Glacial cycles
[2008-05-16]

animation: Lisa Roberts
Sydney 2008

dancers: Christine McMillan
and Lisa Roberts

data: Dominic Hodgson, British Antarctic Survey,
referred to: Wikipedia
Online accessed 2008-05-05

Milankovitch cycles data, Wikipedia

Past and future Milankovitch cycles.
VSOP allows prediction of past and future
orbital parameters with great accuracy.
ε is obliquity (axial tilt).
e is eccentricity.
ϖ is longitude of perihelion.
esin(ϖ) is the precession index,
which together with obliquity,
controls the seasonal cycle of insolation.
\overline{Q}^{\mathrm{day}} is
the calculated daily-averaged insolation
at the top of the atmosphere,
on the day of the summer solstice
at 65 N latitude.
Benthic forams and Vostok ice core
show two distinct proxies
for past global sealevel and temperature,
from ocean sediment and Antarctic ice respectively.
Vertical gray line is current conditions, at 2 ky A.D.

Cycles within cycles of change
(Roberts, Lisa and Wilson, 2008),
Plan for a 400 frame animation
representing Earth’s complex motion around the sun,
with each frame representing one year.

This is coming along nicely.

The final graph (glacial -interglacial cycles)

needs a label to appear with it,

as do the shaded columns marking the interglacials.

I am sure you are doing this anyway.

Amazing, isn't it,

that the inerglacials represent such short periods of time.

From these graphs one can really see

that Earth is mostly in a glacial state,

and that the interglacial in which we now live

is a relatively unusual event;

one that has allowed our civilisation to flourish.

I am glad you are seeing the beauty in the scientific data

- these are incredible graphs that explain so much

about the history of our planet

and its ability to support us.

Dominic Hodgson

Paleocologist/quaternary scientist
British Antarctic Survey

16 May 2008