This article was first published in The Geographer – The newsletter of the Royal Scottish Geographical Society, (Spring 2020 issue, p 27).

‘Net Zero’ is a term that is seemingly everywhere at the moment. In its essence it describes a future where we do everything possible to cut greenhouse gas emissions but still have some emissions that are unavoidable – such as from food production – and so then have to soak up these residual emissions to reach a balance of our ongoing inputs to the atmosphere and what we drawdown from it.

Net zero has become a hugely important term in discussions on climate action, from individual organisations, through cities and states, right up to the global scale. Inevitably though, it has its complications.

In Scotland we have a net zero target of 2045, with the UK-wide target being 2050. Both refer to net zero greenhouse gas emissions (Net Zero GHG), so include methane, nitrous oxide and other powerful greenhouse gases, as well as carbon dioxide (CO₂). Globally the push is also for ‘net zero’ by the middle of the century, but here the 2050 focus is on ‘Net Zero CO₂’ rather than hitting the net zero balance for all greenhouse gases.

Worldwide, net zero CO₂ by the middle of the century gives us an evens chance of hitting the Paris Climate Goals and so avoiding more than a 1.5 degree increase in global average temperatures (we’re already at > 1 degree of heating compared to the pre-industrial baseline). As most developing countries have less ability to cut emissions as rapidly as developed nations, it follows that developed nations like Scotland and the UK should go beyond net zero CO₂ by 2050 and either achieve this target much earlier and/or deliver net zero for all GHGs by this date. For the global emissions account such concerted early action by developed nations could then provide the development headspace needed in the rest of the world. All nations would still have to hit net zero GHGs in the second half of the century to keep that 50:50 chance of achieving the Paris Climate Goals alive.

The Net Zero approach is certainly not without its critics. Some have called for gross or absolute zero, where all greenhouse gas emissions, everywhere, are stopped. This is theoretically possible for some activities and maybe even whole sectors – renewable power generation coupled with effective storage and multinational distribution networks could get the carbon intensity of UK electricity down to near zero for instance. However, there’s no way (yet) to achieve this complete zero emissions transition in other important areas, such as food production or long-haul aviation.

These so-called ‘unavoidable’ or ‘residual’ emissions are real and must be balanced by enhanced drawdown, but they open the door to a whole load of familiar protectionist ruses.

Both the UK Climate Change Act in 2008 and Climate Change (Scotland) Act in 2009 set a target of an 80% cut in greenhouse gas emissions by 2050 compared to 1990. Here, the 20% residual was intended to cover the really hard or impossible-to-mitigate sources (due to extremely high costs, social and technological barriers for instance). Naturally, every sector quickly identified areas of its own that should be included in this 20% allowance – it represented a nice buffer that allowed Business-As-Usual practices to continue based on everyone’s assumption that they were a special case.

In theory the new Climate Change Acts and their net zero targets mean that comforting emissions buffer has gone, but now of course there’s the real danger that the ‘net’ in Net Zero becomes another magic carpet under which to sweep weak mitigation actions and entirely avoidable ‘unavoidable emissions’.

For the 2050s and beyond it is hoped that emerging technologies like ‘Direct Air Carbon Capture and Storage’ (DACCS) – where CO₂ is chemically trapped from the air, concentrated, and piped to geological stores – will increasingly provide the balance to unavoidable emissions. In the mean time the focus is firmly on trees, and a rapid expansion in woodland cover in the coming decades.

Tree planting (as well as soil carbon enhancement, peatland restoration and other so-called ‘Nature-based Solutions’) certainly have an important part to play in achieving net zero in Scotland and the UK. Yet our finite land surface is already asked to meet a swathe of demands, not least providing the food we need. The danger is that we assume land use gives us a handy ‘Get Out of Jail Free’ card when it comes to making far-reaching cuts in our own emissions. It doesn’t.

The truth behind net zero is that we have to do everything possible. It is not ‘decarbonise the power sector OR reduce aviation emissions’. It is not ‘revolutionise home heating OR plant trees’. It is ‘AND, AND, AND…’.

By cutting emissions across every sector and activity AND protecting and enhancing natural carbon sinks AND investing in emerging technologies like DACCS we give ourselves and future generations a fighting chance of avoiding the worst impacts of climate change.

The Net Zero narrative is here to stay. Now we need to turn its story into reality.