Why is an increase of 2° Celsius such a big deal?

The key factor in all climate change articles and especially the Paris Agreement, is that we should not let the temperature increase beyond 2° Celsius. According to current trends, with all our mitigation efforts, the temperature of our Earth is expected to rise by 3.5° Celsius at the end of this century. And without any effort on our parts, if we were to allow the temperature to rise at the current rate, then we would see an increase of 4.1-4.8° Celsius at the end of this century.

Well, a lot of people in the world without a background in science think this is not such a big deal. Go speak to any layman and ask them if they think this should worry everyone. Their answer will be an amused and firm “NO”.

Why is the larger human population not concerned with this monumental change in global climate? Do they not care? Or they do not understand it’s significance?

I believe that the reason for such a flippant attitude to this staggering (not) figure is that they simply do not understand what “rise in temperature of (insert temperature figure) by the end of this century” means.

That sentence, which seems quite obvious and understandable to a person with a rigorous scientific education, is actually riddled with ambiguity that makes it sound insignificant. This ambiguity is why a layman will respond to that sentence saying, “So what? That much change in temperature happens everyday!”

You see, when scientists say “increase in temperature”, they actually mean an increase in global average temperature. The “global average temperature” of the Earth has been measured over the course of at least a period of 30 years (most study span 100 years of temperature data), and is the average of the temperature of every single part of the Earth.

The range of this value, therefore, is HUGE. And I cannot overstate that. Huge, because the value of current global average temperature and the projected increase has been arrived at by taking into account the temperature of every place where temperatures have been recorded on earth, every year for the last 30 years at least. 

That means that the temperature of Antarctica and the Himalayas and Siberia, often in negative temperatures, have been clubbed and averaged with the temperatures of the Sahara, Texas and Southern India, where the temperatures are really high most of the year. The daily variation that you see has all but vanished because the temperatures of more than 30 years have been taken into account and they have been averaged out. 

If you look at this graphically, then this is what it would like like:

(Please excuse my hand-drawn graph and poor camera quality)

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Figure 1: Temperature variation over days
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Figure 2: Temperature variation over months
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Figure 3: Temperature variation over years.

As you can see, the temperature variation that we see daily in figure 1 has all but disappeared when we look at temperature variation over many years in Figure 3.

What is important to note is that in Figure 3, over the years, there has been a slight and gradual increase in temperature. If we were to “zoom in” to that second part of the curve and look at the temperatures during the DAYS of those years, you will find that the daily temperatures were much higher than the temperatures recorded in earlier days, and the variation was also probably greater.

And that is what we seem to be heading towards, in the current climate change scenario. If, over 100 years there has even been a slight increase in temperature like in Figure 3, then it is a major cause of worry because that means that the daily temperatures have increased dramatically over the years and will hold much greater variation over months (instability or changing climate).

So, the next time you are questioned about why we should be worried about a seemingly insignificant increase of 2°C, do remember this post and my graphs and explain this to them. I’m sure you will see understanding dawn on their faces and they will probably treat this more seriously.

 

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2 thoughts on “Why is an increase of 2° Celsius such a big deal?

  1. Have you ever heard of the Milankovitch theory?

    Remember, prior to 1920, we believed the world was cooling. Now past 1940-1950’s we are seeing a annual warming trend in global temperatures.

    That theory could potentially explain what we call Global warming/cooling. There is no denying, that we in the past have seen annual declines in global temperatures, and annual global rises.

    Liked by 1 person

    1. Yes, I have heard of the Milankovich theory.
      From my understanding, though, the effects of the theory on earth’s climate are seen over 20,000-40,000 years. It does affect the changes in temperature and climate. It may be that we are at a period right now when that is happening, but it’s still highly debated. Most scientists today agree that the current climate change has been accelerated by humans.

      Like

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