Tarawa! And the War Against Sea Level Rise

Guest by metaphor mixing by David Middleton

Right after geology & geophysics, my favorite hobby is military history, particularly that of the U.S. Navy and Marine Corps. The constant whining about Kiribati being washed away by carbon-fueled sea level rise inspired me to employ geology and military history in a combined offensive against the sea level rise “crisis”.

Anyone else fed up with crap like this?

[…]

So the world kept getting hotter. The global community sailed past the 1.5 degree Celsius “‘safe’ threshold of warming” mark around 2038, and summers of Saharan intensity became an annual norm in Europe—often in North America, too. These extreme bouts of heat—too routine now to be dubbed “heat waves”—claimed annual death tolls of thousands in many countries, while wildfires courted the specter of mass famine by burning up billions of dollars’ worth of cropland. Around 80 percent of Earth’s coral reefs died off, tanking fishing and tourism economies around the world. The ocean rose about 1.5 feet, exposing an additional 69 million people every year to regular extreme flooding. Residents of the tiny Pacific island nation of Kiribati, which sits an average of a little less than six feet above the precrisis sea level, began to flee to Australia and New Zealand en masse.


The world’s population ballooned to 12.6 billion by the end of the century, and Earth’s temperature rose by 4 degrees Celsius—twice the level that scientists…

[…]

Today, at 4 degrees, there is still civilization. But there is no Kiribati, given that sea levels have risen three feet since the beginning of the century. Most of the nation’s 110,000 people have fled to Australia and New Zealand—both of which are struggling with climate-driven scarcity in their own economies, and reverting to uglier forms of discrimination from their shared colonialist past. Australia has continued its practice of housing migrants in inhumane offshore detention centers in Papua New Guinea—except now, drought has dried up the rainwater tanks that supplied New Guinea’s drinking water, and salt water from the rising sea has leached into the soil, further decimating agricultural production on the island.


And Kiribati is but one snapshot of the new global normal.

[…]

The New Republic

Kiribati…

Kiribati (/ˌkɪrɪˈbæs, -ˈbɑːti/),^[8] officially the Republic of Kiribati (Gilbertese: Ribaberiki Kiribati),^[1][3][9] is a sovereign state in Micronesia in the central Pacific Ocean. The permanent population is just over 110,000 (2015), more than half of whom live on Tarawa Atoll. The state comprises 32 atolls and reef islands and one raised coral island, Banaba. They have a total land area of 800 square kilometres (310 sq mi)^[10] and are dispersed over 3.5 million square kilometres (1.3 million square miles).

Wikipedia

While Kiribati comprises a whole lot of islands, the main island group is Tarawa Atoll.

Geography
Location Pacific Ocean
Coordinates 1°20′N 173°00′E
Archipelago Gilbert Islands
Area 500 km² (190 sq mi)
Highest elevation 3 m (10 ft)
Administration
Kiribati
Demographics
Population 56,284 (2010)

Wikipedia

(Make a mental note of the current highest elevation.)

Anyone who has ever seen the classic John Wayne movie, The Sands of Iwo Jima, is probably familiar with the Battle of Tarawa.

It was one of the costliest battles in US Marine Corps history. If the history holds no interest for you, skip past the excerpt that follows. For anyone interested in the Battle of Tarawa, I highly recommend reading the entire article.

Across the Reef: The Assault on Betio
Despite abysmal conditions and mistakes in execution, the 2d Marine Division wrested control of Tarawa Atoll’s key island in 76 hours of vicious fighting.

By Colonel Joseph H. Alexander, U.S. Marine Corps (Retired)
December 2008 Naval History Magazine Volume 22, Number 6

Rear Admiral Harry Hill’s Southern Attack Force bore down on Tarawa at full speed the night before D-day, each vessel at general quarters and “darken ship.” The Marines spent a restless night confined to their sweltering troop compartments, each man alleviating his pre-D-day anxieties by recalling fond memories of the past eight months of New Zealand hospitality. Earlier that evening, Major General Julian Smith, commanding the 2d Marine Division, dispatched a message to his troops, saying: “A great offensive to destroy the enemy in the Central Pacific has begun. Our Navy will support our attack tomorrow with the greatest concentration of aerial bombardment and naval gunfire in the history of warfare.”¹

Deceptively soft-spoken, Julian Smith was a steel-nerved, distinguished marksman and a proficient trainer. His Navy Cross attested to earlier valor against Nicaraguan guerrillas, but Operation Galvanic, the codename for the invasion of the Gilberts, would be the 58-year-old general’s first encounter with the Japanese and his first major landing. He did not exaggerate the scale of the preliminary shelling that would commence at dawn. In terms of duration and weight of munitions, Tarawa’s three hours of preassault bombardment would exceed any amphibious prep fires in the war to date.

[…]

Betio was three miles long and less than a half-mile wide—an unremarkable 300 acres of sand dunes and palm trees. On military maps the island resembled a bird lying on its back, its head pointed toward the west, its long tail, east. A 600-yard pier ran from the bird’s belly to a landing at the reef’s edge. The stubby Burns-Philp wharf jutted out east of the pier. The airfield overwhelmed the long axis of the island. Although the perimeter bristled with fortifications, the most formidable Japanese positions were to be found between the wharf and the pier, where a series of mutually supporting strongpoints were located, and along the northern re-entrant—the “bird’s throat” or “Pocket.”

[…]

‘The Tide That Failed’
A neap tide occurs at the first and last quarter of the moon when there is the smallest rise and fall in tidal level. But something strange happened that caused the battle for Tarawa to be remembered for “The Tide That Failed.” Not only did the morning’s tide fail to rise its anticipated three to four feet, it hardly rose at all for the next 30 hours—a phenomenon later discovered to have been an apogean neap tide that occurred only twice in 1943. One of those occasions coincided with D-day at Tarawa.¹⁰

Japanese gunners feasted on the clots of Marines stumbling shoreward, rifles raised over their helmets.

[…]

Issue in Doubt
The Marines were in a particularly tight spot the first night of the battle. Five thousand men had crossed the reef; 1,500 had fallen. The balance were scattered in uneven pockets along one mile of shattered shoreline. “This was the crisis of the battle,” Julian Smith recalled. Veteran war correspondent Robert Sherrod had survived the unnerving wade ashore to Red Two. He knew the Japanese proficiency in night fighting and how thin the Marines’ lines were. “I was quite certain that this was my last night on earth,” he said.¹²

[…]

After 76 hours, the battle for Tarawa was over. In the end, some 5,000 men lay dead in close quarters—1,100 Marines, the rest Japanese. The island reeked. Correspondent Sherrod tried to describe the stench: “Betio would be more habitable if the Marines could leave for a few days and send a million buzzards in.”¹⁴

[…]

Hard Lessons
“There had to be a Tarawa,” stated both Julian Smith and Merritt Edson to Congress after the battle, as they emphasized the operational, logistical, and tactical lessons learned. Material shortfalls, faulty decisions, inexperience, and poor luck had led to a high cost in flesh and blood. Yet the doctrine of amphibious assault had proven valid. If the principles worked at Tarawa under the worst imaginable hydrographic and tactical conditions, they would work again at places like Normandy, Luzon, Iwo Jima, and Okinawa.

[…]

Naval History Magazine

Here’s a description of Betio Island in 1943:

Intelligence reports from Betio were sobering. The island, devoid of natural defilade positions and narrow enough to limit maneuver room, favored the defenders. Betio was less than three miles long, no broader than 800 yards at its widest point and contained no natural elevation higher than 10 feet above sea level. “Every place on the island can be covered by direct rifle and machine gun fire.” observed Edson.

Across the Reef, The Marine Assault on Tarawa

Key points about Betio’s physical geography in 1943:

• Betio… —an unremarkable 300 acres of sand dunes and palm trees.
• Betio was less than three miles long
• no broader than 800 yards at its widest point
• contained no natural elevation higher than 10 feet above sea level

Here’s a 1943 USMC intelligence map of Betio:

I digitally planimetered the area of the island:

Since Kiribati is supposedly being inundated by Gorebal sea level rise, one might think that it must have shrunk in size over the past 76 years of climate crisis. So I planimetered a Google Earth image of Betio. Note that I cropped off the man-made jetty.

Betio appears to have a larger land area now than it did in 1943.

In 1943 “Betio was less than three miles long”.

In 1943, Betio was “no broader than 800 yards at its widest point”.

In 1943 Betio “contained no natural elevation higher than 10 feet above sea level”.

GEOLOGY
Tarawa is a coral atoll formed on top of a volcanic seamount which rises steeply from 4000 m of water. The atoll is roughly triangular in plan and comprises a chain of small islands on the south and northeast sides which partially enclose a central lagoon (Fig. 2). The islands are generally 2-3 m above present sea level. The surface material of most of the islands is coral sand. In places, cemented coral hardpan forms a terrace 1.5-2 m above sea level. The first four bores drilled on Bonriki and Buariki intersected coral sand to depths of 7.5-11.5 m below the ground surface (Appendix 1). Beneath the sand, these bores intersected buried coral reef, 1.5-12.0 m thick. Beneath the buried coral reef, some of the bores encountered interbedded limestone and sand; others had a limestone sequence extending to 30 m below surface, the maximum depth of drilling. The total thickness of the limestone sequence is unknown. The nearest atoll to Tarawa that has previously been drilled is Funafuti in the Ellice Islands (Fig. 1), where volcanic basement was not encountered even at 330 m. The nearest atoll where basement has been intersected is Enewetok in the Marshall Islands, where basalt was encountered beneath 1300 m of limestone.

HYDROGEOLOGY OF TARAWA ATOLL, KIRIBATI by G. Jacobson & F.J. Taylor, 1981

3 meters is about 10 feet.

I visited Dave Burton’s awesome Sea Level Info website to see what tide gauge stations might be available and found one from NOAA and several from PSMSL. These stations are scattered over a pretty wide swath of the Pacific Ocean (Kanton Island is about 1,100 miles ESE of Tarawa); but they all tell the same story.

Sixty years of relentlessly rising seas amounted to the width of the trigger guard on an M1 Garand rifle.

So, I extrapolated the sea level rise crisis out to 2100.

Over the next 80 years, sea level is likely to rise from just below the side skirt of an LVT-2 all the way up to just below the side skirt of an LVT-2.

While the sea level crisis would have posed no challenge to the LVT “amtraks,” the seawall was a different story.

Eighty-seven amphibian tractors, old and new, made the six-hour odyssey from the ill-chosen Transport Area and delivered about 1,500 Marines ashore, losing only eight vehicles to enemy fire—a remarkable performance under the conditions. Admiral Shibasaki was astonished by what he described in his 0930 report to his headquarters at Kwajalein as “amphibious tanks” (also described by one of his men as “the little boats on wheels”), the tracked landing vehicles that could travel from so far at sea, cross the exposed reef, and debark assault troops on the beach.⁹ David Shoup’s great gamble had paid off.

But now the “wheels” came off. Few of the LVTs could negotiate the seawall and force their way inland. Japanese machine-gunners recovered from their initial shock and shot many Marines as they struggled awkwardly to roll over the top of the 8-foot-tall vehicles and drop to the beach. A few drivers extracted their emptied vehicles from the shore and began shuttling the Marines of the fourth and fifth waves from the reef, as planned, but heavy fire from four 75-mm guns in the Pocket took a toll. Their lower hulls peppered with shell holes, many tractors filled with water and sank. Others simply ran out of gas after six hours of heavy acceleration. The shuttle plan failed. The Marines stranded on the reef took a deep breath and began wading the 500 to 600 yards to shore against relentless fire. 

Naval History Magazine

Shocking! Betio needed a seawall in 1943!

Conclusion

The men of the 2nd Marine Division faced a genuine existential threat during those 76 hours of Hell in November 1943. Too many did not survive. However, their sacrifice undoubtedly saved many thousands of American lives in future amphibious landings.

It is truly ironic that the location of this historical genuine existential threat has become one of the poster children for today’s fake existential threat: The climate crisis.