Connecting climate change
The Earth is a dynamic system, constantly changing. It may appear static because the underlying dynamics have reached an equilibrium state or because changes are occurring over very long time frames.
The dynamics arise because different parts of the system interact with one another - chemicals react, waves erode coasts, animals eat each other. Because there are so many parts to the system, it is hugely complex. Researchers therefore tend to focus on a subset of factors of most relevance to their area of interest.
Nevertheless, in principle it is possible to describe the behaviour of a system in terms of the nature of the interactions between its different components. The relationship between them can take several forms, such as:
- positive responses (e.g. more sunlight, more plant growth)
- negative responses (e.g. more sheep, less grass)
Interactions are often complicated or non-linear: how an element responds is dependent on the size of the change.
A change may also affect itself, through feedback mechanisms:
- negative feedback (more predators, less prey; predators starve and their numbers fall; prey recovers)
- positive feedback (fish stocks run low, fishermen catch smaller fish; fewer fish reproduce, fish stocks fall further).
Negative feedback loops are stabilising forces and common in biological control systems and ecology.
Positive feedback systems, by contrast, can be powerful drivers of change. A major fear in climate change is that positive feedback systems could push us over a ‘tipping point’, whereby environmental factors begin driving temperatures up on their own. An example might be the sudden release of huge quantities of methane from melting permafrost or reserves buried under the oceans.
Systems that are highly sensitive to starting conditions are described by chaos theory. Although governed by rules, they appear chaotic and unpredictable. Chaos theory is often likened to the ‘butterfly effect’, a term coined by Edward Lorenz, who died in 2008, whereby the flapping of a butterfly’s wings in one part of the planet sets off a tornado somewhere else.
For people, the implications are far-reaching. Increased greenhouse gas emissions are not being harmlessly absorbed into the atmosphere. They are triggering profound chemical, geophysical, meteorological, biological and social changes. Butterflies’ wings are flapping like mad all over the globe.