Thread by @olirubes

To kick off #Sustainuary then, let's talk about #dairy alternatives like nut juice, oat juice and various other #plantbased drinks. We've never had more choice, but what are the actual #sustainability credentials of these products vs animal milk? #Veganuary

#Dairy production has received widespread criticism for its #carbonfootprint .
The average UK dairy system produces around 1.2Kg Co2eq. per Kg milk . However this varies hugely, mainly depending on the cows' diets and how much fertiliser is used on the pasture. #sustainuary

The most #sustainable #dairy farms in the UK can have carbon footprints as low as 0.5 KgCO2 eq. per Kg milk produced, which are comparable to many dairy alternatives. #Sustainuary #Veganuary

Carbon footprint of #dairy all depends on how farms are managed. Optimising cows' diets, efficient & targeted use of nitrogen fertiliser and incorporation of waste products into feed (i.e. brewers grains or rapemeal) helps lower footprint. #Sustainuary

#Dairy in UK is mostly pasture based. #Methane from ruminant digestion tends to make up most of carbon footprint. Much of this is already mobile, as part of the #carboncycle, although feed production and fertiliser on pasture also contributes to the footprint. #Sustainuary

When you produce crops such as soy or oats, in most cases this requires artificial fertiliser - which is very energy intensive to produce - as well as lots of tractor fuel. All derived from #fossilfuels . #Sustainuary

These carbon emissions were once locked up in hydrocarbons like oil, so not contributing to climate change. Crop production then releases them into the atmosphere. Therefore, these are very different to emissions from grazing cows's digestive systems. #Sustainuary

So, although total #carbonemissions from crop production are often measured as lower than #dairy products, often you're unlocking new carbon, rather than recycling existing carbon, within the active carbon cycle. This is hard to incorporate into sustainability assessment though.

The balance of this all depends on how much of the cows' diets comes from grazing pasture rather than grain or soy, as well as how much mineral fertiliser is applied to the pasture. So, it's not cows that are the issue, but how they're farmed.

Here's a diagram of the carbon cycle. In pasture-based #dairy systems, emissions from ruminant digestion will mostly be part of this active carbon cycle. In contrast, fertiliser and tractor fuel require unlocking new, previously immobile carbon from fossil fuels. #Sustainuary

There are plenty of #sustainability issues with #dairy production, but the aim of this thread is to illustrate how it's not simply a case of comparing overall carbon footprints. Everything depends on how the dairy or crop farms are managed. #Sustainuary

Here's where I got the figures for the UK dairy sector from dairy.ahdb.org.uk/resources-libr…

Here's a PHD study with some really informative info on carbon footprints of #dairy alternatives programme.exordo.com/isie2017/deleg…