At the time, I wrote an account of how the lockdown might affect our climate-warming (greenhouse gas) emissions. Since then, there's been a fair amount of speculation and study into this impact, both here and overseas. Let’s take a quick look at what we’ve learnt over the past two months.
My initial analysis was very much a broad brush approach. It went through 130 emission sources of NZ's greenhouse gas (GHG) inventory and estimated how much relative activity there would be during the lockdown. Overall, I arrived at an estimated drop in emissions of just under 25% compared with the business-as-usual (BAU) case.
As I mentioned back then, emissions from our agriculture and food sector (a little over 50% of our total GHG emissions, allowing for on-farm and processing emissions), would remain more or less unaffected by the lockdown.
It was not as straightforward to estimate the changes for our other significant sources - transport (road and air), electricity and other fuels (in our homes, offices and commercial buildings), and our main industrial activities (like cement, steel and aluminium production).
For road transport (approximately 20% of our overall emissions), I estimated that emissions would decline by 75%, by far the most significant estimated drop. This was based on assuming the average light vehicle would only travel about 10% of normal, whilst heavy vehicles (like trucks and buses) might only drop by 25%. For air travel, I estimated a drop of 95% in emissions.
For electricity use, I guessed that demand would drop to only 25% of normal for commercial and industrial sites, but increase by 50% in our homes - overall a 21% drop in emissions. For major industrial activities, reports in the early stages of lockdown suggested that much activity (including heavy emitting industries like cement and steel production) would fall to maintenance levels (say 10%), The one main exception was aluminium which initially continued to operate normally.
Waste to landfill is an interesting one - whilst no doubt volumes to landfill would drop significantly this wouldn't make any difference to emissions immediately, given the long lag before organic waste decomposes into methane in landfills. It’s also worth noting that landfills only contribute about half of the emissions from the waste sector, so just about 2% of NZ's overall emissions.
So, what information has emerged in the meantime? It is limited, but offers some insights.
In early April, Z Energy reported a decline in fuel sales of 80%, so that matches quite well with the estimated drop in road and air transport emissions. Electricity generation data from the Electricity Authority shows a 15% decrease in April 2020, compared with April 2019, a bit less than my estimated 21% reduction. For the purposes of this exercise I'm assuming the sources of generation used each April were the same.
This means the emissions from generation would have also been the same. Unofficial data from the waste sector suggests that waste volumes to landfill dropped by about 40% during the lockdown.
As you may have read, there have been various estimates of how much global emissions may drop in 2020 as a result of the pandemic. One of the most comprehensive is from Nature. This major analysis estimated carbon dioxide emission reductions for 69 countries (including New Zealand), collectively responsible for 97% of global emissions. It estimated each country's emissions drop based on the type of lockdown (level of confinement) in place, using a variety of data sources for reference. It covered six main sectors - power, industry, surface transport, public buildings and commerce, residential and aviation. It didn't consider agriculture or waste.
It estimated that New Zealand's carbon dioxide emissions decreased by 41% per day of the Level 4 lockdown compared with BAU. NZ had the second largest estimated reduction of all the 69 countries (after Luxembourg). The average drop in emissions across all countries was 17%.
How does that 41% decrease compare with my estimate of about 25%? They can't be compared directly, as the Nature study only accounted for carbon dioxide, not the other GHGs (like methane and nitrous oxide). Given that carbon dioxide (CO2) emissions account for 45% of NZ’s GHG emissions, and assuming our non-CO2 emissions are unaffected (a reasonable assumption) then the Nature study suggests that NZ's GHG emissions reduced by about 19%. Lower than my original estimate of 25% but in the same 'ballpark'.
So, an interesting academic exercise for some. But what relevance does it have for the future?
The study suggested that global emissions might drop by up to 8% in 2020 (back to 2006 levels), depending on the speed of return to normal economic activity. This drop is in line with the year-on-year reduction we need to meet the 1.5 degree warming containment goal.
need this level of reduction, but without the severe economic impacts. Unfortunately, as the global economy recovers, emissions are likely to return to recent levels. The International Monetary Fund is estimating a GDP rebound of 5.8% in 2021 - a similar jump in emissions is likely.
This just underscores the urgent need for climate friendly recovery investment, both here and overseas. If we don't invest in low carbon activities then we're imposing a double dose of eye-watering debt on our children and grandchildren - the tens of billions of debt to fix the economy, and then tens of billions more to fix the climate crisis down the track.
It should be a no-brainer and has the support of many scientific, economic and political leaders, such as the UK’s Prime Minister Boris Johnson.
Last month we launched our new Climate Action 20/25 project to help smaller businesses act on climate over the next five years. We kicked it off with our report examining the issues and opportunities and the pathway for action. Read it now.