The movie "The Day After Tomorrow" (see http://www.thedayaftertomorrow.com/) has caught the public imagination with its depiction of catastrophic rapid climate change. But could a shutdown in North Atlantic ocean circulation really happen, and what would the consequences be? Could global warming really lead to a new ice age?

In a project started on 22nd June 2004 the climateprediction.net distributed computing team launched an experiment where your home or work computer can be used to help run a climate model to see if these outcomes are feasible in the real world.

Since its start in September 2003, the climateprediction.net experiment has been developed to allow a state-of-the-art climate prediction model to be run on home/ school/ work computers (unfortunately not yet for Apple computers). By getting data from thousands of climate models, climate.net will generate the world's largest climate prediction experiment.
Even with the incredible speed of today's supercomputers, climate models have to include the effects of small-scale physical processes (such as clouds) through simplifications (parameterizations). There is a range of uncertainty in the precise values of many of the parameters used - we do not know precisely what value is most realistic. Sometimes this range can be an order of magnitude! This means that any single forecast represents only one of many possible ways the climate could develop.

The intention is to run hundreds of thousands of state-of-the-art climate models with slightly different physics in order to represent the whole range of uncertainties in all the parameterizations. This technique, known as ensemble forecasting, requires an enormous amount of computing power, far beyond the currently available resources of cutting-edge supercomputers. The only practical solution is to appeal to distributed computing which combines the power of thousands of ordinary computers, each computer tackling one small but key part of the global problem.

To take part, click on the link to climateprediction.net and from there you can download the software. At the moment you will need a PC operating either a recent version of Windows or Linux.

http://www.climateprediction.net/index.php

image copyright 20th Century Fox

Above: How will climate change in the future? Could the story from the movie "The Day After Tomorrow" come true? Could the glaciers return? Will Britain become a chilly snow-sports destination, or have a Mediterranean climate?

The North Atlantic might seem a long way from Antarctica but in fact the Southern Ocean acts as a link between all of the planet's major ocean basins. Data gathered from the cold Southern waters is essential for understanding the global ocean system. The aim of the UEA-led North Scotia Ridge Overflow Project project is to study the influence of the North Scotia Ridge on Antarctic Circumpolar Current. The science team have conducted a hydrographic section (measuring temperature, salinity, dissolved oxygen, nutrients and ocean currents) between the Falkland Islands and South Georgia and deployed three current meters and two bottom pressure recorders (BPRs) in Shag Rocks Passage. The moorings and bottom pressure recorders will be deployed for 18 months and will hopefully be recovered in the Autumn of 2004. See:

http://www.mth.uea.ac.uk/ocean/srp/

UK oceanographers have been making repeated measurements on a short section across a deep ocean basin, the Rockall Trough, since 1975 (red line on the map). The section consists of a series of stations from the Scottish continental shelf to a tiny rocky outcrop called Rockall. The time series was established by David Ellett and thereafter has borne his name. The Ellett line is one of a relatively small number of high quality physical time series in the North Atlantic Ocean and is very important for investigating oceanic climate variability. It is particularly relevant to the UK and north-west Europe because the warm water flowing through the Rockall Trough moderates the climate.

A research cruise from Glasgow to Iceland and back takes place in July 2004 on board the German research vessel "Poseidon". The cruise is led by Jane Read from SOC.

For more information see:

http://www.soc.soton.ac.uk/GDD/hydro/nph/ellett/index.php

http://www.cgam.nerc.ac.uk/aboutcgam/cgamaboutcgam.html

http://www.higem.nerc.ac.uk

is an international effort that aims to deploy some 3000 profiling floats throughout the global ocean, giving a much needed boost to the amount of upper-ocean data that is available to oceanographers and climate change scientists. The UK is playing an active part, and over 80 floats have been contributed so far.

Above: Mid-2003 map of global distribution of Argo floats. UK floats shown in red.

Left: Dr Brian King on board RRS Charles Darwin about to deploy an Argo float. THe floats are robust and can be launched from ships or dropped by parachute from low flying aircraft. Life expectancy can be up to 5 years.

For further information about Argo see:

http://www.noc.soton.ac.uk/JRD/HYDRO/argo/index.php (UK Argo)

http://www.bodc.ac.uk

http://argo.jcommops.org/ (main Argo site)

At the University of Reading, Prof. Brian Hoskins is coordinating research to determine what processes control the nature of the North Atlantic storm track.

A view of storm-tracks being determined by feature propagation in the upper troposphere and vertical coupling in specific regions has been proposed. For the first time, features in various fields such as potential temperature on the dynamic tropopause have been tracked automatically using the ECMWF 15 years of reanalysis data. The NH wintertime track density (shown right) shows a track for upper tropospheric features from the subtropical Atlantic through N. Africa and Asia to the Pacific, and across N. America to the Atlantic and perhaps through northern Eurasia to eastern China. For more information see:

http://ugamp.nerc.ac.uk/annrep2001/bh.htm

Objective 1 of the RAPID programme is “to establish a pre-operational prototype system to continuously observe the strength and structure of the Atlantic meridional overturning circulation (MOC)”. The MOC is defined as the zonally integrated meridional flow, as a function of latitude and depth. While parts of the MOC are wind-driven, the basin-scale Atlantic MOC is largely buoyancy-forced. Observing the Atlantic MOC is a fundamental observational requirement in assessing the role of the Atlantic thermohaline circulation (THC) in rapid climate change. While much of RAPID is focussed on the high latitudes, it is ultimately the ocean heat transport around 25°-35°N that has the greatest influence on north European climate.

A number of projects have been funded by NERC to monitor the MOC, some of which are collaborations with US NSF funded projects. Professor Jochem Marotzke, Dr Stuart Cunningham, and Professor Harry Bryden (Southampton Oceanography Centre) are observing the meridional overturning circulation in the Atlantic at 26.5 degrees N using a combination of moored arrays (temperature, salinity, currents and pressure), satellite observations (sea level, winds), the opportunistic use of hydrographic section and float data, and cable measurements (Florida Strait transport), plus modelling to synthesise the observations. The backbone of the observing array is a pair of profiling CTD probes near the end points of the section. The array was deployed from RRS Discovery in early 2004. See:

http://www.noc.soton.ac.uk/rapidmoc/

Crew deploying moorings from RRS Discovery, April 2004 (S. Cunningham)