Climate modelling: from Manabe and Wetherald to supercomputer JASMIN
Climate models are an essential tool in understanding climate change and its potential impacts. This is the story of the first climate model — and the modelling we do today.
Modelling the Earth’s climate is an incredibly complex task. As well as the physics of how heat from the Sun is absorbed and reflected by the Earth, you have to take into account the atmosphere, the oceans, clouds and how each of these impacts the other.
Now scientists have access to powerful supercomputers that can do their calculations for them, but back in the 1960s this was not the case. However this didn’t stop one scientist from creating a model that still holds up to this day.
In 1967, Syukuro Manabe created the world’s first computer model of Earth’s climate. This pioneering work opened the door to a whole new field of science.
The very first model of Earth’s climate
In the mid 1960s, Syukuro Manabe was working as a senior research meteorologist at the National Oceanic and Atmospheric Administration (NOAA) in America.
At that time, huge advances in weather forecasting had been made. But Manabe was interested in applying those advances to studying Earth’s climate instead.
His department, the Geophysical Fluid Dynamics Laboratory in Princeton, New Jersey, had recently acquired one of the first commercial computers, so, working with colleague Richard Wetherald, Manabe set about putting it to work.
The computer was thousands of times slower than modern computers and took hundreds of hours to run simple simulations. Because of that, Manabe deliberately made the model as simple as possible.
Nevertheless, the model incorporated all the major components that contribute to Earth’s climate, including the atmosphere, oceans and clouds — and the relationships between them.
To test the model, Manabe decided to change levels of various greenhouse gases, such as carbon dioxide, to see what impact this had on the Earth’s temperature.
The results were remarkable. Taking out all of the greenhouse gases from the atmosphere reduced the planet’s temperature by 30C. Conversely, raising levels of greenhouse gases dramatically increased temperatures.
Writing up their findings in a 1967 edition of the Journal of Atmospheric Sciences, Manabe and Wetherald wrote:
‘According to our estimate, a doubling of the CO2 content in the atmosphere has the effect of raising the temperature of the atmosphere (whose relative humidity is fixed) by about 2 °C.’
Measurements from the pre-industrial revolution until today match that prediction extremely well. Since the 1880s we have increased CO2 by about 50%, and temperatures have increased by 1.1 °C.
Still, at that time, Manabe had no idea how important the idea of greenhouse gases would become.
In the 1960s, climate change wasn’t seen as much of a threat. Scientists had known that gases such as carbon dioxide, water vapour and methane could trap heat and warm the planet since the 1860s. However most scientists weren’t that concerned, probably because global temperatures had fallen slightly in the 1950s and 60s.
Maybe for that reason, the study didn’t have much impact at first. It took more than a decade before people began to realise the merit of the researchers’ approach.
However eventually that changed. In 2015 their study was voted as the most influential climate change paper of all time. In 2021, Manabe was awarded the Nobel Prize in Physics for his work on understanding Earth’s climate.
The next generation of climate models
Today, climate models are at the heart of environmental science. Their predictions of what a 2C warmer world could look like have driven governments around the world to overhaul their economies and curb their carbon emissions.
Over the past 50 years, climate models have become rather more complex than the original one devised by Manabe and Wetherald.
A typical global climate model now can take hundreds of scientists years to build, contains enough computer code to fill 18,000 pages of printed text, and can require a supercomputer the size of a tennis court to run.
To help them run such complex models, researchers in the UK and Europe have access to JASMIN, a giant supercomputer which also acts as a data store.
Co-managed by RAL Space’s Centre for Environmental Data Analysis (CEDA), and the Science and Technology Facilities Council’s Scientific Computing Department, JASMIN can reduce the time it takes to run simulations from months to hours. It can also store 44 petabytes of environmental data, equivalent to over 10 billion photos.
Half supercomputer, half data store
JASMIN’s combination of computing power, massive storage and a very fast internal network means that scientists can now analyse data at scales that simply weren’t possible before.
For example, often researchers want to take the output of a climate model that’s been produced on a supercomputer and compare it with findings from other models.
They then want to share those results with their collaborators. However you can’t simply upload data like this onto a memory stick, or send it in an email. Instead, researchers can upload their data onto JASMIN, and share it with colleagues from all over the world.
This is exactly what happened in the Primavera Project, led by the Met Office and University of Reading. In the project, over 100 scientists from 21 institutions across Europe used JASMIN to simultaneously share climate simulations from seven different climate models. JASMIN allowed the scientists to store all their data and do most of their analysis online.
Why does this matter?
Ultimately projects like this mean that climate scientists can now analyse decades worth of data in days.
This means that scientists have never been in a better position to understand the Earth’s climate, and predict how it will change in the future.
Want to know more?
If you’re a UK taxpayer, your contributions help fund the work of researchers modelling climate change, via UK Research and Innovation — the UK’s largest public funder of research — and the nine research councils. Projects in this article are funded by the Natural Environment Research Council and the Science and Technology Facilities Council. You can read more about what we do here.
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