen at any time, including minima years (eg the 1986 storm),
however there is 20 fold increase in likelihood of an event happening
during maxima years. Discussions also centred on the robustness
of 1% likelihood of a Carrington-like event and whether this was
a sufficiently reliable statistic on which to base investment
in more resilient technologies.
(4) Concerns were raised about the amount
of credible data available which could be used to make predictions
about future solar events. It was reported that, while UK Flood
risk assessment exploits decades of data from similar streams
in different catchment areas to construct long statistical datasets
(hundreds of years of data), accurate solar data has only been
available for the past 40yrs, and with only one source; the Sun
within the Solar System. Around 500 years of good recorded data
would be needed to estimate 1/100 year events with high degrees
of confidence. Ice core readings containing trapped nitrates have
provided data which may be used as a proxy of solar radiation
storms over the past 400 years, but no proxy yet exists for geomagnetic
storms. It was noted that there has been a very strong scientific
focus on the Carrington Event in recent years and that other storms
should also be considered to construct a reasonable worst case
scenario.
(5) The direction of solar events was discussed.
The impact of a Coronal Mass Ejection (CME) of Carrington magnitude
is dependent upon the direction of the ejection and the orientation
of its magnetic field, relative to that of the earth. In November
2003, a large CME plumed on the west side of the Sun as seen from
the Earth. The effects were far less severe than would be expected
had the ejection pointed towards the Earth. If the earth were
impacted by a severe solar event, disruption would likely be global.
The effects would first be directed to the northern and southern
Polar Regions by the geomagnetic field but would rapidly extend
to lower latitudes through changes in the upper atmosphere. While
a direct event passes earth quickly, magnetosphere instability
would last for many days.
(6) Impacts on the Communications, Transport
and Energy Sectors. There were informal presentations from representatives
from the Communication, Transport and Energy sectors on the possible
impact on assets in their sectors.
(7) International Co-operation. The Meteorological
Office is working with the US NOAA (National Oceanic and Atmospheric
Administration) Space Weather Prediction Centre to collect space
weather information.
| 
