Land-based temperature records are also important. However, microclimates on land can lead to large variations in temperatures within a small area — for example, a shaded valley may be cooler than an open plain — which means that historical records can be unrepresentative.
That doesn't mean the scientists won't use the land surface temperatures — they will! Just that sea surface temperature is particularly valuable.
"There had been quite an ongoing effort for a long time in developing sea surface temperature sets," says Allan, "and we have a long set of sea surface temperatures so this project is to see if we could recover more sea surface temperature data."
The amount of work involved in delving into the logbooks to uncover the weather observations is huge! The work involved is way too much for a small team, but with the power of citizen science, the information can be unlocked by sharing the load.
Unfortunately, it's not the sort of thing that a computer can be trained to do. Reading handwritten text is a skill that people and not computers excel in. Humans are also better at identifying important information.
The weather observations found by our citizen science weather detectives will add to our understanding of our planet's weather history.
They'll go into a database called Atmospheric Circulation Reconstructions over the Earth (ACRE) which will be available to anyone.
"The idea was to get a bigger better database of the weather, where we pick up more events like El Niño, La Niña or storms," says Allan.
"So instead of 40 or 50 years of recent data you could get 150 maybe longer years of data. And then you suddenly get this much more valuable tool to feed into whatever you want to use it for."
Ambitiously, ACRE aims to put together a full history of our planet's weather back to 1850 — providing weather details all over the globe for 200 kilometre by 200 kilometre resolutions for every three to six hours. The weather details will then be used to reconstruct a 3D picture of what was happening with air masses and air pressure systems at the time. It's really like something out of a science fiction film!
It's an incredibly ambitious project that is well underway and should reap some very useful results — from improving weather forecasting, to understanding climate change to re-analysing serious past weather events, such as the Knickerbocker Storm of 1917.
A significant use, and one of the reasons the project was started — is to verify seasonal forecast models which are used by farmers and primary producers for crop production.
On a regional level, it could be really useful for understanding how particular climatic phenomena — such as El Niño — may respond to climate change. And that extra length of records may give us more information about how likely extreme events, such as heatwaves or floods, are to occur in the future.
Note: Anyone can help read the logs but the competition component of this annual citizen science project -- for National Science Week in Australia -- is open to residents of Australia only.