The more recent history, from the middle ages and up until now, show increasing temperatures, rising as the world emerged from the Little Ice Age (LIA), around 1850. With the industrial era, human activities have at the same time increased the level of carbon dioxide (CO2) in the atmosphere, primarily through the burning of fossil fuels. Carbon dioxide is one of the main greenhouse gases, and scientists have been able to connect human activities as one of the drivers to climate change and global warming. The top part of the CO2 measurements, the observations, are what is referred to as the 'Mauna Loa curve' or the 'Keeling curve'.
From collection: International Polar Year (IPY) educational posters
Hugo Ahlenius, UNEP/GRID-Arendal