Key issues to consider
Anthropogenic Climate Change is a consequence of new greenhouse gas (GHG) emissions arising from human activities. Such activities are typically burning fossil fuel, releasing high climate impact gases, forest clearance, and soil disturbance resulting in carbon release.
Significant gases for New Zealand are carbon dioxide (CO2) and methane. CO2 comes from fossil fuel combustion and some industrial uses of limestone. New Zealand has high methane emissions from ruminant animal digestion. Methane is also released from landfills and coal mines. CO2 is stripped from some natural gas and released to the atmosphere.
Sinks in new exotic forests are significant in offsetting emissions, but require ongoing planting of new unforested areas to continue to have an impact. Permanent production forest still has a sequestration benefit but less than unharvested forest. We know little about the amount of carbon loss from the degradation of indigenous forests. It is not covered by international treaties and hence is a low priority for quantification. Ultimately the world has to considerably reduce its net GHG emissions.
Energy Efficiency is linked to climate change. Where there is direct use of fossil fuel, such as petrol in cars, natural gas in heating, increasing efficiency of use reduces CO2 emissions in relation to the work done or to the economic output. However if the economic output is still increasing faster than the efficiency gains the overall level of GHG emissions will continue to rise. Where electrical energy is being used, increasing efficiency of use has a benefit to the climate only when the saved energy would have been generated from fossil fuels. Most electicity at the margin of growth and use does come from fossil fuels.
Renewable Energy does not involve the combustion of fossil fuel. Typical forms are hydro-electricity, geothermal energy, wind energy, wave energy, biomass combustion from sustained sources and photovoltaics. Renewable energy does not have to be converted to electricity to have a useful effect. For instance geothermal energy used for heat in an industry situated at the steam bore head is using renewable energy without conversion. Some renewable energy may be quite inefficient in its production yet still have a climate benefit. For example combustion of wood may be thermally inefficient compared to say coal, but if sourced from a forest managed for sustained yield is renewable. Ultimately renewable energy has to displace conventional energy to reduce GHG emissions.
Wind energy and energy from combustion of wood from sustained production forests have a large potential in New Zealand. New Zealand has long been good at renewable energy, with hydro and geothermal sources currently achieving 29% of energy sourced renewably. Some renewable sources may have consequent GHG emissions. The production of cement used in concrete dams. and methane release from vegetation flooded by dams can be significant.
Hydrogen as a fuel is renewable only if the energy source creating the hydrogen is itself renewable. The Government has a renewable energy target (see below) as an absolute figure rather than as a proportion of energy. Hence with an expanding economy the target might be met but still the non-renewable energy use expand.
