Presentation on theme: "Global Warming The problem of scale. The imperceptible and the vast (1) As human beings we can judge: • temperatures • close to ‘normal’ • weights • in."— Presentation transcript:
Global Warming The problem of scale
The imperceptible and the vast (1) As human beings we can judge: • temperatures • close to ‘normal’ • weights • in the range a few grammes to a hundred kilogrammes • distances. • from a few kilometres to less than a millimetre • times • from a fraction of a second to periods of a few years.
The imperceptible and the vast (2) As human beings we cannot judge: • temperatures • more a few degrees away from ‘normal’ • weights • beyond a few tonnes or less than a gramme • distances • beyond a few kilometres or much less than a millimetre. • times. • much less than a second or greater than a fraction of a lifetime
The imperceptible and the vast (3) Quantities and qualities that extend beyond our range of familiarity seem either: imperceptible or vast •It is important to retain an ability to quantitatively assess quantities we perceive as imperceptible or vast • Becoming familiar is an important part of understanding • But then we can become too familiar!
Diameter: 12,800 km Deepest hole: 10 km Atmosphere: Scale Height 8.4 km The Planet Earth
The Sun Diameter: 1,390,800 km Earth
Powers of Ten Very Very Small Very Very Large
Powers of Ten Very Very Small Very Very Large 1 metre m m
Powers of Ten (Global Warming) Length scale in metres Very Very Small Very Very Large Human Relationships Diameter of the Earth Distance to the Sun Tallest Mountain Deepest Trench Atoms & Molecules Microbes The phenomenon of global warming involves physical processes with length scales spanning 20 powers of 10!
Powers of Ten (time) Time scale in seconds Very Very short Very Very Long second 1 Year the Earth moves once around the Sun Milankovitch Cycles A human lifetime Time for a molecule to jiggle Typical survival time of a civilisation Age of the Earth End of last ice age Electoral Cycle Deep Ocean Current Circulation time The phenomenon of global warming involves physical processes with time scales spanning 25 powers of 10!