Climate change or global warming: a primer

Climate change is a significant change in temperature, wind patterns and precipitation that occurs over a long period of time. Some of these changes occur in cycles over decades, hundreds, thousands and millions of years; some could be random occurrences. These result in precipitation (rain or hail, snowfall) and wind patterns, or extreme weather events like thunderstorms, cyclones, tornados etc.

So, is there a problem?

These are all normal occurrences, even the random ones. We experience these throughout our lives. And every school going child learns that there are climate cycles that last thousands of years that give rise to the Ice Ages and their reverse. These occur due to natural processes within the climate system such as ocean circulation; other natural factors are slow changes in the Earth's orbit around the Sun, or changes in the intensity of the Sun itself.

So what is the problem? Why have climate change and global warming suddenly become such crucial issues?

In the 20th century, scientists began to detect that the Earth was warming up abnormally. They suspected that the recorded temperatures exceeded the projections for normal long term trends. And in the first decade of the new millennium the common people began to feel the effects.

Heat waves across the world, monster storms hitting coastal areas, massive tornados tearing across the countryside, rivers flooding to unprecedented levels, and debilitating droughts across vast swathes of land began to be reported from all corners of the globe.

Is this for real? Or is it that due to massive strides in telecommunication, especially the spread of audio-visual media, we were impacted by the immediacy of these events?

Well, to deal with such questions, extensive studies of these phenomena were undertaken, and over the years, in fact decades, the probability kept on increasing that yes, something unusual is happening, the earth's atmosphere is heating up, which is causing all these problems; and that it has been happening for decades, but it is only now that we can actually experience the changes.

This is no ordinary, natural climate change. This is human induced climate change.

Human intervention in the industrial era accelerated global warming, and this has resulted in the climate change that we hear about and are now experiencing for ourselves.

What is the difference between climate change and global warming?

Both, global warming and the opposite phenomenon global cooling, result in different patterns of climate change. Today when we talk of climate change we refer to the patterns caused by human induced global warming. And hence, the terms "climate change" and "global warming" are used interchangeably.

And what causes global warming?

Currently global warming is being caused by greenhouse gases (GHGs) resulting from human activity, mainly industrial development and urbanization, agriculture and changes in land-use patterns.