We are heading for a New Cretaceous, not for a new normal

The climate change we're witnessing is more dramatic than we might think.

A lazy buzz phrase – 'Is this the new normal?' – has been doing the rounds as extreme climate events have been piling up over the past year. To which the riposte should be: it's worse than that – we're on the road to even more frequent, more extreme events than we saw this year.


We have known since the 1980s what's in store for us. Action taken then to reduce emissions by 20 per cent by 2005 might have restricted the global temperature rise to less than 1.5 degrees Celsius. But nothing was done, and the welter of climate data mounting since then only confirms and refines the original predictions. So where are we now?

Last November, the COP23 UN Climate Change Conference in Bonn reported that warming by 3°C by 2100 is now the realistic expectation. With no check on emissions, we are on course to see preindustrial levels of CO2 double (from 280 to 560 ppm, or parts per million) by 2050 – and then double again by 2100. In short, we'll be generating climate conditions last experienced during the Cretaceous period (145-65.95 million years ago) when CO2 levels reached over 1,000 ppm. What might that mean, given that we already achieve such levels of CO2 in bedrooms at night and in poorly ventilated crowded places, and when we know that, under sustained conditions of such high carbon-dioxide concentration, people suffer severe cognitive problems?

As it happens, the Cretaceous is one of my favourite geological periods. It gave us the great chalk hills and cliffs that straddle Europe. It gave us figs, plane trees and magnolias. It nurtured little mammals, who suddenly blossomed when the then-lords of creation – Triceratops, Tyrannosaurus and their cousins – went extinct at the end of the period. It was also very warm, with global temperatures 3-10°C hotter than preindustrial levels.

­Should it come to pass, any new era with a Cretaceous-like climate wouldn't precisely mirror the original. For a start, the continents were then in very different positions: India was an island still thousands of miles south of its union with Asia; a broad ocean separated Africa (with South America still attached) from Eurasia. But in a Cretaceous rerun, there would very likely be no ice at the poles once again, and sea levels would be about 216 feet (66 metres) above current levels. We would also see the creation of vast warm shallow seas with mineral deposits similar to those that produced 1,300 ft (400 metre)-thick chalk strata in the old Cretaceous; while, in place of the larger mammals that would become extinct, reptiles might radiate across the globe and grow large in form – a fitting dinosaur revenge?

The only way I can possibly conceive of humans living in a New Cretaceous age is as a rump of scientists and technologists working in artificial, protected shelters, rather like the denizens of the novelist Italo Calvino's invisible city of Baucis, in which people live up on stilts above the clouds 'contemplating with fascination their own absence'.

We have recently become aware of a red line that humans are going to hit long before we approach Cretaceous conditions. In 2010, researchers showed that our species cannot survive for more than six hours at what's called a 'wet bulb' temperature of 35°C (95°F). Wet bulb here means 100 per cent humidity, so it's not 35°C as we know it. But in the great Indian agricultural belts of the Indus and Ganges, high-40s temperatures combined with 50 per cent humidity (which equates to that wet-bulb temperature of 35°C ) are going to prevail within decades.

While this is happening in hot agricultural regions, the urban world will face a perhaps even greater catastrophe. The UN's most-likely temperature-rise prediction of 3°C would see forests growing in the Arctic, and entail the loss of most coastal cities through irreversible sea-level rise by the end of the century.

It is now widely accepted, by scientists at least, that human beings have become geological agents, hence the assignment of a new geological epoch: the Anthropocene. Human inputs into the environment, including artificial nitrogen fertilisers as well as CO2, now outstrip the natural cycles. The popular idea that geology and human concerns are totally incommensurate is belied by the fact that at times the Earth has moved very fast. Two great warming events – with a long cooling period in between – ended the last Ice Age 12,600 years ago, around 9,600 BCE. Both produced 10-degree spikes in Greenland ice cores. The first happened over only three years; the second, which ushered in the relatively stable conditions of the Holocene, happened over a period of around 60 years.

A lesson for today is that such a sudden and lasting change to the climate has consequences lasting thousands of years. That first warming caused an enormous lake to spread across North America as the Laurentide ice sheet melted, then eventually burst, leading to large-scale sea-level rise, and forming the Great Lakes and Niagara Falls some 2,500 years later. Britain was finally sundered from Europe 3,500 years after the start of the Holocene; and as the northern ice sheets melted, the land beneath them rose. This continues today in Sweden at a rate of almost 1cm a year.

This epoch, our epoch, is technically an interglacial one, and it was always going to end. The Earth has generally been violently unstable, or stably hostile, for long periods, either too hot or too cold for human civilisation. Had we not forced global temperatures upward through CO2 emissions, we would most likely now be facing a new Ice Age; as it is, the Holocene is ending as fast as it began with a new temperature spike occurring during normal human lifetimes.

So while we prattle about 'the new normal', we need to recognise that there was nothing 'normal' about the Holocene. Expert analysis of how human civilisation developed during the Holocene's 10,000-year benign spell is only now becoming common knowledge. The geneticist David Reich leads the way, with his myth-busting account Who We Are and How We Got Here (2018), using research based on ancient DNA to link human movement with language development. Such deep knowledge of the period argues that our problem is not confined to post-industrial-era CO2 emissions (global warming, in any case, probably began with forest clearance for early agriculture), but insists that the Holocene was a freakish gift to humanity that we have exploited and taken for granted. We are now assisting at its funeral.

If we are to avoid coming to grief on the road to a New Cretaceous, this awareness needs to extend way beyond the geologists and biologists who have taught us where we came from and where, unless we change, we are headed.Aeon counter – do not remove

Peter Forbes

This article was originally published at Aeon and has been republished under Creative Commons.

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What can 3D printing do for medicine? The "sky is the limit," says Northwell Health researcher Dr. Todd Goldstein.

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An organism found in dirt may lead to an anxiety vaccine, say scientists

Can dirt help us fight off stress? Groundbreaking new research shows how.

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Are modern societies trying too hard to be clean, at the detriment to public health? Scientists discovered that a microorganism living in dirt can actually be good for us, potentially helping the body to fight off stress. Harnessing its powers can lead to a "stress vaccine".

Researchers at the University of Colorado Boulder found that the fatty 10(Z)-hexadecenoic acid from the soil-residing bacterium Mycobacterium vaccae aids immune cells in blocking pathways that increase inflammation and the ability to combat stress.

The study's senior author and Integrative Physiology Professor Christopher Lowry described this fat as "one of the main ingredients" in the "special sauce" that causes the beneficial effects of the bacterium.

The finding goes hand in hand with the "hygiene hypothesis," initially proposed in 1989 by the British scientist David Strachan. He maintained that our generally sterile modern world prevents children from being exposed to certain microorganisms, resulting in compromised immune systems and greater incidences of asthma and allergies.

Contemporary research fine-tuned the hypothesis, finding that not interacting with so-called "old friends" or helpful microbes in the soil and the environment, rather than the ones that cause illnesses, is what's detrimental. In particular, our mental health could be at stake.

"The idea is that as humans have moved away from farms and an agricultural or hunter-gatherer existence into cities, we have lost contact with organisms that served to regulate our immune system and suppress inappropriate inflammation," explained Lowry. "That has put us at higher risk for inflammatory disease and stress-related psychiatric disorders."

University of Colorado Boulder

Christopher Lowry

This is not the first study on the subject from Lowry, who published previous work showing the connection between being exposed to healthy bacteria and mental health. He found that being raised with animals and dust in a rural environment helps children develop more stress-proof immune systems. Such kids were also likely to be less at risk for mental illnesses than people living in the city without pets.

Lowry's other work also pointed out that the soil-based bacterium Mycobacterium vaccae acts like an antidepressant when injected into rodents. It alters their behavior and has lasting anti-inflammatory effects on the brain, according to the press release from the University of Colorado Boulder. Prolonged inflammation can lead to such stress-related disorders as PTSD.

The new study from Lowry and his team identified why that worked by pinpointing the specific fatty acid responsible. They showed that when the 10(Z)-hexadecenoic acid gets into cells, it works like a lock, attaching itself to the peroxisome proliferator-activated receptor (PPAR). This allows it to block a number of key pathways responsible for inflammation. Pre-treating the cells with the acid (or lipid) made them withstand inflammation better.

Lowry thinks this understanding can lead to creating a "stress vaccine" that can be given to people in high-stress jobs, like first responders or soldiers. The vaccine can prevent the psychological effects of stress.

What's more, this friendly bacterium is not the only potentially helpful organism we can find in soil.

"This is just one strain of one species of one type of bacterium that is found in the soil but there are millions of other strains in soils," said Lowry. "We are just beginning to see the tip of the iceberg in terms of identifying the mechanisms through which they have evolved to keep us healthy. It should inspire awe in all of us."

Check out the study published in the journal Psychopharmacology.

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We were gaining three IQ points per decade for many, many years. Now, that's going backward. Could this explain some of our choices lately?

The Flynn effect appears to be in retrograde. (Credit: Shutterstock/Big Think)
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