Drip … drip. We've all watched water drip into a glass until, like the final straw, the water spills over and runs into an ever-widening pool. This is a tipping point.
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There are some fascinating things to observe about this scenario that reflect the nature of tipping points. The first is that it only takes a tiny drop to send the water over the edge. The second is that the amount of water that pools at the base of the glass is much more than the tiny drop that caused it all to happen.
Unless you stop the dripping, you're going to have a whole lot more water to tidy up. You might ask what's a little water? It could be the difference between a standing wall and one that has been washed away. The thing about a tipping point is that a final, tiny nudge has a huge effect.
In climate science, tipping points are critical thresholds that are reached by small events (known as "forcings") that tip the system into a significant change. With climate change, incremental increases in greenhouse gases cause change in the whole system. The warming causes ice to melt, the ocean to warm (and expand), increases the amount of water vapour in the atmosphere, and ultimately takes the entire climate system into a new, warmer state.
Like the water in our cup, the change to climate is larger (or faster) than the cause of it. And like the camel's broken back, the change to our climate is permanent – we can't reverse it.
A major reason for this is the critical role of the polar ice sheets in reflecting incoming sunlight back to space – an effect known as "albedo", and once it's gone, it cannot be regrown. When we lose the albedo effect of the ice sheets, we will permanently change the climate conditions of Earth.
Climate change is rife with tipping points. We have them in our ice sheets, in drought events, alterations to weather patterns such as the monsoons, ocean circulation, permafrost, and clathrates. With all these tipping points on the horizon, you can't help wondering if there is a tipping point for human action.
These are the sorts of things we will explore in the climate game CO2peration, which you can support through our Kickstarter campaign.
Response by: Inez Harker-Schuch, ANU Centre for the Public Awareness of Science
The Fuzzy Logic Science Show is 1100am Sundays on 2xx 98.3FM. Send your questions to AskFuzzy@Zoho.com Twitter @FuzzyLogicSci
