Dear Editor, I applaud Clive for the views he expresses on the issue of Climate Change and the impacts us humans have had and are increasingly having on our planet and all it systems. People like Chris L. and his accusation on Clive's views as ‘socialist propaganda and scaremongering’ absolutely beggars belief!

What planet does Chis L. live on — obviously not on the planet I live on. To dredge up the conspiracy ‘propaganda’ of Christopher Monckton and a small retinue of other sceptics is pretty trite — sorry, Monckton is a shonk and totally unbelievable.

And the statement Chris L. makes that a majority (90%) of scientists do not believe in anthropogenic Climate Change is absolute rubbish. In some of the very dubious magazines that tout these conspiracy views they state opinions as facts! I have researched many of these dubious magazines and wonder who is behind all of them and their glossy presentations, i.e. who really funds them?

And yes, a warming climate could have major repercussions for the planet and particularly the Gulf Stream – the huge current that brings warm water and warm air from the Gulf of Mexico and gives the UK and many parts of Europe the climate it currently has.

If the Gulf Stream stopped, and this could happen with the melting of ice floes and Greenland, and consequent warming of water in the northern hemisphere. And if this happened the repercussions for Europe would be dire, and yes, an Ice Age.

This is what the science tells us: Trade winds from Africa drive water in the Atlantic westward until it hits the coastline and gets pushed northward. In turn, the Gulf Stream affects the climate of the areas closest to the current by transferring tropical heat toward the northern latitudes.

There is a consensus among scientists that the climate of western and northern Europe is warmer than it would be otherwise because of the North Atlantic Current, one of the branches of the Gulf Stream. Trouble is with people like Chris L., they don't get the science — they cherry-pick some of the data without seeing the full picture.

And yes, I am also a mother and I want to ensure my children have viable futures. To this end, I do what I can to help to educate those around me on reducing our footprint on this one, lovely planet that we all inhabit. I aim to be a good role model for all who come my way, including family.

Good on you Clive. I know that you understand the science and the complexity of earth and climate science, and the huge systems that operate within a given ‘balance budget’ on the planet.

For the planet, Gayle R.

Dear Clive, I suppose you should be commended for not censoring out the contribution from Chris L. accusing you of publishing propaganda. It seems Chris’ strong suit is not irony! As for his three ‘facts’, they are all fictions.

The first assertion that 90% of the last 10,000 years were warmer than now appears to be based on Greenland ice core data. The first problem with this is that Greenland ice cores do not equal global mean air temperatures. The paleo-climate data set used to support this claim, ends in 1855, which is before human induced warming began to occur. When proper reference points and calibration issues are considered, this claim falls apart.

The second claim that the earth is in a 65 million year cooling trend is a nonsense when in fact glacial and interglacial cycles occur on twenty to hundred thousand year cycles driven by variations in the earth’s orbit.

The current and rising carbon dioxide levels now overwhelm the ‘forcing’ of the climate by orbital factors. The Intergovernmental Panel on Climate Change states “Climate models simulate no glacial inception during the next 50,000 years if CO₂ concentrations remain above 300 ppm”. [AR5 WG1 report, chap. 5, pp. 387]

As for the consensus on human causes of global warming, there have been numerous surveys which show an overwhelming agreement — in the high 90%'s — among practising climate scientists. You are quite right in that we should all tread as lightly as possible. Growing our own food is one great way to do that. Michael H.

Dear Clive, your comments in the letters pages suggesting that Anthropogenic Climate Change “Deniers” are probably the same group who resisted progress on smoking bans, health labelling of food and supported the wars in Vietnam, Iraq and Afghanistan is absurd. It harks back to the days when people's views on every debate were controlled by whatever church they belonged to or political party they supported, both of which were more often than not accidents of birth rather than informed decisions. Hopefully, we have progressed to having a far more educated populace who can evaluate the arguments on any debate for themselves and decide where they stand on any particular debate.

With the vast majority of debates in our society, both sides generally have a suite of quite rational arguments and it is a matter of weighing up the arguments of either side and coming to a conclusion. These debates are not black and white but contain many shades of grey. Regards, Brett L.

Dear Brett, thanks for your email.
I guess I am what would be called a progressive which means we are generally impatient about delays of near certainties in the future. Could we say that renewables are certain to replace fossil fuels, it's just a question of how soon?!
Australia will become a republic it's just when is uncertain. Cars are cluttering our cities so funding freeways rather than public transport seems out of step.
But on every one of these issues the conservatives hold back progress until it's almost too late as in the case of climate policy. I am not conservative in a political sense but simply to suggest that denial of inevitable change is barely tolerable. Best wishes, Clive

Dear Clive, I quite agree with you that a home garden is more resource-efficient for most fruit and vegies, and I enjoy your thought-provoking points of view.

However someone needs to stick up for us farmers against startling statements that seem to get quoted and re-quoted without challenge, including "It takes 100,000 litres of water to produce just 1kg of beef".

Beef cattle here in South Australia run on land that is not arable and not irrigated. In summer their feed is sometimes supplemented with hay or grain, which is also grown without irrigation. Compared with humans, cattle drink more, but they don't wash or flush the toilet, so their water use is not extreme.

Beef cattle on unirrigated pasture gain much more than a kilogram a week over their lifetime. Feedlot cattle can gain as much as a kilogram a day. Could we make sense of the "100,000 litres of water per kilogram" claim by including rainfall that grows the grass?

But if we removed all vegetation that relies on rainfall, we would have massive soil erosion problems, as well as being hot and hungry. South Australian farmers have indeed had water restrictions, as licensed water allocations are cut down in droughts, even when fruit trees die because of it.

Modern farmers do their best to use water efficiently. They care about water, their land and the environment, all of which have to remain sustainable. Home gardens are great, but farmers are not the enemy! Yours, Margaret M.

Dear Margaret, the figure of 100,000 litres of water to produce 1kg of beef I think came from Professor Meyer at the University of Adelaide. When we do yield comparisons with vegetables (which is something we have been doing for 20 years) and compare with beef the comparisons a truly dramatic.
By our calculation beef needs 10⁷ times as much water to produce a kilo as vegetables and fruit, which is why economists and ecologists say when farming land gets scarce we will need to switch beef for vegetables.
However I do accept that animals recycle grass into fertiliser and many of the low rainfall areas are too dry or unsuitable for the switch. I hope this explains the story better. Best wishes, Clive