Victoria University Associate Professor makes fundamental error in his calculations that led him to conclude that the single biggest change an individual can make to increase the chances of temperature increases remaining below 2 degrees is to eat less meat and dairy products.
In an article published in Stuff the associate professor of glaciology based his statement on the fact that half our greenhouse gas emissions come from agriculture, but what he does not realise is that these emissions he refers to are emissions of carbon and not all carbon emissions are the same.
Agriculture might well produce half our carbon emissions, but carbon emissions sourced from livestock are quite different to carbon emissions sourced from fossil fuel. To make conclusions based on comparing one carbon emission with another, without taking this difference in to account, is a mistake. That is why carbon footprint calculators and comparisons are meaningless.
Most of the carbon livestock produce are sourced from methane and most of those are produced in a stable state of production. This means that they do not cause the atmospheric concentration of greenhouse gas to increase, while all CO2 emissions from fossil fuel on the other hand do.
Nick Colledge recommends people switch from animal protein to plant sourced protein, and in doing so advocates people switch away from livestock production systems that cause very little increases if any in atmospheric greenhouse gas, and switch to plant production system that do cause long term increases in atmospheric greenhouse gas through the CO2 emitted by cultivation machinery and soil carbon losses.
The advice Nick Colledge gives is not only wrong, it is counterproductive to the goal of reducing global warming. This type of advice highlights a real concern some climate scientists have expressed, which is that reducing methane emissions will very likely lead to increasing CO2 emissions and this is an example of that. The reason this is a problem is that scientists recognize that it is only reducing CO2 emissions that can ultimately stop global warming, methane is just a sideshow.
By advocating people eat plant protein instead of dairy and meat protein, Nick Colledge is advocating they increase their harmful CO2 emissions, in order to reduce methane emissions, which is exactly the opposite of what climate scientists say is needed to keep peak temperatures below 2 degrees above pre industrial times.