Climate change and the end of civilisation was the dramatic title of the latest Whanganui Science Forum talk, given by Professor James Renwick last week. Frank Gibson was part of a packed house at the Davis Lecture Theatre.

The end of civilisation. Sounds a bit apocalyptic ... are we entering the end times?

Well not quite but, according to Professor James Renwick, unless we (the human race) get our act together in the next few years we could be in for some pretty unpleasant times.

This is important stuff so we need to be sure of our sources.

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James gained his first degree in mathematics and then did an MSc in Statistics. Statistics is where mathematics hits the real world.

In the list of James' work over the past 35 years the words variability and predictability crop up regularly. Looking at how and why things change and using this knowledge to make predictions are what a statistician does.

Professor Renwick has applied these techniques to climate data.

Checking reliability is important because of the worrying trend for public opinion to be based upon who shouts the loudest rather than who has carried out the best research.

James gave examples of the sort of journalism which implies that in the not too distant future irreversible, cataclysmic climate changes will end life on earth.

His opinion on this, in common with the vast majority of genuine researchers is that no, humans are not going to be wiped out any time soon. However, without immediate measures to halt and eventually reverse climate change, humans may wish they had been wiped out.

So what is this climate change and what causes it?

The basic mechanism is the same as what happens in a greenhouse. Think of the glass windows of the greenhouse as having the same function as the earth's atmosphere.

Light energy from the sun passes through the atmosphere (without heating the air) and warms the surfaces that it hits. These warmed surfaces re-radiate the energy as infra-red radiation.

However, some wavelengths of infra-red are absorbed by gasses in the atmosphere thus warming the atmosphere.

Without some level of greenhouse effect most of the energy from the sun would be re-radiated into space and the Earth would be a frozen globe. We need some greenhouse effect but not too much. The important greenhouse gasses are carbon dioxide, methane and water vapour.

Water vapour can increase rapidly by evaporation from the oceans and can decrease rapidly as rain.

Atmospheric methane takes less than a decade to chemically break down (in the process creating more carbon dioxide and water vapour).

Carbon dioxide stays in the atmosphere for centuries with its effects lasting correspondingly long. Methane is a more effective greenhouse gas than carbon dioxide but its lower concentration and short life span in the atmosphere is much less important.

So where does this carbon dioxide come from?

Natural processes such as plant growth and decomposition of plant and animal life are pretty much in balance in terms of generation and absorption of carbon dioxide. The same is true of the oceans.

In fact, both land and oceans absorb slightly more carbon dioxide than they generate but the difference is tiny.

Carbon dioxide generated by human use of fossil fuels has no corresponding mechanism of absorption. It releases carbon which nature sequestered into oil and coal deposits over millions of years.

With no net reabsorption and the longevity of atmospheric carbon dioxide the effect is cumulative. Some of the carbon dioxide you breathe today was made by coal-fired steam engines in the late 18th century.

The energy output of the sun fluctuates by about 0.1 per cent on a regular 11-year cycle. This is tiny and, when averaged out over the past 150 years or so, the output has been very close to constant with a tiny fall ( about 0.05 per cent) over the past 20 years.

The effect of these tiny fluctuations on earthly atmospheric temperatures are so small as to be lost in the noise of other effects.

In the 100 years between 1880 and 1980, the mean atmospheric temperature rose by about 0.25 degrees C.

Between 1980 and 2018 this figure was 0.8 degrees C — this is an eight-fold increase in the rate of rising temperature.

Ice laid down in Greenland and Antarctica traps bubbles of atmospheric gas. Analysis of these trapped gasses gives measurements of the composition of the atmosphere at the time the ice was formed.

Measurement of the relative concentrations of different carbon isotopes in the trapped gas gives precise values for the age of the samples.

From about 10,000 years ago to the beginning of the industrial revolution, the concentration of carbon dioxide was gradually rising from about 260 ppm (parts per million) to about 280 ppm.

Around 1800 it began to climb and went from about 285 ppm to about 295 ppm by 1900. Between 1900 and 2000 it went from 295 ppm to about 375 ppm.

Between 2000 and August 29, 2018 — a mere 18 years — it has climbed to 406.42 ppm (source "co2levels.org").

The rate of increase is growing significantly and the correlation between human production of carbon dioxide and atmospheric temperature rise is very clear.

The present level is the highest in about three million years. The last time the atmosphere had this concentration was a time of higher levels of volcanic activity and the change took about two million years as compared to the 200 years of the present peak.

The Paris agreement aims to keep the nations of the world working to keep warming below 2 degrees above pre-industrial levels and ideally below 1.5. We have already passed the 1.1 degree mark.

The news gets worse. The heat that has warmed the atmosphere and begun to melt the ice caps is only about 7 per cent of the heat trapped by greenhouse gasses. The other 93 per cent has gone into the oceans.

Calculations show that without the oceanic heat sink, the average temperature of the atmosphere would have increased by as much as 50 degrees and life on earth would not even be a memory.

As the oceans get warmer, the water expands causing sea levels to rise. This warm water will eventually get under the land-based ice caps of Antarctica causing melting and further rises in sea level.

Sea levels have risen before but the process has been very slow. Humans have assumed the sea will more or less stay where it is and so have built cities close to where they can get cargoes from ships.

Rising sea levels will soon cause major problems for London, New York, Shanghai and other port cities.

Glaciers are retreating at an accelerating rate. This has little effect on sea levels but has a major impact on areas that depend on glacier runoff for a water supply.

Several towns in the Andes region are becoming untenable as their glacier-fed water supply disappears.

Professor Renwick gave much more information and, while researching for this article, I came across several alarming stories in just two days of international newspapers.

■Due to climate change Lake Chad in Northern Nigeria has almost dried up. Around ten million people have been displaced with some evidence the stress is partially responsible for the Boko Harum insurgency in the area.

■Suggestions that a root cause of the Syrian conflict has been drought.

■French Environment Minister quits saying his government is not doing enough.

■Rising levels of carbon dioxide could make food crops less nutritious.

■Global warming is intensifying El Nino weather.

We are left with two questions. What can be done and why are we not doing it?
We need to stop pushing carbon dioxide into the atmosphere which means the quick end of our use of fossil fuels.
If we wish to maintain our present way of life this needs to be combined with huge investment in renewable energy sources. Only industries that use renewable energy should be allowed to build new plant.
Technologies are under development to actively remove carbon dioxide from the atmosphere but they are a long way from being practical on a scale that would make a difference.

A simpler solution is to plant more and more trees. We need to move away from an economy based upon methane-farting cows.

In order to have a chance of halting the carbon dioxide rise in perhaps 15 years we need to be making a lot of effort now.

So why are so many people apathetic?

Do they think it will go away if they ignore it? Do they think the politicians will fix it? Do they think worrying about climate change is just for greenies and hippies and nothing to do with the real world?

It is probably a mixture of these and other factors. Well listen here! The effect is real and getting worse. Whatever changes are made to emissions, extreme weather events will increase.

We need to be telling our political representatives that these are issues they need to be working on.

■A link to a YouTube video of Professor Renwick's presentation will be available at "totallyfrank.org" in the next week or so.

Frank Gibson is a semi-retired teacher of mathematics and physics who has lived in the Whanganui region since 1989.