Climate Change: Could it just be natural?

By Beatrice Omotosho

The science of climate change is a field in which most laypersons are not knowledgeable in nor familiar with. Now this means if you: like I, are a fellow believer, you may find yourself faced with a situation where a climate change sceptic is disputing the facts you believe to know, and asks you to prove either that climate change is happening, or that it is in fact anthropogenic (caused by humans), and not natural. In this 4-part article series, I will present you with some of the research and the science that can give you some grounds for argument.

Overview

The earth is made up of different systems. These include the Lithosphere: made up of rocks and the earth’s crust, the biosphere: the web of all living things and organisms, the cryosphere: all of the world’s ice, the hydrosphere: all of the world’s waters, and the atmosphere: an envelope of air and gases. These are all interrelated and constantly interact with one another through the constant movement of mass and energy within but also between these different spheres. The atmosphere is living and moving and there is constant circulation and transportation of different elements, however these natural interactions can be disrupted by human activity. In order to understand what the climate is and therefore what climate change constitutes, we must first understand this. To provide contextual substance, let me begin by outlining initially, the components that make up our earths system, how they interact with one another, how the earth forms its climate and the components that affect this. Within part 1-4, I’ll explain briefly how we define and understand climate and therefore how we can measure changes in said climate. I will then outline how the climate has changed since 1900s, the trends we see and the natural and anthropogenic influences that have fuelled this climate change. I will conclude that though numerous factors and types of factors have impacted global climate change, when looking at the timeframe of post 1900, anthropogenic influences have been the major determinants in this change, which is the argument you’ll need to get the sceptics off your back.

Scientific Background

      Scientists explain that “The climate and the biosphere are two highly intertwined, aggregate components of the whole-Earth System”. Within the biosphere, we have key cycles such as the carbon cycle where we see the integration and interrelationships between it as well as the atmosphere and geosphere. We see the constant production and cycling of Carbon, a key and natural gas in our earths system; a cycle which can sometimes be broken into, through certain activities. Earth receives energy from the sun in the form of short-wave radiation. Some of  this radiation: about 6 per cent according to scientists is reemitted by the earth back to space by atmospheric molecules in the form of longwave energy, some more radiation is also reflected back (around 10 per cent) by the surfaces of the oceans and land and the remainder is absorbed by the earth and warms the earth’s surface, approximately 288 watts per square metre. In order to be balanced, the net incoming solar radiation should equate to the amount that is absorbed and the reflected thermal radiation.

 Longwave radiation can be absorbed by different components of the atmosphere, which is then re-radiated by the atmosphere. CO2 and H2O: two naturally existing elements, trap some of this longwave radiation. This is what makes the earth habitable as without an atmosphere i.e. without these gases, earth’s average temperature would be about -18 degrees Celsius and we would all probably be dead. The main absorber is H2O: in the troposphere and ozone: in the stratosphere. This process is known as the greenhouse effect and it is natural and well understood. Figure 1 shows a spectral energy curve of solar radiation and the effect gases in the atmosphere have on the absorption rates of radiation and also shows what the spectrum of absorption would be like with a clear sky. A clear sky would also be prime time to just lay on the grass and watch the glittery stars. Figure 2 shows the information presented by figure 1 in a much less scary way. It also shows more dramatically, the effects of the gases in comparison to if there was no atmosphere at all. Trust me, that’s a scarier thought than you care to know. In part 2 of this series, I’m going to present the phenomenon of ‘climate’ and the data to show the ‘natural’ influences on climate, which I prove cannot be the cause of post 1990 climate change. Although most of us struggle to admit it, we really are wreaking havoc on earth.

Figure 1
Source: Lacis and Hansen 1974
Figure 2
Source: (secondary) Doug Benn, 2019

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