How satellites are helping us understand NZ climate change

2 March 2018

Baz Macdonald


NZ is set to have its second satellite earth observation conference from March 6-7 at Te Papa in Wellington. At this colloquium experts and scientists from all over NZ and the world will be discussing how NZ is, and will be, effected by space technologies. In the last of a three-part series running up to the conference, Baz Macdonald investigates the role Earth observation satellites are playing in helping us to understand NZ climate change.

The rise in humanity’s technological prowess has undoubtedly played a role in its impact on the Earth’s environment. However, though technology has played a role in creating these problems, it is also helping scientists better understand and tackle them.

Researchers are developing and implementing a sophisticated array of modern instruments for the purpose of measuring climate change factors such as greenhouse gas inventories.

Increasingly, Earth observation satellites are being used around the world to not only measure greenhouse gases, but also to catalogue associated influencers of climate change, such as water levels and forestry stocks.

NZ is part of this movement, using and developing earth observation data in order to better understand and manage the country’s carbon footprint, as well as track NZ’s progress in meeting its Kyoto protocol obligations.

Unfortunately, these increasingly thorough readings are showing that we are veering off track.

Under the Kyoto Protocol, NZ has been budgeted an emission quantity of 509.9 million tonnes of carbon between 2013-2020.  If you add up all of NZ’s sources, from industry, fuel consumption, and agriculture – which represents 48% of our country’s emissions – we far exceed this amount.

 A greenhouse inventory report released by the Ministry of the Environment last year showed that we are on track to release 647.5 million tonnes of carbon in this measurement period – exceeding our budget by 137 million tonnes. With the current carbon price for New Zealand set at $16.45, this emission quantity equates to a financial liability of $2.3 billion dollars.

Going partway in mitigating this amount, is the country’s carbon sinks. These sinks are ways in which the C02 is absorbed out of the atmosphere – primarily through vegetation such as forests. The carbon budget is the balance of the sources of greenhouse gas emissions against the carbon sinks.

Earth observation satellites offer scientists ways to measure these carbon sinks, as well as find ways to better harness and calculate the effect of them.


Reading the tree leaves

 One of the programmes using earth observation in this way is the Ministry for the Enviroment’s Land Use Carbon Analysis System (LUCAS) – through which the ministry monitors land use in New Zealand.

This is just one of the many programmes the NZ government have in place to monitor the emissions and removals of greenhouse gases in the country. Information from these programmes are compiled and submitted to the UN as part of the Government’s ongoing commitment to the Paris and Kyoto agreements.

The primary purpose of LUCAS is to monitor how much of the country is occupied by forestry. Forestry levels are a key component in understanding NZ’s footprint, because they indicate the amount of carbon being processed out of the atmosphere.

Deborah Burgess is the leader of the LUCAS programme. She and her team use earth observation satellites to monitor all land use changes, but Burgess said the focus is keeping track of the planting and harvesting of forest stocks throughout NZ.

“Using satellite imagery, we can capture the extent of the forest. Really importantly, we can monitor how deforestation is occurring – because that is a big emission.”

“When we lose forest, through it being chopped down and converted to another land use, then we have to pay for that - it becomes a negative on our emissions balance sheet.”

When committing to the Kyoto agreement, NZ decided that 1990 was going to be the baseline for emissions and inventories. Around this time there was a big push for forestry plantations in NZ, and as a result, forestry stocks were very high around the time the baseline was set. 

However, these plantations were commercial stock intended to be harvested for timber. As such, the trees planted in 1990 came into maturity in the past 5 years and were harvested. This was one of the major factors in why the most recent greenhouse inventories report shows net emissions have risen 63.6% since 1990 – because as well as creating more emissions, NZ has also lost a portion of its carbon sink to harvesting in recent years.

 As well as losing the carbon sink of these trees when they are harvested, timber stock also emits C02 as it decays or is burnt - meaning timber harvesting not only stops carbon removal from occurring, but creates more carbon in the atmosphere in doing so.

Compounding this problem is the shift in land use over the past several decades, in which planting has slowed and a portion of forestry land has been converted into other uses – such as agriculture.

As a result of these trends, forestry has gone from offsetting over 50% of NZ’s greenhouse emissions in 1990, to around 30% in 2015.

Though the trend is not moving in the desired direction, this depth of understanding of NZ’s emissions allows the Government to better strategize a counter to this rise. The more information they have, the more possibilities open up.

The technology used to create this data is evolving all the time, allowing researchers to better construct the picture of NZ’s carbon emissions and uptake.