Interview with Kim Hill

On the morning of Saturday 3 September 2016, I was interviewed by Kim Hill at Radio New Zealand. She is the master interviewer in New Zealand, and we had a lot of fun. We discussed optimal exposure times to achieve vitamin d sufficiency without getting sunburnt – which is to be avoided as it can be a precursor to the development of skin cancer. I emphasised that to make sensible decisions on this you need to know the UV index (UVI), which is now available in real time everywhere through the development of apps such as “uv2Day”  (restricted to the South Pacific region), and “GlobalUV”. The apps also give appropriate  behavioural advice based on the current UVI and the skin type. Both apps are available for free on iphone and android systems.  For more information, listen to the full interview (about 15 minutes long).


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Time to Make Climate Action Count

As published in the Mirror, and Stuff, Dec 2015

Tens of thousands of New Zealanders took to the streets last weekend to express their concern about climate change, and to show support for strong action at the Paris Sustainable Innovation forum (COP21). The action, part of a series of international marches co-ordinated by the environmental organisation, wasn’t confined to just the main centres. In Alexandra (population 5,000), where I was one of the march’s organisers, more than 125 people showed up at 9am on a Saturday to make their voices heard.


Intrepid marchers relaxing at the Courthouse Café in Alexandra.

The aim of is to ensure we leave our planet in good condition for our grandchildren. To do that, we need to limit the global temperature rise to no more than 2°C. To achieve that, we have to reduce the concentration of carbon dioxide in the atmosphere from its current level of 400 ppm to 350 ppm (hence – still far above its pre-1950 level of 280 ppm. To meet the 350 ppm target, 80% of all the fossil fuel reserves that we know are still in the ground must stay there. To achieve that, we need to replace fossil fuels with renewables. And it needs to happen now.
On a per capita basis, New Zealand’s carbon footprint is among the world’s worst – it’s more than twice that of China, the world’s biggest polluter. Despite promises made in Kyoto, our net emissions soared by 42% between 1990 and 2013, second only to Turkey.
But we are well placed to make a difference. With over 70% of our electricity already from renewable sources, it would be easy to serve our remaining needs from solar energy without the need for any further capital investment from the government. The public will switch to solar anyway because the panels pay for themselves within a decade, but the transition needs to happen faster.
Any excess energy produced from small rooftop solar systems will go towards powering a new generation of electric vehicles that will inevitably replace the current fleet of petrol cars. Of course, multinational oil corporations such as Exxon Mobil will want to continue to slow down that transition, as they stand to lose billions. As recent reports have shown, they have known about the climate problem and its end-game for the last 25 years. But, rather than cut their profits, they instead responded with disinformation campaigns that have duped so many, stalling the needed transition. Unfortunately, our own government cannot escape similar conflicts of interest – it still owns 50% of our existing power stations, and it receives $800 million per year from oil and gas revenues.
Even with a strong commitment in Paris, the government will need mechanisms to implement it. A good place to start would be by shutting off subsidies for exploration and exploitation of fossil fuels. The government should also enforce a price on carbon, either via an Emissions Trading Scheme (ETS) or an emissions tax coupled with a credit for sequestration. Charging $50 per ton of carbon dioxide for all sectors of the economy would increase our petrol bills by $10 per 1,000 kilometres, but it would also provide a huge incentive to reforest the country. Together, these actions will simultaneously encourage smart personal choices, such as installing solar panels, insulating homes, or driving electric cars.
With the right attitude and commitment, we can ensure our grandchildren have a decent life on this planet, but we can’t continue down the path we’ve been treading. Last weekend, from Alexandra to Auckland, the people of New Zealand made their message clear: it’s time for serious climate action.


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Calculation of UVI for Smartphone Apps

The linked document Calculation-of-UVI-for-Smartphone-Apps (revised July 2017) describes in detail how the UV Index (UVI) is calculated in the recently released GlobalUV app.

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uv2Day available on iPhone

The uv2Day app is now available (for free!!) on iPhone as well as Android smartphones. Enjoy!!


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Climate March, Alexandra

Please follow the link below, and register.

The event will include a question and answer session, which will involve some of New Zealand top atmospheric research scientists, as well as any other concerned members of the public. I hope there will also be a media presence. By scheduling the event for 9 am on Saturday, I had hoped it would be the first one in the world, but I see a group in Auckland has beaten us to the punch by 1 hour. I’m hoping that after the meeting, we can adjourn for coffee at a nearby café. Please let me know if you can help with organising posters or banners. Also, please help by circulating this email in your contact circles, and through social media such Facebook and Twitter (where I am deliberately inactive).

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A friend and I have been working on a smartphone app (Uv2Day), which provides UV information for 

New Zealand, Australia, and the Pacific region …..

UVI App Icon14launch icon

The UV Index (UVI) is a measure of skin-damaging ultraviolet radiation. This App provides an estimate of the current UVI, and how it is expected to vary throughout this day at your current location (or at other selectable locations). Although small amounts of UV radiation are beneficial to health, overexposure can lead to skin cancer. New Zealand and Australia have the highest rates of skin cancer in the world, and the Cancer Societies of both countries recommend that you take protection whenever the UVI is greater than 3. The main determinant of UVI is the sun’s elevation angle, so UVI values are greatest in the summer, especially near solar noon (typically around 1:30 pm in the NZ summer). In winter, peak UVI values are generally less than 2, but in summer they can exceed 12. These peak values are about twice as high as in the UK, but the highest values in the world occur in the high altitude altiplano region of Peru, where they can exceed UVI=25. In New Zealand and Australia, UVI values are considered “extreme” when they exceed 10. For that UVI value, skin damage in fair-skinned people occurs in about 15 minutes, so it is important to take steps to protect yourself by avoiding direct sunlight, or by liberally applying a sunscreen with a high SPF factor to exposed skin.

Why do we need the app?
The app helps us to plan our daily activities to optimise sun exposure: to minimise the risk of sunburn (which is a risk factor for skin cancer) in summer, and to provide information on when it is safe to expose ourselves to sunlight in winter to help maintain sufficient levels of vitamin D. At present, this information is available only through the NIWA web pages. The only information provided by the media to the New Zealand public is the daily “alert period” (when the UVI exceeds 3), with no information about actual UVI values. Further, these alert periods are only provided during summer months. The app was developed in response to a request from a medical colleague who wanted to provide quantitative information on UVI levels for melanoma patients.


What does the App tells us?
The App provides current UVI values, and peak UVI values for the day, along with corresponding behavioural messages for the town nearest to the current location, as determined from a GPS fix. Corrections are applied to account for seasonal changes in Sun-Earth separation, and also for changes in altitude, mean aerosol optical depth, (and for surface reflectivity in the case of ski fields). Geographical coverage is currently limited to New Zealand, Australia, and the Pacific region, including Antarctica. Other locations with these regions can be selected with drop-down menus. A subsequent screen shows the variations in the clear-sky UVI forecast for the day, along with appropriate behavioural messages, using an interactive display. UV alert periods are displayed at the top of the graph. For locations that fall within the domain of NIWA cloud forecast model, cloudy sky forecasts are also provided. Warnings are issued if the forecast data are out of date.


 At present, the App is available only for Android phones at present. We are currently working with the Cancer Society of New Zealand to provide an iPhone version. The app, which is free, will be available soon on from iTunes. It may also be downloaded from here. Another UVI App, with global coverage, is also under development.

The UVI data used in this app are provided by NIWA. Clear-sky UVI values are calculated using a radiative transfer model. The ozone fields used as inputs to the model are forecasts that are based on global measurement from NOAA polar orbiting satellites. In the NZ region, estimates of UVI that include cloud effects are derived from a regional climate model that is run daily at NIWA.
For more information, see The app was developed by JGR Burke (

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Smog, Solar Power, and Electric Car Batteries

 Here is an opinion piece I wrote for the Otago Daily Times. It was published on Monday 28 July, 2014

“Solar power gets round high line charges”

Richard McKenzie of Alexandra suggests a solar smog solution

Tesla Model S

Dense energy storage … The battery pack in this Tesla Model S has a capacity of 85 kW hours, enough to run a two bar heater continuously for nearly two days.

Winter is upon us, and we are stoking our fires.

We are regularly reminded of our failure to curb the long-standing pollution issues in Alexandra, Milton, and Cromwell. Last year Alexandra breached the National Standard for Air Quality Standard [1] 47 on days. By year 2016, we are supposed to achieve to no more than 3 such polluted days per year.

Clearly, we won’t meet that target. Regardless of impacts on health and tourism, our failure to meet these targets can impede our economic progress and development, because the clean air act has teeth.

According to the Ministry for the Environment’s 2011 “Clean Healthy Air for All New Zealanders: National Air Quality Compliance Strategy to Meet the PM10 Standard”, if the standards are not met then the Minister for the Environment “may commence an investigation of the performance of any non-complying councils”. This could curb future commercial investment.

I first raised the smog issue with the Central Otago District Council in 1991, and subsequently with the Otago Regional Council. Many of my recommendations were implemented, albeit much later, in the Otago Regional Council’s Regional Air Plan which was developed in 1996.

One of my suggestions was to use more electric heating appliances. It should have been a win-win situation because heat pumps, with efficiencies up to four times greater than conventional heaters, were not yet widespread – and their rollout in the years that followed should have solved the problem.

But, following Max Bradford’s so-called “deregulation” of the electricity industry, prices have skyrocketed at about four times the rate of inflation [i]; and despite the gains in efficiency of heat pumps, we can’t afford to heat our homes electrically. Many are reverting to wood burners – and our winter smog persists.

To reverse that trend, power prices have to be lower. About two thirds of our winter power bill goes towards Aurora Energy’s lines charges, this is the obvious place to look for future economies.

One option is harvesting our own electricity from solar PV systems on our roofs. But for systems that have available up until now, there is no guarantee that any power company will purchase unused power at suitable rates over the long period needed to recover the substantial capital outlay – especially now that power generation companies are being sold off to private enterprise.

But Vector Energy ( have a plan that may help. Key differences with their scheme are: (1) No large capital outlay is needed; only a relatively small installation fee, followed by a monthly rental fee; and (2) It includes on-site storage batteries, so energy produced during the day can be used at night (and hopefully energy produced in summer can be used in winter) without having to sell it and then repurchase it at costs that include these excessive lines charges.

Currently, they can supply only in the Auckland region. But there is a huge potential in Central Otago/Lakes District where the lines cost component of electricity represents over 60% of the total bill (compared with 30% in the Waitaki district for example, [2] and probably much less in Auckland). This factor, and the high sunshine hours in summer, heavily outweigh the slightly reduced capability of solar PV generation during the winter months. It represents a huge opportunity for companies like Vector. I want to be first in line for one in our region.


[1] 50mcg per cubic metre of airborne pollutant, with a particle size below 10 microns

[2] It’s interesting to note that in other regions, line charges seem to be much less than in Central Otago. For example, in the Waitaki region, they represent only 30% of the bill (ODT, 5 Feb 2014,, rather than over 60% of ours. The difference is probably because at deregulation, the Waitaki Region retained their lines, whereas in Central Otago we sold them to Aurora Energy, and retained the generation capacity (Pioneer), vested in the Central Lakes Trust.

The day after this opinion piece appeared in the ODT, Waitaki Lines company reported record profits. The Waitaki region has similar demographics to Central Otago, but their lines charges are only 1/3 of the power bill, not 2/3. The difference is that their lines company is still in community ownership. For more details, see

[i] See my earlier opinion piece, published in the ODT on 18 Nov 2013 (also published here).

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September 7, 2014 · 10:33 am