What is climate change? The definition, causes and effects

Climate change is one of the biggest crises facing humanity. Let’s all get a grip on exactly what it is?


On June 1, 2013 south of Lake Hughes, California, wildfire ran rampant for days, destroying thousands of homes overnight. Spreading through brush and dry land, the blaze engulfed a total stretch of 19,500-acres.

Credit: David McNew/Getty Images

Carbon dioxide is colourless. We produce it just by breathing. But combustion – from fuel or friction – leaves darker traces. Once a point of contention, manmade climate change is now scientific fact. More than 97 per cent of climate scientists agree that changes to the global climate in the last century have been caused by anthropogenic activity.
The so-called ‘Consensus on consensus’ has drawn more attention to an issue that, since the start of this century, has divided many. But the evidence is overwhelming. Since the industrial revolution, global emissions of carbon dioxide and other greenhouse gases have been exorbitant, leading to the phenomenon that, until relatively recently, has been known by the misnomer ‘global warming’.

The change in terminology to ‘climate change’ was to emphasise that the pollution of our atmosphere could result in a variety of extreme weather events, not just warming. With increases in global temperatures, processes such as desertification are transforming once thriving areas into arid environments. And yet, since warm air is capable of holding far greater quantities of water, due to higher evaporation rates, storms and other extreme climate events have become more frequent and intemperate.

Here’s the lowdown on exactly what climate change is, what it means and why climate change denial is a disaster.

What is climate change ?

The United Nations Framework Convention on Climate Change (UNFCCC) defines it as a change of climate that is attributed directly or indirectly to human activity, altering the composition of the global atmosphere.

Human activity includes the pollution that arises from industrial activity and other sources that produce greenhouse gases. These gases, such as carbon dioxide, have the ability to absorb the spectrum of infrared light and contribute to the warming of our atmosphere. Once produced, these gases can remain trapped in the atmosphere for tens or hundreds of years.



Produced primarily through the burning of fossil fuels (oil, natural gas, and coal), solid waste, and trees and wood products. Deforestation and soil degradation add carbon dioxide to the atmosphere, while forest regrowth takes it out of the atmosphere. Carbon dioxide’s lifetime in the atmosphere cannot be represented with a single value because the gas is not destroyed over time, but instead moves among different parts of the ocean–atmosphere–land system. Some of the excess carbon dioxide is absorbed by natural processes, but some remains in the atmosphere for thousands of years, due to the slow process by which carbon is transferred to ocean sediments.

Emitted during the production and transport of oil, coal and natural gas. Methane emissions also result from livestock and agricultural practices and from the anaerobic decay of organic waste in municipal solid waste landfills. Its average lifetime in the atmosphere is 12.4 years

Emitted during agricultural and industrial activities, as well as during combustion of fossil fuels and solid waste. Its lifetime in the atmosphere stands at 121 years

A group of gases that contain fluorine, including hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride, among other chemicals. These gases are emitted from a variety of industrial processes and commercial and household uses and do not occur naturally. Sometimes used as substitutes for ozone-depleting substances such as chlorofluorocarbons (CFCs).

The greenhouse effect is the cycle by which these gases become trapped in the atmosphere and heat the planet. The term was coined in 1827 by Joseph Fourier, a French mathematician and physicist, who envisioned that the warming process of the Earth acted in the same way as a greenhouse traps heat – a process of visible light and invisible radiation, with Earth’s atmosphere acting as the glass barrier.

The visible radiation from the Sun that passes through the Earth’s atmosphere can be absorbed by land, water and vegetation – but some of this infrared radiation remains trapped in the atmosphere. While this is a natural process, it remains in a state of fine balance.

While oxygen and nitrogen, key components of our atmosphere, cannot absorb infrared radiation, CO2 and others can. These gases feed off this heat energy and emit a second source of radiation to warm to surface of the Earth. This heat energy remains trapped in the atmosphere and worsens depending on the levels of gases that can absorb it. As the level of greenhouse gases grow, they are able to absorb more infrared radiation, thus trapping more heat in the atmosphere.

The carbon cycle is the exchange of carbon between all natural components, including the atmosphere, oceans and rivers, rocks and sediments, and living things. While trees can absorb carbon through photosynthesis, deforestation and other factors have limited the ability of forests to regulate global carbon emissions. The carbon cycle has also been disrupted by the sheer volume of greenhouse gases produced by human activity. In the last 650,000 years there have been several cycles of natural glacial advance and retreat, with the abrupt end of the last ice age about 7,000 years ago marking the beginning of the current climate.

Geological evidence suggests that we have entered a period of unnatural warming – for 400,000 years, carbon levels in the atmosphere had never exceeded 300 parts per million. In 1950, this level was exceeded and has been increasing since. In 2013, CO2 levels surpassed 400 ppm for the first time in recorded history.

This has been directly linked to anthropogenic activity, with the largest sources of greenhouse gas emissions stemming from electricity and heat production (25 per cent of 2010 global greenhouse gas emissions), industry (21 per cent of 2010 global greenhouse gas emissions) and agriculture land use (24 per cent of 2010 global greenhouse gas emissions). As the balance of gases in the atmosphere changes from human pollution, these emissions directly contribute to the warming of the environment, with far-reaching consequences across continents and cultures.

What are the effects of climate change?

The projections of future climate changes are already happening; microcosmic events that stand as hints of future effects. Increasing carbon dioxide in the atmosphere is being absorbed by the oceans, increasing their acidification – damaging coral reefs and marine life. Areas that were once white with snow are now retreating to only the highest points of the world. Incidents of extreme weather are increasing, from flooding to tropical storms. Further ecological issues are the threat of species extinction and major changes to the global landscape. Pressure is mounting on water and food sources, as ecosystems change and global populations continue to increase.

As with most socio-economic problems in the world, climate change is an issue that will prove most damaging for those least able to adapt – he poor, the young and old. But nobody is immune to climatological change – making it a truly global problem.

The effects of climate change are not isolated incidents. When considering the problem of climate change, the world needs to be considered as a whole ecological system. Do not think in terms of political divides, or the boundaries marked out between countries. Melting ice in the Arctic is of the same source of change as increased aridity in Arizona. Flooding in the Maldives and hurricanes across the mid-west of America are part of the same system that governs temperature fluctuations in the United Kingdom. While events like flooding and droughts may seem unrelated or even in opposition to each other, they both stem from the same problem: warmer air.


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With more carbon dioxide in the atmosphere, Arctic ice is absorbing more radiation and melting rapidly. What was once the coldest place on the planet is now steadily cooking.

Only three per cent of Earth’s water is fresh, 70 per cent is frozen. With the volume of frozen water rapidly heating, this run off from the Arctic and Antarctic moves into the ocean, raising global sea levels and flooding coastal areas. In March 2017, Nasa discovered a record low in maximum sea level ice in both the Antarctic and Arctic; an unprecedented change, given that Antarctica has previously shown greater resistance to sea ice level changes.

Tor Eldevik, a professor at the Bjerknes Centre for Climate Research at the University of Bergen in Norway believes that sea ice could vanish in the Arctic Ocean in about “40 years”. This is even with the proposed limit on global temperatures at two degrees agreed by the Paris Accord. Even a two degree celsius rise would still mean a 39 per cent risk that ice would soon disappear in the Arctic Ocean during the summer months.

Desertification is a fundamental cause of famine and food insecurity, and a direct product of climate change. When land is degraded and dried out, it becomes inhospitable and unable to produce good harvests. This exacerbates poverty, particularly in areas where farming land is the main source of income, along with other primary sector roles. With a waning supply but growing demand for food and resources, desertification undercuts national economic growth. In 2001, it was estimated that $40 billion(£30.9bn) in income is lost each year due to desertification in the United States, a figure that continues to grow with global temperatures.

In some countries, desertification can exacerbate ethnic and political tensions and contribute to conflict. Unsustainable agricultural policies in Syria in 2011 meant drought led to collapse of farming in north-eastern regions. From 2006 to 2010, the Fertile Crescent faced the worst drought in the instrumental record. Political theorists suggest this collapse in farming was one of the grievances that led to the 2011 uprising. In the Middle East and low-lying countries dependent upon agricultural practises, climate change induces significant obstacles to individuals and economies.

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The Dust Bowl years of the 1930s in the United States are a glimpse into future shortages of land, food and economic opportunity. Folk stories of farmers listening to the sound of their land cracking as it dried may seem like poetic myths, but the reality of desertification is one rooted in an uncomfortable truth. Today, droughts routinely render California barren, with millions of trees turning to standing tinder, ripe for wildfire, as homes struggle for water security.

In the UK, a variety of extreme weather events have caused growing concern about how we tackle climate change. December 2015 was the wettest month in Britain since the Met Office began collecting data in 1910. In 2003, Britain recorded its highest ever temperature – a staggering 38.5C – which contributed to the deaths of 2,000 people. What was once considered an abnormally hot summer is becoming increasingly more common, putting significant strain on health services and electricity providers. Nearly a third of the world’s population is now exposed to these kinds of heatwaves. And with rising temperatures comes rising fatalities.


The sun sets in Tangier, Virginia, May 15, 2017, where climate change and rising sea levels threaten the inhabitants of the slowly sinking island. Now measuring 1.2 square miles, Tangier Island has lost two-thirds of its landmass since 1850.

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Heat is indiscriminate and affects everyone, regardless of age. Camilo Mora, an academic at the University of Hawaii, found that 48 per cent of people will be at risk of extreme heatwaves by 2100. “Dying in a heatwave is like being slowly cooked, it’s pure torture,” Mora told The Guardian, “The young and elderly are at particular risk, but we found that this heat can kill soldiers, athletes, everyone.”

At the same time, rising sea levels have increased incidences of flooding – a problem exacerbated by low-lying land and populated coastal areas. In addition, heavier rainfall can also contribute to flooding. In December 2016, when Cumbria was devastated by Storm Desmond, people were left without homes or electricity during the Christmas period.

What is being done about climate change?

The effects of climate change have reached a point where the emphasis has moved from proof of its existence to policies of mitigation. There has already been a move towards greener policies in terms of the UK’s fifth carbon budget, as well as amongst the public. Action against Climate Change has become a focal-point of this generation: marches through city streets; recycling initiatives and bids to move towards new, cleaner sources of energy have gained momentum in the public mind.

The argument between financial and environmental values has been a central concern to the climate change debate – how to maintain economies that have, throughout the twentieth century, been reliant on fossil fuels and unrestricted energy consumption for their development. However, research indicates that this issue need not be as divisive as it has been assumed to be.

A study conducted by the London School of Economics in May 2016determined that government policies to combat climate change in the UK have had “little or no negative impact on business competitiveness”. There has been no loss to export competitiveness in the UK or amongst European countries with similar energy regulations. The report surmised that the only negative economic implications impact “approximately two per cent of the economy”, in industries such as coal-mining and petroleum refineries, but that these repercussions could be limited with “compensatory measures”.

Grid-connected Photovoltaic System In Chuzhou

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In China and India, the push towards renewable energy investment is creating significant economic opportunity. In 2016, China’s solar energy production more than doubled. The National Energy Administration (NEA) reported that by the end of the year, China’s solar capacity rose to 77.42 gigawatts, with an additional increase of 34.54 throughout the year. Similarly, India’s investment in solar power is moving the country away from a fossil-fuel based economy.

China’s economic investment in renewable power is estimated to total 2.5 trillion yuan (£292bn) by 2020, according to the NEA. While solar power currently only represents one per cent of China’s total energy output, this increase in investment is set to boost output from renewable energy from 11 per cent to 20 per cent by 2020. China’s investment in renewables will bring an estimated 13 million new jobs to the sector, according to the National Energy Administration (NEA) – signifying an economic opportunity as opposed to a problem.

In late 2015, the United Nations Framework Convention on Climate Change drafted a agreement that attempts to tackle climate change on a global scale. Every single country in the world has now signed up to the Paris Agreement, although in June 2017 Donald Trump announced his intention to remove the US from the agreement. If he choses to follow-through with his plan, the earliest date the US may withdraw is November 2020, just three months before the end of Trump’s first term as President.

Each country that remains signed up to the Paris Agreement must plan and report its own contributions towards reducing global warming, although countries will not be forced to set targets or be penalised if they don’t meet them. Under this scheme, countries are set carbon dioxide emission targets as a proportion of total global emissions. But a paper published in the journal Nature in June 2016 argued that even if they are kept to, those targets will not be enough to keep the global temperature increase to below two degrees.

In light of the Paris Agreement, the significance of renewable energy and Greenhouse gas removal (GGR) technologies seems poised to gain more momentum. The investment into renewable technology in the United Kingdom has already made progress towards cleaner energy, but currently the country’s carbon emissions do not meet the goals set by the Paris Agreement.

The CCC have produced a report on the UK’s Climate Actionfollowing the Paris Agreement. It determines that current UK policy is “not enough to deliver the existing carbon budgets that Parliament has set”, and that this policy gap needs to be closed in order to meet the 2050 zero-net emissions target. However, the CCC have also recommended that the UK “does not alter existing carbon budgets” as they are already “stretching and relatively ambitious”.

The goal set by the Committee is for the UK to begin a larger-scale deployment of carbon cutting schemes by 2030 – to do so as cost-effectively as possible. The sixth carbon budget for the United Kingdom will be determined in 2020 and during this period, the plans for meeting the Paris Agreement’s goals will be solidified.

In light of the time pressures of climate change, the steps towards effective mitigation policies need to now focus on utilising technologies and altering policies to adapt to the problem. These can include investment in renewable energies, desalinisation plants, new agricultural practises and improved global cooperation between countries to work towards regulated climate goals.

Source: www.wired.co.uk