Climate Plagues

Red tide
A Red tide is often the result of a spurt of red-tinged algae growth in a body of water. Image credit:  St Stev via Flickr, although this is not a picture of the Nile or of red algae – it is iron oxide in sea water.

A toxic algae bloom in a primary water source causes a mass die-off of amphibians, attracting insects that become vectors of disease. Changes in weather patterns bring on freak storms and an explosion of vermin, wiping out crops and livestock. The government responds to criticism with crackdowns, worsening the overall debacle. And finally, a deadly food-borne illness turns a joyful holiday into a national calamity.

All of this could be in our climate-changed future. But could it also be what happened almost five thousand years ago, when the Book of Exodus tells us the plagues came to Egypt?

Ever since the birth of modern climate science in the middle of the 20th century (thanks in part, incidentally, to archaeologists working with the Air Force to refine the technique of carbon-14 dating), we’ve known that atmospheric warming affects living systems such as oceans and rivers. In more recent years, articles appearing in peer-reviewed publications have assumed a climatic origin for the Ten Plagues. There is general agreement that it was probably a local climate event, creating a “red tide” in the waters of the Nile, that made the river look like it had turned to blood (Exodus 7:20). That first plague set off a sequence of events, each of which shaped the next in an unspooling series of escalating disasters.

In “Origin of the Old Testament Plagues: Explications and Implications,” which appeared in a 2008 issue of the Yale Journal of Biology and Medicine, N. Joel Ehrenkranz and Deborah A. Sampson review the previous half-century of scholarly literature scientifically examining the plagues. There has been, for instance, debate over the precise breed of microbe that was the likely culprit for that first plague of “blood.” Was it freshwater flagellates such as Euglenia sanguinea, or a protozoan like Trypanosoma evansi, or simply your run-of-the-mill cyanobacteria? 

Whichever it was, Ehrenkranz and Sampson emphasize one point. “The immediate cause of all plagues – in biblical sequence – was unseasonable and progressive climate warming along the Eastern Mediterranean coast.” They call their conjecture a “focal climate change causation” model for the plagues. And they argue that the Land of Goshen, which most archaeologists today locate further inland at the edge of the Nile Delta, was probably less affected by the coastal climate – leading to the Hebrew Bible’s claim that God gave “special treatment to the land of Goshen, where My people live” (Ex. 8:22).

The immediate cause of all plagues – in biblical sequence – was unseasonable and progressive climate warming along the Eastern Mediterranean coast.”

The first four plagues, in a list recited every Passover by participants at Jewish seders, were blood, frogs, swarms of small insects, and swarms of larger insects (Ex. 7-9). (The Hebrew word kinim, which is what Ehrenkranz and Sampson call “small insects,” is translated as “gnats” in the New International Version; but in modern Hebrew it means “lice” and the word for “gnat” is yatoosh, so in this blog post I’m sticking with the more factual description.) Ancient Egyptians and the Semites living among them had pretty sophisticated medical knowledge, so they would have known that the Nile was not actually flowing with blood and could have put this initial series of events together: The red stuff in the river caused the frogs to jump out and die on land, which would lead to greater swarms of the insects the frogs had failed to eat as well as attract bigger ones. 

But for all their advancements, the Egyptians did not have germ theory and wouldn’t have been able to explain the livestock disease that came after the larger insect swarms – much less the boils that succeeded it. Two insect-borne viruses, known as Bluetongue and African horse sickness, have been suggested for the fifth plague. Meanwhile, the boils could have been caused by an explosion in the population of so-called “blister beetles” that feed on carrion along the banks of the Nile, according to two Walter Reed Army Hospital dermatologists publishing in a 2002 issue of The Lancet. Thanks to the piles of dead frogs, the beetles would have had more than enough to eat – and the painful boils they cause when crushed on the skin take 3-4 days to form, which would have made the timing right for a sixth plague.

The seventh plague -hail – would also have been inexplicable given the limits of biblical-era knowledge. But armed with our 21st century understanding of climate, we can draw a direct line between the warming around Egypt’s Mediterranean coast that prompted the original red tide in the Nile, and intense storms causing outsize hail. Massive and sudden hail storms are not unknown in Egypt even today. The elevated temperatures and resulting heavy rainfall would have also nurtured exquisite conditions for locust larvae, leading to an eighth plague that makes regular, if occasional, appearances on TV news and nature shows.

Plague of Locusts
Locust swarm on the move. Locusts are voracious, eating their own body weight in vegetation on a daily basis. Image credit: CSIRO, CC BY 3.0, via Wikimedia Commons

According to Ehrenkranz and Sampson, most scholars agree that “palpable darkness,” the ninth plague (Ex. 10:21), was a sandstorm. This doesn’t ring true to me; anyone living on the African continent must know the difference between a sandstorm and other types of darkness. But as I wrote my novel Goshen, imagining in day-to-day detail what it might have been like for teenage Israelites to live through the Ten Plagues, I realized that with tens of thousands of cattle and horse corpses around, the cleanliness-obsessed Egyptians would have burned the bodies in tremendous pyres to avoid yet another round of insect swarms. The muggy climatic conditions could have made for a massive buildup of smog that would have been highly remarkable in pharaonic times. Usually, smoke from fires will dissipate – but in the theorized extreme heat wave, particulate pollution could easily have lingered for days (Ex. 10:22). And, I figured, “the Israelites had light in their dwellings” (Ex. 10:23) because they hadn’t had to use up all of their lamp oil to start the animal pyres. The kind of light that protected the Israelites is not specified in the Hebrew Bible, and does not necessarily have to come from the sun in a clear sky – in fact, the verse mentions that the light was in the dwellings of the Israelites, implying lamplight.

So far, all of the plagues have had some participation from Earth’s atmosphere. But the final, most devastating plague, when God “struck down every firstborn male in the Land of Egypt” (Ex. 12:29), “has posed the thorniest problem for rational elucidation,” according to Ehrenkranz and Sampson. A few scholars have suggested that it may have been essentially cultural in origin, with the firstborn males – both human and among the livestock – having “had first and greatest exposure” to mycotoxins in food made from moldy ingredients. Since the harvest had been destroyed by hail and locusts, the granaries might have been scraping the bottom to provide citizens with essential needs. 

I took this idea and ran with it in my novel Goshen, imagining an Egyptian new year’s celebration involving big, fluffy breads sweetened with honey for the firstborn sons. I also gave Moses’s sister Miriam the role of a bioterrorist: She sends my twin teenage protagonists to “donate” slightly moldy grain to the neighborhood storehouse in order to harm Egyptians. Knowing that the mothers of Egypt would do whatever they could to keep from disappointing their families on the new year, even if it came to using less-than-ideal flour for their ritual, Miriam figures she can have a hand in convincing the oppressors to let her people go. I see Miriam as a kind of wise crone figure in Jewish lore, with peerless expertise in herbal remedies as well as poisons. But there isn’t much scholarly consensus around the sociological explanation for the “Death of the Firstborn” plague – I just found it easily the most dramatic.

Whatever the explanation for the tenth plague, the ultimate question for the 21st century humanist might be: “If this really is how the plagues happened in ancient Egypt, could something similar happen again today?”

In fact, Ehrenkranz and Sampson warn that their proposal does have “current day public health implications.” They believe that the plagues began and were sustained by a phenomenon called an “El Niño-Southern Oscillation (ENSO) teleconnection” along the Mediterranean coast of Egypt. “The Old Testament record provides an opportunity to consider the breadth of public services that might be required in the event of another series of ENSO calamities,” they write. “Were a populous region to now be struck with catastrophes that parallel the biblical elements, essential public health, medical, and veterinary services likely would be overwhelmed.”

But we have science, you may be thinking, and scientific explanations that cut the superstitions about a Semitic god meddling in Egyptian labor relations down to size. Here I would gently point out the decidedly unscientific “information” still circulating about our own recent plague of COVID-19 and the “miracle” of the vaccines that are helping the world live with it. All of humanity would do well to see our own times – and our lack of preparedness to face disasters of biblical proportions – mirrored in this ancient story.

Statue of Miriam in Siena, Italy
Statue of Miriam by Giovanni Pisano from the façade of Cathedral of Siena. Image credit: Carlo Raso via Flickr.

5 thoughts on “Climate Plagues”

  1. Pingback: Israel in Arabia

  2. Pingback: The Brink of Slavery

  3. Pingback: Introduction

  4. Pingback: Parting Waters

Leave a Comment

Your email address will not be published. Required fields are marked *