TECHNICAL
Are assumptions on climate change based on irrefutable science? In late January the Climate Change Commission (CCC) released its report to the government on its recommendations on how New Zealand can lower its greenhouse gas emissions based on our commitment to the Paris Agreement signed in 2016. Public submissions on the CCC report close on 28 March, after which the political process will begin for deciding what measures will and will not be implemented, so that as a nation we can meet our obligations to the Paris Accord. By Robin Boom : CPAg, Member of the Institute of Professional Soil Scientists The CCC recommendations will impact everybody in some way or another and will prove costly to many businesses. Almost half of our greenhouse gas emissions come from agriculture, largely from enteric methane produced in the rumen of sheep, cattle, goats and deer, but also from nitrous oxide from animal urine and fertiliser nitrogen. Arable and vegetable crop production also produces greenhouse gases from CO2 lost through soil inversion, fallowing and plant desiccation, and nitrous oxide from artificial nitrogenous fertilisers. Soil carbon loss can in part be mitigated through the use of composts, manures and biochar, but there will still be CO2 lost into the atmosphere during the cultivation process from microbial decomposition of organic matter. There have been statements made like ‘the science is settled’ as far as the anthropogenic global warming (AGW) theory goes, yet real science should be able to withstand the challenges of falsification and not be pressured by political agendas and expediency. There is no question that CO2 levels in the atmosphere have risen from the preindustrial level of 280 ppm, to close to 400 ppm today, and that global temperatures have risen almost one degree since 1850. However, 1850 was also the end of what is called the ‘little ice age’ which was a cooling period which began 500 years previously. There is also no question that sea levels rose about 0.3 metres through ice and glacial melt during the 20th century, but when these figures are compared not with what levels were like 150–200 years ago, but with more distant history, the alarmist narrative of AGW theory could be seen as skating on a lot thinner ice. Just 20,000 years ago at the peak of the last Ice Age called the Late Glacial Maximum, the Earth was at its coldest point for the previous 250 million years. Twenty thousand years 60
The ORCHARDIST : APRIL 2021
is less than one ten thousandth of 250 million years, so just a blink of an eye in terms of the planet’s history. On average the planet has been six degrees warmer than today for the past quarter of a billion years, and there were no polar ice caps to speak of. Fifty million years ago, when mammals were starting to appear, the planet was 16 degrees warmer than today, so claims that life will disappear from global warming are wrong. It was only 3 million years ago that the planet started having polar ice caps through a series of ice ages and interglacial periods which occurred every 40,000 to 100,000 years, known as the Milankovitch cycle, believed to be caused by the relation of the elliptical orbit of the Earth around the sun and its axial tilt. It can be argued that we are still coming out of the last ice age, which when at its peak, cities like Chicago would have been under a kilometre of ice, Boston under two kilometres of ice and Montreal under three kilometres of ice. For 12,000 years sea levels rose on average one metre per century due to glacial melt, which was three times greater than sea level rose for the whole of the twentieth century. Twelve thousand years ago Britain was still covered in glaciers, and our own Southern Alps was one massive ice sheet. Ice Ages would appear to have a much bigger impact on life on Earth than global warming, and perhaps increased CO2 levels is a good thing to help stop the planet going into another deep freeze. Plants thrive better with higher CO2 levels, and some glasshouses lift CO2 levels to 1200–1500 ppm, three or four times the current atmospheric levels, to produce bigger crops. Back in the Jurassic period 150 million years ago, CO2 levels were around 2000 ppm, five times higher than they are today, resulting in prolific plant growth which would have fed the large herbivorous dinosaurs alive back then.
