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  • Writer's pictureCharlotte Emily

Earth’s Temperature Cycles

Updated: Aug 16, 2021


Our Earth is burning. There’s no denying that. Whether you agree with Climate Change or not, the science does not lie. However there is disagreement; this comes with the differing beliefs as to why our Earth is experiencing this heat. There are two sides to the argument of Climate Change – it’s natural, or it’s as a result of humans. Both technically, are factually correct. But what does the data show? Is it really much worse that than 400,000 years ago?


So, when looking at the natural cycle of the Earth in relation to temperature, there is a constant pattern. As can be seen from Figure 1a below, it’s very clear to see. So what is it? This graph shows the average temperature every year, from around 425,000 years ago until now. As we can see, every 100,000 years or so the temperature drastically increases. Whilst it fluctuates, the high temperatures typically last for ’only’ 10,000 – 15,000 years, until the Earth cools once again.

Glacials and Inter-Glacials over the last 450,000 Years  

Figure 1a, Energy Education, University of Calgary

These are the Ice Ages and the Interglacial Periods between; and as we all know, these correspond the average temperature of the Earth. These cycles occur in a 100,000 year period, as previously mentioned. The ‘Ice Age’ occurs for predominantly 70% of that time, with the warmer interglacial period the remaining 30%. So where are we now in the graph and in this Ice Age cycle? Well, we are currently in an inter-glacial period. That means that we are in a period of climatic warming between glacials. These usually last between 10,000 and 15,000 years, (as is shown in Figure 1a) and are naturally occurring. These periods are what happen in between Ice Ages, also known as glacial periods – a prolonged cold climate phase lasting for tens of thousands of years, and causing continental glaciation in middle and high latitudes. Let’s think of these two periods as two ends of a seesaw – one end is at the peak, the other is the opposite and represents the trough. We just apply that thought to the graph in Figure 1a as it is a continuous cycle, as the temperature reaches its peak in during the interglacial periods and the troughs are the Glacial Periods.

As we can see in Figure 1a, in each inter-glacial period, there is a time in which the temperature peaks. The years around this, see a fast and dramatic rise in temperature, leading to a reduction after the peak. The rapid fall in temperature is not as drastic as the rise, with evident fluctuations. However, the result is same every 100,000 years with a similar pattern for each event; the global temperature decreases to levels as low as 16°F (-9°C) from looking at this graph.


Looking at where we are in the current cycle, the temperature of this inter-glacial period has already peaked. This is supported by Figure 1b (below), a graph showing the anomalies in temperature compared to CO2 levels of the past 425,000 years. Whilst this temperature data is not made of averages, it’s equally useful as it shows the highest and lowest temperatures reached. As a result, we can compare to the levels that we are seeing now. From looking at Figure 1b below, what’s clear is that the highest temperature reached, clearly isn’t the same in each inter-glacial period. That’s to be expected. It can be seen that the previous four interglacial-periods reached higher temperatures than the current – this is supported with the yearly average temperatures shown in Figure 1a.

Figure 1b, National Oceanic Atmospheric Administration

So what is different about this interglacial-period? It can be seen in Figure 1b, that instead of the temperature decreasing, it is fluctuating, crucially it is increasing periodically. Figure 1a also supports this – it shows that whilst it’s been fluctuating, it is not decreasing. Of course it decreases every other year, but it’s not decreasing at the necessary rate. This is what is causing the problems we are seeing now, and the resulting Climate Change.

So, let’s return to the argument that Climate Change is natural. This is supported to a certain level when looking at this data. Our peak is not as high as previous periods, so is our current situation actually that bad? Surely the Earth can withstand higher temperatures? Well yes, that is true. The graphs clearly show us that the Earth has faced much higher temperatures, although the conditions of these periods will be very different to those now, which may have made it possible for the Earth to withstand those temperatures. Regardless of that factor, the Earth has been hotter. So, are our rising temperatures really that damaging? Well, it’s not necessarily the high temperature that’s the problem – it’s the length of time that the temperature remains at that level. This along with the high CO2 levels in the atmosphere are disrupting all natural processes on Earth. Let’s look at the temperature levels in Figure 1a and Figure 1b. As previously mentioned, they show that the temperature fluctuates, but mostly and more drastically in the glacial periods. Let’s carry that thought through for a minute, as we are not in a glacial period and our temperature is fluctuating. The level of fluctuation is much higher at our current point, than the same point in the past.


So why is this? Figure 1c below is a ‘zoomed in’ graph from Figure 1a and shows the temperature of the lower atmosphere over the last 500 years. We see some gradual rise and fall until 120 years ago. Since then it has been much more intense, with change every year, rather than change over a period of years. In relation to the anomaly in CO2 concentrations shown in Figure 1b, they always seem to positively correlate to the temperature at the same point in time. Until you reach the present. The CO2 levels are not relative to the temperature; in fact they are no where near. When looking at the pattern, it should be a level of around 260ppm. It is in fact, around 285ppm; much higher. 

Figure 1c, Geocraft – Satellite stratospheric data, S. Hemisphere ground temp. data, Vostok Ice Core Data

Back to the temperature – when comparing Figure 1a to Figure 1c it shows that this fluctuation seems to have been happening for the last 10,000 years or so. However, it’s not until you see a smaller scale (Figure 1c) that you can see when it changed. There is one simple explanation for this – the Industrial Revolution. This would be a human effect, but there are also natural effects.


This data shows us that we are at a critical point. Our Earth is experiencing higher carbon dioxide levels and is remaining at a high temperature for a longer period of time – against the cycle of the last at least, 400,000 years. The Earth has naturally been carrying out these cycles, reaching a peak for a short amount of time, then falling. If the Earth cannot naturally withstand these temperatures for such a long period of time, which is evident, then this isn’t just as a result of natural causes. 

As a result, the situation really is that bad, as this is a global cycle that has been affected; not your local weather system for example, Earth’s global systems. 


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