What Is Climate Change? Definition, Causes And Effects


Climate change is one of the biggest crises facing humanity, so let’s take a step back and have a look at exactly what it is, how it happened and why we should care.


Definition Of Climate Change


NASA defines climate change as: “a broad range of global phenomena created predominantly by burning fossil fuels, which add heat-trapping gases to Earth’s atmosphere. These phenomena include the increased temperature trends described by global warming, but also encompass changes such as sea level rise; ice mass loss in Greenland, Antarctica, the Arctic and mountain glaciers worldwide; shifts in flower/plant blooming; and extreme weather events.”


Climate change as a term covers a multitude of sins. In the past people have used ‘climate change’ and ‘global warming’ almost inter-changeably but as you read through this, you’ll understand that the phrase ‘global warming’ has been dropped by the majority of climate scientists and informed politicians (emphasis on the “informed”) because it only tells one side of the story.



Climate change is the catch-all term for the shift in worldwide weather phenomena associated with an increase in global average temperatures. It’s real and temperatures have been going up around the world for many decades. Reliable temperature records began in 1850 and our world is now about one degree Celcius hotter than it was in the period between 1850 and 1900 – commonly referred to as the “pre-industrial” average. The change is even more visible over a shorter time period – compared to average temperatures between 1961 and 1990, 2017 was 0.68 degrees warmer, while 2016 was 0.8 degrees warmer, thanks to an extra boost from the naturally-occurring El Niño weather system.

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While this temperature increase is more specifically referred to as global warming, climate change is the term currently favoured by science communicators, as it explicitly includes not only Earth’s increasing global average temperature, but also the climate effects caused by this increase. Global efforts are now focussed on keeping temperatures from increasing more than two degrees above that pre-industrial average, and ideally no more than 1.5 degrees. That goal may still be possible if the international community pulls together.


What Are The Effects Of Climate Change?


The effects of anthropogenic – human-caused – climate change range from more frequent and severe droughts to snowstorms and extreme winter weather in temperate regions as a result of warming Arctic weather fronts. It’s not only humans that are affected. Warming ocean temperatures are increasing the frequency of coral reef bleaching; warmer, drier weather means that forests in some regions are no longer recovering from wildfires and wildlife habitats around the world are becoming less hospitable to animals.

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Climate change is having economic and socio-political effects, too. Food security is already being impacted in a number of African countries and researchers are studying suggestive links between climate change and an increased likelihood of military conflict.We’re already seeing the first climate refugees as people are displaced by rising sea levels, melting Arctic permafrost and other extreme weather. According to some climate models, The Arctic Ocean may even be ice free in the summer as soon as the 2050s, unless emissions are reduced, the BBC has reported.


When it comes to climate change, we have built our vulnerability into the very fabric of our society. Climate has never changed this fast and, because of that, we’ve become complacent. We’ve delineated outdated flood zones based on how rain used to fall; we’ve parcelled out and over-allocated our arable land and water resources; and we’ve built nearly two thirds of the world’s biggest cities within just a metre or so of sea level, which today is rising at nearly twice the rate of only 25 years ago.

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The UK is among the European countries most vulnerable to sea-level rise, with some 78 per cent of the population living within 50km of the coast. London’s primary defence, the Thames Flood Barrier, is already 35 years old, and now, in the age of rising seas, is due for an upgrade. Climate change’s impacts can be observed across the country, from hotter summers and wetter winters to shifting rainfall patterns and more frequent flooding events. December 2015 was the UK’s wettest in recorded history, with climate change taking what already would have been a very wet month and making it one for the record books.


Climate change also made last summer’s record heatwave far more likely to occur. And all around the world, we’re seeing similar patterns as climate change loads the weather dice against us, making heatwaves more frequent and more severe, heavy downpours more common, tropical cyclones and hurricanes stronger and their rainfall more intense and wildfire seasons lasting longer with the resulting fires burning a greater area.


What Are The Causes Of Climate Change?


We are. While a wide range of natural phenomena can radically affect the climate, publishing climate scientists overwhelmingly agree that global warming and resultant climate effects that we’re witnessing are the result of human activity. Life on Earth is dependent on an atmospheric “greenhouse” – a layer of gasses, primarily water vapour, in the lower atmosphere that trap heat from the sun as it’s reflected back from the Earth, radiating it back and keeping our planet at a temperature capable of supporting life.


Human activity is currently generating an excess of long-lived greenhouse gasses that – unlike water vapour – don’t dissipate in response to temperature increases, resulting in a continuing build-up of heat. Key greenhouse gasses include carbon dioxide, methane and nitrous oxide. Carbon dioxide is the best-known, with natural sources including decomposition and animal respiration. The main source of excess carbon dioxide emissions is the burning of fossil fuels, while deforestation has reduced the amount of plant life available to turn CO2 into oxygen.



Methane, a more potent but less abundant greenhouse gas, enters the atmosphere from farming – both from animals such as cattle and arable farming methods including traditional rice paddies – and from fossil fuel exploration and abandoned oil and gas wells. Chlorofluorocarbons and hydrofluorocarbons – once widely used in industrial applications and home appliances such as refrigerators – were key greenhouse gasses released during the 20th century, but are now heavily regulated due to their severe impact on the atmosphere, which includes ozone depletion, as well as trapping heat in the lower atmosphere. Our warming climate is also creating a feedback loop as greenhouse gasses trapped in Arctic permafrost are released.


Why Is Climate Denial A Thing?


For many years, oil companies were heavily invested in pushing the narrative that fossil fuels did not have an impact on climate change. To this end, they bought advertising and funded organisations to cast doubt on climate change, even while their own research conclusively showed that fossil fuels are a major contributing cause of climate change.


This is still playing out in ongoing lawsuits against oil companies, but even giants such as Chevron now publicly acknowledge the role that fossil fuel use has played in changing our climate. Now, their key defence is that it’s the fault of fossil fuel consumers for using it, rather than of the companies that extracted, marketed and profited from oil.


How Are We Fighting Climate Change?


The UK can take a lead in this global revolution and it has already made amazing strides. In 2017, it celebrated its first coal-free day since the dawn of the Industrial Revolution. Last year, renewables generated a full 33 per cent of power across the country, and demand for electricity fell to the lowest level since 1994 thanks to the widespread adoption of more efficient technologies, such as LED light bulbs. And in June 2019, the UK government committed to cutting greenhouse gas emissions to almost zero by 2050. (Scotland has already committed to reducing greenhouse gas emissions to net-zero by 2045, five years ahead of the UK government’s target).


But we need to aim higher.


In the next ten years, we need to understand that accounting for climate change isn’t a luxury or an evil: it’s an essential part of every decision we make. We can all eat less meat, buy less pairs of jeans and try to fly less, but we should also speak about this as much as we can. To our friends, family, colleagues and communities. (If you don’t know where to start, there is a great article here from climate activate and clinical psychologist Dan RubinHow to Have A Useful Conversation About Climate Change in 11 Steps)

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And over the next decade, that understanding must motivate us to flip the balance between fossil fuels and clean energy, so we’re getting the majority of our energy to heat our homes, power our cars and run our factories from clean sources such as wind, solar, geothermal and more. Only then will we wake up to a world in 2029 that is one we will be able to live in.


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