IntroductionClimate change and its mitigation have now, more than ever, been the concern of many countries, organizations and businesses such as the United Nations (UN), the World Economic Forum (WEF), International Energy Agency (IEA) and the European Union (EU) (Australian Academy of Science, 2015; WEF, 2020). Climate change touches everything and everybody so it must be tackled urgently and clear-headedly (Young, 2010). The world average temperature, since mid-19 th century to the end of 20 th century, moved from dark blue cooler than average years to red warmer than average years (figure 1) and still increasing in the 21 st century (figure 2).