Why New Zealand should not explore for more natural gas reserves

The New Zealand government is introducing legislation to become zero-carbon by 2050, but will consider new permits for coal mining, offshore oil drilling and fracking on a case-by-case basis.
from shutter stock.com, CC BY-ND

Ralph Sims, Massey University

New Zealand’s new coalition government has committed to introducing zero-carbon legislation that would set the country on a course to be carbon neutral by 2050.

At the same time, it is not ruling out new permits for coal mining, offshore oil drilling and fracking during a transition away from fossil fuels.

Natural gas is often touted as a “bridging fuel” to cut the use of coal for heat and power while moving towards a low-carbon economy. Also, this week’s report by the crown research institute Scion shows that New Zealand could build a renewable low-carbon transport fuels industry by switching to biofuels instead of natural gas. Developing new gas resources in New Zealand is a shortsighted strategy that could lead to stranded assets.

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Read more:
2050 climate targets: nations are playing the long game in fighting global warming

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Carbon budget

Carbon dioxide (CO₂) is a long-lived greenhouse gas. Each molecule released into the atmosphere from burning fossil fuels remains there for hundreds of years. Analysis by the Intergovernmental Panel on Climate Change shows that once we reach a total of 2,900 billion tonnes of carbon dioxide (Gt CO₂) in the atmosphere, the planet will likely exceed the internationally agreed target to keep warming below two degrees above pre-industrial levels.

More than 1,900 Gt CO₂ have already been emitted since the late 19th century. We are currently adding around 33 Gt CO₂ from fossil fuel combustion and 5 Gt CO₂ from deforestation every year. The atmospheric concentration of CO₂ has now surged to more than 403 parts per million, the highest in millions of years. The planet is already around one degree warmer than the average pre-industrial temperature.

This graphic shows that we have already used up around two-thirds of the total carbon budget to avoid exceeding a two-degree average temperature rise (with a 66% chance).
IPCC, Working Group 1, 2013, CC BY-ND

The remaining carbon budget, with a 66% chance of staying below the two-degree target, is now at about 800 Gt CO₂. At the current business-as-usual rate of fossil fuel combustion and deforestation, the total budget will be exceeded within 20 to 25 years.

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Read more:
Fossil fuel emissions hit record high after unexpected growth: Global Carbon Budget 2017

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By then, we will have used up around two-fifths of the known global reserves of coal, oil and natural gas. The remaining three-fifths will need to stay in the ground.

Gas as a transition fuel

Natural gas is described as a “transition fuel” that cuts the use of coal. This argument, and the case for providing greater energy security, is being used to justify exploration for deep sea oil and gas in New Zealand waters.

Displacing coal by burning conventional natural gas does indeed produce lower emissions, while providing the same heat or electricity services. A coal-fired power station produces around 900-1100 g CO₂/kWh generated; a gas-fired plant produces around 450-500 g CO₂/kWh. By way of comparison, a geothermal plant varies with the field but can emit up to 50 g CO₂/kWh and emissions from other renewable energy plants vary widely with the circumstances but tend to be much lower.

However, on a life-cycle basis, any carbon dioxide reduction benefits would be partially negated by leakage of methane (CH₄), the main component of natural gas. Leakage is inevitable during the extraction, distribution and use of natural gas. It is difficult to determine the level of leakage, but it is more certain that emissions from coal or gas plants are significantly higher than from a renewable energy plant of similar generation output.

Natural gas has the potential to extend the time before the carbon budget is used up, assuming it displaces coal that would then be left in the ground. But the use of gas cannot deliver the deep cuts in emissions that will be required to stay below two degrees.

Energy security and fossil fuel subsidies

Many nations, including New Zealand, aim to improve their energy security by shifting to more indigenous fossil fuel resources to reduce their dependence on imports and widely fluctuating prices. Exploring for more gas to meet local demands at contracted prices may make good political sense in the short term, but it exacerbates climate change.

Fossil fuel exploration, production and consumption is widely subsidised by many governments. The International Energy Agency estimated the value of consumer subsidies in 2016 was over US$260 billion.

Conversely, divestment away from fossil fuel companies is growing worldwide. For example, New York City is not only intending to divest US$5 billion of its holdings in fossil fuel assets, but also plans to sue the major oil companies over their contribution to climate change.

New Zealand’s economy without more gas

In New Zealand, natural gas is used to generate electricity and heat for industries, to produce methanol (mainly for export) and other petrochemical products such as urea. It also supplies around 277,000 domestic and commercial consumers in the North Island.

Currently around 1,200,000 tonnes per year (t/yr) of coal are consumed in New Zealand, mainly for heat and electricity, emitting around 2.6 Mt CO₂/yr. If all existing coal plants and heating systems were converted to gas, around 1.3 Mt CO₂/yr of emissions would be avoided. This would contribute a little towards the 20 Mt CO₂-eq/yr of emissions reductions needed to meet New Zealand’s current 2030 target under the Paris Agreement.

However, given the Government’s target to reach net-zero emissions by mid-century, gas will ultimately need to be entirely phased out together with coal and oil products. Therefore, the overall aims for New Zealand should be to:

• use our existing reserves of natural gas wisely in order to gain maximum long-term economic benefits by maximising the return on investments already made, as well as reducing our annual CO₂ emissions by displacing coal and minimising methane leakage

• invest significantly in research and development in sustainable energy, including low-carbon and economically viable alternatives for the current uses of existing gas supplies

• clarify and quantify any fossil fuel producer and consumer subsidies and remove them in the near future

• avoid the temptation to explore and develop new gas resources even if they appear to deliver short-term economic benefits; and

• invest in renewable energy technologies, including biofuels, as long as they are produced from crop and forest residues and purpose-grown forests on marginal land, as identified in the Scion report.

Ralph Sims, Professor, School of Engineering and Advanced Technology, Massey University

This article was originally published on The Conversation. Read the original article.

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FactFile: the facts on shark bites and shark numbers

The CSIRO has provided new estimates of population sizes for White Sharks in Australian waters.
Fiona Ayerst/Shutterstock

Jane Williamson, Macquarie University and Vincent Raoult, University of Newcastle

Are there more sharks in Australian waters than there used to be, and are interactions between humans and shark increasing? Some Australian politicians have claimed that to be the case.

Let’s look at the research.

The most reputable source for shark incident data in Australia is the Australian Shark Attack file, which is collated at Sydney’s Taronga Zoo.

The map below, created by The Conversation using data from the Australian Shark Attack File, shows incidents between sharks and humans in Australia between 1997 and 2017.

You can use the filter buttons in the map to explore the data by year, season, the type of injury, the type of shark involved, the type of incident – or a combination of all the filters. Press the ‘show all’ button to reset the search.

https://cdn.theconversation.com/infographics/243/f87e27e72eb6545d5422e204b9894dedaad0f92f/site/index.html

The number of recorded encounters between sharks and humans in Australia increased modestly between 1997 and 2017, but the reason for this is unclear. Over those two decades, the Australian population increased by 33%, but that alone doesn’t explain the increase in recorded shark encounters.

Correcting for the growth in human population in Australia, the data show that between 1997 and 2017:

• incidents resulting in injury increased by 1.59%
• incidents without injury increased by 0.36%, and
• fatalities increased by 0.07%.

Encounters between humans and sharks are extremely variable over time, and difficult to predict. The increases in recorded incidents between 1997 and 2017 are relatively small, and may be explained by factors not related to shark populations – such as increases in the reporting of shark encounters, or increasing beach use.

https://cdn.theconversation.com/infographics/159/62c30e6dedecffbbeb4e059c8ab0e573d756f61b/site/index.html

Are there more sharks off the Australian coast?

White Sharks (formerly Great White Sharks) are recorded as being responsible for 28 of the 36 fatal shark encounters in Australian waters between 1997 and 2017, and are the primary target of shark mitigation strategies of the Western Australian, New South Wales and Queensland governments.

So, has there been an increase in the number of White Sharks in Australian waters?

Estimating population numbers in the marine environment is difficult, especially for long-lived migratory species like White Sharks.

However, there is no evidence that White Sharks numbers are on the rise, either in Western Australia or along the Eastern coast. Despite targeted conservation efforts, the available research show stable or slightly declining numbers in these populations.

There are two distinct populations of White Sharks off Australian coasts – one to the west, and another to the east of Bass Strait, which separates Tasmania from mainland Australia. The eastern population includes New Zealand White Sharks.

Recent work by the CSIRO through the National Environmental Science Program’s Marine Biodiversity Hub using innovative DNA analysis has provided us with the most detailed and reliable estimates of population size we have for this species.

The CSIRO study shows there has been a slight decline in adult White Shark populations since the year 2000.

Current adult abundance for the eastern Australasian population is estimated at 750, with an uncertainty range of 470 to 1,030. The southern-western adult population is roughly double the size, estimated at 1,460, with an uncertainty range of 760 to 2,250.

Including the available information about juvenile White Sharks, estimates of total size for the eastern population in 2017 was 5,460, with an uncertainty range of 2,909 to 12,802.

It’s difficult to detect population trends with White Sharks because of the length of time it takes juveniles to reach maturity – around 15 years. As protection of White Sharks began in the late 1990s, any changes in abundance would only be starting to appear in current populations.

How else can we measure White Shark populations?

The traditional way of measuring shark and fish populations is by examining catches in commercial fisheries over long time periods. By correcting for the level of fishing effort – which is done by looking at things like the number of nets, hooks and tows deployed by fishermen – scientists can assume that changes in the “catchability” of sharks is related to their abundance.

But due to the relative rarity of catches of White Sharks by fishing vessels, this approach is less reliable for this species than the more recent genetic studies conducted by the CSIRO and outlined above.

Western Australia has a detailed measure of White Shark numbers assessed by catch data. A report published by the Western Australian Department of Fisheries in 2016 attempted to model changes in the southern-western Australian White Shark population since the late 1930s. The authors outlined four different plausible scenarios, none of which suggested a continuous increase in the number of White Sharks.

In New South Wales, there has been a cluster of shark bites in recent years. Data from the NSW Shark Meshing (Bather Protection) Program, managed by the NSW Department of Primary Industries, show a recent increase in White Sharks caught in nets placed near ocean beaches.

But when it comes to thinking about shark populations, we should not assume that these two facts are related. It’s important to remember that just because two things may correlate, it doesn’t mean that one caused the other.

These patterns could mean that the animals are coming closer to shore, rather than a population increase (or decrease).

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Shark and human interactions: what factors are at play?

A 2016 paper examined six global shark bite “hotspots” – the United States, South Africa, Australia, Brazil, Reunion Island and the Bahamas – and concluded that when it comes to encounters between sharks and humans, there are a range of causes at play.

These include:

• rises in human population
• habitat destruction/modification
• changes in water quality
• climate change
• changing weather patterns, and
• the distribution/abundance of prey.

The authors also noted that shark encounters appear to happen in clusters. For example, 2009 saw a spike in shark encounters off the New South Wales coast. This coincided with an increase in beach attendance and beach rescues during what was an unusually warm summer for south-east Australia.

A 2011 paper highlighted the popularity of water sports as a factor contributing to increased human-shark encounters. More people are taking part in water sports, and improvements in wetsuit technology mean that people are in the water for longer throughout the year.

However, there is limited information on the number of people who use Australian beaches, so this explanation needs to be further studied.

It’s vital that any strategies put in place to reduce the number of unprovoked encounters between humans and sharks in Australian waters are carefully considered, and based on the best available research.

Jane Williamson, Associate Professor in Marine Ecology, Macquarie University and Vincent Raoult, Postdoctoral fellow, University of Newcastle

This article was originally published on The Conversation. Read the original article.