I’ve Moved ….

Postings about UV, climate, and health

I’ve decided to support my son Hamish who is a founder of Substack, a subscription-based e-mail provider of news and views.

So I’ve started a domain there called UV & You

The story of how ultraviolet radiation affects humans and our planet, brought to you by research scientist Dr. Richard McKenzie.

I’ve migrated old posts here to that site, and most of my future posts will be placed there. Go there now

 

UV App Privacy Statements

Privacy statements are now needed for the UVI smartphone apps. They can be found here:

GloblaUVPrivacyStatementAndroid

uv2DayPrivacyStatementAndroid

uv2DayPrivacyStatementIOS

GlobalUVPrivacyStatementIOS

Saving the Planet

On 9 May, I gave a talk as part of the EcuAction 2019 Forum Series “Climate Change and a Faith Response”  in Christchurch. I discussed climate change from the perspective of atmospheric physicist involved more with ozone depletion and its interactions with climate change. I emphasised the huge impact that man has made during our fleeting appearance on the planet.

Action on climate change is more difficult than that needed to protect ozone, especially with delays caused by the “Merchants of Doubt” (see book of that title by Naomi Ereskes and Eric Conway). But the huge success of Montreal Protocol on Protection of the Ozone Layer shows that we can do it.

A transcript of the talk for Plains FM can be heard here (unfortunately the sound quality is not very good, as we had difficulties with the microphone)

Our Part in Transitioning to the Low Carbon Revolution

I wrote this opinion piece a couple of months ago. Unfortunately, it was not wanted by the Otago Daily Times, or the NZ Listener, so it time for it to see the light of day here. I’d like to thank colleagues Ben Liley and Catherine Leining, who provided useful feedback

To all intents and purposes, the Sun is an unlimited source for all our energy requirements. In less than 2 hours, the energy from it that arrives at planet Earth is sufficient to satisfy the needs of all of humanity for an entire year. But it’s largely untapped by mankind ….

At the middle of a sunny summer’s day, the Sun delivers over 1000 Watts per square metre to the surface around you. That’s about equivalent to the energy from a 1-bar electric heater every square meter, or about 10,000 of these heaters on a football pitch.

Of course, we don’t get that much power from the Sun all the time. Some is lost by absorption in clouds and pollution, and by lower sun elevation angles at other times of the day. At night local access reduces to zero because it’s all arriving on the other side of the planet. As a result, the average rate at any site in the world is around 340 Watts per square metre at the top of the atmosphere, or 161 Watts per square meter at Earth’s surface. But we haven’t been using all that free clean energy as well as we should have. Instead, we’ve taken the path of using fossil fuels, and the consequences are dire.

Before the industrial revolution, our planet was in radiative balance, with the amount of incoming solar energy being balanced by the amount of outgoing infra-red energy. But because we’ve been burning fossil fuels so rapidly, the carbon dioxide that had been locked up in coal, oil, and gas for hundreds of millions of years, has rapidly been released to the atmosphere.[1] Its concentration in the atmosphere has increased by nearly 50%, from its preindustrial level. The problem is thatcarbon dioxide, and other so-called “greenhouse” gases such as methane, nitrous oxide and synthetic gases used as refrigerants, affect the Earth’s radiative balance. They have absorption bands in the infra-red region at the same wavelengths where radiation is emitted from the Earth back to space (wavelengths near 10 microns), while having little effect on the incoming solar energy, which is at shorter wavelengths, mainly in the visible region (wavelengths near 0.5 microns).

As a result, the radiative balance of the planet is currently out of equilibrium. Instead of 340 Watts per square metre being radiated back to space to balance the incoming solar radiation, the amount radiated back is smaller by 0.6 Watts per square metre. Although that imbalanceappears small, it still represents a lot of energy because there are a lot of square metres on the planet. Staggeringly, it is equivalent to the energy released from the detonation of about 300 Hiroshima atomic bombs per minute; and continuing at that rate throughout the day for every day of the year.

The difference between incoming and outgoing energy is absorbed by the atmosphere, land and oceans. So it leads to increasing temperatures, ice-melt, sea-level rise, and changes in weather patterns. In other words, that energy imbalance is the cause of climate change.

We need to reduce our emissions of carbon dioxide to the atmosphere, and so reduce the energy imbalance. The need for change is urgent, so incentives will be needed to encourage the transition from fossil fuels to renewables and from high-emission to low-emission industrial production, food production and land uses.  Internationally, these should include ambitious emission pricing, whether in the form of emissions trading (as we have in New Zealand) or carbon taxes. To be effective globally, these will require inter-governmental agreement. Raising the relative cost of emissions-intensive activities will encourage the transition. Alongside emission pricing, governments can use policies and regulations, information programmes and support for the development and uptake of new technologies. Other governmental incentives, like tax incentives against gas guzzlers, can hopefully help to fund tax incentives to speed the transition to electric cars. Hopefully, New Zealand’s proposed Zero Carbon Bill will be exactly what’s needed to drive New Zealand’s low-emission transition, and set an example for other countries to follow.

If we are to keep temperature increases below even the 2-degree threshold target set in December 2015 by “COP21” in Paris, each person on the planet will need to reduce their carbon footprint on average by about 4 percent per year. And it’s getting harder with every advancing year, especially given that we should really be aiming more for their more ambitious target of 1.5 degrees. On an average per capita basis, the emissions of citizens of New Zealand (and other wealthy counties like Australia, and USA) are more than twice those of the average global citizen, so it is especially important for us to act. If you can continue reduce your own carbon footprint, you will be part of the solution instead of being part of the problem.

Here’s how you can help.

• Reduce your intake of red meat and dairy products. A study by Motu Economic and Public Policy Research found that for the average New Zealand household in 2012, about 40% of its carbon footprint was from food, including both energy and biological emissions.[2] Reducing your intake of meat and dairy products can make a big difference to your carbon footprint – and produce other environmental benefits (e.g., by reducing our usage and pollution of water).
• Reduce your travel and transport. The same study found that about 25% of the average household’s carbon footprint is from transport, so fly less and try walking, cycling and public transport instead of driving. Buy locally to minimize transport costs.
• Improve household insulation and replace inefficient heaters with heat pumps. About 25% of the average household’s carbon footprint is from household energy use, which is largely heating, air conditioning.

As well as benefitting the environment for current and future generations, these measures can improve your personal health, and in many cases will save you money. A triple bottom line if I ever saw one ….

Any carbon calculator will show that the more you earn, the greater your carbon footprint will be. So, if you can afford it, you should try to do a lot more …  

Consider the following options.

• Transition to renewable electricity by harnessing your own solar energy; or buying your electricity from companies that use only renewable energy. A medium sized house of 200 m² intercepts around 1000 kW hours of solar energy each day. Installing 35 square metres of solar panels with a collection efficiency of 20% produces savings of  $200/month. It’s a reasonable assumption that electricity prices will continue to increase over time. But solar energy is free. All you pay is the capital cost of the equipment to harvest it. My own calculations show today’s rates it will take about 10 years to recover the capital costs of my 2.5 kW solar PV installation, provided I can use 70% of the energy it generates; and good quality systems will last much longer than that. It’s hard to find a better safe investment return than that. Don’t believe the advisors who call such changes “disruptive”. Yes, they are disruptive from the point of view of their masters. Our own government’s investments in power production and distribution will be challenged. But moving to renewables is not disruptive from your viewpoint, nor for the environment.
• Switch to an electric car. At the start of the 20^th century, petrol-powered cars took ascendancy over battery-powered cars, which were being developed around the same time in USA. Electric cars lost out then because of the difficulties of storing energy, and because of the recently discovered huge reserves of oil. The resultant proliferation of diesel and petrol-powered vehicles since then is a major cause of our troubles. But the problems of energy storage have now been overcome. It’s time to switch back. A new car is a long-term investment. If you need a new one, get ahead of the game and consider buying an electric one, rather than a conventional one. Like coal-fired power stations, emissions-intensive farming practices, and transport companies that rely on fossil fuels; conventional cars will become stranded assets in a future world with a high and rising price of carbon. With your electric car, you can also make much better use of your rooftop solar PV system. Excess energy from it can be used to charge your electric car, rather than selling it back to the power companies. With an electric car parked in your garage, it will be easy to make use of more than 70% of the energy you generate. It also works in reverse, feeding energy from your car’s batteries back to the house at night if required

There will be problems in the new technologies, as there have been with older technologies. There must be full accounting of the costs of their production and disposal. These costs are significant in these newer technologies; but are much lower than with the old technologies.[3] But you will hear conflicting messages because there will be winners and losers in energy revolution that we’re entering. Listen to the arguments, but don’t be dissuaded by people with vested interests in the status quo without checking their claims using reputable sources (not just the first relevant hit you see with an on-line search).

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[1] Carbon dioxide is also released by deforestation and production of cement and steel.

[2] See  https://motu.nz/our-work/environment-and-resources/emission-mitigation/shaping-new-zealands-low-emissions-future/whos-going-green-decomposing-the-change-in-household-consumption-emissions-2006-2012/

[3] https://blog.ucsusa.org/dave-reichmuth/new-data-show-electric-vehicles-continue-to-get-cleaner

List of My Research Papers

Citations to my work, including links to full text of most papers, can be found at my ORCID siteorcid.org/0000-0002-4484-7057

Flawed UV Advice

It turns out that some of the advice we’ve been getting about UV protection is wrong. We are advised that “no protection” is needed on days when the peak UVI is less than 3. But our recent study shows that on such days, the total UV dose can exceed that needed to cause visible damage (i.e., erythema – or skin reddening) to fair skin by a factor of 5 or more. It’s true that UV doses can be much higher on days when the UVI exceeds 3 (they can exceed the threshold for skin damage by a factor of 30 in mid-summer), and advice to protect is even more important then. But at mid-latitudes about 10% of the total annual dose occurs on days when the peak UVI is less than 3. So if we follow the current advice on those days, we increase our risk of skin cancer. The “no protection” messages should be removed from public advisories when the peak UVI is less than 3, except for the few days when the daily dose is insufficient to cause skin damage. It all depends on how long you will be outdoors in the sun. Sun protection should be advised for extended outdoor periods all year round at mid latitudes. Read all about it here. And an interview with Kathryn Ryan of Radio New Zealand is available here

UV Workshop 2018

The 2018 edition of the ongoing series of NIWA UV Workshops, was held between 6 and 8 April, in Wellington New Zealand. Proceedings of the event, including a workshop summary, are now available here.

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).

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 350.org, 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 350.org 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 350.org) – 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.

 

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.