Many people think of global warming as a gradual process. But 650,000 years’ worth of data from Antarctic ice cores samples indicate that warming often occurs with startling rapidity. For instance, roughly half of the entire warming between the last ice age and the present took place in only a decade. Astonishingly, the earth warmed by at least 9 degrees in ten years.

What drives these sudden changes in temperature? Over the last several years, climate scientists have identified about a dozen tipping points –any one of which, if triggered, could initiate sudden, catastrophic climate change.

An example is the peat bogs of western Siberia. These ancient bogs, containing tens of billions of tons of carbon, have remained frozen since the last ice age. Covering an area approaching 400,000 square miles (roughly the size of France and Germany combined), they contain perhaps one quarter of all the carbon that has been sequestered (stored) by soils and vegetation over the last 10,000 years.

These peatlands lie on the edge of the arctic permafrost: the zone of maximum impact from global warming. Here the average yearly temperature for the last century has been 30.7 degrees. Today, however, it is 32 degrees – the melting point of ice.

The concerns is that as the bogs begin to thaw, they will release their carbon onto the atmosphere as methane - which is at least 20 times as potent a greenhouse gas as CO2.

And thawing they are. Within the last three years, the once supple, spongy surface of moss and lichen has turned into a panorama of lakes that extend unbroken for hundreds of miles. Peat on the bottom of the lakes is converting to methane and bubbling to the surface so fast that the lakes don’t freeze, even in winter.

According to Euan Nisbet of London’s Royal Holloway College, who oversees a big international methane-monitoring program that includes Siberia, methane releases from the western Siberian peat bogs may be as high as 100,000 tons per day. “This huge methane flux depends on temperature,” says Nisbet. “If peatlands become wetter with warming and permafrost degradation, methane release to the atmosphere will dramatically increase.”

There are about a dozen other tipping points around the globe - any one of which, if triggered, could initiate sudden, catastrophic climate change. These include the Amazon rainforest, the polar ice caps, and the Tibetan plateau. These systems have thresholds above which they are extremely sensitive to small changes in temperature. Once its temperature maximum is crossed, the system breaks down, and rapid warming is the result. This warming in turn accelerates its collapse, while also hastening the destabilization of other tipping points around the globe. Not unlike falling dominoes, one triggers the next, as a self-perpetuating feedback loop amplifies runaway carbon release.

   Bottom line: How much the planet's temperature increases is up to us.