This is not about whether climate change caused by human activity is a reality.

I have read plenty on the topic. I have made the effort to understand the physics at the quantum level and the climate science at a macroscopic level. I have no doubts in my mind. It is real.

The questions to answer are to do with what we as a species should do about it. I am not pushing any agenda other than the need for action.

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I recently received an email suggesting I read a book called "The moral case for fossil fuels", by Alex Epstein. The sender told me that the book caused him to modify his opinions. In the name of fairness, I have read the book.

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Mr. Epstein, to my surprise, is not a climate change denier, although he does quibble about the strength of the human effect. His solution to the problem is interesting. He is correct in saying that as exploration techniques develop, extractable reserves will increase.

He then suggests that increasing our use of fossil fuels would allow rapid progress towards controlling the environment and climate. It sounds like a recipe for suicidal genocide to me.

His analysis of why we began to use fossil fuels in the first place was interesting and his logic suggests paths other than renewables.

Far back in time the sources of fuel were mainly wood and peat. These do not give a lot of heat for the mass of the fuel. These sources are not energy dense.

Gathering wood or peat and transporting it back to camp is hard work and as you exhaust the local supply you have to carry it further.

Fossil fuels are much more energy-dense. A sack of coal carries more energy than a sack of logs. The European industrial revolution would never have happened if the only energy source had been wood.

Let us look at some of the problems associated with using solar and wind power instead of fossil fuels.

Solar and wind farms require large amounts of land – the energy density is low and requires large transmission systems to bring the electricity from the countryside to the cities that are the major consumers.

This land requirement and distribution system have been resisted by small rural communities which would become surrounded by solar panels, windmills and a spider's web of distribution cables.

The conservationists are concerned about the impact on bird species of wind turbines. Losing these birds has knock on effects in the food chain thus affecting the whole local ecosystem.

Solar and wind power are intermittent supplies producing power between 10 and 30% of the time averaged over the year. With fossil fuels you can store your energy in a pile or a tank until it is needed.

Could hydroelectric dams be used as storage batteries. When the sun is shining, and the wind is blowing and there is more electricity generated than is needed the excess power could be used to pump the water back to the top of the damn where it would be released when needed.

Unfortunately, you would need to build a complete extra dam to hold the water that you are going to pump back uphill. The possibilities for this are limited by the land formations required, the expense and the fact that in any particular location the demands on the water supply mean that to build such a recycling system could make agriculture in that area marginal.

Few presently functioning hydroelectric dams could actually be converted to such a system.

Covering peak demand directly from solar and wind farms means they need to be larger than is needed for average consumption rates. An alternative to this is to have enough solar and wind for average consumption rates.

Natural gas, which is quick to come on line and easy to control, can be used to cover times of peak demand and days of no sun or wind. This is one reason why gas companies are currently advertising solar power.

At times of low demand and clear skies solar farms may generate excess electricity resulting in solar power companies in California paying neighbouring states to take some of the power in order to avoid blowouts of the local grid.

Domestic cats kill many times more birds than wind turbines. However, the birds that cats kill are the small garden birds such as sparrows and blackbirds. Cats do not kill large birds at the top end of the food chain. Wind turbines kill far more large birds than any other cause with serious consequences for the balance of local ecologies.

We cannot control the energy output of the sun this and so to gather sufficient energy to maintain civilisation as we would wish we would need to cover vast areas of land with solar farms and wind farms along with probably millions of kilometers of transmission cables. Here is a challenge.

Take your camera and take a landscape photograph somewhere in Aotearoa that does not have transmission lines in it. We would need much more.

Germany and California have made huge investments in renewable power and the cost to the consumer has increased by 50%. Just across the German border in France consumers pay about half of what German consumers pay despite France producing almost twice as much clean energy as Germany.

This is because France generates about 75% of its power from nuclear power. It has been said that if Germany had invested the same amount in nuclear as renewables it would now be producing 100% of its energy from clean, zero emission sources.

In the 1970s and 80s I was active in the anti-nuclear movement. We were, and I still am totally against nuclear weapons. I noticed at the time a spill-over of anti weapons fervour into anti-nuclear power fervour to the point of the distinction becoming blurred for many people.

In the past 50 years or so there have been major accidents at nuclear power plants such as Three Mile Island, Chernobyl and Fukushima. These are spectacular front-page events. Evaluating the effect is difficult.

In 1957 over two hundred people were killed by the explosion of a nuclear storage tank at Chelyabinsk in Russia.

It was the blast that caused the deaths not the radiation. From the same accident many thousands were exposed to dangerous radiation but to blame deaths with certainty on the incident many years later is difficult.

A trawl through Google suggests that perhaps as many as 10,000 people have died from radiation from nuclear power accidents since the 1950's. Does this sound bad? Yes! But this should be compared to the World Health Organisation figure of 4.2 million dying each year from air pollution caused by fossil fuel use in power generation and transport.

According to figures from The Lancet, of electricity generated from coal, petroleum, biomass, natural gas and nuclear, nuclear is far and away the safest.

It is also worth considering the relative land usage. For the same power output (assuming the sun is shining) solar power requires between 400 and 500 times the land area of nuclear.

The main worry is what to do with nuclear waste. This again needs to be put in context. The waste from a nuclear power plant is definitely unpleasant stuff.

This has been recognised from the start and as such great efforts have been made to keep it safely away from humans. However, at a rate that has been accelerating for the past 200 years the waste from fossil fuel use has been simply vented to the atmosphere. We are now trying to clean up the mess.

In 1982 I went to an anti-nuclear arms demonstration where almost 1,000,000 people marched through London. The pollution generated in transporting those 1,000,000 people to and from the British capital over a weekend would be comparable to many years of environmental damage from nuclear power.

Solar panels gradually become less efficient and have a useful life cycle of about 25 years. At this point somebody will take on the task of disassembling them and recovering the metals chromium, lead and chromium which are highly toxic.

If the metals are not recycled they are likely eventually to find their way into the water table of the poor countries that would be used for the recycling or dumping process.

Paradoxically, there is a lot of anti-nuclear power feeling while the heat coming to the surface of the planet and driving plate tectonics, earthquakes and volcanoes is derived from the decay of radioactive elements in the core of the earth.

Much of that anti-nuclear feeling comes from the potential for a nuclear power programme being hijacked to manufacture materials for nuclear weapons. If the programme is based on Uranium this is a risk.

There is another way. This is to base the programme on Thorium. The Thorium process was rejected in the cold war years largely because it does not produce weapons materials. It gets better.

Thorium is more common in the earth's crust than Uranium and require much less processing. Thorium produces about one thousandth of the amount of waste as Uranium and this waste is much less long lasting than that from Uranium. Thorium based reactors run at a much lower pressure than Uranium based devices so there is minimal risk of explosion.

This means the huge containment dome of a Uranium reactor is not needed which makes construction much cheaper. Perhaps best of all the Thorium process is not self-sustaining and so unlike a Uranium reactor can be simply switched off if it begins to malfunction. China and India are currently investing large amounts of money into Thorium based research

New Zealand did investigate nuclear power in the late 60's and early 70's but with Maui Gas and Huntly coal coming on line it was abandoned in 1972.

In 1987 New Zealand became a Nuclear Free Zone. This does not ban land-based nuclear power plants.

If you think I am using this article to be the devil's advocate you may have a point but the recent world wide statement by the young that they feel we have let them down should tell us that we need to take action and quickly.