Posts filed under Environment (46)

January 8, 2015

Climate trends

From an interview with Robert Simmons, a data visualisation designer specialising in environmental data, this graph was created by Chloe Whiteaker (at Bloomberg) working with NASA’s Gavin Schmidt. It shows a thirty-year global temperature trend centered around each year.


If you just plotted the central point of each line segment you’d have a ‘local linear smoother’, one of the standard ways of drawing a smooth curve through a set of data. Plotting the whole line segment makes it clearer how the curve is computed.

(via Alberto Cairo)


August 22, 2014

California drought visualisation


From XKCD. Both the data and the display technique are worth looking at



Presumably you could do something similar with New Zealand, which is roughly the same shape.

May 21, 2014

Sea rise visualisation

A new map to let you see the impact of rises in sea levels on your area: this is Auckland with 13m sea rise



This doesn’t show the impact of storm surges, which are the big problem for a lot of eastern coastal Auckland (though not so much for Manukau Harbour).

(via everyone on twitter)

March 14, 2014

The wind and the rain

Cyclone Lusi, from the earth wind animation



And coloured by total precipitable water (orange: dry, light blue: very wet)


Keep safe.


March 1, 2014

It’s cold out there, in some places

Next week I’m visiting Iowa State University, one of the places where the discipline of statistics was invented. It’s going to be cold — the overnight minimum on Sunday is forecast at -25C — because another of the big winter storms is passing through.

The storms this year have been worse than usual. Minneapolis (where they know from cold) is already up to its sixth-highest number of days with the maximum below 0F (-18C, the temperature in your freezer). The Great Lakes have 88% ice cover, more than they have had for twenty years.

Looking at data from NOAA, this winter has been cold overall in the US, very slightly below the average for the past century or so.


However, that’s just the US. For the northern hemisphere as a whole, it’s been an unusually warm winter, well above historical temperatures



This has been your periodic reminder that weather news, for good reasons, gives you a very selective view of global temperature.



February 13, 2014

Commuting costs are housing costs

There’s an interesting story in the Herald about research on the combined cost of commuting and housing in Auckland.

“If you just look at housing costs alone, outlying areas appear really affordable and it initially seems to make sense to say, hey, let’s open up greenfield sites on the urban periphery and develop here,” Mr Mattingly said. “But when you include these broader costs, they are not as affordable as they seem.”

This is the sort of conclusion I like to see, as a non-driver, so I looked at the research paper (there wasn’t a link, but the Herald did give the researchers’ names and journal name). I was disappointed that the impact of commuting costs wasn’t higher, at least until you got out to Pukekohe or Warkworth.

Since the journal is published by a company known for its dedication to preventing knowledge being disseminated for free, I won’t show any whole maps, but here are the central chunks of the cost maps with and without commuting costs. Or perhaps the other way around.


February 5, 2014

With friends like these

Stuff has fallen for an egregiously over-promoted paper on future temperature-related deaths in the UK

Deaths caused by hot weather are projected to rise by more than 250 per cent, with the elderly most at risk, the New Zealand Doctor magazine reported today.

The increased death rate, driven by climate change, population growth and ageing, would occur by the middle of the century, according to research published in the Journal of Epidemiology and Community Health on Monday.

It was found that “in the absence of any adaptation of the population”, heat-related deaths would be expected to rise by about 257 per cent by the 2050s, and cold-related mortality would decline by 2 per cent.

Stuff attributes this story to NZ Doctor, but all they did was reprint an explicitly unedited Green Party press release. [update: it looks as though NZ Doctor did also have a story that provided the last four paragraphs of the Stuff story]

Professor David Spiegelhalter has already savaged this one elegantly on his blog.  All the projected increase in temperature-related deaths in the UK is due to the increase in the number of elderly people.

If you compare people of the same age, the projections say cold-related deaths will fall by about twice as much as heat-related deaths rise, as his graph of the numbers from the paper shows.  That is, the paper actually predicts that global warming will reduce the number of temperature-related deaths in the UK.

bar chart of age-standardised deaths, showing decreases are larger than increases

In the USA or Australia, let alone Africa, India, and other less-wealthy tropical places, there is going to be a real problem with temperature-related deaths from global warming.  In many more parts of the world, there’s a potential for weather-related deaths from drought, flood, storm, and ‘tropical’ disease.

Heat waves in the UK are not in the top ten list of things to worry about from global warming. Pretending they are is likely to be counterproductive.

January 6, 2014

In the deep midwinter

It’s cold in the United States at the moment. Very cold. Temperatures in places where lots of people live are down below -20C (before worrying about the wind chill).This isn’t just hypothermia weather, this is ‘exposed skin freezes in minutes’ weather, and hasn’t been seen on such a large scale for decades. So why isn’t this evidence against global warming?

It will be a month or two before we have the global data, but the severe cold snaps in recent years have been due to cold air being in unusual places, rather than to the world being colder that week. For example, November 2013 was also cold in the North America, but it was warm in northern Russia; the cold had just moved (map from NASA).



The cold spells in Europe in recent years have been matched by warm spells in Greenland and northeast Canada. You don’t hear about these as much, because hardly anyone lives there.  The ‘polar vortex‘ being described on the US news is an example of the same thing: cold air that usually stays near the pole has moved down to places where people live. That suggests the global temperature anomaly maps for December/January will show warmer-than-usual conditions in other parts of the far northern hemisphere.

For contrast, look at the heat wave in Australia last January, when the Bureau of Meteorology had to find a new colour to depict really, really, really hot. This map is from the same NASA source (just a different projection)



Not only was all of Australia hot, the ocean south of Australia was warmer than typical. This wasn’t a case of cold air from the Southern Ocean failing to reach Australia, which causes heat waves in Melbourne several times a year. It doesn’t look like a case of just moving heat around.

No single weather event can provide any meaningful evidence for or against global warming. What’s important for honest scientific lobbying is whether this sort of event is likely to become more common as a result. The Australian heat waves definitely are. The situation is less clear for the US winter cold: the baseline temperatures will go up, which will mitigate future cold snaps, but there is some initial theoretical support for the idea that warming of the Arctic Ocean increases the likelihood that polar vortices will wander off into inhabited areas.


[note: you can also see in the Jan 2013 picture that the warm winter in the US was partly balanced by cold in Siberia that you didn’t hear so much about]

September 30, 2013

For advertising purposes only

Bogus polls are only useful for advertising, but as long as they are honest about it, that’s not a problem.

As a meritorious example, consider Forest & Bird’s Bird of the Year poll, which starts today. It exists to raise awareness of NZ birds and to get stories in the media about them, but it’s not claiming to be anything else.

At the time of writing, the kereru, ruru, and albatross were tied for first place. They’ve got more security to prevent multiple voting than the newspapers do — you can only vote once per email address — but it’s still just a self-selected poll of a tiny fraction of the population.

Radio NZ science broadcaster Allison Ballance is lobbying for the albatross, which is an excellent choice, but the only official StatsChat advice is to watch out for the penguins.

September 27, 2013

Nuclear warming?

From the Guardian, some time ago

Jeremy Clarkson had a point – and that’s not something you hear me say every day (indeed, any day) – when in a recent Sun column he challenged the scientists […] who had described a slab of ice that had broken away from Antarctica as “the size of Luxembourg”.

“I’m sorry but Luxembourg is meaningless,” said Clarkson, pointing out that the standard units of measurement in the UK are double-decker London buses, football pitches and Wales. He could have added the Isle of Wight, Olympic-sized swimming pools and Wembley stadiums to the list.

These journalist units of measurements are useful only to the extent that they are more familiar and easily understood than the actual numbers.

From The Conversation, more recently, David Holmes begins

The planet is building up heat at the equivalent of four Hiroshima bombs worth of energy every second. And 90% of that heat is going into the oceans.

This image comes originally from John Cook, who writes


So I suggest a sticky way to communicate global warming is to express it in units of Hiroshima bombs worth of heat. This ticks all the sticky boxes:

  • It’s simple – nothing communicates a lot of heat like an A-bomb.
  • It’s unexpected – whenever I explain this to audiences, their eyes turn into saucers. Almost noone realises just how much heat our climate system is accumulating.
  • It’s concrete – nobody has trouble conceptualising an A-bomb. Well, much of the younger generation don’t know about Hiroshima – when I test-drived this metaphor on my teenage daughter, she asked “what’s Hiroshima?”. But it’s easily recommunicated as an atomic bomb.
  • It tells a story – the idea that second after second, day after day, the greenhouse effect continues to blaze away and our planet continues to build up heat.
  • The only downside of this metaphor is it is emotional – the Hiroshima bomb does come with a lot of baggage. However, this metaphor isn’t used because it’s scary – it’s simply about communicating the sheer amount of heat that our climate is accumulating. I’ve yet to encounter a stickier way of communicating the scale of the planet’s energy imbalance.

I think he’s wrong about the  downside.  The real downside is that the image of Hiroshima has nothing to do with heat production.  The Hiroshima bomb was important because it killed lots of people, many of them civilians, ended the war, and ushered in the age of nuclear weapons where a small number of military or political leaders had the ability to destroy industrial civilisation and kill the majority of our species (which nearly happened, 30 years ago today).

If we set off four Hiroshima-scale bombs per second, global warming would become a relatively unimportant side issue — and in fact, nuclear weapons are much more widely associated with nuclear winter.

You could also invoke public health concerns and describe the heat accumulation as equivalent to everyone in the world smoking seven cigarettes per second (1185 cal/cig: data). That would be wrong in the same ways.