What is Climate Change – The Definitive Guide 2021

What is Climate Change – The Definitive Guide 2021

Climate change is a term that has been gaining traction for decades and its origins have been historically tracked to scientific research as far back as the 19th century. So what is climate change and why do we no longer refer to it as global warming? 

This is ‘What is Climate Change – The Definitive Guide 2021’.


Want to discuss more topics like this and become part of a wider community then join our friendly Facebook group!


What is Climate Change

In truth, the definition of climate change is scientific, long-winded and actually quite difficult to understand quickly (see examples below). Instead, we want to create a universal definition climate change so that it is understandable for all. 

The leading authorities on climate change including the IPCC and the UNFCCC each define it slightly differently due to the fact that our climate changes both due to natural or human activity. 

While the IPCC definition makes the distinction between ‘natural’ and ‘human’ changes to our climate, the UNFCCC definition explicitly states that climate change is a result of human intervention, which in turn causes changes in our climate contrary to what is typically expected. 

When the term climate change is mentioned in the media, they are most likely referring to the UNFCCC definition, where human activity is primarily responsible for the rapid changes in our climate that we are seeing. 

Atmosphere | 01/02/2021

Climate Change Definitions

Based on this information, one can define climate change as: 

A change in our climate caused by human activity that alters the natural or average climate that is considered normal for our planet. 

By defining climate so simply we miss an important aspect that climate change occurs thanks to both human (anthropogenic) influences as well as natural changes.

Therefore, it is very important that overly simplistic definitions like these are used carefully and only for foundational understanding. 

Hence why the IPCC and UNFCC definitions are so long-winded: 

Refers to a change in the state of the climate that can be identified (e.g. by using statistical tests) by changes in the mean and/or the variability of its properties, and that permits for an extended period, typically decades or longer. Climate change may be due to natural internal processes or external forcings such as modulations of the solar cycles, volcanic eruptions and persistent anthropogenic changes in the composition of the atmosphere or in land use. – IPCC

A change of climate which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability observed over comparable time periods. – UNFCCC

History | 01/02/2021

How Our Climate Changes & A Brief History

As far back as the 19th century, scientists have been exploring the changes in the Earth’s atmosphere related to what we now term climate change. 

One of the biggest breakthroughs was in 1896 when a Swedish chemist named Svante Arrhenius discovered how reducing carbon dioxide levels (a common gas) in our atmosphere would also in turn reduce the average temperature of the planet. 

At the time, he suggested that cutting carbon dioxide concentrations by half would cause an ice age. Conversely, doubling it would raise average global temperatures by up to 5℃. 

Despite Arrhenius’s discoveries and numerous other scientific discoveries linking greenhouse gases with temperature changes and the natural cycles of ice ages, these theories were largely ignored and undervalued for half a century. 

It was not until the 1950’s when climatologists used state of the art analysis and equipment to accurately measure greenhouse gases not only in the present but also in the past from ice cores in Greenland and Antarctica. 

By understanding the changes in temperatures, the composition of our atmosphere and the concentrations of greenhouse gases in both the present and the past, these previously proposed theories of climate change became clearer and clearer. 

Ultimately, the scientific advancements of the 20th century has allowed us to understand how our climate changes due to the impact of different greenhouse gases that move around our Earth system in their various forms. 

That seems like quite a vague way of explaining things but it is really pivotal to understand that greenhouse gases can take various forms. As we have explored, one significant gas is carbon dioxide (CO2), one of the many greenhouse gases that dictate how warm or cold our planet is. 

More carbon dioxide in our atmosphere acts like a greenhouse because it traps more sunlight (radiation) than normal, therefore heating our Earth. However, carbon dioxide can change forms. 

Millions of species on our planet, such as plants and algae, use carbon dioxide to create oxygen (via photosynthesis). Therefore, it is important to consider that carbon dioxide is always present in our Earth – it just changes state during its lifetime. 

In summary, the higher the concentration of greenhouse gases in our atmosphere, the warmer our planet. 

But this does not mean we simply eradicate all greenhouse gases forever because these gases also sustain our planet too. Without the greenhouse effect of these gases, our planet would be too cold to inhabit and would be similar to the atmosphere of Mars. 

Forest | 01/02/2021

What causes climate change?

As previously mentioned, carbon dioxide can take various forms. Once it has been removed from the atmosphere by plants (via photosynthesis) it can be stored within these plants until they die. 

Once these plants decay and are buried underneath countless layers of Earth but also are squashed under huge pressure as well as heat, they eventually form coal, a process that takes millions of years. 

In modern society, humans have utilised coal for fuel and we have been burning it to power industry for hundreds of years, with production accelerating during the onset of the industrial revolution. This in turn releases all this ancient carbon back into our atmosphere as carbon dioxide. 

By not leaving coal underground, modern society has allowed excess greenhouse gases to build up in our atmosphere at a rate never seen in the Earth’s history.

This has exacerbated the planet’s natural ‘greenhouse effect’ which resulted in our planet warming on an unprecedented scale. 

Coal is just one of the fossil fuels that causes climate change. Oil and natural gas are other major polluters that drives global climate change by releasing greenhouse gases into our atmosphere. 

In addition, carbon dioxide is not the only greenhouse gas that causes climate change. For example, methane is a much more dangerous gas as it can trap more sunlight than carbon dioxide.

However, carbon dioxide is the most prevalent greenhouse gas in our atmosphere. 

Consequently, many have been actively campaigning for decades to reduce fossil fuel use in modern society with some countries finally beginning the process of decarbonisation via alternative fuel options such as renewable energy. 

Cloud | 01/02/2021

So Why is it Climate Change and Not Global Warming?

For a long period, global warming seemed to be the media buzz word, yet, it quickly reverted back to climate change. The term global warming is not obsolete, however, and the distinction between them serves an important purpose. 

The distinction highlights how climate change focuses on overall change to climate, while global warming only refers to warmer temperatures. Although this may sound obvious, it is perhaps something that we overlook when thinking about the complexity of climate change. 

Importantly, our climate is comprised of many different aspects including but not limited to temperature, precipitation (rain/snow), humidity and atmospheric pressure.

Considering that due to climate change, many different areas around the world are experiencing variations in these climatic parameters, it is therefore inaccurate to describe all of these areas as experiencing global warming. 

For example, some regions in the world are predicted to experience wetter climates as a result of climate change as opposed to just warmer climates. Therefore, they will experience climate change not just global warming. 

Global warming is described as just one aspect of climate change. It refers to the average warming trend of the entire globe.

Hence, the term global warming is often used when exploring the changes we are seeing in the Arctic. 

Global warming directly results in a warmer than average climate for the Arctic, which year after year does not seem to slow. 

Furthermore, it is important to reiterate how these examples are not weather predictions. Neither global warming nor climate change are referring to short-term weather changes. Instead they are describing either climatic warming or climatic changes, which by definition are longer-term (30 years) than weather patterns. 

Therefore, one colder than average day in the middle of summer is not evidence for or against climate change. Instead, you would have to consider this day over decades of climate data to discern climatic changes. 

It is also important to reiterate that global warming is still driven by the same causes as climate change. In other words, global warming is human-induced just like climate change.

Disaster | 01/02/2021

The Impacts of Climate Change

Climate Change has resulted in warmer temperatures across many regions, shifts in rainfall patterns, increases in droughts and heatwaves as well as more intense storms.

These changes are, rather worryingly, projected to get more intense over time. As we continue to emit greenhouse gases into our atmosphere by burning fossil fuels, the impacts of climate change are likely to become more accentuated. 

In order to better comprehend how climate change is affecting our planet, we can observe how it is already impacting us now. To do this we can look at the high-confidence observations surrounding climate change that are being reported by the leading authority; the IPCC 

Here we have summarised just a few impacts of our changing climate: 

The obvious place to start is with the temperature changes that have occurred due to climate change. The most widely known plight of any natural system and its inhabitants is the Arctic.

Due to increasing greenhouse gases in our atmosphere, temperatures at the North pole have also been increasing and we have witnessed the plight of the Polar Bear along with its icy habitat. 

In fact, the amount of Arctic sea ice surrounding the North Pole is continuing to decline in every month of each year; these declines are unprecedented and have not been experienced for at least the last millennium. 

This intense example of climate change and the fact that average temperatures are increasing more profoundly here is known as ‘Arctic Amplification’. 

This is a serious problem as sea ice is great at reflecting a significant proportion of the sun’s heat, which is a process we desperately cannot lose considering how much greenhouse gases are currently enabling our Earth to heat up. 


Want to discuss more topics like this and become part of a wider community then join our friendly Facebook group!


Staying with the colder extremes of our planet, another profound impact of climate change is the increasing air temperatures that threaten the world’s glaciers and ice caps. 

The melting of glaciers and ice caps has caused much of the global sea-level rise that we have experienced over the last 150 years. In fact, since 1880 mean sea level has risen by 21-24 centimetres with a third of that coming in the last 25 years.

Furthermore, warmer ocean temperatures also cause sea levels to rise through thermal expansion

Global sea-level rise already threatens over 600 million people who live in low-lying coastal areas but with the number of people living in these areas set to increase and sea-level rise accelerating, it is predicted that up to 800 million will be at risk by 2050. 

This double-edged sword of global sea-level rise is further exacerbated by the impact of climate change on storms globally. There is growing evidence suggesting storms are increasing in intensity and frequency thereby increasing the risk of greater damage to coastal communities, towns, and cities. 

As previously mentioned, oceans are also heating up due to global warming with the average global temperature of the upper few metres of the ocean having risen by 0.13℃ per decade over the past century

Worryingly, there is a large lag time between the heating of the Earth’s atmosphere and its oceans. This means that the oceans have not yet absorbed all the additional heat available in the atmosphere caused by global warming. 

These increasing ocean temperatures not only cause disruption to aquatic species, but they also have profoundly negative impacts on coral reefs too. 

For example, the Great Barrier Reef in Australia is considered the largest living structure on Earth but is threatened by coral bleaching. This occurs when warmer ocean temperatures cause coral reefs to lose their colour, thus giving a bleached appearance. 

As coral reefs are some of the most biodiverse environments providing habitats for millions of species worldwide, climate change is threatening the existence of many communities of animals throughout the animal kingdom. 

Food security has also already been severely impacted by climate change. Changes in temperature, rainfall, and the greater frequency of extreme events including floods and droughts have negatively impacted agricultural systems globally. 

But the most harrowing impact of climate change is the reinforcement of inequalities that are already present today. 

Despite the richest nations burning the most fossil fuels, they are often far removed from and do not experience these climate impacts previously outlined. 

Poorer nations, many located closer to the equator, are bearing the brunt of climate change even though they are the least responsible for climate change.

Many of the most devastating examples of food insecurity driven by climate change are located in areas where populations and communities are already vulnerable. 

All these impacts do not even take into account ocean acidification, coastal erosion, changes in ocean circulation, wildfires, droughts, insect outbreaks, and disease spread. The impacts of climate change are already widespread and are likely to worsen in the future. 

Smoke | 01/02/2021

Is Climate Change Irreversible?

Using the most powerful computer models, climate scientists are predicting the future climate under various emission scenarios.

For example, in a scenario where emissions are not reduced and we continue as normal, our global temperatures would be on track to reach on average 5℃ warmer by 2100

These scenarios have resulted in significant political targets like the Paris agreement. This political agreement has decided to limit future global warming to below 1.5 degrees. 

They decided on 1.5 degrees as the red tape we should not cross because beyond this threshold, our world is predicted to experience catastrophic impacts of climate change such as devastating weather extremes exacerbating some of the already extreme climatic events we see today. 

However, this increase in temperature creating climatic and environmental shifts will potentially become irreversible and form positive feedback loops. In fact, the UN warns that we have only 10 years remaining to prevent irreparable damage caused by climate change. 

Time is therefore of the essence – the faster we act the better our climate will react. 

These positive loops are not positive in a good way but rather positive in a self-reinforcing and bad way. One example of a positive feedback loop is the increased melting of the poles.

The aforementioned phenomenon of ‘Arctic amplification’ has accelerated melting of ice caps and glaciers in this region. 

Because of global warming, the amount of ice is being severely reduced, reducing the earth’s reflectivity, otherwise known as albedo. At a theoretical point in the future, scientists have hypothesised there could be a tipping point. 

This area of high reflectivity is important because it reflects a huge amount of heat away from the Earth resulting in stable temperatures for life on Earth to thrive.

Once this tipping point has been reached and our poles are uncontrollably losing ice coverage, there would be no way to reverse climate change and global warming from continuing. This would eventually lead to an ice-free Arctic. 

This is just one example of a tipping point but thresholds can be surpassed in many other scenarios too

Despite being theoretical in nature, the IPCC reports warn how these tipping points are actually much closer to occurring than we originally thought. Projections originally suggested these critical thresholds being reached once global warming was above 5℃. 

However, since then IPCC reports suggest tipping points may initiate between global warming between 1℃ and 2℃

Another theoretical (and more far-fetched) scenario is labelled the runaway greenhouse effect. The only analogy we have to this is on our planetary neighbour Venus. 

When the Sun was much smaller and dimmer, Venus once had oceans. However, as the Sun increased in size, the temperature of Venus’s oceans increased rapidly causing the water to evaporate uncontrollably. 

This water vapour formed a thicker atmosphere trapping more of the sun’s heat and the oceans evaporated even faster. Water vapour is a greenhouse gas, just like carbon dioxide and thus greenhouse gas concentrations spiralled out of control. 

The outcome is a runaway greenhouse effect where there is only one uncontrollable direction, However, scientists estimate that for a runaway to also occur on Earth, we would need a considerably higher concentration of greenhouse gases in our atmosphere. 

While the irreversibility of climate change remains largely theoretical and a runaway greenhouse effect is considered unlikely, there are signs that tipping points are closer than we may originally imagine. 

There is growing scientific evidence that a number of different tipping points could start between global warming of 1℃ and 2℃ but also that once one tipping point had occurred that other tipping points from different systems may also follow

An example often cited in research is that a warming planet creates an ice-free arctic – a tipping point.

Simultaneously the melting glaciers in the northern hemisphere results in abnormally high amounts of freshwater entering the Atlantic Ocean, upsetting the balance of saltwater in an already changing ocean circulation system. 

This ocean system controls and impacts many regional weather and climate patterns across the globe and another tipping point could be reached with this freshwater introduction.

By upsetting this balance, the West African and Indian monsoons could be destabilised and rainfall patterns would be interrupted across the Amazon. 

While theoretical, the threat and possibility of irreversible climate change is therefore very real.

Turbines | 01/02/2021

How to Stop Climate Change

Even without the knowledge of the future devastating impacts of climate change and their theoretical knock-on effects, current climate change must be stopped. 

We cannot sit around whilst coral reefs are decimated, forests are razed for agriculture as well as droughts and storms disproportionately destroying the lives of the world’s most vulnerable. 

Instead the world needs to do something but how do we stop climate change? 

By understanding how climate change is currently functioning, we know that burning certain fuels that would otherwise be locked up in our Earth is resulting in greenhouse gases to build up in our atmosphere. 

It is here that we can start to slow climate change from happening. By limiting fossil fuel usage and decarbonising the major nations in the world, we can halt further emissions from building in our atmosphere. 

For example, it is now well known that just 100 companies have generated 71% of global emissions since 1998. If you were to scroll through what these companies do, you will see almost all of them are oil companies (trust us we did it!). 

But to decarbonise means a total overhaul in energy use. All the major polluters in the world are still primarily built upon using fossil fuels and thus an efficient and inexpensive alternative needs to be provided. 

A controversial alternative to fossil fuels is nuclear power. Despite not emitting greenhouse gases into the atmosphere, many remain fearful of it because of the Chernobyl and Fukushima disasters that have rendered the surrounding areas uninhabitable.

Additionally, questions have been raised about disposing nuclear waste thus making it an unviable alternative in the long term. 

The most sustainable alternative is renewable energy from natural sources. Renewable energy has been rapidly developing to become more efficient and less expensive resulting in it becoming more and more attractive over time. 

Renewable energy harnesses nature in order to provide energy. For example, hydropower has been used successfully for decades by utilising dams to allow water to pass through turbines, thereby generating electricity. 

It was originally thought that water will always flow in these huge river systems. However, in some cases, climate change is causing shifts in rainfall patterns and droughts that severely impact electricity generation.

Although it calls into the question whether some hydropower systems will be a truly infinite source of energy it is certainly renewable.

But for the most part, these hydropower systems function without severe impacts from climate change and are widespread across the planet.

Hydropower contributes to over half of all the renewable energy generated in the world. The next widely used renewable energies are wind and solar power. 

Although wind power contributes more to electricity production, recent developments in solar power have meant solar energy is the fastest growing type of renewable energy. 

By decarbonising we can generate electricity without polluting our atmosphere in its current form. However, decarbonisation would take a huge shift in technology and would cost vast sums of money to successfully implement renewable energy technologies across the world. 

Also, does it seem fair to encourage countries who have not yet benefitted from fossil fuels, to then spend money on decarbonising fully to new energy systems? After all the developed nations of the world have become prosperous by benefitting from fossil fuels. 

Fossil fuels also take multiple forms and are used in a variety of ways. It is not only in the energy sector that a revolution needs to occur. 

One of the most commonly used materials in everyday life is plastic. Plastic is formed using oil, gas and coal. By halting new production of plastic material, we can prevent another huge source of fossil fuel use, stop atmospheric pollution and stop environmental pollution from plastics too. 

Plastics can take up to thousands of years to disintegrate into our environment and thus wasting them or dumping them, not only encourages more fossil fuel use but pollutes our natural environments. 

Most worryingly is the recent research in micro-plastics. As plastics disintegrate and get worn down by natural processes, tiny plastic particles can be eaten by animals.

Bearing in mind we also eat these very same animals, there is growing evidence that plastic is finding its way into our bodies. Even in new-born babies! 

In order to successfully prevent future plastic being used, we can draw from the existing bank of plastic in our world. Effective and efficient recycling allows us to use plastics again and again (as they do not disintegrate for thousands of years) in something known as a circular economy. 

By simply targeting these two forms of pollution, we can considerably reduce our emissions and pollution that are driving climate change. These are merely two solutions to stopping climate change. 

There are a plethora of alternatives including drawing down greenhouse gases from the atmosphere in both natural and man-made ways. In addition, climate engineering is another way to reduce climate change. 

Politics | 01/02/2021

Climate Change Denial

But it all sounds too easy, doesn’t it? In one sense it is, however, there has been a considerable rejection of the ideas of climate change. This is because climate change threatens the profits of some of the largest and wealthiest companies in the world. 

These are the very same companies that are responsible for 71% of all emissions since 1998. 

All this wealth brings great political and economic influence, thus these companies have pushed an agenda of ‘climate denial’ or ‘climate scepticism’. 

Being a climate denier brings certain rewards, particularly if you are a politician as you can gain favour with large oil companies in a world where the scientific consensus tells us that climate change is man-made. 

The most famous climate denier is perhaps Donald Trump. The fervent denier of climate change has no doubt used his position to maintain favour among the wealthiest in the country. 

He has continuously allowed oil sites to open up and doesn’t believe any connections between climate change and the devastating wildfires across the United States. This had led to a trickle-down effect through US politics during his tenure. 

In fact, within the final weeks before leaving his tenure as president, two scientists appointed by the Trump administration were removed from their posts in the Office of Science and Technology Policy due to publishing inaccurate papers downplaying the climate crisis

Another problematic example can be seen among Australian politicians. Australia is a very unique developed nation as it is one of the few economically prosperous nations to strongly feel the brunt of climate change. 

Despite being harshly impacted by climate change, they are the largest exporter of coal in the world. Clearly, if the Australian government were to support climate change action then they would also support eliminating their coal export economy. 

However, it makes up a significant proportion of their economy and removing these profits would seriously harm their economy. 

Hence, why this self-destructive climate denial remains rife in Australia and similar to Trump, Australian prime minister Scott Morrison denied the link between climate change and the destructive wildfires in 2019 that decimated large swathes of Australia. 

It is important to remain sceptical of the links between climate change and a single climatic event because the science is very complicated and the science of attribution (attributing climate change to a single climatic event) is quite a new area of study but to deny any link at all still contradicts the scientific consensus. 

It has led to a lack of comprehensive climate action in Australia for decades. Not only has this been to the detriment of the Australian people but also to the world. These are just a few examples of climate denial – just the tip of the iceberg. 

Protest | 01/02/2021

How to Fight Climate Change

Unfortunately, climate change is occurring whether you like it or not. We have also allowed it to get out of hand. The 10 warmest years globally on record have all occurred since 1998, with 9 of these occurring since 2005. This trend is very likely to continue. 

Therefore, we need to take action. This action is so urgent that there has been a resurgence in climate activism in the mainstream. Key figures such as Greta Thunberg and David Attenborough have stirred the public into mounting pressure on governments to take action. 

By taking the fight to your government, the pressure soon becomes too much and politicians increasingly make room for climate targets as part of their political agenda. 

As established previously in the climate change guide, time is of the essence. The quicker we act, the more damage we can prevent and the more lives we can save. 

In addition, what is truly unique about climate change is how it requires global action. Clearly, some nations are more polluting than others, but everyone contributes in some way to climate change, and thus fighting climate change can take place on a very personal level as well as a collective level. 

Not only can personal climate activism make a big difference in your local area, but that local impetus can grow among a collective eventually impacting regional policy and even national policy. 

Activism has played a pivotal role in creating positive change with climate strikes around the world catching the attention of the world media and the political systems that govern our world. 

As climate action can take such a personal form, one of the most effective ways to reduce your impact on the planet is to change your diet. More precisely, by reducing your meat intake and becoming vegetarian or vegan. 

Much research has attempted to estimate the pollution attributed to a carnivorous diet and although estimates vary, they all agree that eating meat is one of the most detrimental practices that we do to our planet. Particularly eating red meat. 

This is largely due to agriculture being responsible for extensive deforestation, huge methane emissions associated with rearing cattle and animal feed where it is predominately soybeans (which is further responsible for deforestation but also is associated with large export emissions). 

The West’s insatiable appetite for beef is marinating the average household’s emissions extremely high but reducing your meat intake or going vegetarian altogether fights climate change and is the fastest way to tackle climate change. 

Another way to quickly reduce your emissions and fight climate change is to think about your transport. For many, it may be impossible to get to work without driving a car but does this car need to run off fossil fuels, what about going electric? 

If you live in a city, do you need to use public transport, how about cycling? The emissions you save is circumstantial but it is well known that changing transport significantly reduces your impact on the Earth and in turn fights climate change and air pollution also. 

A final quick way to fight climate change is to change the energy you consume at home. In fact, changing to an electric car only significantly reduced your carbon footprint if its energy supply is renewable. 

Thus, changing your energy supply at home where your car will be doing the majority of its charging will not only decarbonise your future transport but will decarbonise your day-to-day activities at home too. 

It also shows energy suppliers that fossil fuels are obsolete and there is a decreasing demand for them. By indicating to energy suppliers that you want renewable energy, it will give large corporations no choice but to adopt renewable energy and fight climate change in the process. 

There are many additional ways, but these are the most effective of the fastest ways to reduce your carbon footprint and in the process tackle climate change. 


This has been What is Climate Change – The Definitive Guide

To read more, explore our Environment, Sustainability or Culture definitive guides.

Follow ecoLogicc to get notified of new articles

Leave a Reply