Global Warming: The Scientific Facts

We explain the science behind man-made global warming, and explain what makes it so different from other episodes of climate change. We examine its causes, as well as its effects, and what we can do to stop it.
Rising temperatures due to global warming are causing wildfires around the world
Bushfires in Steels Creek, Victoria, Australia. Photo: CC BY 3.0

‘Global warming’ refers to the continuing rise in the temperature of the Earth’s surface and atmosphere, caused largely by man-made emissions of greenhouse gases (like carbon dioxide), from the combustion of fossil fuels (like coal, oil or natural gas). 1 See also: 50 FAQs About Global Warming and 50 Climate Change FAQs.

The term was first coined in 1975 by the American geophysicist Wallace Smith Broecker (1931-2019), in his report “Climate Change: Are We on the Brink of a Pronounced Global Warming?”, although it is now most often used to describe the dramatic increase in Earth’s temperature which has occurred since the 1970s.

Average global temperature has already increased by more than 1°C (1.8°F) since the pre-industrial era (defined by the IPCC as the latter half of the 19th century) 2 while the rate of warming has nearly doubled since 1975.

The main effects of a warmer planet include: extreme weather events, melting polar ice, rising sea-levels, and damage to Earth’s ecological systems, including loss of wildlife species due to loss of habitat. 3

Earth's Global Average Temperature Chart: Since 1880. Clear evidence of global warming.
Global mean surface temperatures since 1880. Source: NASA

Rising Temperatures

  • The five hottest years have all occurred since 2014.
  • Twenty of the 21 hottest years in NASA’s 134-year history of record-keeping have occurred since 2001. 4
  • So far, the year 2016 is the hottest on record. 5
  • The planet’s average surface temperature has increased by about 2.0°F (1.1°C) since the late 19th century. This increase is mostly due to man-made emissions of carbon dioxide (CO2) and other greenhouse gases accumulating in the lower atmosphere. 5
Cracked bed of Lake Hume, NSW, Australia in the 2007 drought. Global warming is intensifying droughts.
Cracked bed of Lake Hume, NSW, Australia during the 2007 drought. Image suburbanbloke (CC BY 2.0)

In 2018, in order to avoid the worst environmental disaster scenarios, the Intergovernmental Panel on Climate Change’s Special Report on Global warming of 1.5 °C recommended that the rise in temperature be kept below 1.5° Celsius, this century. This requires a 45 percent reduction in carbon dioxide emissions by 2030, reaching “net zero” about 2050. 6 Without such corrective action, some climate models are predicting that a warming of 4°C could occur as early as the 2060s. 7 According to the World Bank, a 4°C rise in world temperature could cause catastrophic damage to the planet, including:

  • The submergence of many islands and coastal cities.
  • Dangerous heat waves and other extreme weather events in many regions.
  • Glacier shrinkage as well as the disappearance of polar ice.
  • Irreversible loss of species and animal habitat, including all coral reefs.

Is It Too Late To Stop?

Some research suggests that we may already be too late. A United Nations Environment Program (UNEP) polar study shows that a tipping point may have already been reached, initiating an irreversible melting of the Greenland and Antarctic ice sheets and an accelerated rise in sea levels around the world. 8 9

Is Global Warming Real?

The Climate Change Denial machine says that the world has warmed and cooled quite often over the centuries, that the recent episode of global warming is merely part of that naturally occurring pattern, and therefore there is nothing to be worried about. Is this true?

No. Absolutely not. The Earth warming we are now experiencing is totally unique. It has never happened in this way before. This is the view of the United Nations Framework Convention on Climate Change (UNFCCC), and the Intergovernmental Panel on Climate Change (IPCC), as well as the vast majority of climate scientists throughout the world. 10 11In fact, scientists are now openly warning of a Climate Emergency. 12

IPCC Climate Science Assessment Reports

Every 6 years or so, the IPCC produces an Assessment Report on the state of climate change and what climate change mitigation is needed. The report is compiled by the top 150 scientists (or thereabouts) in climate related disciplines, and is viewed by the United Nations and most governments as the authoritative statement on Earth’s climate. 

The IPCC’s latest Assessment Report (2014) states that climate change is taking place at a rate unprecedented in history, and it is 95-100 percent certain that human influence has been the dominant cause since 1950. This assessment was the scientific basis for the Paris Climate Agreement held in 2015.

What Do Experts In The United States Say About Global Warming?

Nearly all environment experts in the U.S. Administration are in full agreement with the unprecedented nature of our climate crisis. Back in 2009, the U.S. National Oceanic and Atmospheric Administration (NOAA) issued a report confirming ten unmistakable signs of global warming: 13

(A) Warming of lower atmosphere. (B) Higher air temperatures over land. (C) Higher air temperatures over the oceans. (D) Glacier melting. (E) Shrinking sea ice. (F) Less snow cover. (G) Rise in sea levels. (H) Higher ocean temperatures. (I) Rising sea surface temperatures. (J) Increasing humidity.

In a recent 500-page environmental impact statement (2018), the U.S. National Highway Traffic Safety Administration (NHTSA) forecast a rise in global temperature of roughly 4 degrees Celsius (7 degrees Fahrenheit) above the mean temperature of the period 1986-2005. Such a rise would be an unprecedented event in environmental history, over the past 2,000 years. 14

What Makes Today’s Global Warming So Different?

It is important to recognize that the current climate crisis is fundamentally different from the weather fluctuations of the past 2,000 years. Whereas before 1750 climate changes were regional and influenced mostly by volcanoes, today’s changes are global and are caused by man-made emissions of greenhouse gases warming up the atmosphere.

Three recent studies demonstrate how different today’s global warming is. Researchers replayed the climate conditions that existed over the past 2,000 years using 700 measurements of temperature changes, like tree rings, corals and lake sediments. Special attention was given to significant peaks and troughs, including the “Roman Warm Period” (250-400 AD), the “Medieval Warm Period” (950-1250 AD) and the intermittent cooling/warming periods during which overall temperatures declined (1300-1850). They found conclusive evidence that none of these earlier climatic events occurred on a global scale. Any significant peaks or troughs in temperature occurred in less than half the globe at any one time. 15 16 17

Today’s global warming, by contrast, is a worldwide event. Indeed, for 98 percent of the globe, the reports say, the warmest period of the past two millennia is the period from 1900 onwards. In this connection, read our article: When Did Global Warming Start?

The causes of global warming are gradually becoming clearer – due largely to increased research budgets and more accurate climate models, supported by more precise data from Earth-orbiting satellites and other technologies. But solutions remain elusive.

In order to eliminate CO2 emissions by 2050, as per IPCC recommendations, fossil fuel consumption must be slashed and replaced by renewable energy. But with global population due to nudge 11 billion by the end of the century – an increase of 3.5 billion on current figures – it is hard to see how a combination of energy conservation and ‘clean’ fuel is going to meet the energy needs of the world in 2100.

When Did Scientists Realize That The World Was Getting Warmer?

Climatology did not really take off as a scientific discipline until the 1970s. The lack of reliable data made climate analysis a matter of guesswork. Thus despite the efforts of individual scientists – such as the French mathematician and physicist Jean-Baptiste Joseph Fourier (1768-1830), who determined that Planet Earth would be much colder if it had no atmosphere; or the Swedish Nobel prize-winner for Chemistry Svante August Arrhenius (1859-1927), who concluded that man-made emissions of carbon would eventually lead to global warming, albeit after thousands of years – it wasn’t until the advent of computers and satellites during the 1970s that scientists were able to generate precise global data and produce climate models of any real accuracy.

It was during this decade that scientists first began to amass firm evidence that the world was rapidly getting hotter. As well as Broecker’s seminal book, the 70s saw the publication of “Man-made Carbon Dioxide and the ‘Greenhouse’ Effect” by British meteorologist John Sawyer (1916-2000). The technological advances of the 70s coincided with an upward trend in the temperature of the planet that continues to this day: a trend which is now continuously monitored and analyzed around the clock by a host of satellites, supercomputers and research bodies. In addition, recent record-breaking temperatures, extreme weather events along with their localised consequences (forest fires, drought, ice melt), along with dangerously high levels of urban air pollution in cities around the world, have lent a sense of urgency to efforts by the United Nations, the EU and also individual governments to come to terms with the planet’s climate emergency.

What’s The Evidence?

Over the past 45 years, climate scientists have recorded millions of measurements via Earth-orbiting satellites, land stations, weather balloons and ships. After careful analysis of these signals, independent teams of scientists have concluded unanimously that average global temperature has risen by about 1°C (1.8°F) since the period 1850-1900 (the pre-industrial baseline). According to NASA’s Goddard Institute for Space Studies, the Earth’s mean surface temperature has increased by roughly 1.1 degrees Celsius (2.0 degrees Fahrenheit) since the late 19th century. 5 More disturbingly, the evidence shows that the speed of warming has accelerated rapidly since 1975, and continues to do so. The evidence for rapid climate change is now universal and undeniable.

The Oceans are Getting Hotter

Scientists have established that the top 700 meters (2,300 feet) of ocean water have heated up by more than 0.4°F since 1969. The oceans are absorbing approximately 90 percent of the heat trapped by our carbon emissions. If all the heat absorbed by the oceans from 1955 onwards was suddenly added to the atmosphere, air temperatures would skyrocket by more than 60°F. In 2018 the top section of the ocean, down to 6,500 feet, increased in temperature by just over one tenth of a degree Celsius. For more, see: Effects of Global Warming on the Oceans.

10 signs that the world is heating up: infographic
Source: NOAA

Arctic Sea Ice is Shrinking

Arctic sea ice is now declining at a rate of nearly 13 percent per decade (compared to the 1981-2010 average). The twelve lowest ice extents have all occurred since 2007.

The Ice Sheets are Getting Smaller

The Greenland ice sheet is shrinking rapidly. According to a new study published in Nature, Greenland lost 3.8 trillion tons of ice between 1992 and 2018. What’s more, the rate of loss has risen from 33 billion tonnes a year in the 1990s, to 254 billion tonnes a year in the past decade. 18

The West Antarctic and East Antarctic ice sheets are also shrinking faster than believed. Overall, between 1992 and 2017, the Antarctic ice sheet lost 2.7 trillion tonnes of ice. That’s according to a new climate study funded by NASA and the European Space Agency – the Ice Sheet Mass Balance Inter-comparison Exercise (IMBIE) – drawing on 24 satellite surveys of Antarctica and involving 80 scientists from 42 international organizations. 19

In another study, glaciologists from the University of California, Netherlands’ Utrecht University, and NASA’s Jet Propulsion Laboratory found that Antarctica suffered a sixfold increase in annual ice mass loss between 1979 and 2017. 20

Glaciers are Retreating

Glaciers are in retreat almost everywhere around the world — including in the Alps, Himalayas, Andes and Rockies. 21

Sea Levels are Rising

Global sea level rose about 20 centimeters (8 inches) in the last century. The rate in the last two decades, however, is nearly double that of the last century and the rate is accelerating every year. 22

According to the recent IPCC Special Report on the Ocean and Cryosphere in a Changing Climate (2019), global sea level is expected to rise by the end of this century by 0.43 meters (1.4 feet) under a low emissions scenario, and by 0.84 meters (2.8 feet) under a high emissions scenario.

However, the IPCC raised its worst-case maximum (above its previous worst-case in its Fifth Assessment Report 2013) by about 10 cm, to 110 cm (43 inches). In addition, it conceded that the rate of sea level rise is “unprecedented” over the past century and that, if fossil fuel emissions continue on their present path, then a rise of 2 meters (6.5 feet) by 2100 “cannot be ruled out.” Much of this concern is based on new research into the stability of the West Antarctica Ice sheet. 23

What Are The Causes Of Global Warming?

Warming occurs when greenhouse gases (GHGs) build up in the atmosphere trapping the solar heat and radiation given off by the Earth’s surface. This process is known as the “Greenhouse Effect” because the atmospheric gases keep heat from escaping, just like the glass walls of a greenhouse. For many thousands of years this mechanism has worked well. Levels of GHGs remained fairly constant, as did average global temperatures. However, over the last fifty years or so this beneficial mechanism has started to break down because of a rapid increase in man-made GHGs, causing a surge in temperature.

The Greenhouse Effect

To understand what’s happening it’s worth taking a closer look at the greenhouse effect in operation. It works like this: (1) Sunlight beams down onto Earth. (2) Some of it is immediately reflected back into space by reflective surfaces like ice and clouds, while the rest is absorbed by the Earth’s surface. (3) Some of this absorbed solar energy is then released (in the form of heat) back up into the atmosphere, where about 90 percent is absorbed by the various GHGs and the remaining 10 percent escapes into space.

Overview of U.S. Greenhouse Gas Emissions

Greenhouse gas emissions 2020 by type of gas.
Greenhouse gas emissions by type of gas. Total Emissions in 2018 = 6,677 Million Metric Tons of CO2 equivalent. Source: U.S. Environmental Protection Agency, 2020

What Are The Most Common Greenhouse Gases?

The most abundant GHGs in Earth’s atmosphere are water vapor, carbon dioxide, methane, fluorinated gases, ozone and nitrous oxide, of which water vapor and ozone are almost entirely natural in origin. The others, being man-made, are the chief causes of our climate problem, and it is these that need to be eliminated. The IPCC’s Fourth Assessment Report (2007), for example, concluded that increases in anthropogenic greenhouse gas concentrations are “very likely to have caused most of the increases in global average temperatures since the mid-20th century.”

Globally, man-made greenhouse gas emissions break down as follows: carbon dioxide 72.6 percent; methane 18.7 percent; nitrous oxide 5.4 percent; fluorinated gases 3.3 percent. (Source: UN Emissions Gap Report 2020.)

In the United States, the latest breakdown is: Carbon dioxide 82 percent; Methane 10 percent; Nitrous Oxide 6 percent; Fluorinated Gases 3 percent. (Source: “Overview of Greenhouse Gases 2020.”

Global Warming Potential of Greenhouse Gases

Greenhouse gases vary enormously in their heat-trapping capacity and in the length of time they remain in the atmosphere. To facilitate comparisons, scientists have given each gas a so-called ‘global warming potential‘ (GWP), which is a measurement of its effect in comparison to carbon dioxide.

Where Do Greenhouse Gases Come From?

Fossil fuels. More than three quarters of all greenhouse gas emissions come from the burning of fossil fuels – like petroleum (oil), coal, its precursor peat, and natural gas – chiefly from coal-burning power stations and from motor vehicles and other types of engines used in the transportation industry. 24 Cement manufacture is a particularly heavy producer of CO2 emissions, contributing roughly 8 percent of all CO2 emissions. 25 Wood burning is another source of CO2 emissions.

For roughly 10,000 years up until about 1800, levels of carbon dioxide in the atmosphere stayed in the range of 260-280 ppm (parts per million). Since then it has increased by almost 50 percent with half this rise occurring since 1970. The average concentration of CO2 measured at the Mauna Loa Observatory in Hawaii has risen from 316 ppm in 1959 to 396 ppm in 2013 – and in May 2019 topped 415 ppm. 26

Paleoclimatologists continue to investigate historical levels of carbon dioxide, so the picture will no doubt continue to evolve. For instance, according to one prestigious study which studied core samples covering a period of 40 million years, today’s level of 415ppm is the highest for 14 million years. 27

Why Do Some People Still Deny Climate Change?
People adopt unusual or extreme viewpoints for many reasons, including financial self-interest, a desire to stand out, lack of knowledge and so on. There are some perfectly normal people who still believe the Earth is flat, or that Neil Armstrong never landed on the moon, or that the U.S. government was responsible for 9/11. Don’t bother trying to persuade climate deniers that they are wrong. If 97 percent of scientists who study and report on climate can’t convince them, they won’t be changing their mind anytime soon. That said, a recent study suggests that discussing global warming leads to a greater acceptance of climate science. 28


Another important cause of climate warming is man-made deforestation and tree-clearing. This is because trees and plants play a vital role in regulating the climate as they soak up carbon dioxide from the air during photosynthesis. (They currently absorb about one quarter of the CO2 that humans add to the atmosphere.) It’s true that they also emit some CO2 back into the air during respiration, but overall they absorb more CO2 than they emit.

Unfortunately, every year humans clear about 18.7 million acres of forest around the world for intensive farming or for urban and infrastructure development. This deforestation is a double whammy because it transforms a carbon-removing environment into a carbon-emitting environment. The point is, when forest biomass is removed or burnt, the stored carbon is released back into the atmosphere as CO2, contributing to global warming. An estimated 9-10 percent of global greenhouse gas pollution is caused by deforestation and forest degradation. This percentage has decreased slightly in recent years due to the faster growth of fossil fuel emissions. Some 80 percent of forest clearance is driven by investment in agriculture, including plantations for higher value crops such as coffee, tea, palm oil and rubber, and the like. The logging industry, responsible for harvesting almost 10 million acres of timber a year, is another contributor.


Along with fossil fuels and deforestation, livestock farming is the third major cause of global warming due to its production of methane (CH4). Methane is produced by domestic livestock including cattle, pigs, sheep, and goats as part of their normal digestive process. These animal-derived emissions are the largest source of CH4 emissions in America. Although there is far less methane in the atmosphere than CO2, CH4 can soak up 25 times more heat in the atmosphere over a 100-year period. Agriculture also produces significant emissions of nitrous oxide (N2O), an even more powerful greenhouse gas than methane.

Latest Figures On Greenhouse Gas Emissions

The latest figures on global greenhouse gas emissions – for the year 2020 – are as follows: total emissions were 59.1 GtCO2e (billion tons of CO2 equivalent), of which 6.8 GtCO2 came from deforestation and land use. Of the remainder, 38.0 GtCO2 came from fossil fuels and industry; 9.8 GtCO2e came from man-made methane emissions; 2.8 GtCO2e came from man-made nitrous oxide; and 1.7 GtCO2e came from fluorinated gases. (Note: like most statistics on GHG emissions, these are approximate figures only. Source: UN Emissions Gap Report 2020.) See also: Greenhouse Gas Statistics Lack Consistency.

Solar Energy And Volcanoes

Two final factors include variations in sunlight, and volcanic activity, neither of which makes much of a contribution to today’s climate change. The amount of solar energy received by the Earth has shown no net increase since the 1950s. Over the same period, global temperature has risen significantly. What’s more, computerized climate models have been unable to reproduce the recent rapid rate of global warming when taking into account only variations in solar output and volcanic activity. Scientists estimate that these two factors combined contribute no more than two percent to recent warming. 29

Now that you know the conventional causes of our climate crisis, please see: What’s the Root Cause of Climate Change?

Climate Feedbacks

Climatologists divide the factors that control global warming into two types – forcings and feedbacks. Climate forcings are the direct causes, or drivers. The best example of a forcing is the rise in greenhouse gases. Climate feedbacks on the other hand boost or reduce the impact of forcings. The best example of a positive feedback (one that boosts warming) is the role of water vapor. As the Earth’s temperature rises, it increases the amount of vapor in the atmosphere, which leads to more warming. In other words, it’s not a climate forcing, it’s a feedback.

Here’s how it works. The amount of water vapor in the air is directly related to the temperature. If the temperature rises, more water evaporates and becomes water vapor. If it falls, water condenses back into liquid.

So when something else causes the temperature to rise (like carbon dioxide emissions from fossil fuel combustion), then more water evaporates into the air as vapor. But, because water vapor itself is a greenhouse gas (meaning, it has heat-trapping abilities) the additional water vapor causes the temperature to go up even further. In other words, water vapor doesn’t control the temperature, it’s controlled by the temperature.

By how much does water vapor boost the warming caused by greenhouse gas emissions? Studies show that water vapor feedback roughly doubles the warming effect caused by fossil fuel emissions. So if there is a 1°C warming effect caused by CO2 emissions, the extra water vapor it creates will cause the temperature to go up another 1°C. If additional feedback loops are involved, the total warming may reach 2-3°C. 30

Also, when comparing the effects of CO2 versus water vapor, it’s worth remembering that water vapor is constantly evaporating (as temperatures warm), condensing back into liquid (as temperatures cool), and then falling as rain (or snow). So the amount of water vapor that remains in the atmosphere typically varies enormously, according to weather conditions. So even though water vapour does have a significant amplifying effect on atmospheric warming, it’s pretty short-lived. By contrast, carbon dioxide remains in the atmosphere for hundreds, even thousands of years.

Melting ice is another example of positive feedback. Ice reflects sunlight back into space, so as it melts it leads to greater warming. The point is, major positive feedbacks may add significantly to the rise in temperature and lead to effects that are irreversible. 31

What Are The Effects Of Global Warming?

The effects of global warming are massive and affect every country, animal species and ecosystem in the world. The damage can be seen on TV almost every day. Toxic urban smog in Asian cities, widespread Australian and Artic wildfires, heatwaves in Europe and North America, drastic polar ice melt, polar bears dying of starvation, the extinction of penguin colonies – there seems to be a never-ending list of extreme events.

And this is only the beginning. Because these warming effects will worsen for decades even if we eliminated all fossil fuels tomorrow. Why? Because the global community is still not prepared to mobilize sufficient willpower and resources to tackle the climate crisis.

As a result, the Earth is almost certain to exceed both the 1.5°C and 2°C threshold and may even exceed the 4°C threshold. If so, here is a short summary of the consequences. 32 For lots more details, see: What Are the Effects of Global Warming?

What Happens If Temperatures Rise 2 Degrees Celsius?

A rise of just 2°C would result in a significantly greater number of extreme weather events resulting in severe flooding, record-breaking drought or forest fires. For example, the year 2019 witnessed unprecedented Australian bushfires, following earlier record-breaking wildfires in northern Scandinavia, Alaska and Siberia. Experts at the Copernicus Atmosphere Monitoring Service (Cams) pointed to the unusual intensity of these fires, as well as their large area. A key factor behind the outbreak of these fires was the scorching ground temperature. June 2019 was the Earth’s hottest June since records began. Such extreme weather, allied to melting polar ice, is likely to make certain areas of the world less habitable for humans.

Global sea levels have risen by about 8 inches since 1880. It is predicted to rise another 1-4 feet by 2100. As a result, many coastal cities (including even Miami, New York or London) will have to make major structural changes to avoid inundation. In addition, most coral reefs are likely to suffer major loss, causing ecological effects throughout the oceans. Polar habitats will contract sharply leading to the widespread loss or extinction of polar species.

Other effects of an average rise in temperature of 2°C include:

  • Sea levels rise between 2 and 6 feet, by 2100
  • 80 percent chance of an ice-free Arctic summer
  • 25 percent increase in the number of hot days
  • 37 percent of the population face one severe heatwave every 5 years
  • Average rainfall increases by 4-10 percent
  • Average length of droughts increases by 4 months
  • Crops lose nutrition. See: 7 Effects of Climate Change on Plants
  • The number of category 5 tropical cyclones rises
  • 59 percent annual likelihood of a summer heatwave in Europe
  • Frequency of extreme rainfall in Eastern North America increases by 52 percent
  • 99 percent of all corals will die due to ocean acidification and bleaching. See: Effects of Climate Change on Animals

    (Source: – “Impacts of climate change at 1.5C, 2C and beyond.”)

What Happens If Temperatures Rise 4 Degrees Celsius?

The effects of a 4°C increase in temperature will be far worse. Yet new reports suggest there is a strong possibility that this will happen as early as the 2060s. 33

The impact of the extreme heatwaves predicted for a 4°C world are likely to vastly exceed the consequences experienced so far (extreme temperatures, flooding, drought, heat-related deaths, loss of harvests) and may even overwhelm the resources of many systems and societies.

The warmest July in the Mediterranean basin, for instance, may well be 9°C warmer than today’s warmest July, while the coolest months are likely to be markedly warmer than the hottest months at the end of the 20th century. All this has grave consequences for cities prone to heat-amplified levels of ground-level ozone, and for tinder-dry forest ecosystems.

The massive Arctic fires that swept across Alaska, Canada and Siberia in 2019, and the equally damaging Australian bushfires that followed, may be no more than curtain-raisers for the wildfires to come.

But the greatest danger from a 4°C rise in temperature is that we will almost certainly cross one or more tipping points – such as an irreversible loss of food production, or irreparable damage to certain biomes, or the collapse of the West Antarctic Ice Sheet, an event which would lead to much higher sea levels and irreparable floods in coastal areas.

The Social Impact

Unless checked, the planet’s climate emergency is going to place irresistible pressure on a global community struggling to cope with the 3.5 billion extra human beings that are projected to appear by 2100. The predicted effects of global warming on humans include adverse impacts on water availability, ecosystems, crops, and health, all of which is likely to trigger large-scale migrations of populations, with adverse consequences for relations between the developed and less-developed worlds. Sadly, in this type of scenario it is always the poor and deprived who suffer the most. For this reason, global warming must be seen as a social as much as a climatic threat. 34

What Can We Do To Stop Global Warming?

Effective climate action involves four things:

  1. We need to cut greenhouse gas emissions dramatically by decarbonizing our energy system and reducing our use of fossil fuels.
  2. We need to develop viable alternatives to fossil fuels in the form of renewable energy sources (wind, solar power, hydropower, biomass and geothermal), bearing in mind that our total energy needs are likely to soar given the 3 billion projected rise in world population.
  3. With many more people competing for a (practically) finite amount of energy, richer nations need to conserve resources and reduce consumption.
  4. We need to preserve (and hopefully expand) our carbon sinks in order to continue capturing CO2 from the atmosphere.

1. Cut Greenhouse Gas Emissions Dramatically

Greenhouse gas is emitted whenever fossil fuels (like coal, or its precursor peat, oil or petroleum and natural gas) are burned.

In order to make serious cuts in our greenhouse gas emissions, we must drastically reduce our use of fossil fuels.

The largest sources of man-made greenhouse gas emissions are:

Transportation (30 percent) which mostly burns gasoline and diesel for cars, trucks, trains, ships and planes.
Electricity generation (27.5 percent) which uses coal and natural gas.
Industry (22.2 percent) which uses various fossil fuels in a range of chemical processes, including cement manufacture.
Heating of residential and commercial properties and waste disposal (11.6 percent) which also burns a variety of fuels.
Agriculture (9 percent) responsible for methane discharge from livestock. 35

The good news is, if fossil fuel phase-out begins immediately, with the scrapping of fossil fuel-burning infrastructure as soon as it reaches the end of its lifespan – that’s 40 years for power plants, 15 years for cars; and 26 years for planes – a recent study indicates that there would be a 66 percent chance of the global temperature rise remaining below 1.5C. Overall, the study assumes that carbon emissions would decline to zero over the next four decades. 36

Fossil fuels are an entrenched feature of our industrial landscape. A power plant responsible for a continuous energy supply for a city of 1 million people is almost inconceivable without enough coal, oil or natural gas to fuel it.

However, research has been published in the prestigious Dutch academic journal Energy Policy which shows that converting the globe to 100 percent renewable energy by 2050 is both feasible and affordable. 37 38

A Note About the Ethics of Climate Change
Any climate action must pay due regard to the ethics of climate change and be fair to those countries who are still developing, as well as those who are established. The former need to be allowed to increase their emissions to combat poverty.

2. Develop Viable Alternatives To Fossil Fuel

We can’t stop using coal oil and gas overnight. As of January 2021, they supply roughly 84 percent of global primary energy. The rest is supplied by nuclear (4.5 percent), hydropower (6.5 percent) and other renewables (5 percent). 39

Electricity generation is also dominated by fossil fuels (62 percent), with remaining demand supplied by nuclear energy (10.5 percent), hydropower (16 percent) and other renewables (11.5 percent). 39

“Other renewables” in both cases, include: solar energy, organic biomass and other bioenergy, geothermal energy, offshore and onshore wind power and wind/tidal power.

Creating a sustainable energy system based on renewables requires major intervention by national governments, to educate, incentivize and persuade consumers to switch to greener, low-carbon energy sources.

In order to reduce emissions, consumers of fossil fuels need to understand, monitor and lower their carbon footprint, and consume less energy. A good start is to switch to electric vehicles (EVs) or other form of electrically-powered transport, powered by renewable energy.

It will also necessitate the building of many more solar power systems and wind turbines, as well as new technology in a variety of areas, including enhanced transmission grids and energy storage (batteries), all of which is perfectly doable.

However, it also needs far greater political support to overcome resistance from entrenched interests. This issue is highlighted in a 2013 report “Post Carbon Pathways”, which states that the biggest obstacles to the development of sustainable energy are: climate change denial, political inaction, the fossil fuels lobby, unsustainable energy consumption, and outdated energy infrastructure. 40

Numerous countries and cities have made a commitment to achieving carbon neutrality, but no entity has actually achieved it.

Furthermore, while renewable energy is growing more quickly than expected, at least in some areas, it still needs to achieve a far greater level of magnitude if it is to satisfy the needs of 11 billion people by 2100. In fact, according to the 2019 report “Global energy transformation: A roadmap to 2050” published by the International Renewable Energy Agency, it needs to grow six times faster to limit global warming to 2°C (3.6°F).

One worrying statistic is the fact that, average energy demand per capita in China increased from 17 gigajoules/head in 1978, to 97 gigajoules/head in 2018. 41 That’s a 570 percent increase in 40 years.

With so many developing countries set to complete their development by 2100, one wonders how solar, wind and other renewable energy sources can possibly cope with the massive increase in demand for reliable power, let alone how battery manufacturers will be able to upscale to provide reliable electric vehicles. See, for instance: Our Climate Plan Can’t Cope.

Is Nuclear Power a Viable Source of Renewable Energy?

The Greens say No. The U.S. Democrats say No. Some experts say Yes. The real question is, can we provide enough green energy for our needs? If we can’t, then we will have to use high-emission fossil fuels or nuclear energy.

Unfortunately, this scenario looks more plausible than it should, from a clean energy viewpoint. Because right now, there’s a huge gap between the amount of green energy being produced and the amount needed. But even though nuclear energy is a reliable source of power, providing steady electricity, its costs and its safety are huge concerns – especially since not one single nuclear plant has yet been fully decommissioned. For an in-depth review of this topic, please read our article: Is Nuclear Energy a Replacement for Fossil Fuels?

For some of the issues, please see: (a) The problems of nuclear waste, as described in a new report by Greenpeace (2019). 42 How nuclear power reduces mortality and greenhouse gas emissions. 43 The health impacts of radiation and other health problems in the aftermath of nuclear accidents, with an emphasis on Fukushima. 44

For the latest news on nuclear energy, see our article on cutting edge technology: Nuclear Fusion: A Necessary Gamble?

3. Boost Energy Conservation

As well as changing the type of energy we use, it’s also vital to reduce our overall energy consumption. This can be done by promoting efficient energy use (e.g. via low-energy light bulbs, heat pumps, passive solar building design) and reducing waste (e.g. more effective thermal insulation), as well as choosing a greener life (e.g. know your carbon footprint, plan fewer plane journeys, bicycle whenever feasible, or choose electric cars). The introduction of smart technology to regulate heating systems can also reduce domestic energy consumption.

Many authorities have started to introduce energy or carbon taxes in order to incentivize consumers to cut their energy consumption. For example, the state of California has a staged energy tax system under which every consumer receives a baseline energy allowance which requires them to pay only a small amount of tax. But as their energy consumption rises above this baseline, the tax increases substantially. The idea is to protect low-income households while obtaining a higher price from high energy consumers. 45

Energy efficiency initiatives in the form of subsidies or grants to help individuals with home insulation can also lead to energy saving opportunities. But working with groups to create low carbon communities is probably the best way to raise awareness about climate change and find sustainable energy solutions for the public at large.

4. Preserve our carbon sinks

Carbon capture and storage (CCS) is one of the key climate mitigation strategies championed by the IPCC to help achieve net-zero carbon emissions by 2050. Unfortunately, the implementation of CCS in the power generation and cement manufacturing sectors, has been dogged by problems.

Natural carbon sinks (such as rainforests, peat bogs, permafrost tundra, wetlands, mangrove forests) are tried and trusted carbon capture and storage systems, able to capture millions of tonnes of CO2, and they don’t cost a penny. All we need to do is look after them.

Finally…. we need to convince Policymakers

One last thing. We need to convince policymakers in both high-income countries and high-emissions countries, to set aside sufficient resources to finance the necessary climate action, and reduce fossil fuel consumption, respectively.

NEXT: See our: Climate Change Essay in 1000 Words.


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