Planet Earth From Space

Planet Earth: Facts And Information

Inside The Goldilocks Zone

Planet Earth lies within the so-called “Goldilocks zone” around the sun, where temperatures are “just right” to maintain life. It is the only planetary object known to have an atmosphere containing free oxygen, as well as liquid water on its surface, which provides it with a unique climate system and biodiversity of species. Earth is the only planet in our solar system with a large amount of liquid water. It’s because of the oceans, which cover 71 percent of Earth’s surface, that people call it the “blue planet”.

Earth is the fifth largest of the planets in the solar system. It’s smaller than the two “gas giants” — Jupiter and Saturn – and the two “ice giants” – Uranus and Neptune – but bigger than the three other rocky planets, Mercury, Venus and Mars.

Planet Earth’s Orbit

Earth orbits the sun once every 365.25 days. Because our “calendar year” only has 365 days, we add an extra day every four years to settle the difference.

Earth travels through space, at an average speed of 29.6 km (18.5 miles) a second. Its orbit, lies on average 148.8 million km (93m miles) away from the sun – a distance defined by astronomers as one astronomical unit (AU). It takes about 8 minutes for sunlight to reach Earth from the sun.

Earth rotates on its axis (an imaginary line that runs from the North Pole to the South Pole) every 23.9 hours, which gives us our daytime and night time. This rotational axis is tilted 23.4 degrees away from the plane of Earth’s orbit around the sun. This means that the Northern and Southern hemispheres will point towards or away from the sun, according to the time of year, which gives us our seasonal changes in climate.

Like all the planets in the solar system, Earth’s orbit is not a proper circle but rather an oval-shaped ellipse. This leads to the planet being closest to the sun in early January (known as the Perihelion point) and farthest away in July (known as the Aphelion point). However, the variation in temperature produced by this variation in proximity is not as pronounced as the heating and cooling effect caused by the tilt of Earth’s axis.

Hopetoun Falls, Beech Forest, Australia
Hopetoun Falls, Beech Forest, Australia. Photo: © David Iliff, CC BY-SA 3.0

Origins Of Earth

Scientists date the “Big Bang” to about 13.8 billion years ago. The Sun formed about 9.2 billion years later – about 4.6 billion years ago – from the collapse of a giant molecular cloud. 1 Planet Earth – according to the so-called “core accretion model” – was formed about 4.54 billion years ago, out of the leftovers from the vast interstellar cloud of dust, hydrogen, helium and other ionized gases (nebula) that made the Sun. 2 3

It’s possible that the Moon was formed after a collision between the Earth and a smaller planet. Astronomists believe that fragments from both planets broke off and coalesced to form the Moon. 4

For more about the timeline of our planet and our current climate crisis, see: History of Earth in One Year (Cosmic Calendar).

Structure

Earth is round because its gravity pulls matter into a ball. But, it’s not a true sphere. Its shape is slightly flatter at the poles, making it an “oblate spheroid”. Thus, for example, the circumference of the planet at the equator is roughly 40,075 km (24,900 miles). However, the meridional circumference (from pole-to-pole) is only 40,008 km (24,860 miles). It has a diameter of roughly 13,000 km (8,000 miles).

Earth is made up of four main layers, starting with an inner core at the center, surrounded by an outer core, mantle and crust.

The inner core comprises a solid sphere, made of iron and some nickel, measuring about 2,440 km (1,516 miles) in diameter. The temperature of the inner core is believed to reach 7,000 degrees Celsius (12,600 degrees Fahrenheit). The inner core is responsible for the planet’s magnetic field, which deflects harmful charged particles shot from the sun. Surrounding the inner core is the outer core. This layer is about 2,200 km (1,367 miles) thick, and mostly consists of liquid iron and nickel. The temperature of the outer core is roughly 3,700 to 4,300 degrees Celsius (6,700 to 7,800 degrees Fahrenheit).

Around the outer core is the thickest layer, known as the mantle. Roughly 2,900 km (1,800 miles) thick, the mantle is a viscous mixture of molten rock with the consistency of treacle. The final layer, Planet Earth’s solid crust, has an average depth of about 30 km (19 miles) deep on land. At the ocean floor, the crust is usually thinner, extending to a depth of about 5 km (3 miles). At the foot of the continental crust, temperatures are about 1,800 degrees Fahrenheit (1,000 degrees Celsius), rising about 1 degree Celsius (3 degrees Fahrenheit) per mile below the crust.

Why Do Volcanoes Erupt?

Volcanic eruptions happen when magma – formed when the mantle melts – rises to the surface of the earth carrying bubbles of gas. This gas causes pressure to build up inside the volcano, and it eventually explodes. The magma that is spewed out of the earth, is called lava.

Planet Earth’s Chemical Composition

Core

Earth’s core consists of iron (88.8 percent), nickel (5.8 percent), sulfur (4.5 percent), and less than 1 percent other things, including oxygen. 5

Mantle

The mantle consists of iron and magnesium-rich silicate rocks. It is the largest carbon reservoir on the planet.

Crust

The most abundant element in Earth’s crust, is oxygen which makes up about 47 percent of the weight of all rock. After this comes silicon (27 percent), aluminium (8 percent), iron (5 percent), calcium (4 percent), followed by sodium, potassium and magnesium (about 2 percent each). Actually, there are two types of crust. The dry rock of the continents is mostly made of granite and other silicate minerals, while the sea beds mostly consist of a dark, dense volcanic rock known as basalt.

Seismologists monitor a surface rupture after earthquake, California
Seismologists monitor a surface rupture near Ridgecrest, California in 2019 after a pair of large earthquakes struck. Photo: © Ben Brooks/USGS.

How Movements In Earth’s Crust Can Cause Earthquakes, Volcanoes

Earth’s crust floats on the mantle, like a piece of wood might float on treacle. As a result, the continents (more accurately, their separate jigsaw-like plates) move very slowly. 6 It’s this movement of the plates that causes earthquakes, volcanoes and very occasionally the formation of mountain ranges like the Himalayas.

Plates can move around in one of three ways. (a) Two plates can approach each other (“convergent” plate edges). This can cause the formation of islands (such as Japan), volcanoes, or high mountain ranges (such as the Himalayas or the Andes). 7 (b) Two plates can move apart from each other (“divergent” plate edges). This allows the molten rock inside the earth to come out. This can result in an upsurge of mountains from the ocean floor, or large lowland areas like Africa’s Great Rift Valley. Plates are able to grind alongside each other as well (“transform” plate edges) as illustrated by the San Andreas Fault in California. 8

What Causes an Earthquake?

An earthquake is caused when massive underground tectonic plates rub against each other and then get stuck. Pressure builds up and eventually the strain becomes so great that rock suddenly breaks creating a sudden release of energy. This causes the seismic waves of energy that travel through the Earth’s layers and make the ground shake. The sudden release of energy caused by the rock snapping is what we call an earthquake.

What Are Planet Earth’s Spheres?

Scientists divide up the Earth into a number of different but overlapping “environmental systems”, called “spheres”. These environmental systems – covering the air, the oceans, frozen water, surface soils, and the rocks just below it – interact with each other in numerous ways – notably in the maintenance of the biogeochemical cycles – and make critical contributions to planetary life and climate. The six most important spheres are as follows:

The Atmosphere

This consists of a layer of gases that we call “air”, held in position around the Earth by the force of gravity. The atmosphere helps to support life in 6 ways. It contains the air we breathe; it absorbs harmful UV rays from the sun; it’s thick enough to ensure that most meteorites burn up before reaching Earth; it maintains a cosy surface temperature of 15°C (59°F); and it minimizes the diurnal (day/night) temperature variation. The atmosphere also plays an important role in the carbon cycle, the oxygen cycle and the sulfur cycle, as well as the water cycle, all of which circulate chemicals that are essential to life.

Layers of the Atmosphere: Diagram
Layers of Planet Earth’s Atmosphere from the Troposphere to Outer Space (Exosphere)

Facts About The Atmosphere

Earth’s atmosphere is about 480 km (300 miles) thick and contains five main layers: the troposphere, stratosphere, mesosphere, thermosphere, and exosphere. There is no specific boundary between the atmosphere and “outer space” – the atmospheric gases simply get thinner and thinner until no trace remains. But scientists use an imaginary line about 100 km (62 miles) above the Earth’s surface, called the Karman line, to denote where space begins. Air pressure decreases with altitude. At sea level, it’s about 1 kilogram per square cm (14.7 pounds per square inch). At 3 km (10,000 feet), the air pressure is 0.7 kg per square cm (10 pounds per square inch).

The chemical composition of the atmosphere is: 78 percent nitrogen, 21 percent oxygen, 1 percent argon, 0.04 percent carbon dioxide, together with trace amounts of hydrogen, helium, methane, krypton and neon. It also includes water vapor – on average about 1 percent at sea level. About 90 percent of the gases and other microscopic matter in the atmosphere resides within the first 16 km (10 miles) of the surface.

The Troposphere

The troposphere protects, warms and nourishes the Planet. It’s the lowest layer of the atmosphere, and contains most of its gases and heat, and almost all its weather. For example, it includes nearly all Earth’s clouds, which cover roughly 67 percent of the Earth’s surface at any one time 9 and which reflect about 33 percent of all sunlight back into space. 10

The troposphere is also the site of the greenhouse effect, where greenhouse gases accumulate and intercept heat radiated outwards by the Earth, resulting in higher-than-normal temperatures. Unfortunately, the effects of climate change are being felt very strongly in the troposphere, with knock-on effects across the globe. The troposphere is also a key player in the water cycle, in which moisture evaporates from the ocean and forms clouds, which are then transported by winds across the land masses, which they refresh with their rain.

Facts About The Troposphere 

Earth’s surface is cooler because of clouds than it would be without them. If there were no clouds to reflect sunshine or trap escaping heat, the world would be 5°C warmer. 11 See also: How Do Clouds Affect Climate?

Thanks to the water cycle operating in the troposphere, one billion tons of rain, on average, falls on the earth every single minute. 12 Up to 500 million litres (132 million US gallons) of rain can fall in the course of a single thunderstorm. The heaviest deluge of rainfall in one minute (31.2 mm/ 1.23 inches) occurred on 4 July 1956 at Unionville, Frederick County, Maryland. 13 The largest ever hailstones fell on Vivian, South Dakota on July 23, 2010. Their diameter was officially measured at 20 cm (8.0 inches). 14

About 505,000 cubic kilometres (121,000 cu miles) of water falls as rain each year; 398,000 cubic kilometres (95,000 cu mi) of it over the oceans. Given the Earth’s surface area, this means the global average rainfall is roughly 99 cm (39 inches) per year. 15 The global average rainfall over land is 71.5 cm (28.1 inches) per year. 16

Thanks again to the water cycle – in this case, cloud cover – the two regions with the highest average sunshine are (a) the central and the eastern Sahara Desert, extending across Egypt, Sudan, Libya, Chad, and Niger, and (b) the Southwestern United States (Arizona, California, Nevada). Both areas experience about 3,700-4,000 hours of sunshine per year (10-10.9 hours per day). 17 Areas in the interior of the Arabian Peninsula receive 3,600–3,800 hours of sunshine per year. But the sunniest time and place in the world is Eastern Antarctica, in December, which experiences an average of almost 23 hours of sunshine daily. 18

Conversely, those latitudes above 50° north/south tend to have much cloudier weather, and therefore the lowest values of sunshine duration annually. Examples of such regions include northwestern Europe, the northwestern coast of Canada, and areas of New Zealand’s South Island. The cloudiest areas include parts of Scandinavia, southern Alaska, northern Russia, and around the Sea of Okhotsk. 19 In the United States, the cloudiest place on Planet Earth is Cold Bay, Alaska, which has an average of 354 days of heavy overcast. 20

Local conditions are often important factors in climate. For example, certain low-latitude basins encircled by mountains, such as the Sichuan and Taipei Basins in China, can experience exceptionally low levels of sunshine, as cool air consistently sinks to form fogs that winds are unable to disperse. 21

The Hydrosphere

The hydrosphere is Earth’s water. Water vapor, water in rivers, lakes, plus ocean water and all frozen water. The hydrosphere is a critical component of Earth’s climate system and its water cycle.

For example, the ocean acts as a buffer against climate change by absorbing more than 90 percent of the excess heat in the climate system. 22 It also transfers heat and energy (by evaporation) from the ocean surface to the atmosphere, and from there to different places on the planet. For more about the impact that oceans have on climate, see our in-depth article: How Do Oceans Influence Climate? For more about the impact of climate change on the seas, please see: Effects of Global Warming on the Oceans.

The oceans also supply a wealth of valuable resources. Phytoplankton, for instance, photosynthesize sunlight and dissolved carbon dioxide (CO2) in the water, producing oxygen as a by-product. They are believed to produced up to 85 percent of all the oxygen in the atmosphere. The primary productivity of these marine plants may be threatened by our current climate crisis. See, for example: 7 Effects of Climate Change on Plants.

Phytoplankton, together with zooplankton and shrimp-like crustaceans called krill, also act as the base of the marine food web that feeds most of the fish in the ocean. Through its role in the water cycle, the ocean connects the hydrosphere with five other spheres: namely, the atmosphere, cryosphere (frozen water), pedosphere (soils), lithosphere (rocks) and biosphere (living things).

Interconnection: Hydrosphere, Pedosphere and Lithosphere
Simple Diagram of Planet Earth’s Hydrosphere, Cryosphere, Pedosphere and Lithosphere. Note: the Biosphere (Earth’s “zone of life”) extends to wherever life can be found – in practice, this means from roughly 40,000 feet below the ocean surface to 40,000 feet above sea level.

Facts About the Hydrosphere

The oceans cover 71 percent of the Earth’s surface (361,132,000 sq km/ 139,434,000 sq miles), and contain around 97 percent of all water on Earth. Of the remaining 3 percent or thereabouts, 68.7 percent is found in glaciers and ice sheets; 30.1 percent resides in groundwater; and 1.2 percent divided between permafrost, ground ice, lake and river water, soil moisture, water vapor and wetlands.

These bodies of water harbor an astonishing 97 percent of the Planet’s volcanoes, as well as the “Mid-Ocean Ridge” – the most extensive chain of mountains (and volcanoes) in the world, stretching 65,000 kilometers (40,390 miles) in length. The ridge runs along a fault line – the boundary between divergent tectonic plates – and decorates the ocean floor like seams on a baseball. Most of the ridge line is in deep water, at an average depth of 2,500 meters (8,200 feet) from the surface.

The ridge is created by huge eruptions of molten rock, caused by the separation of the underlying plates. The cooling rock (basalt) forms an irregular mountain scape whose topography varies with the scale and speed of the eruption, as well as how fast the plates are diverging.

Two famous stretches of the mid-ocean ridge are the Mid-Atlantic Ridge, running down the center of the Atlantic Ocean, and the East Pacific Rise, which runs south from the Gulf of California almost to Antarctica. The mid-Atlantic ridge rises above plates that are diverging from each other at about 2.5 cm per year, or 25 km (15.6 miles) every million years. Over the past 100 to 200 million years, this process of separation has caused the Atlantic Ocean to expand from a tiny strip of water between the continents, into the enormous 3,000-mile wide ocean of today.

The Cryosphere

The cryosphere is Planet Earth’s frozen water. It incorporates polar snowfall, glaciers, ice sheets and sea ice in Antarctica and the Arctic Circle, as well as high altitude ice caps and snow cover. The main climate function of the cryosphere is to maintain this reserve of frozen water, which is used to cool the globe through the transfer of cold water via the thermohaline circulation of deep ocean currents. A secondary climate function involves the cryosphere’s albedo effect, which is responsible for reflecting four-fifths of the sunlight it receives, thus reducing the impact of global warming on the Planet.

Facts About The Cryosphere

The length of time an amount of water remains frozen in polar ice or in glaciers, varies widely. Snow cover and freshwater ice are essentially seasonal, as is sea ice, in the Arctic Ocean. However, the same water – when lockeed away in glaciers, polar ice sheets, or ground ice – can stay frozen for anything between 10,000 and 100,000 years or longer. Meantime, deep ice sitting 1.5 miles below the Antarctic ice sheet or the Greenland ice sheet may have an age in excess of 1.5 million years. 23 This ice could provide paleoclimatologists with key data about Earth’s climate and greenhouse gases from the mid-Pleistocene epoch, as far back as 1.5 million years ago.

One critical relationship studied by glaciologists trying to predict sea level rise, is the connection between levels of atmospheric CO2 and sea-level. In one study, scientists based at the National Oceanography Centre Southampton, compared pairs of CO2 level/sea-level recordings taken over the past 40 million years. They found that greenhouse gas concentrations similar to the present (400 parts per million) were associated with sea levels at least nine meters (29 feet) above current levels. 24

The cryosphere is also the scene of one of the worst climate feedbacks – the thawing of sub-surface permafrost in the tundra and taiga of the circumpolar region. It’s a feedback rather than a climate forcing, because it amplifies rather than causes global warming. After three decades of elevated temperatures, followed by several recent heatwaves, the frozen ground is thawing across Siberia and Alaska, releasing considerable amounts of carbon dioxide (CO2) and methane (CH4).

The Pedosphere

The pedosphere is the top layer of Earth’s surface. It includes fine particles of weathered rock, augmented with moisture-retaining humus and other organic debris, known collectively as soil. Soil is where plants establish their roots and it contains zillions of living organisms, such as algae, decomposers like fungi and bacteria, as well as lichens, worms and bugs, all of whom keep it healthy. Which is good news, because without healthy soil, plants can’t photosynthesize, or participate properly in biogeochemical pathways, such as the nitrogen cycle and the phosphorus cycle, to name but two. For more, see our in-depth article: Why is Soil So Important?

The pedosphere also plays an important role in the carbon cycle by storing huge quantities of heat-trapping CO2 in its trees and vegetation 25

Facts About The Pedosphere

There are more microorganisms in a teaspoon of healthy soil than there are people on the planet. 26

Regular tillage (the preparation of soil by digging, stirring, and ploughing) undermines the soil’s structure – the habitat that soil microorganisms depend upon to carry out nutrient cycling and other tasks. Tillage also lowers the soil’s content of organic matter and increases erosion, both of which reduce the sustainability of our agri-food system. 27 Soil erosion in particular is one of the most damaging effects of deforestation around the world.

The most infamous example of runaway soil erosion, was America’s Dust Bowl crisis of 1934, 1936, and 1939–1940, which centered on the panhandles of Texas and Oklahoma. During the 1920s, in an attempt to switch from grazing to more lucrative “cultivated crops”, farmers used their newly acquired farm machinery to plough the virgin topsoil of the Great Plains. In the process, they displaced the indigenous, deep-rooted grasses, that trapped soil and moisture even during periods of low rainfall and high winds.

During the droughts of the 1930s, the soil turned to dust. And because there was no grass to hold it in place, the wind stripped away 75 percent of the desiccated topsoil and scattered it in vast dust storms. In all, some 100 million acres of once-fertile grassland was severely degraded, causing the ruination and displacement of more than a half a million people. Despite this, farmers still rely largely on tillage and (now) chemical pesticides and fertilizers to keep their crops healthy, and in so doing, continue to degrade the soil ecosystem.

Pichavaram mangrove forest in India
Pichavaram mangrove forest is one of the largest mangrove forests in India. Mangroves around the world are being deforested at a worrying rate, with between 30 and 50 percent lost over the past 50 years to agriculture, aquaculture and infrastructure development.

Another cycle of soil degradation and damaging land use is currently taking place throughout the tropical rainforests of Africa and South America, where forest trees and vegetation are slashed and burned to create space for cattle, soybean, and oil palm cultivation. Deforestation has already destroyed much of Africa’s and Sumatra’s rainforests, while deforestation in the Amazon Rainforest is continuing at a rapid pace.

Unfortunately, the soils that support rainforests are often extremely poor. All the nutrients are locked up in the forest trees and plants, so after they are burned and the nutrients from their ashes used up, the smallholders and other farmers are left with completely depleted and unproductive soil. Which is why, after a year or so at the most, they move on to the next patch of forest and repeat the process with the same result. 28  (See also our article: Tree-Planting: Is it the answer to Global Warming?)

The Lithosphere

The lithosphere includes the pedosphere (the outermost layer of Earth’s surface) as well as the Planet’s solid crust. Its regulation of Earth’s climate derives from its role in the slow carbon cycle, in which trees and other plants die but do not fully decay. Instead, their remains are compacted by other falling debris or dead matter, and – over millions of years – become lithified into sedimentary rock. These carbon-rich organic remains are today’s coal deposits. The semi-decayed remains of trees and vegetation that are swept into rivers or inland seas, and then buried in layers of sea-bed sediments, become today’s deposits of petroleum (crude oil and all other derivatives) and natural gas.

Another means of lithification is by chemical weathering of exposed rock surfaces, especially carbonate rocks, which leads to the sequestration of CO2 via the marine calcification process.

By locking up large quantities of CO2 in rocks, the lithification process helps to regulate the greenhouse effect and maintain a stable climate. It also preserves a large stock of CO2 for future use. Sometimes, the CO2 trapped inside rocks is degassed into the atmosphere via volcanic activity, or vented into the ocean via fissures in the ocean floor.

Facts About The Lithosphere

The lithosphere contains a wide variety of elements, metals and chemical compounds that are of special interest to geoscientists. One of them is lithium. Why lithium? Because lithium, sometimes referred to as “white metal” or “white petroleum”, is a key component in energy storage technologies – notably batteries for electric vehicles (EVs), cellphones and other digital devices – and in recent years demand has skyrocketed.

Although lithium is found around the world, it does not naturally occur in a free form due to its high reactivity. 29 Instead, it is mined from pegmatite or recovered from the mineral spodumene. Due to its solubility as an ion, lithium is also obtained from salar brine pools, found below the surface of dried lakebeds known as salars. The resulting lithium chloride is mixed with potassium chloride in a ratio of 55 percent lithium chloride to 45 percent potassium chloride, and electrolyzed. 

At present, the brine process is seen as the most economical and environmentally friendly method of extracting lithium, although new methods of spodumene-processing are narrowing the gap. 30 As of 2019, the world’s top 3 lithium-producing countries were Australia, Chile and Argentina. 31 The border region shared by Chile, Bolivia, and Argentina makes up the area known as the “Lithium Triangle”, which is famous for its high-quality salt flats. The United states and China are also major producers. 32

Paradoxically – given its application in “green vehicles” – lithium mining leads to significant greenhouse gas emissions and has a noticeable impact on the environment. Around 50 percent of lithium production comes from brine extraction while the rest is rock mining, which is even more damaging to the environment. Fortunately, recent studies into electric car production indicate that the higher the demand for new EVs, the more efficient the manufacturing process will become and the less pollution it will generate. In addition, the recycling of these energy storage devices is expected to increase, thereby reducing the need for new mining endeavors. 33

If the successful installation of Tesla’s battery in South Australia is anything to go by 34, lithium batteries are likely to have a key role in shaping the new electric transport system. For example, in 2015, there were three huge lithium factories in the pipeline, with a total capacity of 57 gigawatt hours (GWh). As of 2018, there were 33 such facilities due to come on stream by 2023, with a capacity of 430 GWh globally. And each 20 GWh of capacity needs about 16 thousand tons of lithium. 35

Forecasts in 2019 suggest that by the year 2025, demand for lithium will reach 1.3 million metric tons of LCE (lithium carbonate equivalent) – more than five times today’s levels.

However, even though energy storage is going to be a vital part of our low-carbon future, new technologies will be needed to maximize the use of our limited lithium resources.

Hippopotamus in a crowded pool, Zambia
Hippopotamus Conservation Status: vulnerable species. Seen here are hippos in a pool in Luangwa Valley, Zambia

The Biosphere

The biosphere (ecosphere) is the “living Earth” – the global ecological environment to which rising temperatures now poses an existential threat. Already, a number of Planet Earth’s biomes (e.g. rainforests, Arctic sea ice, tundra and taiga, coral reefs) are threatened, as well as thousands of regional ecosystems, along with habitats and animal species in both hemispheres . If climate change is not brought under control, almost every ecosystem on Earth is likely to suffer drastic change. 36

The last six full years (2014-19) have been the hottest ever, with record-breaking heatwaves in the Arctic, Europe, Australia, the Indian sub-continent and in several oceans. The Australian bushfires provide an object example of what can happen when global warming amplifies other weather systems, in this case the Indian Ocean Dipole and the Southern Annular Mode. 37

Facts about Animal Species in the Biosphere

In order to convey a sense of what’s happening to living creatures as climate change gradually worsens, let’s look at some examples from Britain, based on The State of Nature Report (2019) from the UK’s top conservation bodies. The report says that 15 percent of wildlife species are under threat from extinction, from climate change, pollution, intensive farming, an increase in non-native predators and the destruction of woodlands and wetlands.

Birds have suffered grievously. Barn owls have declined by 66 percent; turtle doves by 95 percent; house sparrows by 90 percent; golden eagles are now extinct. Hedgehog numbers have also plummeted, by 50 percent since 2000, as have numbers of moths (down 25 percent) and butterflies (down 17 percent). Human agriculture remains the No 1 cause of this decline, but global warming and its consequences further exacerbate the situation.

Craig Bennett, CEO of Friends of the Earth, describes the last decade as a disaster for nature. “In my lifetime we’ve seen a 41 percent decline in UK wildlife abundance.” 38

Globally, the biggest impacts from global warming include the relocation of habitats away from the equator, forcing animals and birds to migrate to new areas. Many habitats – such as ice environments in the Antarctic, or forest environments within tropical rainforests – are also shrinking forcing species to compete for scarce food and shelter.

World Population, Food, Energy And Climate

Humans dominate the biosphere – a fact reflected in the recent proposition to rename our era the Anthropocene epoch. As of January 2020, there are 7.7 billion people living on the Planet. 39 By 2100, assuming median estimates of future growth, there will be 9.8 billion by mid-2050 and 11.2 billion by 2100. An increase of 45 percent. 40

According to projections contained in the recent U.N. report “World Population Prospects”, published in 2019:

  • By 2100, five of the world’s 10 largest countries will be in Africa. By then, half of all babies born worldwide will be born in Africa, which will overtake Asia in births by 2060.
  • India will overtake China as the world’s most populous country by 2027. Nigeria will surpass the United States as the third most populous country by 2047. Meanwhile, Africa’s population will increase from 1.3 billion to 4.3 billion by the end of the century.
  • By 2073, there will be more people aged 65+ than under 15. By 2100, the number of those aged 80+ will rise from 146 million to 881 million.

Population growth is the biggest obstacle to climate change mitigation because higher numbers of people means higher food consumption, higher energy consumption and lots more greenhouse gas emissions.

Food Consumption

The consequences of having an extra 3.5 billion mouths to feed will be profound. For example, a recent study predicts that global calorie needs will increase by 80 percent by 2100, 41 while a 50 percent increase in food demand is forecast for 2050. 42 And a significant percentage of the extra calories needed, comes from a rise in calories per person. It must be remembered that consumption of food calories per person worldwide, increased by about one-third during the period 1961-2011, while the average consumption of meat and vegetable oils has more than doubled. 43

The global need for food will inevitably put pressure on governments to create more space for growing crops. If past performance is anything to go by, this means a widespread change of land use to permit the growth of soy, palm oil and other similar products. It means more intensive farming, with more chemical pesticides and fertilizers, which will only add to global warming and the problems it brings.

Energy Consumption

According to researchers, having one extra child can generate an extra 60 tons of CO2 emissions per year. 44 Having billions of extra children raises that emissions figure considerably.

How is the world going to cope with a 45 percent increase in global energy consumption from its extra 3.5 billion inhabitants? How are governments and environmental organizations planning to cope with this issue? It’s the biggest climate issue we face but no one seems to be paying it very much attention – least of all China, India and the United States. Planet Earth deserves better.

Further Reading

“Planet Earth: Facts About Its Orbit, Atmosphere & Size.” Charles Q. Choi. October 10, 2018. Space.com
“Planet Earth, explained.” Michael Greshko. National Geographic.
Sanchez-Lavega, Agustin (2010). An Introduction to Planetary Atmospheres. Taylor & Francis.
Comins, Neil F. (2001). Discovering the Essential Universe (2nd ed.). New York: W. H. Freeman.
The 17 Spheres of Earth.” Earth How. October 6, 2019.
“Troposphere”. Concise Encyclopedia of Science & Technology. McGraw-Hill. 1984.

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