The nature of climate

The nature of climate interview with Professor Bogdan Chojnicki

Michał Kępski, TRAKT CTC: Let’s start with the basics. What is climate?

Bogdan Chojnicki: Climate is a description of weather in a given place created on the basis of observation carried out over the period of many years (at least 30 years), whereas weather are temporary meteorological conditions. This difference could be illustrated with the use of similar terms such as: human personality and emotions. Weather can be compared to emotions we feel in a given situation, whereas climate is our personality. Weather, just like emotions, can change really fast. On the other hand, to describe our personality, we need many years of observation. Thus, when we are talking about climate change we do not mean change in the temporary weather conditions but change in the overall conditions in a given place.

In today’s Wielkopolska, about 12,000 years ago the last glaciation of the prehistoric Pleistocene, which formed for example the unique landscape of this region, came to an end. The average temperature was about -2oC. Since the beginning of the age of humans we have also been noticing climate fluctuations, such as for example the Medieval Warm Period (with average temperature of 0oC) or the Little Ice Age (with average temperature of -1oC). What are the factors contributing to climate change?

Changes in the climate have always been happening and their causes have been both natural and anthropogenic (resulting from the influence of human beings). Subtle changes in the Earth’s position in relation to the Sun have shaped global climate for hundreds of thousands of years – they are taking place even today. However, the contemporary abrupt rise in the temperature on the Earth cannot be explained by natural causes, as this change has been taking place over the period of hundreds of years, whereas geological processes causing climate change take place over the period of tens or even hundreds of thousands of years. By the way, according to geological predictions, currently we should be noticing a slow drop in temperature. The conditions in Europe during the so-called Medieval Warm Period are often mentioned, however, it is worth noting that temperatures occurring at that time were similar to the ones observed in the 1980s. Since then, there has been an even greater rise in global temperature and now it is even higher than during this period. People, due to the emission of the greenhouse gases, have contributed to the warming up of the atmosphere.

The world is comprised of different climate zones. Are the changes which are taking place also different?

Global rise in temperature means that we can expect for example conditions which may contribute to drought alternated with rainstorm. This also leads to changing the conditions in particular