CLIMATE CHANGE

CLIMATE CHANGE:
PAST
FUTURE
PRESENT

	CLIMATE VARIATIONS - El Niño
	Impacts on Health

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Ice cores give wonderful climate records:

Many other sources of info. on past climate:

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Ice Age Cycles:

	Global - and approximately globally synchronous
	Timing matches timing of orbital variations
	Can be modeled with some skill if CO2 is specified
	We know the CO2 changed, but how?
	Models tend to underestimate changes
	Which suggests that models are under-sensitive
	With implications for forecasts of future climate change

Many of the changes in the paleoclimate record were abrupt

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Abrupt Climate Changes

	Real - they happened
	Large - 1/3 to 1/2 of glacial/interglacial changes
	Global (as far as we can tell)
	Rapid - in as little as 10 years (meaning big changes every year)
	Repeated - not unusual with the long view
	In warm times, not just ice ages
	No satisfactory theory for them
	Our models (the ones we rely on to predict the future) do not generate them
	Societies have often not survived them

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Kilimanjaro 1970

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"CLIMATE VARIATIONS - El Niño"

	CLIMATE VARIATIONS - El Niño
	Impacts on Health

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iri.columbia.edu

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"The climate record shows many..."

	The climate record shows many examples of rapid changes in both glacial and warm times
	These abrupt climate changes have had major impacts on civilizations
	Models do not simulate these changes; they appear to be less sensitive than nature

"We are in the Anthropocene..."

	We are in the Anthropocene Age
	and we are not getting out of it any time soon
	There will be surprises; sudden surprises
	Do models underestimate what lies ahead of us?
	It is difficult to disentangle current effects of greenhouse warming and natural variations
	Natural variations such as El Niño have profound impacts on human affairs, including health
	Predictions of El Niño have been used to mitigate impacts

Will we apply what we have learned to
 
CLIMATE CHANGE?