International perceptions of New Zealand’s environmental performance have justifiably been taking a battering lately.

We really are slipping badly on environmental performance and it is hard to know how much longer we can keep up the clean-green pretence.

Global comparisons don’t make for good reading.

It sounds good when the Yale University environmental performance indicator ranks New Zealand as the 14th best performer in the world, until you realise it omits our three worst impacts – biodiversity loss, water quality and non-CO2 greenhouse gas emissions.

Another global study from the University of Adelaide ranking New Zealand about 120th in the world is a bit closer to reality – it includes biodiversity loss and water quality – but is still conservative as, like the Yale study, it does not include non-CO2 emissions.

So forget 100% anything. We have a long road to catch up, and we need to start now.

At home, Kiwis are given a clear message: you must accept the many serious environmental impacts resulting from intensive dairy production because, like it or lump it, dairy is the backbone of our economy. Implicit in this message is that negative impacts on rivers, lakes and soils are inevitable, so don’t question them.

In fact, it’s the opposite – the most economically viable farms have the smallest impacts and the pressure the dairy industry puts on New Zealanders to accept degradation of the environment, particularly waterways, is simply a subtle form of blackmail.

The biggest impact from intensive dairy farming is nutrient loss. Losing valuable nutrients that are leaking from the farms and polluting waterways is not economically or environmentally viable.

Nitrogen is produced using fossil gas, some from New Zealand but mostly from the Middle East, and phosphate is mined from fossil rock mainly in Morocco.

To be sustainable, the nutrients must be cycled back into growing food and not allowed to leak out and destroy lakes, rivers and contaminate groundwater and drinking water.

If nutrients were kept on farms, there would be no requirement to import them from halfway around the world. This is known as closing the nutrient loop.

It is what we must do and what is happening in dairy in other parts of the world.

The crucial point is that the impacts from intensive dairy reflect decades of unregulated industrialisation, each year becoming more dependent on inputs sourced off-farm, and largely from overseas.

The impacts on water, soil and the atmosphere come from wasteful over-intensification that has grown primarily from the absence of any cost on pollution, and the emphasis on producing the cheapest possible commodity – milk powder.

The mantra for two decades at least has been: just produce more and more each year, without any real questioning of sustainably or the true costs.

Looking back what happened was totally predictable: in a market environment with no cost on externalities, the most polluting industry naturally becomes dominant.

New Zealand leads the world in milk production, but not much of it is indigenous production. To achieve this amazing level of output, we also have the world’s highest per-capita consumption of nitrogen and phosphorus, and we import more palm kernel than any other country.

Aside from the environmental impacts resulting from this industrialised process, both nitrogen and phosphate fertilisers used are non-renewable, and palm kernel is a byproduct of environmentally dubious overseas palm-oil production.

Put simply, the three big inputs behind our impressive milk production highlight just how unsustainable the industry is.

We are neither really clever nor efficient. Rather, we are simply world-leading consumers of non-renewable fertiliser to be world-leading producers of low-value milk powder.

There are many downsides to this because most of the external costs are borne by all Kiwis, not just the dairy industry.

Undoubtedly the dairy industry is a large contributor to gross domestic product but, if the true costs were included, dairy would be shown to be economically marginal at best.

Our geographic isolation makes it crucial for New Zealand Inc to be perceived overseas as different, special, safe, sustainable and clean, not just for all primary producers but the tourism industry also.

Unfortunately, though, just one sector – dairy – has almost single-handedly jeopardised overseas perceptions of New Zealand both environmentally and in the food-safety arena.

The problem is both primary producers and the tourism industry are tarred with the same brush.

We must do everything possible to get dairy sustainable and clean starting now.

Instead of weakening the environment with Resource Management Act changes, we should strengthen it and live up to our United Nations commitments to put a price on pollution.

Dr Mike Joy is a senior lecturer in environmental science/ecology at Massey University.