What is global warming?

So what indeed is global warming?

Is it just the increase in temperatures we experience in many parts of the world?

Well, that’s a very simplistic and rather inaccurate definition of global warming.

Sure, global warming does signify an increase in temperature of the Earth’s surface – both temperature on land and on oceans/water – as well as the temperature in its atmosphere. But we are not talking about such increases year on year. Nor are we talking about increases in specific parts of the world.

Global warming represents the increase in the average temperatures worldwide, measured over many decades!

Allow us to explain in some detail: You take the sum of temperatures from many different parts of the world for different seasons for each year, and then arrive at averages. You continue doing this year after year. When you consider these averages, you will be surprised that these are fairly constant year after year, even though there could be significant temperature variations in specific regions during these years.

That is, the winter and summer temperatures this year in your location might be lower than what it was last year, but the global average of all temperatures from all locations is likely to be almost the same as the one measured for the previous year.

Now, extend this comparison of average temperatures over a few decades. When scientists do this, they see that this average global temperature has been increasing significantly in the last few decades, much higher than what it did in the past for similar timelines.

This increase in average global temperatures over many decades is termed Global Warming.

To give you some stats on how these global average temperatures have trended:

Scientists estimate that when ice ages ended in the past, it took about 5,000 years for the planet to warm between 4 and 7 degrees Celsius. On the other hand, the warming in the past hundred years alone has been 0.75 degrees Celsius. This works out to about 8-10 times faster than the ice-age-recovery warming!

Even within the last century’s 0.75 degree C increase, about two thirds (0.5 deg C) have occurred since 1975 alone. Thus the rate at which global warming has increased between 1975 and now (2017) is about 13 times the rate at which the average temperatures increased in the past!