The ‘Oasis Lodge’ in Loiyangalani became my favorite destination on Lake Turkana, for relaxation, well-being, and dreaming – let’s just say, for my soul. Loiyangalani lies on the southeastern shore of the lake, on the foot of Mt Kulal. The first time I stayed there, I had that magical past-life experience again. It was that same feeling I had on the Djibouti train as a young man when, on the way down into the Awash, I conceived Lucy’s call to Africa. And the Oasis Lodge may be the reason for which I decided that the Cradle of Mankind is somewhere around Lake Turkana. Mt Kulal was still active and spitting lava, in the Stone Age when our genus of Homo came about. Today, the volcano is cold and eroded. And unfortunately, the Oasis Lodge is run down and unhospitable. In the first years of his reign, Uhuru Kenyatta, the President of the Republic, grabbed it from its German owner and left it to a political friend. The downturn of tourism in Kenya certainly contributed to the decline but the Oasis Lodge is out because of poor management. It is certainly no longer a spot for idling and musing about our human past and future.

West of Loiyangalani in the lake lies South Island. It is covered by thin vegetation and volcanic rocks of all sizes. Animal life is limited but bird watchers have counted at least 23 species that breed there. Of course, there are crocodiles and due to the mysterious nightly after-glow of the volcanic rocks, it is also home to various ghosts and spirits.

Beside ‘South Island’, Lake Turkana has two more islands: At the northern end of the lake, it is ‘North Island’ and in the middle of the lake near Eliye Springs, we have ‘Central Island’. All three are actually volcanoes through which lava streamed to the surface out of the fault line of the Kenyan Rift, under the lake. Central Island is the biggest of them and much more worth a visit than South Island. It has several craters on it and the last volcanic eruption there was recorded in the 1970s. Three older craters have filled with water and become small lakes on the volcano in the big lake. Each lake has its own complexion of minerals and water. ‘Flamingo Lake’ has developed the algae flamingos feed on and is home to colonies of the Greater flamingo. The ‘Greater’ flamingo is basically white and is called so because it has longer legs than its ‘Lesser’ pink cousin. Somehow, Tilapia fish from the big lake found their way into ‘Tilapia Lake’ on the island. And the biggest of the three lakes is ‘Crocodile Lake’. Lake Turkana is home to the world’s largest population of the Nile crocodile and together, the three lakes of Central Island are their breeding ground. And this gives Central Island its other name, ‘Crocodile Island’.

So, with all these crocodiles in and around the lake, what are fossils of whales and stingrays doing in the Turkana Basin? Those are ocean animals. Well, Lake Turkana in its present form is not that old. But the volcanic activity of the region is 35 million years old, and the East African Rift goes back 25 million years. The area has thus been moving and changing for a very long time. There is scientific evidence that the Omo and the Turkwell Rivers feeding the lake today, used to converge in the area of the lake to flow southeast and into the Indian Ocean. Whales and stingrays are known to swim up-river, and some must have swum up the phantom ‘Turkana River’. But then, some 4 million years ago, there was powerful volcanic activity along the whole East African Rift. And Mt Kulal, a mighty active volcano then, through its eruptions closed the basin, cut off the rivers from their path to the Indian Ocean and confined them to what is today, Lake Turkana. – But this is not the end of the story.

Rivers and Lakes don’t like to be confined and when their water level rises, they will find or create the necessary runoff. Over the time of its existence and in response to climate change, the level of Lake Turkana has fluctuated by more than 100 meters. And at several peak heights since its runoff to the southeast had been blocked, the water took its way westward into the upper Nile system, in today’s South Sudan. The last two such periods of overflow occurred as recently as in the early Holocene, around 9’000 years ago and then again 6’000. Biologists support these geological findings and point out that through such repeated and lasting overflows, the Nile perch arrived in Lake Turkana. They say the same of the Nile crocodile. Having myself observed and studied the Nile crocodiles around the lake over several decades, I have developed a different theory: The Nile crocodile as we know it today, is only around 3 million years old. And if it was not in the area since its beginnings, it is invasive enough to have made it to the Lake Turkana Basin without depending on such phases of overflow.

So, at Lake Turkana, we are not only in the middle of the story of human evolution and the Nile crocodile but also the one of volcanoes changing the Earth. Not counting the three islands in the lake and Mt Kulal, the Kenyan Rift Valley running South counts twelve more volcanoes. To the north of the lake, the Ethiopian Rift counts another fifty or so volcanoes. And volcanoes don’t only change the topography of the Earth, they also change her climate. The East African Rift remains one of world’s main regions with volcanic and diffuse emission of carbon dioxide, CO2. And there is still a lot of CO2 the volcanoes can release: Just 0.2% – two tenths of one percent – of the Earth’s carbon dioxide is above the surface, in the oceans, on the ground and in the atmosphere. The rest is sub-surface, in the cold crust, the mostly solid mantle and the hot core of the Earth. And the volcanoes of the East African Rift are continuously releasing it.

If Venus and Mars are anything to go by, Earth should be an absolute desert. The volcanoes of all three planets have spewed out so much carbon dioxide into their atmospheres that life on all three of them should not be possible. So, why is there life on Earth? – Around a billion years into her existence, Mother Earth somehow allowed organisms like single-cell bacteria, algae, and multi-cellular plants to evolve. To live, they absorbed the CO2 coming out of the Earth from the volcanoes. Over the millions of years since then – actually, it’s 3.5 billion! – our planet has established a natural cycle for the flow of CO2. Through the volcanoes it comes from the deep Earth to the surface and into the atmosphere and oceans. There, it is soaked up by the living organisms and as they perish, it is returned into the Earth again. And in some places, over millions of years, it turned into coal and oil. The first animals – sponges – joined the older living organisms in the carbon cycle only 800 million years ago. 225 million years ago, the crocodiles, 65 million years ago, the mammals and 2.6 million years ago, our human ancestors followed.

50 million years ago, the carbon cycle was thrown out of balance. The volcanoes overdid their output. CO2 in the atmosphere is measured in ‘parts per million’ (ppm) and massive volcanic eruptions had lifted CO2 levels to 1’500 ppm. For modern humans this is not a health- or life-threatening level. CO2 as such is not poisonous but it replaces the oxygen in the blood and thus mainly affects the brain. A healthy human adult will feel fine in an environment with 350-450 ppm. Up to 600 ppm is still comfortable. Topping levels of 1’000 ppm, you will feel the air is stuffy and your concentration and thinking will begin to slump. Working in an office or a conference room, it’s time to open a window. If your retired and at home, take a nap. At 5’000 ppm, your cognitive capacities will begin to be affected and you may start feeling fatigue, dizziness, nausea, and headache. Labor law prohibits more than eight hours of work in such an environment. But only at 40’000 parts of CO2 per million, will your health and life really be in danger and do you risk collapse and coma.

The evolution of Homo sapiens happened in an atmosphere with a concentration of something below 300 parts of CO2 per million. In 1951, I was born into something above 300 ppm and from then to 2020, it has jumped to 412 ppm. I was an active runner and knew that long distance running is all about your breath. Inhale lots of fresh air and replenish your body with oxygen. Exhale and release the excess CO2, the one you have taken in and the one you have produced by burning all that energy. And running along the shore of magnificent Lake Turkana or on the slopes of the great cold volcano Mt Kulal, I trained increasing my intake of oxygen and enhancing my discharge of CO2, while keeping my breathing slow, controlled, and regular. My heart rate learned to follow, and my body became used to managing high levels of CO2. To this day, I pride myself of the resulting endurance and stress tolerance that I enjoy. In sports and life.

The problem with CO2 is that when the carbon dioxide concentration in the atmosphere goes up, temperature also goes up. CO2 is a greenhouse gas; it absorbs and radiates the heat coming from the sun and the Earth’s surface back into the atmosphere and the ground. Without it, our planet would be frozen, like Mars. That’s what I like about global warming, it makes me forget that we are still living in an Ice Age. But with too much CO2 in the atmosphere, temperature will rise above the comfort zone. And while some living organisms will thrive, others will be stressed and yet others will suffer. They all have to adapt to a changing habitat in which other species are also affected. And the faster the climate changes, the tougher the challenge to the species’ survival. Evolution is a slow and generational process. When plants or animals cannot make the necessary turn in their evolution, they die and when too many of them die, the species risks extinction. Extinct means gone. Forever. And when multifold species disappear, we call it a ‘mass extinction’.

But 50 million years ago, when the volcanoes overdid their output and brought the CO2 level to 1’500 ppm, the carbon dioxide had built up the ‘Hothouse Earth’ over a longer time span. Plants and animals had time to adapt. For the animals, we had reached the age of mammals, but humans were nowhere near yet. Our human lineage of primates had not even gotten to the apes, our direct ancestors. The monkeys were just about to branch off the tarsiers who had overtaken the lemurs – except for Madagascar where the lemurs live in isolation to this day. The crocodiles were already there, as ever. Having survived the global winter and the mass extinction that followed the hit of Earth by the meteorite 15 million years earlier, they were delighted by the heat. They thrived and started diversifying into different species, like the alligators and caimans. Parts of Africa will have been inhabitable for them. But the Arctic was iceless, a vast freshwater lake or swamp. And research in the Arctic Circle of Canada has revealed that some of the crocodiles moved up there. The unearthing of crocodile fossils so far north was of no surprise to me. It is in line with my theory on the intrusive nature of the ‘Genus Crocodylus’.

The previous Hothouse Earth of 250 million years ago, was different. Over only 60’000 years or so, the volcanoes pushed the carbon dioxide level of the planet to 3’000 ppm. The resulting rise in temperature of more than 10° Centigrade was too much, too fast. It led to the biggest mass extinction in the 3.5 billion years since which our Earth supports life. It is estimated that up to 90% of all then existing marine and terrestrial species died off.

 And now the really bad news: Since humans have started tapping into the CO2 inside the Earth – coal and oil – on top of exploiting the natural carbon cycle on its surface – firewood –, carbon emissions from human activities have outdone the volcanoes by hundreds of times. And today’s rising levels of CO2 and global warming are much faster than they were 250 million years ago. A manmade mass extinction and destruction of the human habitat are a daunting scenario for the future of mankind. – I don’t live in an apocalyptic mindset and trust that science and technology will lead us to better remedies than thoughts of doomsday. But I don’t join those who say that science and technology will allow us to build new artificial habitats for ourselves in outer space – on Mars for instance. And that for their survival, humans will be able to flee the Hothouse Earth. This may be in line with our most basic instinct of ‘fight or flee’ and we could demonstrate to the crocodiles that we are even more invasive than they are, but I would never flee to Mars. I’d stay behind on Earth. With the crocodiles.