What is climate change? The definition, causes and effects

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Carbon dioxide is colorless. We produce it just by breathing. But combustion – from fuel or friction – leaves darker traces. Once a point of contention, man made climate change is now scientific fact. with more than 97 per cent of climate scientists agreeing that changes to the global climate in the last century have been caused by anthropocentric activity.

The so-called ‘Consensus on consensus’ has drawn more attention to an issue that, since the start of this century, has divided many. And yet for researchers in this field, the evidence has long been 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 emphasize that the pollution of our atmosphere could result in extreme weather events, not limited to that of warmer weather. With increases in global temperatures, processes such as desertification are transforming once thriving areas into arid environments, where water is scarce and arable land is in decline. 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.

CAUSES OF CLIMATE CHANGE EXPLAINED


Carbon dioxide
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.
Methane
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
Nitrous oxide
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
Fluorinated gases
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 created 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. Changes in greenhouse gas levels can increase the rate at which infrared radiation is trapped in the atmosphere, leading to excess heat energy.

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 such as the rainforest to regulate global carbon emissions. Similarly, the carbon cycle has 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 modern climate as we know it.

However, 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 – only divided by geographic distance. 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.

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.

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