In complex systems, especially big complex systems, feedback loops can develop. Lets take the earth as an example. It is by just about everyones measure a very large, and very complex system, it has many feed back loops. A good example might be the melting of arctic sea ice, the ice melts (due to global warming) exposing more dark sea water which absorbs more heat than the reflective ice, which warms the water, which melts more ice…it’s a vicious cycle. There comes a point in that process, a tipping point, in which the system spirals rapidly out of control, a victim of its own feedback. Arctic sea ice melting is not the only process on earth with a feedback loop, and it is not the only one that could experience a tipping point.

A number of key components of the earth’s climate system could pass their ‘tipping point’ this century, according to new research led by a scientist at the University of East Anglia.

Published by the prestigious international journal Proceedings of the National Academy of Science (PNAS), the researchers have coined a new term, ‘tipping elements’, to describe those components of the climate system that are at risk of passing a tipping point.

The term ‘tipping point’ is used to describe a critical threshold at which a small change in human activity can have large, long-term consequences for the Earth’s climate system.

In this new research, lead author Prof Tim Lenton of the University of East Anglia (UEA) and colleagues at the Postdam Institute of Climate Impact Research (PIK), Carnegie Mellon University, Newcastle University and Oxford University have drawn up a shortlist of nine tipping elements relevant to current policy-making and calculated where their tipping points could lie. All of them could be tipped within the next 100 years.

It reads like a recipe for disaster. None of these sound very nice, and the fact that all of them could happen in the next couple hundred years makes it even more scary. If any of these events were to occur it could set off others on the list, meaning that we had better do something about green house gas emissions very very soon.

The nine tipping elements are (includes how long it might take for it to happen, and the level of uncertainty):

1. Melting of Arctic sea-ice (approx 10+ years, small uncertainty). As sea-ice melts, it exposes a much darker ocean surface, which absorbs more radiation than white sea-ice so that the warming is amplified. This causes more rapid melting in summer and decreases ice formation in winter. Over the last 16 years ice cover during summer declined markedly. The critical threshold global mean warming may be between 0.5 to 2 degrees Celsius, but could already have been passed. One model shows a nonlinear transition to a potential new stable state with no arctic sea-ice during summer within a few decades.
2. Decay of the Greenland ice sheet (more than 300 years, small uncertainty). Warming over the ice sheet accelerates ice loss from outlet glaciers and lowers ice altitude at the periphery, which further increases surface temperature and ablation. The exact tipping point for disintegration of the ice sheet is unknown, since current models cannot capture the observed dynamic deglaciation processes accurately. But in a worst case scenario local warming of more than three degrees Celsius could cause the ice sheet to disappear within 300 years. This would result in a rise of sea level of up to seven meters.
3. Collapse of the West Antarctic ice sheet (more than 300 years, large uncertainty). Recent gravity measurements suggest that the ice sheet is losing mass. Since most of the ice sheet is grounded below sea level the intrusion of ocean water could destabilize it. The tipping point could be reached with a local warming of five to eight degrees Celsius in summer. A worst case scenario shows the ice sheet could collapse within 300 years, possibly raising sea level by as much as five meters.
4. Collapse of the Atlantic thermohaline circulation (approx 100 years, intermediate uncertainty). The circulation of sea currents in the Atlantic Ocean is driven by seawater that flows to the North Atlantic, cools and sinks at high latitudes. If the inflow of freshwater increases, e.g. from rivers or melting glaciers, or the seawater is warmed, its density would decrease. A global mean warming of three to five degrees Celsius could push the element past the tipping point so that deep water formation stops. Under these conditions the North Atlantic current would be disrupted, sea level in the North Atlantic region would rise and the tropical rain belt would be shifted.
5. Increase in the El Niño Southern Oscillation (approx 100 years, large uncertainty). The variability of this ocean-atmosphere mode is controlled by the layering of water of different temperatures in the Pacific Ocean and the temperature gradient across the equator. During the globally three degrees Celsius warmer early Pliocene ENSO may have been suppressed in favor of persistent El Niño or La Niña conditions. In response to a warmer stabilized climate, the most realistic models simulate increased El Niño amplitude with no clear change in frequency.
6. Collapse of the Indian summer monsoon (approx 1+ year, large uncertainty). The monsoon circulation is driven by a land-to-ocean pressure gradient. Greenhouse warming tends to strengthen the monsoon since warmer air can carry more water. Air pollution and land-use that increases the reflection of sunlight tend to weaken it. The Indian summer monsoon could become erratic and in the worst case start to chaotically change between an active and a weak phase within a few years.
7. Greening of the Sahara/Sahel and disruption of the West African monsoon (approx 10 years, large uncertainty). The amount of rainfall is closely related to vegetation climate feedback and sea surface temperatures of the Atlantic Ocean. Greenhouse gas forcing is expected to increase Sahel rainfall. But a global mean warming of three to five degrees Celsius could cause a collapse of the West African monsoon. This could lead either to drying of the Sahel or to wetting due to increased inflow from the West. A third scenario shows a possible doubling of anomalously dry years by the end of the century.
8. Dieback of the Amazon rainforest (approx 50 years, large uncertainty). Global warming and deforestation will probably reduce rainfall in the region by up to 30 percent. Lengthening of the dry season, and increases in summer temperatures would make it difficult for the forest to re-establish. Models project dieback of the Amazon rainforest to occur under three to four degrees Celsius global warming within fifty years. Even land-use change alone could potentially bring forest cover to a critical threshold.
9. Dieback of the Boreal Forest (approx 50 years, large uncertainty). The northern forests exhibit a complex interplay between tree physiology, permafrost and fire. A global mean warming of three to five degrees Celsius could lead to large-scale dieback of the boreal forests within 50 years. Under climate change the trees would be exposed to increasing water stress and peak summer heat and would be more vulnerable to diseases. Temperate tree species will remain excluded due to frost damage in still very cold winters.

The paper also demonstrates how, in principle, early warning systems could be established using real-time monitoring and modeling to detect the proximity of certain tipping points. It also points out that global warming doesn’t necessarily have to be a slow process.

“Society must not be lulled into a false sense of security by smooth projections of global change,” said Prof Lenton.

“Our findings suggest that a variety of tipping elements could reach their critical point within this century under human-induced climate change. The greatest threats are tipping of the Arctic sea-ice and the Greenland ice sheet, and at least five other elements could surprise us by exhibiting a nearby tipping point.”

Meaning, that one year everything seems mostly normal, and next year everything is crazy horrible bad. These tipping points could rapidly and negatively affect the climate in as little as 5 to 10 years. There are historic data records to suggest that this sort of rapid climate change has happened in the past.

This list isn’t even complete, they leave out the methane/permafrost feedback loop, and don’t really take into account the kind of crazy wars that these sort of rapid climate change events would cause. Imagine if China and Russia got in a spat over fresh water supplies (both have nukes), or India and Pakistan over farm land, or even different states in the west. Throw in millions of climate refuges looking for a new home and you have a recipe for the end of human civilization as we know it.