We’re collecting a few basic links to the climate record. Contributions of superior data and interpretations would be much appreciated. The Lisiecki and Raymo graphic above has a complex derivation, summarized briefly here — don’t mistake it for anything analogous to familiar contemporary temperature records.
The sudden onset of glaciation can be appreciated from the recent 450kyear reconstructions of Antarctic temperature
Moving from the recent climate history shown in the two graphics above, here is a 65 million year reconstruction:
Continuing our interest in sudden climate shifts, here are a couple of short papers that look interesting. First is Sudden climate transitions during the Quaternary, which is in preparation by Jonathan Adams (1), Mark Maslin (2) and Ellen Thomas (3). The authors caution:
Article in press in Progress in Physical Geography This represents an earlier version of our text. Some changes have been made since we stopped modifying this web version: e.g. we have added a discussion of the role of volcanic aerosols in sudden climate changes…evidence suggests the rapid cooling at the end of the Eemian interglacial was due to a big explosive volcanic event. Other ‘volcanic’ cooling events occured during the Holocene.
Excerpts from the Abstract and Introduction:
The time span of the past few million years has been punctuated by many rapid climate transitions, most of them on time scales of centuries to decades or even less. The most detailed information is available for the Younger Dryas-to-Holocene stepwise change around 11,500 years ago, which seems to have occurred over a few decades. The speed of this change is probably representative of similar but less well-studied climate transitions during the last few hundred thousand years. These include sudden cold events (Heinrich events/stadials), warm events (Interstadials) and the beginning and ending of long warm phases, such as the Eemian interglacial. Detailed analysis of terrestrial and marine records of climate change will, however, be necessary before we can say confidently on what timescale these events occurred; they almost certainly did not take longer than a few centuries.Various mechanisms, involving changes in ocean circulation, changes in atmospheric concentrations of greenhouse gases or haze particles, and changes in snow and ice cover, have been invoked to explain these sudden regional and global transitions. We do not know whether such changes could occur in the near future as a result of human effects on climate. Phenomena such as the Younger Dryas and Heinrich events might only occur in a ‘glacial’ world with much larger ice sheets and more extensive sea ice cover. However, a major sudden cold event did probably occur under global climate conditions similar to those of the present, during the Eemian interglacial, around 122,000 years ago. Less intensive, but significant rapid climate changes also occurred during the present (Holocene) interglacial, with cold and dry phases occurring on a 1500-year cycle, and with climate transitions on a decade-to-century timescale. In the past few centuries, smaller transitions (such as the ending of the Little Ice Age at about 1650 AD) probably occurred over only a few decades at most. All the evidence indicates that most long-term climate change occurs in sudden jumps rather than incremental changes.
Until a few decades ago it was generally thought that all large-scale global and regional climate changes occurred gradually over a timescale of many centuries or millennia, scarcely perceptible during a human lifetime. The tendency of climate to change relatively suddenly has been one of the most suprising outcomes of the study of earth history, specifically the last 150,000 years (e.g., Taylor et al., 1993). Some and possibly most large climate changes (involving, for example, a regional change in mean annual temperature of several degrees celsius) occurred at most on a timescale of a few centuries, sometimes decades, and perhaps even just a few years. The decadal-timescale transitions would presumably have been quite noticeable to humans living at such times, and may have created difficulties or opportunities (e.g., the possibility of crossing exposed land bridges, before sea level could rise). Hodell et al. (1995) and Curtis et al. (1996), for instance, document the effects of climate change on the collapse of the Classic period of Mayan civilization and Thompson (1989) describes the influence of alternating wet and dry periods on the rise and fall of coastal and highland cultures of Ecuador and Peru. The beginning of crop agriculture in the Middle East corresponds very closely in time with a sudden warming event which marks the beginning of the Holocene (Wright 1993). Even the burial in ice of the prehistoric mummified corpse of the famous ‘Iceman’ (e.g., Bahn and Everett, 1993) at the upper edge of an alpine glacier coincided with the initiation of a cold period (‘Neoglaciation’) after the Holocene climate optimum (Baroni and Orombelli, 1996). On longer timescales, evolution of modern humans has been linked to climatic changes in Africa (e.g., de Menocal, 1995). But the full implications of these sudden changes for biogeography and for the evolution of human cultures and biology have barely begun to be considered; there has simply not been time for the message to be absorbed by biogeographers, archaeologists and palaeoanthropologists, and this review is intended to help the process along.Sudden stepwise instability is also a disturbing scenario to be borne in mind when considering the effects that humans might have on the climate system through adding greenhouse gases. Judging by what we see from the past, conditions might gradually be building up to a ‘break point’ at which a dramatic change in the climate system will occur over just a decade or two, as a result of a seemingly innocuous trigger. It is the evidence for dramatic past changes on the timescale of centuries to decades which will be the subject of this review.
More background from the Quaternary Environments Network (QEN)* can be found in A quick background to the last ice age where we learn of more evidence for sudden jumps in climate.