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ScienceSeptember 17, 2018

The climate visualisations that leave no room for doubt or denial


Data visualisations created by Ed Hawkins have offered a less traditional approach to popularising climate science, and now New Zealand has a ‘warming stripe’ of its own, writes Veronika Meduna

Courtesy of serendipity, social media and datavis genius, Aotearoa now has its very own warming stripes.

The latest data visualisation to come out of the lab of University of Reading climate scientist Ed Hawkins, climate stripes track the long-term rise in temperature for a particular region. They look like a barcode of bands that move from cooler shades of blue to ever warmer reds.

Our very own climate barcode is the result of a cross-hemisphere tweet. On Friday, champion of participatory science Victoria Metcalf was giving a talk at a conference focused on New Zealand’s transition to a low-emissions future. She’d asked a few people for examples of effective climate communication, and I suggested Hawkins’ climate data visualisations. Neither of us had any idea that his first PhD student, Nathanael Melia, would be in the audience. He worked with Hawkins in 2012 but has since moved to New Zealand to join climate research at the forestry research institute Scion.

“Whenever I see Ed’s datavis or anything else he’s done I tweet him. It’s kind of a running joke. I can move to the other side of the world but still can’t get away from him.”

Hawkins tweeted back, asking if NZ might want its own warming stripes. Climate scientist Andy Reisinger (disclosure: my husband) joined in and pointed him to NIWA’s long-running temperature monitoring data. Within hours, Hawkins posted a graphic of our year-by-year temperature stripes. “Lots of variability in New Zealand temperatures (1909-2017), but overall trend still very clear.”

The NZ climate stripes

Hawkins used temperature data from NIWA’s seven-station series, collected at seven sites between Auckland and Dunedin that have been chosen to provide both broad geographical coverage and long records, going back to 1908. The data show clearly that New Zealand has warmed by just under one degree over the last century.

The high variability from year to year doesn’t surprise NIWA climate scientist Sam Dean. “There’s a couple of reasons for that,” he says. “New Zealand is small, long and thin, and we’re in the mid-latitudes.”

First there is the statistical aspect. If you average temperatures for a smaller area, say New Zealand, the year-to-year variability is always larger than if you work with temperature measurements collected across a much larger area, for example the United States.

Then, there’s geography. The main islands span across 14 degrees in latitude (from 34 degrees south to 48 degrees south) and mid-latitudes experience much higher variability than the tropics. Year by year, Aotearoa might be more exposed to warmer air masses from the north or feel the nip of icy winds and ocean currents coming straight from Antarctica. On a scale of decades, it also rides along with changes between El Niño and La Niña seasons and a polar ring of climate variability known as the Southern Annular Mode, or SAM. Nevertheless, on top of all this variability, the trend of rising temperatures is clear, with particularly rapid warming over the last decade.

Ed Hawkins is perhaps best known for his climate spirals. When he posted his first spiral of rising global mean temperatures between 1850 and 2016, it went viral instantly. It featured in the opening ceremony of the Rio Olympics and, within a year, clocked more than three million views.

More effective than any words, this kind of climate visualisation leaves no room for doubt or denial.

“Ed has a gift for turning data into intuitive and eye-catching visualisations that speak to the heart of climate change,” says Nathanael Melia. “The wide reaching and easy to understand visualisations create a bridge between the complicated climate science we do in academia, over the raging torrent that is climate scepticism, and to the concerned and engaged members of the public.”

Melia’s own project was part of the Hawkins lab’s wider programme on the future of Arctic sea ice and shipping routes. This, too, was picked up widely, including an interactive feature in the New York Times.

The warming stripes have taken a perhaps less traditional route of popularising climate science. They have been turned into ties and scarves, even cuff links and jewellery, and weather presenters across networks in the US made a coordinated effort to wear the ties on summer solstice.

Ed Hawkins sees his data visualisation work as one way of communicating a complex topic as simply as possible. “The world faces a range of risks in the future but the story of climate change can often seem rather remote – it’s a global scale problem that will happen over many decades. But, the effects of climate change are felt locally, by everybody. By highlighting how the climate has already changed where people live, it raises awareness that this is an issue to take seriously.”

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