This illustration of data recently appeared in the journal, Nature (links below). It provides a view we can extend into mid century, telling us the pace of change for the average global air temperature.
The pace of global air temperature increase is an oscillation that before the industrial revolution was a full cycle swing up-and-down about an average, that spanned half a century. Ever accumulating heat has turned this rhythm into a stair step climb toward a hotter world. The shorter term El Niño / La Niña cycles ride the back of this long term, intermittent upwelling of deep cold water in the eastern tropical Pacific, that is triggered by extreme La Niña conditions.
The cold water once cooled the world through a quarter of a century, followed by a quarter century of warmth. It was a back and forth pace, a climate pendulum.
In modern times, this ocean based cooling phase, like an air conditioner laboring against a hot summer night, barely masks the relentless heat accumulation from the growing greenhouse gas blanket humans have thrown over the planet. The pendulum has been turned into a ratchet. When the cold, deep upwelling switches off again, the world's air will warm much faster, as it did during the last quarter of the 20th Century.
There still is "noise" in the record; that is to say, we can't yet account for the exact weather consequences year-to-year of the sea surface temperatures that influence the wrap of weather around the globe. But the beat of long term climate (by human measure) has been revealed as a clear signal.
We can now view the decades up to mid century with greater certainty. We are due for about fifteen years of a climate regime that allows denial to thrive, followed by extreme panic.
The argument that the pendulum has been turned into a relentless rachet will fall upon denial deafened ears. If the air temperature rise has "leveled off", then the deniers will say the data shows they are right, there is no global warming. We are likely due about a couple of decades of this resistance, the air temperature data not helping the case for climate change without the kind of qualifications that make public attention drift.
Of course, there are other factors at work. Trapped heat is still accumulating, even if the air temperature is being masked by an age old internal cycle of global air conditioning from belched deep ocean water. Trapped thermal energy is being converted to kinetic energy, which affects the weather in ways we cannot currently predict. The deep ocean itself is warmed in the process of cooling the air, which could affect the weather and climate through shifts in global ocean circulation. As there is a randomness to weather, the deniers have a line of defense on this battlefield, also.
Nature will return to validate scientific predictions with undeniable air temperature evidence as the 2030s dawn, global heating of the air resuming with the vengeance of forestalled truth. It is possible, and rather frightening, to consider that even during the air conditioning phase of the next fifteen years or so, the air temperatures might rise, the heat overwhelming the capacity of the air conditioner.
If the heating phase of the cycle that resumes around 2030 has been preceded by an overwhelmed air conditioned phase, then we are in very serious trouble for the quarter century following 2030. The unmasked warming of air, augmented by resumed warm sea surface temperatures, will race ahead so fast that the consequences will be immediately obvious, and could provide the trigger for a tipping point event. It seems likely that the methane rich frozen tundra, the ice cap of Greenland, and the West Antarctic Ice Shelf, will suffer rapid change from a relentless increase in air temperatures over a 25 year span. The frozen world is a frozen house of cards, and accelerated heating resuming in the 2030s could make it fall before 2100.
Another academic paper in a related science journal, Nature Climate Change, reports how game theory demonstrates the need for increased certainty before the majority of the public can reach a resolve to act. We now have increased certainty about the pulse of the planet's heat rise that allows the setting of planning and action horizons, gives us a relatively stable period (by the grace of Nature's planetary air conditioner) in which to respond, and makes clear what is in store.
Original sources:
http://www.nature.com/news/climate-change-the-case-of-the-missing-heat-1.14525
http://www.nature.com/nature/journal/v501/n7467/full/nature12534.html
http://www.nature.com/nclimate/journal/v4/n1/full/nclimate2059.html
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