Effects of Global Warming on Earth

We look at 5 major impacts of global warming on the planet. (a) Extreme weather patterns. (b) Damage to the cryosphere. (c) Rising sea levels. (d) Overheating and acidification of the oceans. (e) Loss of biodiversity and other ecological effects, including the consequences for polar bears and penguins.
Bushfires near Canberra, ACT. Wildfires are among the most damaging effects of global warming on Earth.
Wildfires – one of the worst effects of global warming on Earth. Image: Nick-D (CC BY 4.0)

Climate Change Is Affecting Ecosystems Around The World

The effects of global warming are becoming more severe with every passing day and are now felt in every corner of the globe. Already, wildfires have ravaged vast areas of boreal forest across Canada, Alaska and Siberia, as well as large parts of the Amazon rainforest, California, Spain, Greece and, most recently, Australia.

The ice sheets of Greenland and West Antarctica are becoming dangerously unstable, and monster storms have destroyed several Carribean islands. Thousands of birds, insects, polar bears, penguins and other organisms are on the brink of extinction, through increased stress, loss of habitat and lack of food. Already, the rate of sea level rise has doubled since 1990.

The effects of global warming on humans have been profound, with millions displaced by flooding, forest fires and damage to low-lying coastal areas. Other consequences include loss of crops, lack of freshwater supplies and the inevitable spread of disease. The message is clear. Without an effective global climate change mitigation strategy, the damage to Earth’s environment and ecological structure could become irreversible.

NOTE: To understand why governments and corporations are dragging their feet over climate action, please see our article: What is the Root Cause of Climate Change.

How close are we to any tipping points? Nobody knows. This is because the Earth takes time to respond to climatic changes – a phenomenon known as climate inertia – making it difficult to pinpoint the pace and extent of climate change, and how close we might be to any irreversible changes in the planet’s climate system.

Five Major Effects of Global Warming

In this article we examine five particularly harmful consequences of climate change. These are: (a) Extreme weather patterns and events. (b) Damage to the cryosphere – the planet’s supply of frozen water. (c) Rising sea levels. (d) Damage to the ocean, and (e) Loss of biodiversity and other ecological resources.

1. Extreme Weather Patterns

There is clear evidence of rising temperatures across the globe. Furthermore, scientists are now 95 percent certain that this warming is due to human action, namely the burning of massive amounts of fossil fuels – like coal, petroleum and natural gas – causing the unchecked emission of heat-trapping greenhouse gases into the atmosphere. 1

Remaining in the lower atmosphere, or troposphere, these gases trap some of the heat trying to escape from the surface of the planet, and radiate it back down to Earth. This so-called “greenhouse effect” is the reason behind global warming and its calamitous effects. The main greenhouse gas is carbon dioxide, a significant percentage of which can remain active in the troposphere for centuries or even millennia. The present level of CO2, for instance, is the highest for 14 million years. 2

World’s Top 10 Warmest Years (1880–2018)

Chart showing the effects of global warming on Earth - The 10 Hottest Years On Record
Chart showing the world’s hottest years on record. Rising temperatures produce some of the worst effects of global warming on Earth.

Note: Although the U.S. National Climatic Data Center’s temperature record only began in 1880, replication of earlier temperatures indicate that the years listed above may be the warmest for several centuries, or millennia, or even longer.

Where does all the heat from global warming go?
Roughly 93 percent ends up in the oceans. About 3 percent warms the continents and land masses. Another 3 percent melts ice around the world. The final 1 percent remains in the atmosphere. 3

Unpredictable Swings

Global warming upsets Earth’s carbon cycle and climate state – the state of equilibrium that avoids most extremes. Established patterns of precipitation, wind and temperature start to erode, altering the extent of the seasons and upsetting the ecological balance. Floods become more severe, ocean storms become more powerful, while ocean currents and flows become disturbed. In a nutshell, the climate becomes much more unpredictable.

One factor that worsens meteorological and atmospheric unpredictability, is the growing amount of water vapor in the atmosphere, caused by global warming. The warmer the air, the more moisture it can hold

Scorching Ground Temperatures

One of the most measurable effects of global warming is ground level heat. In 2019, a continuous series of unprecedented wildfires ravaged areas throughout northern Russia, Alaska and Greenland, as well as California, Greece, the Iberian Peninsula, Australia and the Amazon rainforest.

Experts at the Copernicus Atmosphere Monitoring Service – run by the European Centre for Medium-Range Weather Forecasts, which provides continuous data on atmospheric composition – pointed to the unusual intensity of these fires, as well as their large area. A critical factor behind the fires was the scorching ground temperature. The month of June 2019, for example, was the Earth’s hottest June since records began. 4(See also: Global Temperature Projections For 2100.)


Droughts are among the most expensive and tragic of natural disasters, with destructive effects on animals’ agricultural communities, ecosystems and biodiversity. But understanding how climate change affects global drought risk has not been easy. It’s true that more greenhouse gas emissions cause air temperatures to rise, causing more moisture to evaporate from lakes and rivers as well as from plant soils. Which also harms plant life so when rainfall does come to drought-stricken areas, the soils are less able to hang on to the water. (See also: Why is Soil So Important to the Planet?)

However, proving a link between global warming and drought has been difficult. Until now. A new study, led by Dr Kate Marvel, a research scientist at Columbia University and the Nasa Goddard Institute for Space Studies (GISS), has finally nailed human activity as a key factor in droughts. The study compared tree ring and meteorological records going back 600-900 years with model simulations of the climate from 1900 to 2100, and found a clear climate-change signal in drought risk, except for the latter part of the 20th century – an anomaly due to aerosol-induced cooling. 5

Using tree rings, ice cores, corals, and sediment records, another recent study reconstructed 800 years of seasonal rainfall patterns across Australia. It revealed that parts of Northern Australia are wetter than at any time in recent history, and that major droughts of the late 20th and early 21st centuries in southern Australia (like the Millennium drought 1997-2009), are unprecedented over the last 400 years. 6

Global Warming Exacerbates Natural Weather Variations

In 2010 and 2011, China and East Asia were hit by severe droughts (and dust storms) that affected tens of millions of people in Yunnan, Guizhou, Guangxi, Sichuan, Shanxi, Henan, Shaanxi, Chongqing, Hebei and Gansu in China, as well as parts of Southeast Asia including Thailand and Vietnam and Thailand. 7

The effects of El Nino, exacerbated by global warming, are believed to have been responsible. The combined phenomenon of El Nino and La Nina is known as El Nino Southern Oscillation (ENSO). CLIVAR (Climate and Ocean: Variability, Predictability and Change), one of the projects run by the World Climate Research Programme is bringing together scientists from around the world to study links between ENSO and global climate change. Michael Jarraud, former secretary-general of the World Meteorological Organization, stressed the importance of this research because of the danger of a combined effect. “This naturally occurring El Nino event and human induced climate change may interact and modify each other in ways we have never before experienced,” he said. 8

The Indian Ocean Dipole is another similar variation in weather that has been exacerbated by rising global temperatures, with severe effects on both the east coast of Africa (floods) and Australia (widespread wildfires). 9

Severe Cyclones, Hurricanes

Global warming is characterized by the introduction of less predictable, increasingly severe weather events, including tropical hurricanes and cyclones. Experts say that meteorological monsters, such as Cyclone Idai (March 2019) and Hurricane Dorian (Aug/Sept 2019), are evidence that the destructive power of storms is likely to increase as the world gets hotter.

According to Dr. Paulo Ceppi, of the Grantham Institute at Imperial College London, “there is a direct link between global warming and cyclone intensity.” Dr Rebecca Emerton, of the National Centre for Atmospheric Science at the University of Reading spoke about the higher incidence of storms: “It has been an active cyclone season in the Indian Ocean this year with seven intense cyclones already, compared to an average usually of three.” 10

2. Damage To The Cryosphere

The cryosphere – the area of Earth’s surface covered by frozen water – includes the continental ice sheets of Greenland and Antarctica, all ice caps, glaciers, and areas of snow and frozen ground (called permafrost). It also includes shelf ice – the bits of continental ice sheets that extend outwards onto the surface of the sea surface – as well as other sea ice, lake and river ice. In all, it adds up to about 30 million cubic km of freezing cold ice.

The cryosphere plays a critically important role in the Earth’s climate, because snow and ice reflect solar energy from the sun back into space, through a process known as the “albedo effect“. (Latin for “whiteness”.) In this way ice and snow help to regulate the planet’s temperature. Any loss of reflective white ice or snow leads to more of the sun’s energy being absorbed by the Earth, which only increases the pace of heating. Furthermore, if land-based ice melts, it leads directly to a rise in sea levels. For more on this, see below.

Greenland Ice Sheet Melting

From 1979 to 2006, summer melting on Greenland’s ice sheet – the world’s second biggest ice sheet after Antarctica – increased by 30 percent, reaching a new high in 2007.

But recently, Greenland’s ice sheet has been melting at record rates in heatwave weather. According to Ruth Mottram of the Danish Meteorological Institute, surface ice declined in July 2019 alone by 197 gigatonnes, equivalent to about 80 million Olympic swimming pools. An additional 65 gigatonnes is likely to have been lost from glaciers and icebergs. These high temperatures are predicted to accelerate the fragmentation of the giant Petermann glacier. Huge chunks of ice – each several kilometers in length – are expected to collapse into the sea over the next 4-5 years. 11

Why does Greenland matter? Because its ice sheet occupies 1.7 million square kilometers (656,000 square miles) – that’s seven times bigger than Florida – and is 2-3 km thick. It holds so much frozen water that if the whole sheet melted, it would raise sea levels around the globe by almost 23 feet.

How fast is Greenland’s ice sheet melting? Since 2002, it has lost almost 4 trillion tonnes of ice. Since 2014, for example, the surface of the Sermilik glacier has lowered by an extraordinary 100m, more than halving in thickness. The pace of warming has been quickened by the growth of tiny algae that appear to flourish in the melting ice. (Note: About 350 billion tonnes of melted ice raises the average ocean level by 1mm.)

One of the scientists studying the ice sheet, Dr Jason Box of the Geological Survey of Denmark and Greenland (GEUS), says he’s unnerved by the possible dangers. “Now that I’m starting to understand more of the consequences, it’s actually keeping me awake at night.” 12

West Antarctic Ice Sheet Melting Fast

In Antarctica, whose ice sheet takes up 14 million square kilometers (5.4 million square miles) – eight times more land-based ice than Greenland – scientists are closely watching the massive Thwaites Glacier (192,000 square kilometers, or roughly the size of Florida) – one of the most unstable glaciers in the West Antarctic ice sheet – because it contains enough ice to increase global sea levels by nearly 2 feet (50cm). 13 A 2014 satellite study of Thwaites Glacier, conducted by the University of Washington, has forecast that it will gradually melt, leading to an irreversible collapse, possibly within the next 200 years. 14

More recently, a Nasa-funded study 15 predicted a probable tipping point for Thwaites after which it would be impossible to stop it flowing into the sea. Alex Robel, the study’s leader, expressed concern that if it became too unstable (because of problems caused by the bedrock topography under the ice) it could be lost in the space of 150 years, even if warming ceased. “It will keep going by itself,” he said.

Other Antarctic glaciers are similarly unstable. Recent studies indicate that the pace of ice loss from five glaciers had doubled in six years and was five times faster than in the 1990s.

In the catastrophic event of a total loss of the entire Antarctic ice sheet, global sea levels are predicted to rise by about 58 meters (190 ft), submerging coastal cities around the world.

A separate study last week found that the amount of sea ice around Antarctica had suffered a “precipitous” decline since 2014. Satellite data showed Antarctica lost as much sea ice over the past 4 years as the Arctic lost in 34 years. 16 (For more, see: Arctic Sea Ice: How fast is it Melting?) Fortunately, unlike the melting of ice on land, sea ice melt doesn’t raise sea levels.

Strangely, Antarctic sea ice had been gradually increasing since about 1975, reaching its maximum extent in 2014, before declining markedly. The reason for the abrupt turnaround remains unknown. 12

Alps Also Shedding Ice

European mountain ice caps are also shrinking. Alpine authorities have warned that the slopes around the Matterhorn’s 4,480-metre peak are becoming increasingly unstable and prone to avalanches because the ice-core is warming. High-altitude lakes of meltwater have also been observed in the Mont Blanc area of France. In Switzerland, alpine glaciers have lost 800 million ton of snow and ice during the last two years, according to glaciologist Matthias Huss. 17

What Is Permafrost? Why Is It Thawing?

Permafrost is defined exclusively by temperature, nothing else. It can comprise 90 percent ice, or virtually no ice at all. It can be covered by 20 feet of snow, or none at all. Permafrost regions occupy roughly 22.79 million square kilometers (about 24 percent of the exposed land surface) of the Northern Hemisphere 18 Permafrost – basically permanently frozen earth – comprises soil, sediment, or rock that remains frozen for a minimum of two years. Its thickness varies from 1 meter to more than 1 km. Some permafrost has been frozen for hundreds of thousands of years.

From Carbon Sink To Carbon Source

Much of the Northern Hemisphere permafrost is overlain by evergreen boreal forest or taiga, a biome characterized by coniferous forests of pines, larches and spruce trees. These forests act as both a source and a sink of carbon. In fact, the region contains almost 33 percent of Earth’s stored soil carbon. In the words of biologist and permafrost specialist Merritt Turetsky of the University of Guelph, in Ontario, “the region is a vast, global refrigerator for carbon that has been stockpiled from the atmosphere.”

If this area were to experience a significant temperature increase – and during 2019 it did – the soils would start releasing carbon into the atmosphere, which would lead to greater concentrations of CO2 followed by higher temperatures, driving the cycle of carbon release and further warming. 19 20 21

Carbon Dioxide And Methane

In addition to carbon dioxide, the thawing of permafrost also releases methane into the atmosphere. These emission processes are fairly complicated. Permafrost contains the carbon-rich residues of plants and fungi, as well as animals, that froze before they could properly decompose. As this frozen material thaws, it resumes decomposition. If oxygen is present during this process, carbon dioxide is emitted as a by-product. If no oxygen is present because (say) the decomposition takes place in water or underground, methane is emitted. Some of this is converted to CO2 by methanotrophic bacteria. The rest finds its way into the atmosphere. These emissions of CO2 and methane are already well under way and cannot really be controlled by human intervention. (See also; Why are Methane Levels Rising?)

Scientists believe that the world’s permafrost stores about 1,500 billion tons of carbon – double the amount that is in the atmosphere. Unfortunately, as permafrost warms and thaws, it releases carbon dioxide and methane into the air. As the global thermostat rises, instead of storing carbon, permafrost will become a major source of greenhouse gas emissions. And once the thaw starts in earnest it could trigger an irreversible, runaway process of global warming.

Rapid Thawing

Reports from Canada, Alaska and Russia suggest that thawing is already under way. Communities throughout the region have been recording lopsided homes and crumbling roads for years – in parts of Alaska, thawing permafrost has caused the ground to subside more than 15 feet (4.6 meters) 22 – as well as the “big soupy mess” that thawing leaves in its wake.

A new feature of 2019 was the large numbers of wildfires that swept the region. They included slow-moving fires characterized by flameless smouldering combustion, which persist for longer during cold and wet conditions because the peat soil contains huge stores of the combustible gas methane. These Arctic fires represent a much greater threat to climate change since they burn for longer, and so transfer heat deeper into the soil, burning twice as much carbon-rich earth as normal fires. 23

3. Rising Sea Levels: One of the Most Alarming Effects of Global Warming

One of the biggest threats of climate change to human society is a sea level rise that submerges low-lying coastal cities. So how does global warming affect sea levels? By doing three things:

(1) By raising the temperature of the ocean, causing the seawater to expand – a process known as thermal expansion. (2) By melting the polar ice sheets in the Arctic (Greenland) and the Antarctic. (3) By melting the ice in some of the world’s 200,000 glaciers.

Analysts estimate that during the period 1993-2018, these factors have contributed to sea level rise as follows: thermal expansion 42 percent; glacier melt 21 percent; Greenland ice sheet, 15 percent; and Antarctica, 8 percent. 24

How Fast Are Sea Levels Rising? 

Average sea level rose by about 20 centimeters (8 inches) in the last century. However, the rate in the last two decades is nearly double that, and the rate is accelerating every year. 25 Moreover, as climate research leads to improved computer models, projections of sea level rise have continually increased. 26

How High Can Sea Levels Go?

The IPCC’s Fifth Assessment report projected a rise of up to 90 cm (3 feet). According to NASA, levels are projected to rise by another 1-4 feet by 2100. 27 Several later studies have stated that a global average sea level rise of 200-270 cm (6.5 to 9 feet) this century, is plausible. 28

If Sea Levels Rise What Will Happen?

Sea levels will impact severely on human populations in coastal and island regions, causing widespread flooding, especially if aggravated by storm surges and high tides. Other potential effects are loss of agricultural land and urban disruption. Rising levels of saline seawater will also contaminate wetlands and aquifers, and degrade habitats for birds and plants. 29

Everything depends on how high temperatures go. If warming ever reached 4°C, for instance, the impact on low-lying cities could be catastrophic.

Why Is West Antarctica The Biggest Danger For Sea Level Rise? 

Antarctica is a huge landmass – about half the size of the African continent – and holds enough ice to raise sea levels by 58.3 meters (190 feet). 30 East Antarctica is relatively solid, but the effects of global warming on West Antarctica – notably its two largest and fastest-melting glaciers, Pine Island and Thwaites – is much more visible.

Recent studies by scientists Robert DeConto and David Pollard 31 into marine ice-cliff instability have led scientists to examine more pessimistic projections. Instead of a 1-4 feet increase in ocean levels by the end of the century, six feet is more probable, according to DeConto and Pollard’s findings. If carbon emissions continue to rise, then under certain conditions the total 11 feet of ice locked up in West Antarctica might be released, their study showed. 32 33

4. Overheating & Acidification Of The Oceans

The effects of global warming on oceans are not yet fully understood. This is due to marine climate inertia – the delayed response of the oceans to climate change. Oceans play a critical role in Earth’s increasingly fragile climate system. To begin with, they absorb a huge amount of surplus heat from the air, becoming warmer in the process. Second, they act as “carbon sinks” (natural stores of carbon) absorbing excess amounts of CO2 from the atmosphere. When CO2 dissolves in the ocean, it forms carbonic acid and raises the water’s acidity level. With the huge rise in man-made greenhouse gas emissions over the past century, the oceans have been unable to cope with the corresponding rise in acidification.

These two processes, warming and acidification, are proving fatal for reef-building corals, one of the first marine ecosystems to suffer from human-induced climate change.

To begin with, when water is too warm, corals become stressed and react by expelling the special type of algae (zooxanthellae) which lives inside their tissues. These algae provide the corals with their rainbow colours, along with an effortless food supply thanks to photosynthesis, which gives corals the strength to grow and reproduce. After evicting the algae, the corals lose all their colour and become completely white – a process known as “coral bleaching”. It is not automatically fatal to the corals, but without the algae they become even more stressed and many starve. 

At the same time, the increase in ocean acidity prevents the take-up of calcium carbonate that corals need in order to build their skeletons. But studies show that calcium take-up is severely reduced when pH levels are low, preventing corals from calcifying properly. 34

What Percentage Of Coral Reefs Will Die Because Of Global Warming?

Loss of coral ecosystems is one of the most destructive effects of global warming on marine life. According to the IPCC’s Special Report on Global Warming of 1.5°C, between 70 percent and 90 percent of coral reefs are likely to die if the temperature increase reaches 1.5°C. If global warming reaches 2°C, 99 percent are likely to die.

Coral reefs form the most diverse habitat and marine ecosystem in the ocean, supporting 1 in 4 of all marine species. Their survival is also vital to the survival of thousands of other marine species – many of which we rely upon for food. The reefs also provide a livelihood for as many as 500 million people around the world.

5. Loss of Biodiversity and other Ecological Effects of Global Warming

Migration And Extinction Of Species

  • According to the latest climate models, the effects of climate change on animals and their habitats are expected to be profound and widespread, causing a disastrous loss of biodiversity due to ecosystem damage. According to a report from National Geographic, many species of plants, animals, insects, birds, fish and other organisms are already moving their range northward or to higher altitudes due to the increase in temperature, and other related effects of global warming. An analysis of more than 4,000 species from around the globe shows that roughly 50 percent are on the move. Some individual species are migrating rapidly. Atlantic cod and Europe’s purple emperor butterfly, for example, moved more than 125 miles in a single decade. 35
  • Unfortunately, many animals will not be able to survive in their new ecosystem and may go extinct. In a report by Stanford University researcher Dennis Murphy, on the ecology of the Great Basin Mountains in the western United States, Murphy calculated that 44 percent of the mammal species, 23 percent of butterflies and a smaller percentage of bird species, would disappear in the event of a 3°C rise in global temperature. 36
  • One of the problems facing birds and insects, involves phenology, the impact of climate on the life cycle events of plants and animals. Many species are showing changes, such as earlier onset of migration, egg-laying and breeding. According to the U.S. Environmental Protection Agency, migratory birds and insects are now arriving in their summer feeding and nesting habitats several days or weeks earlier than they used to back in the 20th century. In the UK, for instance, butterflies are now appearing on average 6 days earlier (in spring) than they did in the 1990s. 37
  • As reported in the journal Climatic Change, NASA scientists noticed the exact same migration away from the equator. Researchers observed a shift of biomes away from the equator towards the poles or higher elevations. Ecologically sensitive “hotspots” – that is, areas projected to witness the greatest turnover of species – included the Himalayan bioregion, eastern equatorial Africa and southern South America, as well as North America’s Great Lakes and Great Plains areas. In addition, the study forecast that global warming will disrupt the ecological balance, reduce biodiversity and adversely impact Earth’s water, energy, carbon and other cycles. 38
  • Forests will be especially hard hit as climate zones spread out from the equator, since trees will find themselves rooted to an environment for which they are no longer adapted. Comparatively small increases in temperature could see the death of large areas of forest. For example, the decline in numbers of red spruce trees in the eastern United States has already been attributed to the effects of global warming. Other trees, like the eastern hemlock, yellow birch, sugar maple and beech are similarly at risk if CO2 greenhouse gas emissions continue to increase. 39 See also: 7 Effects of Climate Change on Plants and Trees.
  • On the West coast, half the lodgepole pines in a 33 million-acre stretch of pine forest in British Columbia, have been severely hit by a beetle infestation, which has gone unchecked since 1998, due to the unseasonal warmth of the area. In previous years a short spell of icy weather would have killed off all the beetles. 40
  • The IPCC’s Fourth Assessment Report (2007) estimated that approximately 1 in 10 of species are at an increasingly high risk of extinction for every 1°C rise in global average temperature. Those ecosystems particularly affected by climate change include aquatic freshwater habitats and wetlands, tropical mangroves, coral reefs, arctic and alpine habitats, and cloud forests. Montane species and endemic species have been identified as being particularly at risk because of narrower climatic and physical ranges, but all terrestrial ecoregions are affected. 41
  • The effects of global warming are felt particularly strongly by the coral kingdom. According to the IPCC, a warming of 2°C (above 1900 levels) will result in the mass extinction of coral reefs; a warming of 3°C (above the 1990 level) by 2100 was likely to transform global vegetation into a net source of carbon; a 4°C increase in global mean temperature was highly likely to trigger the extinction of many freshwater species, as well as other major extinctions around the globe. 42
  • Reviewing the data concerning the link between Earth climate and extinctions over the past 520 million years, researchers from York University, England, concluded that the temperatures predicted for the planet in the coming centuries might plausibly trigger a new “mass extinction event”, during which over half of all animal and plant species would be wiped out.”43
  • The IPCC’s Fifth Assessment Report (2014) was no less pessimistic and warned of the risk to biodiversity and ecological habitats, as follows: “A large fraction of both terrestrial and freshwater species faces an increased risk of extinction under projected climate change during and beyond the 21st century, especially where climate change interacts with other stressors, such as habitat modification, over-exploitation, pollution, and invasive species (high confidence).”

Effects of Climate Change on Polar bears & Penguins

Will Climate Change Harm Polar Bears?

Sadly, Yes. One of the effects of global warming is that Arctic temperatures are rising twice as fast as the global average and sea ice cover is diminishing by almost four per cent per decade. As far as polar bear survival is concerned, research shows that it’s the loss of sea ice that is critical.

Polar bears feed on ringed and bearded seals that live at the ice edge, obtaining two thirds of the energy they need for the entire year during late spring and early summer. With the ice retreating earlier in spring and forming later in winter, polar bears have less opportunity to hunt prey and have to survive without food for longer. This lack of calories and nourishment weakens their physique and produces lower average weight in adult females. Fewer bear cubs survive and those that do are smaller, research indicates.

Less sea-ice also forces bears to swim longer distances, which depletes their energy stores further and can lead to drowning. Changes in sea ice also undermine the efforts of pregnant females to build suitable maternity dens.

Incidents and interactions between humans and bears – including, no doubt, fatal attacks on humans, are almost certain to increase as the ice retreats even further compelling hungry bears to search for prey on land.

According to Professor Andrew Derocher, a specialist in polar bear ecology and conservation at the University of Alberta: “Without sea ice, there is no sea ice ecosystem and losing that ecosystem includes losing polar bears.”

It is difficult to estimate the number of polar bears in existence, since they have been poorly documented as a species. However, biologists roughly estimate a global bear population of between 20,000 and 30,000. 44

The International Union for Conservation of Nature, Arctic Climate Impact Assessment and many polar bear biologists have voiced serious concerns about the impact of global warming on bear habitats, warning that climate change is a major threat to the survival of the polar bear. 45 46 In September 2015, due to growing concern, the United States, Canada, Norway, Greenland and Russia all signed a Circumpolar Action Plan (CAP), designed to strengthen international cooperation on the issue of polar bear conservation. 

Will Climate Change Harm Penguins?

The Antarctic continent is warming as a whole, and nowhere faster than along the western Antarctic Peninsula, where sea ice is shrinking in size, harming Emperor penguin chicks and adults. 47 Emperor penguins (Aptenodytes forsteri) rear their chicks on land-locked sea ice, so if sea ice fragments before their chicks have grown their waterproof feathers, the latter will die of exposure in the water. For adult Emperor penguins, the loss of sea ice results in less food availability, which can result in weakness and an increased mortality rate. 48

Another Antarctic penguin damaged by the effects of global warming is the Adélie penguin (Pygoscelis adeliae). Unlike the Emperor penguin, the Adélie does not raise its chicks out on the sea ice. Instead, it makes a nest out of pebbles on the sparse Antarctic foreshores that are free of ice and snow. 49 In western Antarctic, warmer temperatures causes higher humidity resulting in more snowfall in the region. Adélie penguin populations are thus under threat as they are increasingly unable to find snow-free ground for nesting. The reduction in winter sea ice in this area is also impacting the Adélie’s food supply.

According to one study, a temperature increase of 1.3°C (due by about 2040) will endanger 40 percent of the world’s Emperor penguins and 70 percent of the world’s Adélie penguins – largely because of diminishing sea ice. 50 Researchers also forecast that the disappearance of sea-ice will push the Emperor penguin colony that featured in “March of the Penguins” close to extinction by 2100. 51

For the penguins that inhabit the Southern Ocean, which encircles Antarctica, climate change is also becoming a major problem. On the Atlantic side of the Southern Ocean, ocean warming and the ice-melt are both linked to the decline of krill, the penguins’ principal food supply. Krill have declined by as much as 80 percent since the 1970s. 52 Krill feed on algae growing under the sea ice, thus the loss of ice results in fewer krill. Scientists predict that a 1°C rise in sea temperature in this region could trigger a further 95 percent loss of krill. Such a blow to the food supply would be catastrophic for penguins like the Macaroni, which has already suffered a 50 percent collapse in numbers at its main breeding site on South Georgia. 53

Two recent investigations by the Woods Hole Oceanographic Institution both examined the effects of global warming on the Emperor penguin.

The first – based on a mathematical model that calculated how the loss of sea ice would affect a big colony of emperor penguins at Terre Adélie, Antarctica – found that emperor penguins could find themselves on the brink of extinction by the year 2100 due to global climate change. The study projected an 87 percent decline in the colony’s population, from three thousand breeding pairs in 2009 to four hundred breeding pairs in 2100. 54

The second study confirmed that Emperor penguins were at risk from climate change, due to melting sea ice. This study projected that by 2100 all 45 colonies of Emperor penguins will be declining in numbers, due to loss of krill and loss of their sea ice habitat. Loss of ice reduces the supply of krill, which is a primary food for emperor penguins. 55

For more about how to reconcile human rights and animal rights, as well as several other ethical issues, see our article on the ethics of climate change.

Effects of Global Warming: Conclusion

The effects of global warming on Planet Earth, are now widespread, well documented and undeniable. The climate science may not yet be fully understood but ongoing research enhanced by satellite technologies is highlighting a clear trend – and it looks scary. Unless we make deep cuts in our consumption of coal and petroleum and natural gas, thus reducing our greenhouse gas emissions, our planet may not be habitable for much longer.

For the sad story of international efforts to resolve the climate crisis, see: UN Climate Talks & Timeline.

Frequently Asked Questions About Our Climate Crisis

For answers to popular questions on all aspects of our ailing climate system, please see: 50 Climate Change FAQs, and 50 FAQs About Global Warming.


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