---
title: "Climateprediction.net"
chunk: 2/4
source: "https://en.wikipedia.org/wiki/Climateprediction.net"
category: "reference"
tags: "science, encyclopedia"
date_saved: "2026-05-05T04:11:42.306440+00:00"
instance: "kb-cron"
---

Classic Slab Model - The original experiment not under BOINC. See #The original model for further details. This model remains in use solely for the OU short course.
BOINC Slab Model - The same as the classic Slab Model, but released under BOINC.
ThermoHaline Circulation (THC) Model - An investigation of how the climate might change in the event of a decrease in the strength of the ThermoHaline Circulation. This experiment has now been closed to new participants as they have sufficient results. It was a four phase model totaling 60 model years. The first three phases were identical to the above Slab Models. The fourth phase imposed the effects of a 50% slowdown in the Thermohaline circulation by imposing SST changes in the north Atlantic derived from other runs.
Sulfur Cycle Model - An investigation of the effect of sulfate aerosols on the climate. The experiment will model sulfur in a number of compound forms including dimethyl sulfide and sulfate aerosols. This experiment started in August 2005 and was a pre-requirement for the Hindcast. It is a 5 phase model totalling 75 model years. Timesteps are around 70% longer, making the model around 2.8 times longer than the initial slab model. While a few models are still tricking, model have not been issued since 2006.
Coupled Spin-Up Model - Inclusion of oceanic influences into the basic model in a more dynamic and realistic way than the initial Slab Model. This was a pre-requirement for the Hindcast. This has been completed and, as planned, was not publicly released. The fastest 200 - 500 computers were invited to join because it is a 200-year model and results were needed by February 2006 for the transient coupled model launch.
Transient coupled Model - This comprises an 80-year Hindcast and an 80-year forecast. The Hindcast is to test how well the models perform at recreating the climate of 1920 to 2000. It was launched February 2006 under BBC Climate Change Experiment branding and later also released from the CPDN site.
Seasonal Attribution Project - This is a high resolution model for a single model year to look at extreme precipitation events. This experiment is much shorter due to its single model year, but there are 13.5 times as many cells and timesteps are only 10 minutes instead of 30 minutes. This extra resolution means it requires at least 1.5 gigabytes of RAM. It uses the HadAM3-N144 climate model.

== History ==
Myles Allen first thought about the need for large climate ensembles in 1997, but was only introduced to the success of SETI@home in 1999. The first funding proposal in April 1999 was rejected as utterly unrealistic.
Following a presentation at the World Climate Conference in Hamburg in September 1999 and a commentary in Nature in October 1999, thousands signed up to this supposedly imminently available program. The dot-com bubble bursting did not help and the project realised they would have to do most of the programming themselves rather than outsourcing.
It was launched September 12, 2003, and on September 13, 2003, the project exceeded the capacity of the Earth Simulator to become the world's largest climate modelling facility.
The 2003 launch only offered a Windows "classic" client. On 26 August 2004 a BOINC client was launched which supported Windows, Linux and Mac OS X clients. "Classic" will continue to be available for a number of years in support of the Open University course. BOINC has stopped distributing classic models in favour of sulfur cycle models. A more user friendly BOINC client and website called GridRepublic, which supports climateprediction.net and other BOINC projects, was released in beta in 2006.
A thermohaline circulation slowdown experiment was launched in May 2004 under the classic framework to coincide with the film The Day After Tomorrow. This program can still be run but is no longer downloadable. The scientific analysis has been written up in Nick Faull's thesis. A paper about the thesis is still to be completed. There is no further planned research with this model.
A sulfur cycle model was launched in August 2005. They took longer to complete than the original models as a result of having five phases instead of three. Each timestep was also more complicated.
By November 2005, the number of completed results totalled 45,914 classic models, 3,455 thermohaline models, 85,685 BOINC models and 352 sulfur cycle models. This represented over 6 million model years processed.
In February 2006, the project moved on to more realistic climate models. The BBC Climate Change Experiment was launched, attracting around 23,000 participants on the first day. The transient climate simulation introduced realistic oceans. This allowed the experiment to investigate changes in the climate response as the climate forcings are changed, rather than an equilibrium response to a significant change like doubling the carbon dioxide level. Therefore, the experiment has now moved on to doing a hindcast of 1920 to 2000 as well as a forecast of 2000 to 2080. This model takes much longer.
The BBC gave the project publicity with over 120,000 participating computers in the first three weeks.
In March 2006, a high resolution model was released as another project, the Seasonal Attribution Project.
In April 2006, the coupled models were found to have a data input problem. The work was useful for a different purpose than advertised. New models had to be handed out.

== Results to date ==
The first results of the experiment were published in Nature in January 2005, showing that with only slight changes to the parameters within plausible ranges, the models can show climate sensitivities from less than 2 °C to more than 11 °C. The higher climate sensitivities have been challenged as implausible. For example, by Gavin Schmidt (a climate modeler with the NASA Goddard Institute for Space Studies in New York).