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Science - Natural gas? It’s as bad as coal

Natural gas is a fossil fuel that consists almost entirely of methane, which is a molecule that consists of a carbon atom bonded to four hydrogen atoms. Methane is 86 times more damaging than carbon dioxide (CO2) as a heat-trapping greenhouse gas. The level of methane in the atmosphere has increased 250 per cent since pre-industrial times.

Atmospheric methane persists in the atmosphere for about 20 years, but eventually decomposes into carbon dioxide. These carbon dioxide emissions become a permanent and irreversible component of the atmosphere.

The critical conclusion then is that unless both methane spillage and carbon dioxide combustion emissions from natural gas power plants are thoroughly scrubbed or trapped, these dual emissions will represent an accelerating factor in climate warming. Scientific audits have shown that average methane leakage rates in the US were larger than facility-reported estimates by factors of 21 to 120 (at natural gas power plants) and 11 to 90 (at refineries). In addition, climate warming will increasingly release methane from melting permafrost and from melting about 1 million cubic miles of ocean-floor ice structures (known as methane hydrates), which retain ancient methane.

Despite these concerns, natural gas has been proposed as an alternative fuel for power production in New Zealand, and the Australian Government is intending to move from coal to natural gas for power generation. This is driven by cost and the perception that natural gas is an improvement on coal.

Methane from agriculture is the dominant emission in New Zealand. However, an effective commercial solution to this problem has now been developed which involves the use of a methane-busting livestock feed from New Zealand seaweed. On-farm mitigation practices, if widely adopted, could reduce farm methane emissions by 30 per cent.

The move away from gas, oil and coal is the pathway to a sustainable climate for planet earth. How far are we along that pathway? Well, there is an impressive range of emerging climate trends. China, the world's fastest growing carbon dioxide emitter, has declared a two-stage move towards a zero-carbon economy before 2060. China is also planning to become the world's leading nuclear power economy (no new greenhouse gases) within a decade, thereby overtaking the US, which has about 100 nuclear power stations. India is planning to increase the use of renewable sources in power production. Meanwhile, an increasing number of countries are committing to banning coal power, and several leading oil and gas corporations, such as BP and Shell, have set zero-carbon targets and are growing their investments in renewables. The electric transportation revolution will also make a difference, and an increasing number of multi-national consumer companies, such as Unilever with its 400 plus brands, are embracing climate sustainability cultures.
Now the overriding question is, is it already too late? Every lost decade will pump more carbon dioxide and methane into a warming atmosphere with serious consequences for coastal cities and communities, forests and pastoral production. After the exceptional recent wildfires in California, I urge all readers to reflect on this question during the coming regional bushfire season.


Emeritus Professor Ralph Cooney
r.cooney@auckland.ac.nz