Posts filed under Environment (50)

May 31, 2015

Of droughts and flooding rains

Australia’s climate is weird, even in the relatively habitable bits such as Melbourne, so it makes for interesting graphs. This is going to be another post about aspect ratios and alignment in graphs and how to use them for things other than lying with statistics. (more…)

April 7, 2015

Evils of Axis

First, from Mother Jones magazine, via Twitter


The impact of the carbon tax looks impressive, but this is a bar chart — it starts at zero and they’ve only shown the top fifth of it.

They do link to the data, the quarterly Greenhouse Gas Inventory update.  In that report, Figure 8 is


The dotted line is the same data as the bar chart, except that the dotted line has data for every quarter and the bar chart has data only for the July-September quarter each year. And  the line chart has a wider range on the vertical axis — it doesn’t go down to zero, but it isn’t a bar chart, so it doesn’t have to. The other point about the line chart is that there’s a solid line there as well. The solid line is adjusted for seasonal variation and weather. If you wanted to know about real changes in how Australians are using energy, that’s the line you’d use.


Second, a beautiful map of CO2 emissions from fossil fuel combustion, from the Washington Post via Flowing Data


The ‘vertical’ scale here is a colour scale; what’s misleading is that it’s a logarithmic scale. The map makes it look as if a large fraction of CO2 emission comes from transporting stuff through empty areas, but the pale beige indicates emissions thousands of times lower than in the urban/suburban areas. Red ink isn’t anywhere close to being proportional to CO2.

March 19, 2015

Model organisms

The flame retardant chemicals in your phone made zebra fish “chubby”, says the caption on this photo at Zebra fish, as it explains, are a common model organism for medical research, so this could be relevant to people


On the other hand, as @LewSOS points out on Twitter, it doesn’t seem to be having the same effect on the model organisms in the photo.

What’s notable about the story is how much better it is than the press release, which starts out

Could your electronics be making you fat? According to University of Houston researchers, a common flame retardant used to keep electronics from overheating may be to blame.

The story carefully avoids repeating this unsupported claim.  Also, the press release doesn’t link to the research paper, or even say where it was published (or even that it was published). That’s irritating in the media but unforgivable in a university press release.   When you read the paper it turns out the main research finding was that looking at fat accumulation in embryonic zebrafish (which is easy because they are transparent, one of their other advantages over mice) was a good indication of weight gain later in life, and might be a useful first step in deciding which chemicals were worth testing in mice.

So, given all that, does your phone or computer actually expose you to any meaningful amount of this stuff?

The compounds in question, Tetrabromobisphoneol A (TBBPA) and tetrachlorobisphenol A (TCBPA) can leach out of the devices and often end up settling on dust particles in the air we breathe, the study found.

That’s one of the few mistakes in the story: this isn’t what the study found, it’s part of the background information. In any case, the question is how much leaches out. Is it enough to matter?

The European Union doesn’t think so

The highest inhalation exposures to TBBP-A were found in the production (loading and mixing) of plastics, with 8-hour time-weighted-averages (TWAs) up to 12,216 μg/m3 . At the other end of the range, offices containing computers showed TBBP-A air concentrations of less than 0.001 μg/m3 . TBBP-A exposures at sites where computers were shredded, or where laminates were manufactured ranged from 0.1 to 75 μg/m3 .

You might worry about the exposures from plastics production, and about long-term environmental accumulations, but it looks like TBBP-A from being around a phone isn’t going to be a big contributor to obesity. That’s also what the international comparisons would suggest — South Korea and Singapore have quite a lot more smartphone ownership than Australia, and Norway and Sweden are comparable, all with much less obesity.

February 3, 2015

Meet Statistics summer scholar Daniel van Vorsselen

Every year, the Department of Statistics offers summer scholarships to a number of students so they can work with staff on real-world projects. Daniel, right, is working on a project called Working with data from conservation monitoring schemes with Associate Professor Rachel Fewster. Daniel explains:

Daniel Profile Picture“The university is involved in a project called CatchIT, an online system that aims to help community conservation schemes by proving users with a place where they can input and store their data for reference. The project also produces maps and graphics so that users can assess the effectiveness of their conservation schemes and identify areas where changes can be made.

“My role in the project is to help analyse the data that users put into the project. This involves correctly formatting and cleaning the data so that it is usable. I assist users in the technical aspects relating to their data and help them communicate their data in a meaningful way.

“It’s important to maintain and preserve the wildlife and plant species we have in New Zealand so that future generations have the opportunity to experience them as we have. Our environments are a defining factor of our culture and lifestyles as New Zealanders and we have a large amount of native species in New Zealand. It would be a shame to see them eradicated.

“I am currently studying a BCom/BA conjoint, majoring in Statistics, Economics and Finance. I’m hoping to do Honours in statistics and I am looking at a career in banking.

“Over summer, I hope to enjoy the nice weather, whether out on the boat fishing, at the beach or going for a run.”





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.