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What is climate change? Definition and examples

Climate change refers to the long-term shift in Earth’s average temperatures and weather patterns. Specifically, it refers to a large-scale shift; in other words, across the whole planet.

For the past 4.5 billion years, Earth has gone through many ice ages and periods of tropical climate. Since the Industrial Revolution, average temperatures have risen marginally.

Scientists say that the marginal increase in average global temperature is mainly due to the rise in atmospheric CO2. CO2 stands for carbon dioxide. CO2 is a greenhouse gas. Greenhouse gases help keep the Earth’s surface warm.

According to Britain’s Met Office, atmospheric carbon dioxide levels have risen by 40% since the Industrial Revolution. That is an unprecedented rise in at least 800,000 years.

This has triggered a climate change. In other words, our planet’s climate is gradually changing. There is warming throughout the entire climate systems.

Regarding the rise in carbon dioxide levels, the Met Office says:

“This has caused warming throughout the climate system, and multiple indicators show evidence that our climate is changing.”

“The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased.”

The effects of climate change include rising seas, higher temperatures, extinction of wildlife, changing landscapes, and more heat-related diseases. The effects also include stronger and more frequent storms, land erosion, more forest fires, and economic losses.

Climate change vs. global warming

Many people use the two terms interchangeably. However, although we can use both terms in many situations and scenarios, their meanings are different.

Put simply, one is part of the other, just like bananas are fruit but not the other way round.

Climate change

Climate change refers to anything that results in a different climate across the planet. This includes, for example, long-term, average global temperatures dropping by ten degrees. However, a decline in temperature would not be global warming.

If, on the other hand, long-term, average global temperature rose, it would be both a climate change and global warming matter.

Global warming

We only use the term ‘global warming’ when a change in climate involves a rise in global temperatures.

In other words, global warming is one of the possible features of climate change. However, climate change may also include declining temperatures, more/fewer severe droughts, or more/less rainfall.

If there are more hurricanes each year across the world, this is a climate change feature. It is not a global warming feature, although it could be a consequence of global warming.

This image, based on the comparison of atmospheric samples contained in ice cores, and also more recent direct measurements, provides evidence that the atmospheric CO2 level has increased since the Industrial Revolution. (Credit: Vostok ice core data/J.R. Petit et al.; NOAA Mauna Loa CO2 record.)

Climate change – since 1850s

Since the 1850s, the average surface temperature of our planet has increased by about 1 °C. Scientists warn that the temperature rise is about to accelerate.

Each of the past three decades has been successively hotter than any preceding one. Of the seventeen warmest years on record, sixteen have occurred since 2001.

Climate change – our fault?

Today’s warming trend is most probably our fault. In fact, NASA says that the probability that it is our fault is greater than 95%.

NASA specifies that the current rise on global temperatures is most probably due to human activity since the mid-20th century.

NASA adds that the temperature rise is “proceeding at a rate that is unprecedented over decades to millennia.”

Without these greenhouse gases, planet Earth would be an extremely cold place. Rather than its current 59°F (15°C), the average temperature of the planet would be 0°F (-18°C). There would also be a huge difference between day and night-time temperatures.

Greenhouse gases

It is partly thanks to the warmth of the Sun that life on Earth exists. Some of the Sun’s solar radiation, i.e., heat, bounces off Earth’s surface back into space.

Gases in our atmosphere, however, trap a small portion of that heat. In other words, those gases act like a layer of insulation.

We refer to the gases in the atmosphere that trap heat from the Sun as ‘greenhouse gases.’

Carbon dioxide or CO2 is the most important, i.e., most abundant, greenhouse gas. CO2 now traps more heat than at the end of the Industrial revolution because there is more of it.

Consequently, Earth’s average temperature has risen. In other words, high carbon dioxide levels have triggered climate change.

Methane or CH4, a common fuel source, is also a very potent greenhouse gas. Methane is the main component of the fossil fuel natural gas. We use this fuel a lot because it is so abundant.

Most scientists agree that if we are serious about addressing climate change, we need to reduce our emissions of greenhouse gases.

Dr. Chris Hope, a researcher in London, proposes introducing a climate change tax.