Understanding ‘climate change’ and related concepts

In the Anthropology Honours class about science and society that I am currently facilitating, we talked about climate change this week. If you want to understand the debates and issues related to climate change, you have to clearly differentiate between the various related concepts, such as weather versus climate, climate variability versus anthropogenic climate change, and global warming (in another posting I will add ‘changing climate’ to these concepts).

The most useful discussion on the difference between weather and climate most surely is from Neil deGrasse Tyson, host of Cosmos. He explains weather as the short-term (daily and weekly) highly unpredictable changes in atmospheric conditions (measured through quantities such as temperature, precipitation and wind), whilst climate is the longer-term (over years) ‘average weather’, that is more predictable. The analogy he uses of him walking with his dog is revealing: the meandering dog that is running around all over the place (though within the parameters of the leash he is on), indicates the weather. The steady progress of Neil, and the much-more straight path he is walking on, is the climate.

Weather vs climate _ Neil deGrasse

Source: http://plannedresilience.net/wp-content/uploads/2014/10/weather-climate.jpg

Weather then is short-term meteorological events in terms of days, weeks, and months. The popular definition of climate is from the World Meteorological Organisation that explains climate as “a statistical description in terms of the mean and variability of relevant meteorological quantities over a period of time ranging from months to thousands or millions of years.” The interactions between the atmosphere, the hydrosphere, the cryosphere, the lithosphere and the biosphere explains climate.

Whilst this natural science definition indicating the physicality of climate is crucial, the social understanding of climate is just as important. David Hulme (2015:175) states: “My argument is that climate—as it is imagined and acted upon [my emphasis] — needs to be understood, first and foremost, culturally and that the environmental humanities can enrich and deepen such an understanding.”

Another crucial distinction to make is between climate variability and climate change. Climate on earth has always been variable, meaning it had never been constant but has been changing due to various natural process, such as the earth’s tilting, volcanic eruptions, tectonic plate movement, eruptions on the sun, etc. The occurances of ice ages in previous millennia indicates such climate variability. Climate change though is climate variability due to anthropogenic (human-induced) causes; in this definition I am following the  United Nations Framework Convention on Climate Change (UNFCCC). Such climate change is occurring, and thus only observable, over decades and centuries.

The main human-induced cause is rapidly increasing the amount of CO2 and other greenhouse gases in the earth’s atmosphere, leading to an enhanced greenhouse effect, that is causing the average temperature on earth to rise. And that then is global warming:  It is mainly through our burning of fossil fuels for our energy-hungry economies and lives, increased deforestation, and other land-use changes, that we are increasing the amount of greenhouse gases in the atmosphere. And this is leading to “overall warming of the earth, based on average increases in temperature over the entire land and ocean surface” (Davis 2011:16).

For further clarification of various climate change related concepts, see the FAO Climate Change and Bio-energy Glossary.

List of reference

Davis C (ed) 2011 Climate risk and vulnerability: A handbook for southern Africa. Pretoria: CSIR

Hulme M 2015 ClimateEnvironmental Humanities 6: 175-178