It is worse than you thought. Perhaps twice as bad. Perhaps worse than that.
Paleoclimatologists say that the past changes to global climates show that there exist mechanisms which magnify the effect of global warming. These are not well represented in climate models.
That means the models are wrong. That means the projections accepted by the Intergovernmental Panel on Climate Change, and accepted as the basis for action by various governments, including the Paris Accords, are wrong. The current "carbon budget" will not help us stay within two degrees above pre-industrial temperatures, even if anyone was adhering to it.
This is just one study. But it is not the first to call into question the neat linear projections of such agencies as the IPCC. And it is congruent with what has been a growing apprehension in the earth sciences. Catastrophes, from the Mississippi floods to the Cretaceous era mass extinction, are as much the norm as linear or cyclical change.
Natural science since the nineteenth century had been attuned to the cumulative force of minute changes. In a single day, the erosion of a mountain peak is imperceptible. In about a hundred million years, at a millimetre a year, that erosion might be enough to turn it into a sea bed. In a single generation, the accidental differences in a new generation of North American black bears might be negligible. But as Darwin famously suggested, given sufficient time, they might evolve into whale-like marine animals. Mountains and species are not immutable productions, but ephemeral in the scale of geologic time.
The apprehension of time had deepened like an oceanic trench. Robert Hooke was working in a world a few thousand years old. Kant was writing about a world that was seen as probably millions of years old. Charles Lyell and his colleagues brought us "deep time". Experiments in the second half of the twentieth century gave us an earth about 4 billion years old, and a universe about 14 billion years old. As Lyell noted, with this deepening of time crept a low, melancholy note of infinity into the human world, for it was "too vast to awaken ideas of sublimity unmixed with a painful sense of our incapacity to conceive a plan of such infinite extent."
Lyell nonetheless declared a principle for the analysis of this infinite plan of infinitessimal global change, which his disciplinary followers called Uniformitarianism. This avers that active geological processes, such as mountain-building or rock sedimentation, have always operated in a similar, imperceptibly slow and gradual way.
The enemy here were the 'catastrophists', so dubbed by Lyell: those whom the self-serving rhetoric of the field said were crude theological apologists who denied science and attributed global change to miracles. This, as Stephen Jay Gould has shown, travesties the catastrophists who were indeed scientific in their approach and had substantive disagreements with the uniformitarians.
And the catastrophists were right in several respects. The emphasis on a constant rate of global change was a dogma, which left geologists struggling to account for evidence of several rapid and deep transformations in the planet's surface. Gould gave the example of the Washington scablands which were formed by about forty cataclysmic floods over a period of about two million years.
If geologists were unable to accept the evidence for this, evolutionary theorists were in a similar conundrum when faced with evidence of giant punctuations in the evolution of life. Darwin, influenced by Lyell, cleaved to the axiom that nature did not proceed by leaps. To this day, the more doctrinaire Darwinians, such as Dawkins and Dennett, seek to explain away the paleontological evidence which points to leaps in the name of a rigorous pan-selectionist approach.
When faced with gradualist dogma, the logical question is, what is the belief in this dogma a belief in? One has to make room here for the role of the unconscious in the formation of scientific knowledge. To believe in a gradualist view of climate, of earth's mineral evolution, or of the biochemical evolution of its species, is clearly not to be led there by the evidence. It is therefore worth asking what emotional investments are involved, and what unconscious fantasies subtend them? What sort of universe does it imply? If it's not the sort of place where catastrophes regularly happen, what sort of emotional and moral inflection does this have? What sort of yield, in terms of satisfaction, do such fantasies entail?
It is logical that paleoclimatology, a relatively new area formed from the convergence of disparate disciplines, has returned to a 'catastrophist' view of geo-history. Whatever its unconscious fantasmatic bases, this view is at least supported by evidence of massive, catastrophic changes repeatedly occurring in earth's history. While following Lyell's basic intuition about the value of the fossil record for determining past climates, paleoclimatology has emerged in part from the breakdown of 'uniformitarianism' within geology and related disciplines. And it has established that the earth's climate is -- not merely acutely, but catastrophically -- sensitive to changes in albedo, biochemistry (such as the levels of radiately active chemicals in the atmosphere), volcanic emissions, ocean circulation and the biological cycling of carbon, nitrogen, phosphorus and other elements.
In the scale of deep time, catastrophe is routine. The only thing that is really novel about climate change, as ecologists keep stressing, is how fast it is happening. It is happening on a human scale, at the speed of generations, years, days, not epochs. The last major mass extinction event took around 60,000 years, a dot on the planet's history. The current mass extinction event is taking place with accelerating speed over decades. The background rate of extinction is currently around 150-200 species a day, bigger than anything since the Permian Triassic extinction event. And it is accelerating. And, there is no escaping this, our dependency on other species is such that mass extinction is a threat to human survival. No bees, not enough food, mass starvation.
Recently, we learned that two species of the baobab tree are heading for extinction, due to climate change. This is only a single example of man-made mass extinction, but it has a certain significance of its own. Our relations with the past are overwhelming constituted by death. We find fossils as old as could be. As soon as the conditions for life appeared, the fossil evidence shows that life existed. As soon as creatures could walk, we find fossil evidence for footprints. Ancient life, in worlds eternities from our own. Worlds whose appearance, temperature, atmosphere, climate were radically unlike anything we know. But trees vastly outlive most animals, and baobab trees, which have existed for about ten million years, can live for thousands of years. They point to Methuselan scales of existence, longevities that presently lie outwith our comprehension. And in real time, as with so many other species, they are going extinct.
This is a catastrophe that is happening even as, at some level, millions of people don't believe it really can. It seems so wildly improbable after all. Mass extinction? Floods? Rising sea levels? The end of the human race? Who could believe such a thing? What sort of rapturous religious imagination would take this prospect seriously? What sort of fantasy underlies this sort of End Times catastrophism? Those are all perfectly excellent questions. It's just that, the catastrophe is real.