This story falls prey to the misconception that climate change is caused by a huge increase in carbon dioxide, such that the atmosphere is radically changed. However, this very real threat is due to a small rise in carbon dioxide from a low level to a slightly higher level, which nevertheless traps a lot more heat from the sun.
When The Doctor's air sensor is saying "Oxygen Level, 1%....." there are several bonfires burning vigorously. At such a low level of oxygen, the fires would've guttered out.
In fact some fire prevention systems work by reducing the oxygen level from a normal 21% to just 15% - which is too low to support combustion, but still adequate to sustain life.
In fact some fire prevention systems work by reducing the oxygen level from a normal 21% to just 15% - which is too low to support combustion, but still adequate to sustain life.
When the group is escaping through the tunnels, they push a huge vault door closed and turn the wheel handle to lock it, but then you can see it immediately pop open a bit again.
The Doctor "explains" how plants are the opposite to humans, they breathe in carbon dioxide and breathe out oxygen, which is not true. Plants have the same type of cells as animals - they obtain carbohydrates from the environment, "burn" them with inhaled oxygen, and then exhale the resultant carbon dioxide.
The difference is that animals obtain their carbohydrates from plants or other animals, while plants obtain their carbohydrates by photosynthesizing it with the energy of sunlight - so most of their excess oxygen is used up at night, as more stored carbohydrates are "burnt".
The difference is that animals obtain their carbohydrates from plants or other animals, while plants obtain their carbohydrates by photosynthesizing it with the energy of sunlight - so most of their excess oxygen is used up at night, as more stored carbohydrates are "burnt".