Ernest Hemingway made Mount Kilimanjaro famous with his story “The Snows of Kilimanjaro”—though he never climbed the peak.

But many others have. More than 30,000 try each year, with two-thirds reaching the top.

Kili, as it’s called, is the tallest mountain in Africa but the easiest climb of the Seven Summits—the highest peaks on the seven continents.

Its high camps have hosted some world record sporting events, including the highest professional soccer game, with players hailing from 20 countries.

It’s a unique ascent, traversing five different ecological zones, from cultivated lands to rain forest, then moorland, alpine desert and finally an arctic summit.

The summit of Mount Kilimanjaro is actually three volcanic cones. The last major eruption ended 170,000 years ago, and all peaks are thought to be either extinct or dormant.

There are glaciers in the highest areas, but they’re disappearing quickly, down more than 80 percent since the early 1900’s. It’s thought this is mostly related to human deforestation in the valleys surrounding the mountain, disrupting its microclimate.

The valleys have fertile volcanic soils and ample rainfall, producing the tallest trees in Africa. Tanzania has recently pushed to protect them from logging and is now replanting millions of indigenous trees in an effort to reforest the area.

Through careful stewardship, the mountain could be protected from the further impacts of humans.

Why do zebras have stripes? It’s probably a combination of things.

Zebras’ main predators are lions. Black and white stripes actually make zebras stand out against their grassland home, rather than camouflage them.

But when many zebras are running simultaneously, the cacophony of stripes may confuse predators as to how many zebras there are and which way they’re moving, making it more difficult to target an individual.

However, lions are ultimately successful at catching zebras, so this optical confusion deters but doesn’t prevent predation.

It’s also thought that the alternating black and white areas may be a thermoregulation strategy. The black stripes are 20 degrees Fahrenheit warmer in the sun, which may help the zebra absorb the sun’s heat on cool mornings, while white stripes reflect heat in the hot afternoons.

But perhaps the most beneficial quality of the stripes is to deter biting flies. Researchers have found that the stripes confuse the flies’ depth perception, making it difficult for them to land and bite.

In tests, scientists dressed horses in striped coats and put them with captive zebras and solid-colored horses in fly-infested areas.

They found that flies preferred the solid-colored animals four to one, and either hovered over, or bounced off, the striped animals.

Scientists accept it’s probably some combination of all these beneficial traits that led the zebra to develop stripes.

Utah’s Great Salt Lake may seem like a wasteland, ringed by toxic deposits of mercury and arsenic, and filled with water so salty that only brine shrimp can live in it.

However, those shrimp feed 10 million migrating birds. And the lake provides eight thousand jobs and two billion dollars in industry, harvesting salt and other minerals. It’s vital to the region’s ecology and economy.

But the lake is in danger.

Great Salt Lake is the remnant of Lake Bonneville which, in ancient times, was nearly as big as Lake Michigan.

Then, 18,000 years ago, the lake found a drainage path to the Pacific Ocean through the Snake River Valley, and its level fell 400 feet.

Fifteen thousand years ago, as glaciers retreated from the region, the climate became drier. The lake became landlocked again and started to evaporate, falling another 600 feet to stabilize at its modern size.

But over the past century, its been gradually shrinking. In 2022, it hit a record low.

This is due to rising temperatures and drier summers in the region, and, importantly, to lower inflow—as the rivers that feed the lake have been increasingly diverted for agriculture and mining. So, Utah began water conservation measures.

Then 2023 saw the most snowfall in 70 years, which may lead to record runoff.

Only time will tell if Utah’s people, and weather, can save the Great Salt Lake.

The megalodon, Earth’s largest shark, is thankfully...extinct.

It was twice the length of a school bus. Larger than most of today’s whales and three times the size of the biggest great white shark—with up to 10 times the bite force.

Its jaws were filled with hundreds of six-inch teeth, which fell out and were replaced every few weeks. The megalodon’s large range meant that fossilized teeth have been found around the world.

This fearsome giant prowled Earth’s oceans for 20 million years—and an animal that size required a great deal of food.

Megalodon teeth have been found embedded in fossilized whale bones, and teeth gashes are visible in their petrified vertebrae. But it also could have eaten dolphins, large fish, other sharks...pretty much whatever it wanted.

Then, around 3 million years ago, Earth’s climate and oceans cooled. This killed off a third of most marine animals, especially localized species at the base of the food web.

In turn, that may have restricted the megalodon to a smaller range of warmer tropical waters, where prey continued to thrive.

Researchers believe that megalodon gave birth to their six-foot young in shallow coastal areas. As Earth’s water froze into continental glaciers, sea level fell and many of these areas would have disappeared.

We’ll never know exactly what wiped out this mighty species. But there are plenty of modern ocean creatures that are probably happy it’s gone!

Have you ever seen the brilliant hues of petrified wood and wondered how it gets its colors?

When trees die, they typically fall to the forest floor, where they decay.

But if they fall in a place without oxygen—in water, a swamp or bog, or are buried by volcanic ash or flood silt—they may not decay.

After thousands or millions of years, water seeps into the pores of the wood, carrying dissolved silica. The silica bonds with the cellulose and replaces it.

Then other mineralized water enters the silica–cellulose framework, where those compounds replace the rest of the organic material.

We’ve found nearly 40 minerals in petrified wood, many containing iron, manganese and chromium, which provide its spectacular red, orange and blue colors.

The lithification process also preserves the physical structure of the tree, sometimes down to the microscopic level.

Eventually, erosion exposes the fossilized logs—some dating back over 300 million years for us to discover...

And they’ve helped us study the long history of tree evolution while providing valuable information about the environmental conditions of the ancient past, such as rainfall, drought, fire and insect populations.

Petrified Forest National Park in northeastern Arizona is one of the most famous sites. Definitely worth a trip, especially in the spring or fall when temperatures are mild, to find beautifully colored windows into the past.

When a thunderstorm forms over the desert, it may not produce rain—but could form a deadly dust blizzard called a haboob.

When rain droplets condense within a thunderhead, they cool the air, which rushes toward Earth with the rain.

If this happens over a desert, the rain will often evaporate before reaching Earth. The evaporative cooling further chills the air, which falls faster.

Eventually the current of air strikes the ground, at high speed, and expands outward.

The blast often carries dust and sand into the air, to form a huge dust storm that advances in front of the thunderhead.

These were first studied in the Sahara, hence were given an Arabic name, haboob. But they form across arid regions of the U.S. as well.

Sand, dust and soil carried by a haboob can sandblast vehicles and buildings. Worse, haboobs often carry bacteria and viruses from the desert floor, causing respiratory problems and skin irritation for those exposed to them.

Even more dangerous, haboobs can suddenly drop visibility to zero. Highway pileups are common in these storms, and the dust can blind pilots and interfere with airplane engines.

If areas like the American West become drier, we could see more frequent haboobs.

If you’re caught in one, first cover your nose and mouth. If driving, honk your horn and pull far off the road. Then turn off all your lights so other cars don’t steer toward and hit you.

So-called water spiders aren’t spiders at all but insects specially evolved to walk on water.

There are 1,700 species of these water striders, which have existed on Earth for millions of years.

If you’ve ever wondered how they skate so effortlessly across a pond without falling in, the answer is surface tension—and their very specific adaptation to it.

Water molecules, as we’ve discussed on prior EarthDates, bond together tightly, especially where water meets air. This creates a membrane-like surface that the water skaters take advantage of.

Their long legs are useless on land. But they’re equipped with thousands of microscopic hairs that trap air in nanogrooves. The air repels water, keeping the surface tension intact though the insect is moving across it.

And move they do, at up to 100 body lengths a second—the equivalent of a human traveling at 400 miles an hour.

They use their incredible speed to catch prey that also live in this unique environment: other insects, small spiders, and, their favorite food, mosquito larvae.

This makes water striders a beneficial insect in controlling mosquito populations.

In ideal conditions, water skaters can live up to a year, hatching new eggs every two weeks. And when their ponds are drying up, they’re able to spawn a new generation with wings, to fly off to find another pond to skate on.

At the bottom of the ocean lies a treasure. But recovering it could be technically difficult, geopolitically challenging, and environmentally damaging.

Eighty three percent of the ocean is a mile deep, or much more, making the deep ocean the largest environment on Earth, covering 115 million square miles.

Down there, like in the Amazon, species diversity is high. There may be thousands of species we have not yet identified.

Down there, also, are polymetallic nodules and crusts, formed of iron and manganese, and in smaller amounts, cobalt, lithium, molybdenum, rare earth elements and other valuable metals that precipitate out of seawater, very slowly, over millions of years.

Many of these metals are used in new energy technologies, like batteries, so companies and countries are considering recovering them. But it’s complicated.

Most of the deep ocean is in international waters. No one’s quite sure how to regulate or share revenue from mining there.

And the deep ocean is a poorly understood environment. Mining could kill many creatures and damage seafloor ecosystems.

So far, no permits have been issued. But there is pressure on international authorities to do so, as today’s supplies of many of these materials are limited.

Efforts to mine the deep ocean, responsibly and sustainably, may be an area of dispute—and opportunity—in the future.