The concept of abrupt climate change comes from a century of accumulating evidence.

John Cox, Climate Crash, Sacramento Bee reporter
What does abrupt climate change have to do with global warming?

Heightened GHG emissions exaggerates the natural greenhouse effectNew Orleans flood

1. A problem (small)
2. Biggest problem
3. Not a problem

Comfortable time scale and the rate of change is manageable

Gradual rise in the past is nolonger about changes in the present especially thermal changes in the immediate future.

"global mean temperatures" is meaningless
"regional climate matters"

How do we gage the pace of future events? Are they too positive or too negative?
"We are being too optimistic."

Will Mother Earth take care of us?
What sort of climate system would not be conducive to humans in the future?

New context, the natural behavior of the climate
"the record of the past is clear…"
"sometimes its changes are"… "large and rapid"

It can occur in four to twenty years

The prospect of change poses serious dangers.
"the system is tipping"
"teeter, wobble and flop"

"it is chaotic" … "it is nonlinear" … "not good news"

The message is clear "changing the composition of the atmosphere is pushing the climate system towards an abrupt change

"triggering mechanisms are still out there"
Volatility of the natural system makes it the "dirty Harry of climate"
Concept of abrupt climate change

Concept of abrupt climate change has only recently (1980s) emerged.
Where did the concept of abrupt change come from?

Only recently has weather been understood (1880s)
Paleoclimatology is even younger

1906, John Walter Gregory
"Present climate has been maintained"

Ice Ages
"Eternal climate stability was not long for this world"

Germans studied glaciers; 4 ice ages interrupted warm stability were defined.


Scandinavian plant researchers – palenology—studied pollen grains in ponds
Younger Dryas (13,000)

ocean sediments reversed the German findings of 1920s
many more ice ages and the glacial periods last longer than the abrupt warming!

From 1930s pollen grain analysis emerged evidence for:
The Younger Dryas was a climate crash or "cold snap" or a miserably cold and dry period that lasted for 1,300 years. Came on suddenly and persisted.

1958, U.S. Geophysical Year: Greenland polar ice "can be read like a book"

Two-mile deep ice cap 100,000 years of accumulated snow into layers of ice.
Langway, Dansgaard, Oelschlag: mass spectrometer measurements 016:018

Reveled a clear picture, jaggedness of the ice evidence – Camp Century core—the differences in the evidence from what was expected was unnerving. Was it troubling noise?

1980s abrupt change was a focus, after Wally Broecker heard Oelschlag speak of the ice core evidence.
Vostok Ice core

Changes in ocean circulation Dr. Wally Broecker suggested could bring on abrupt changes, based on the Greenland ice data.

By the late 1980s a coherent theory of natural variation and abrupt change emerged.

1990s, Greenland Ice cores were revisited to see if the abrupt changes shown in the ice were either real or noise. In 1990s the disruptive and abrupt patterns were confirmed.

24 episodes of sharp plunges and climbs in temperature (ice age cold, Holocene warm)
Ice agesRecent ice ages

"nothing suggests gradualness"

Contemporary evidence

Ocean sediments and other ice cores show the same saw tooth patterns. During the past 10,000 years temperature is not the key foci and the precipitation pattern is more important.


Moon Lake N.D. sediments – show many more and longer periods (50-60-100 years) of drought

200-400, 700-800 AD, 1200-1300 AD are much longer and dryer than during the dust bowl.
So the dustbowl was less severe, less dry, and persisted for a shorter time than the pollen evidence for the last 2000 years suggest.


"be prepared to do…sort of unthinkable things…changing certain habits…."

We should prepare for abrupt change, decline in water supplies, and prolonged drying.

Instability means we have to prepare for the worst, not the best scenario.

Norse in Greenland at 1000 lasted for three centuries; ice core work shows that the colony failed when the Native Inuit were thriving, Why? The existence of an adaptive superiority of the Inuit changing to meet the newly emerging colder drier conditions accounted for their cultural success while the Norse alleged European superiority over the pagan savages was counter productive to their sustaining their colony.

The Norse chose extinction, rather than adapt the Inuit ways of life, the boats, hinged harpoon, manner of fishing.

Are we adapting?

Western water is dependent on snow, not rainfall. If the winter snows come as rain, the dependence on water in the west would not have the storage capacity for the floods and the damages that those floods entail.


Reservoir capacity is the key here, as is timing and distribution of water storage for agricultural, municipal, and utility uses that advanced societies rely on for development.


Books by Cox: