With the election of an American president who denies the very existence of climate change, the snow that was late this year in our own Tromsø and the abnormal high temperatures on the North Pole and Svalbard, it’s once more time to put global warming and climate change in focus.
Text: Flore Van Maldeghem
Why does the climate change?
The climate has always fluctuated throughout geological time. These fluctuations are driven by different factors. First of all, the strength of the sun, because almost all the energy that affects Earth’s climate originates from the sun. However, the energy output from the sun is not constant and varies over time. A second factor is the Earth’s orbit around the sun. This is an ellipse but this ellipse can change shape. The closer the Earth is to the sun, the warmer our climate and vice versa. Besides the rotation around the sun, the Earth also rotates around its own axis. This axis leans at an angle which can change over time. When the angle increases, summers become warmer and winters become colder. The quantity of greenhouse gases in the atmosphere also contributes to the warming of the climate. A final important factor is the ocean circulation. The currents carry heat around the Earth. Their direction can shift so that different areas become warmer and cooler.
The greenhouse effect and the anthropogenic influence
Nowadays, the greenhouse effect (Figure 1) is driven by two components: a natural one caused by the amount of greenhouse gases naturally found in the atmosphere and a man-made one caused by the amount of greenhouse gases that humanity adds to the atmosphere as a result of its activities. These gases are water vapour, carbon dioxide, nitrous oxide, methane and ozone. Since the start of the industrial revolution in 1750, human activities have greatly increased the concentrations of these gases. The main sources for these gases are burning fossil fuels (which leads to higher CO2 concentrations), farming and forestry, cement manufacture and aerosols. The dramatic rise in CO2 is very clear when looking at the record derived from ice cores on Antarctica (Figure 2). The atmosphere of the past is preserved in the little air bubbles in the ice, so this provides us with a continuous record. In the past 800,000 years the values have never been so high, nor have they increased that fast, as they do now. Before 1750 the concentration was approximately 280 ppm, now it’s 387. The increasing rate is 2-3 ppm/year. If it continues like this, these changes may possibly cause an increase of 1.4-5.6°C between 1990 and 2100.
Predicting the consequences of global warming is one of the most difficult tasks because other natural processes and expected effects of global warming are dependent on many factors. It is also difficult to predict the size of the emissions of greenhouse gases in the coming years. There are, however, some effects that can be predicted: more drought and more flooding, less ice and snow, more extreme weather incidents and a rising sea level.
A possible solution to reduce or at least stop the rise in CO2 emission is by storing the CO2. There are three main ways to do this: in deep geological formations, in deep ocean water or in the form of mineral carbonates. But these techniques are still experimental and not on point yet. Another (maybe better) solution is to reduce CO2 emission by using green energy, recycling and using our resources with a common sense. Something to think about if we don’t want to ruin mankind, because Earth will survive everything we throw at it, but we won’t be able to cope with the changes.