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| Source: goinyk/elements.envato.com |
The planet Earth is getting warmer, and the climate is certainly changing. Global warming is real, and humans are behind it. But how warm has our planet gotten, and what is the basic science behind the warming?
Also read: Global-Scale Pollution (Part 1): How Does Construction Industry Contribute to Global Warming?
How much warmer is the planet now?
Over the past 50 years, we have severely undermined the environmental integrity of our Earth's planet and threatened our continued life here. Our post-Industrial Revolution lifestyles have caused massive damage to all our natural systems. The concentration of greenhouse gases (GHGs) in the atmosphere today exceeds anything since well before the last ice age, mainly because of the uncontrolled use of fossil fuels and vast deforestation.
Our world is getting hotter. We have already warmed the planet by 0.9℃ more than the average temperature before the Industrial Revolution. Under the Paris Agreement, all nations committed to collectively limiting warming to 'well under 2℃, ideally no more than 1.5℃, through national emissions-reduction efforts that substantially increase every 5 years. To start the process, in 2015, 184 countries registered details of what they would do in the first five years and agreed to come back every 5 years to make stronger commitments.
The world we are now creating is leading to a warming of more than 3℃. If governments, corporations, and individuals make no further efforts than those registered in 2015 for the Paris Agreement, we will go to a warming of at least 3.7℃ by 2100. Worse yet, if they do not fulfil even the registered commitments, we can expect a warming of 4-5℃.
How does the planet get warmer?
To answer this question, we need to understand the basic science of the greenhouse effect, both the natural and human-enhanced versions.
The natural greenhouse effect is a good thing
The greenhouse effect is a natural process that warms the Earth's surface. Our thin layer of the atmosphere contains just the right amount of natural GHGs. GHGs and the greenhouse effect are a troposphere story because it occurs in the troposphere. Troposphere is the lowest layer of the atmosphere, between 0-10 km from the Earth's surface.
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| Natural greenhouse effect |
The sun's energy enters the atmosphere through light waves or ultraviolet energy and heats the Earth. Some of that energy warms the Earth and is then re-radiated into space through infrared waves or heat.
Under normal conditions or the natural greenhouse effect, a portion of the outgoing infrared radiation or heat is naturally trapped by the atmosphere - and that is a good thing because it keeps the temperature on Earth within comfortable bounds, around 15℃. Without this small heat trap, the Earth would be too freezing for life to exist, -18℃.
That is why the Earth is sometimes called the 'Goldilocks Planet' - the temperatures here have been just right. Comparatively, the GHGs on Venus are so think that its temperatures are far too hot for humans. The GHGs surrounding Mars, on the other hand, are almost nonexistent, so the temperature there is far too cold.
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| Different levels of GHGs and their effects on temperatures on Venus, Mars and Earth |
Human-enhanced greenhouse effect is a problem
The problem we are now facing is that vast quantities of human-caused CO2 and other GHGs thicken this thin layer of the atmosphere. And as it thickens, it traps a lot of the infrared radiation or heat that would otherwise escape the atmosphere and continue to the universe. As a result, the temperature of the Earth's atmosphere and oceans is getting dangerously warmer. This phenomenon is known as global warming and is what the climate crisis is about.
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| Human-enhanced greenhouse effect |
Global warming and climate change
Global warming is the recent and ongoing rise in global average temperature near the Earth's surface, caused mostly by increasing concentrations of GHGs in the atmosphere, causing climate patterns to change. In other words, the main driver of climate change is the greenhouse effect.
However, global warming represents only one aspect of climate change, which can involve cooling or warming. That is why certain cold countries in Europe suffer more extreme cold winters than they would normally have, and others suffer extreme summers with heat waves. Specifically, climate change is any significant change in temperature, precipitation, or wind patterns, among other effects, that occur over several decades or longer.
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