When I meet new people, the conversation invariably gets on to what I do for a living. “Oh, you’re doing a PhD! That’s so cool! What are you doing it on?”
“Oh… Cool… What?”
Paleoclimatology (or palaeoclimatology if you use the English spelling) is simply the study of past climates. It’s actually a really important component of climate science, since it establishes a baseline for natural climate variability.
Climate observations only go back a hundred years or so (there are some longer records, but generally, the further back you go, the less reliable these observations become). If you consider that climate refers to the long-term changes in weather patterns, then you really need a long-term record to study them.
Unfortunately, the observational record just isn’t long enough on its own. That’s where paleoclimatologists come into things.
Paleoclimatologists use what are called “proxies” to infer what the climate was like before observations were made. Proxies include coral, ice cores, tree rings, stalagmites, sediment cores and glacial deposits – just to name a few. These proxies give us information about certain aspects of climate at the time that they were formed.
For example, we can examine the bubbles in ice cores to get a snap shot of the atmospheric concentrations of gases such as carbon dioxide and methane at the time that the bubble was formed.
Or in my case, we can analyse the chemical make up of stalagmites to get an idea of the amount of rainfall that fell through time at that location.
Paleoclimate records go back hundreds of thousands, and even millions of years. Through these long records, we can see natural changes in the climate as it moves between ice ages and warm interglacial periods. These natural cycles establish the range of natural variability within the climate system.
This is particularly important if you want to conclude that modern climate changes are not natural. The one very convincing indicator that current levels of carbon dioxide in the atmosphere today are not natural, comes from ice cores.
When you compare the range of values over the last 800,000 years, as measured from the bubbles in ice cores, you can clearly see that levels today are way above natural.
Without the baseline paleoclimate information, there’s no context for modern climate changes.
Paleoclimatology is like climate change’s wingman!