ISIS Special Miniseries - Life of Gaia
This miniseries is dedicated to our planet earth, so we may better
appreciate how she lives and sustains all creatures large and small, that we
may learn to dance to the complex rhythms of her life music without stopping
her in her tracks.
Space scientist and inventor Jim Lovelock first proposed in the 1970s
that the entire earth is a self-organizing, self-regulating entity, rather like
an organism. He named the earth Gaia, after the Greek earth goddess.
The idea that Gaia is alive and has a life of her own immediately caught
fire. It inspired many earth scientists to look for the dynamic processes that
organize and regulate the currents of the earth, to make a congenial home for
all her inhabitants. These scientists are richly rewarded.
Records from ice and deep sea cores show detailed globally correlated
changes going back at least 800 000 years, leaving us in no doubt that the
earth behaves from moment to moment as one coherent whole, just like an
organism.
Not only can we can read Gaia’s life-history from her deep memory
stores, we can also tune in to her life-force pulsing as she is living
today.
Gaia spinning in her perpetual dance around the sun, her mighty breath
tumbling from hot belly to the poles, swirling across the continents, bringing
welcome rain to forests, grasslands and crops, or torrential downpours, floods
and hurricanes. Vast slow vortices of water connect her oceans from the
furthest northern reaches to the southernmost haunts, from the shimmering sea
surfaces to the dark deep beds, distributing warmth and nutrients, sustaining
life with life.
Gaia’s breath is our breath, her water our water. Let Gaia live
that we may live.
Abrupt Climate Change Happening
‘Climate change’ conjures up a picture of a gradual process
occurring in the timescale of the earth, hundreds if not thousands of years.
Not anymore. Since the mid 1990s, scientists have been asking if climate change
might be abrupt, in other words, it could happen suddenly, over a matter of
decades or even years, and be global in extent.
Dr. Mae-Wan Ho reports.
The complete document with diagrams, is available in the ISIS members site. Full details here
The picture most people and most policy-makers have of climate change is
the one produced by the Intergovernmental Panel on Climate Change (IPCC), which
gives smooth projections of global warming ranging from 1 to 6oC by
the end of this century, depending on the computer models used. All the models
assume processes occur smoothly and linearly, however, and do not predict
abrupt change.
Real earth processes, however, are nonlinear, often involving positive
feedback and threshold effects that give rise to abrupt, catastrophic jumps or
swings between different states.
As more and more data on ancient climate accumulate, it has become
clear that abrupt climate change is a reality on many different scales, and has
occurred many times in the past.
One way to test a climate model that predicts the future is to see how
well it post-dicts the past. For example, nine major ice ages have been
found in the geological record, alternating with periods of abrupt global
warming. Can the model predict those given reasonable starting conditions?
How to read the earth’s temperature
Geological records of temperatures can be read by various means. Over
the recent past, scientists look at the growth history of trees that are
hundreds and even thousands of years old. The rings give a record of yearly
growth and are thicker during warmer years.
Over periods of tens to hundreds of thousands of years, records come
from drilling ice from areas of permafrost. Ice is H2O, the great
majority of oxygen is the isotope oxygen 16, or 16O, a small
proportion is the isotope oxygen 18, 18O. Water containing
18O condenses from the air at a slightly higher temperature than
that containing 16O, so snow falling from colder air contains less
18O, and the ratio of 18O: 16O provides an
estimate of the temperature. Similar methods can be used with other isotope
ratios, such as deuterium to hydrogen 2H:H. The ice also contains
trapped air bubbles, which include gases of interest such as carbon dioxide and
methane, and calcium levels indicate atmospheric dustiness.
The age of the ice can be determined by counting annual deposition
layers back to about 40 000 years ago. Beyond that, other methods, such as
radioactive decay dating are used. A core from "Dome C" in the Antarctica is
expected to produce a record stretching back 800 000 years.
The earth has gone through cycles of rapid warming followed by freezing
every 100 000 years or so, with sub-periodicities of 41 000 years, 23 000, 19
000, 10 000 years and shorter. And there is a remarkable correlation with the
concentration of carbon dioxide in the atmosphere (Fig 1).
Figure 1. Correlated carbon dioxide and temperature changes over the
past 400 000 years.
This close correlation between temperature and carbon dioxide
concentration is one of the reasons palaeoclimatologist Richard Alley at
Pennsylvania State University, USA, who studies ancient climate, believes human
activities affect climate. The recent rate of increase in atmospheric carbon
dioxide simply has no geological precedence in the known history of our earth
(Fig. 2). A newly published study from the University of East Anglia’s
climatic research unit confirms that since 1980, we have been experiencing the
hottest climate for the past 2 000 years.
How well do current climate models of the IPCC post-dict the past? They
are much better than people often give them credit for, Alley says. Climate
changes show up in the right places at the right times, but they just
don’t produce the large, abrupt changes seen in the real world.
At the very end of the ‘Younger Dryas’, a global cooling event
between 13 000 and 11 500 years ago, average temperatures increased by about
6 C within a decade in some places. A huge quantity of melt-water
from North America poured into the North Atlantic in a big hurry, and it got
cold again. Average temperatures fell by 6 C within a
century.
And that could be due to effects on the thermohaline circulation –
a huge convection system that transports warm water from the tropics to the
poles and send cool water back through the depths of the oceans (see "Global
warming and then the big freeze", this series).
Robert Dickson, hydrographer studying water movements at the Centre of
Environment, Fisheries and Aquaculture Science in Lowestoft, Suffolk, believe
that abrupt climate change is already happening. Dickson has been monitoring
changes in the North Atlantic over the past 40 years. Within this period, all
10 of the warmest years since records began happened between 1990 and 2002. It
also includes extremes in the "North Atlantic Oscillation" – the wide
swings in atmospheric pressures between the polar and mid-latitude regions
– that’s responsible for climate variability in the region.
Figure 2. Recent rate of carbon dioxide increase
unprecedented.
Dickson expects these changes to slowdown the THC and accelerate the
global water cycle between the atmosphere and the oceans.
Isolated measurements have already indicated an increased flux of
freshwater into the north Atlantic. At the same time, there is an increase in
saltiness of water further south, through to the equatorial south Atlantic,
which can only be explained by increased evaporation; and that would accelerate
the water cycle between the surface of the earth and its atmosphere. The
Pacific and Indian oceans also show increased salinity in the tropics and
freshening near both poles between the 1950s and 1990s. Water vapour is itself
a greenhouse gas, which would contribute to further warming, a positive
feedback that could precipitate abrupt change.
Policy-makers need to appreciate this abrupt change scenario, as it
leaves little room for slow ‘adaptation’. Instead, every effort must
be concentrated towards prompt action to ameliorate global warming and
preventing the worst from happening.
The complete document with diagrams, is available in the ISIS members site. Full details here
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