Environmental Impact Units or "EIU" for short is a summary of every pollutant that your company is generating around the globe every day. Every building you build will add to this number, as well as every trade route. 

To lower this number, you will have to unlock certain researches, as well as build carbon offset buildings.

The higher your EIU, the more it will bring your Global Perception, which in 0.0.6.0 will effect your influence generation.

Essentially, the higher your EIU, the harder the game will become. 

I haven't added this number to the UI yet, as it will need to go along with the new Global Perception rating, and I haven't implemented any of that yet, but it is calculated every day, and just looks like this in my console:

That little segment is while I was painting mines onto a tilemap. If you do nothing, your EIU will stay the same. Again, your EIU represents your DAILY impact on the environment.

The current buildings have the following ratings:

farm        = 5
mine        = 20
refinery    = 50
factory     = 40
warehouse   = 2
rail        = 10
sea         = 15
air         = 35
coal        = 100
geothermal  = 0
hydro       = 0
lignite     = 120
natural_gas = 25
nuclear     = 1
oil         = 80
solar       = 0
wind        = 0

Just a little look into what is coming, and perhaps a glimpse into my thought process. If you have any thoughts, please feel free to let me know!

-Chett