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What is Global Warming?

Global warming and climate change are terms used to describe the rise in the average temperature of the earth. As our planet warms, temperature changes can be recorded on the earth’s surface, in our oceans and also within the atmosphere.

Throughout history the earth’s climate has gone through numerous cycles of both warming and cooling. In the last 600,000 to 700,000 years alone, it is believed that the earth has seen seven cycles of glacial advancement and retreat which are clear indicators of global warming and cooling.

What’s different about the current warming cycle is that most scientists agree that this is either being caused by or exacerbated by human influence on the “greenhouse effect” and the abundance of greenhouse gases in our atmosphere.

What Are Greenhouse Gases?

Greenhouse gases (or GHG’s) are gases contained within our atmosphere that have the potential to absorb infrared radiation. These gases absorb heat reflected from the earth that would otherwise be lost to space and are vital for helping to keep our planet warm and inhabitable.

The primary greenhouse gases found within the earth’s atmosphere are shown in the following table.

Greenhouse GasChemical FormulaSource(s)
Water VaporH2OEvaporated water (predominantly from the sea.)
Carbon DioxideCO2Industry and fossil fuel combustion in general, becoming more concentrated due to deforestation.
MethaneCH4Industry and fossil fuel combustion, livestock, landfill/waste, agriculture and biomass/biofuels.
Nitrous OxideN2OIndustry and fossil fuel combustion, agriculture, chemical engineering.
OzoneO3Created when Ultraviolet Radiation (UV) from the sun makes contact with the oxygen in the atmosphere. Also, thunderstorms (lightning) and artificial ozone manufacturing.

Greenhouse Effect

The term “greenhouse effect” is used to describe the natural process whereby greenhouse gases trap thermal energy within the earth’s atmosphere. Without the greenhouse effect the earth would be a very cold and inhabitable place.

The greenhouse effect works by trapping heat within our atmosphere. Greenhouse gases allow sunlight to pass through the atmosphere freely where it will be partially absorbed by the surface of the earth and its oceans. Some of this energy will bounce away from the earth as heat (in the form of infrared radiation.) Greenhouse gases contained within the earth’s atmosphere will then absorb some of this radiation, helping to keep our planet warm.

Although the greenhouse effect is a natural process vital to sustaining life on earth, it has become too effective in recent times due to an abundance of greenhouse gases within the atmosphere. This abundance of greenhouse gases is currently helping to warm our planet at a faster rate than ever recorded.

How Much is The Earth Warming?

According to data provided by NASA’s Goddard Institute for Space Studies (GISS), the earth has been warming most years since a brief cooling period of around ten years in the early 1900’s. The same data also suggest we have been experiencing rapid warming of the earth since the mid to late 1970’s.

The following chart illustrates the change in global surface temperature since 1880, relative to 1951 to 1980 average temperatures. The data has been sourced from NASA/GISS.

A chart showing the change in global surface temperatures since 1880.

The Effects of Global Warming

Global warming is projected to have numerous effects on the earth and its oceans, with some of these effects already been felt today. Some of the effects and consequences we are already seeing include:

  • Glaciers retreating
  • Less river and sea ice, with sea levels rising
  • More intense weather events
  • Plant and animal cycles being disrupted

With scientists in agreement that global warming is set to continue for many years ahead, these consequences are likely to get worse and be felt further afield.

Can Global Warming Be Stopped?

The short answer to this is no. Global warming is a natural cycle that’s important in helping to sustain life on earth. However, what can be stopped (or at least reduced) is the impact that humans are having on the greenhouse effect, leaving our earth to follow a more natural warming/cooling cycle, rather than a man-made cycle.

Governments across the world are committed to reducing climate change, however it remains to be seen whether or not this positive attitude will bear any fruit and have any long term impacts.