Guest Author

This is the Sciblogs guest blog, where we run science-related submissions from the Sciblogs community and beyond. Contact Sciblogs editor Peter Griffin about making a submission - or about hosting a blog on Sciblogs.

What the world was like the last time carbon dioxide levels were at 400ppm - Climate: Explained

Jul 08, 2020

Climate Explained is a collaboration between The Conversation, Stuff and the New Zealand Science Media Centre to answer your questions about climate change. If you have a question you’d like an expert to answer, please send it to What was the climate and sea level like at times in Earth’s history when carbon dioxide in the atmosphere was at 400ppm? James Shulmeister, University of Canterbury The last time global carbon dioxide levels were consistently at or above 400 parts per million (ppm) was around four million years ago during a geological period known as the Pliocene Era (between 5.3 million and 2.6 million years ago). The world was about 3℃ warmer and sea levels were higher than today. We know how much carbon dioxide the atmosphere contained in the past by studying ice cores … Read More

Opening New Zealand’s borders – an educational scenario - COVID-19

Jul 07, 2020

Associate Professor Sara Walton At the heart of the discussion on opening up our borders is the dichotomy of health and the economy – both of which are actually intertwined, like many things with our economy, as this epidemic has shown. If we think about our country as a system, an open system deals with the ebbs and flows from the environment in which it operates while a closed shuts itself off. Open systems have feedback loops which cause amplifications of the activities within the system. It is understanding the issue of opening the borders using systemic and interdisciplinary thinking that is needed to assist in this difficult decision. That involves thinking about these feedback loops to be able to predict the plausible possibilities. Plus, developing thinking around plausible outcomes of potential future situations to sensitise us to … Read More

The small numbers problem: distinguishing good luck from good performance - COVID-19

Jul 04, 2020

Dave Heatley Zero community transmission. Just a handful of active cases, all in quarantine. New Zealand is in an attractive situation, at least compared to much of the world. The situation could be robust and enduring – or it might be fragile, just one border incursion away from a “second wave”. How would we tell? COVID-19 just keeps changing and evolving. Not the virus itself – that seems pretty stable as viruses go. What is changing is the phase of the pandemic, and our knowledge of the virus and the effectiveness of public policy responses. Super-spreaders and under-achievers Recent research suggests that some people—most, even—don’t spread the virus to anyone in the course of their infection. Others infect dozens. Studies suggest that 10% of cases lead to 80% of the spread, consistent … Read More

Level with me - COVID-19

Jul 03, 2020

Nik Green Much of the public debate about the response to the COVID-19 pandemic has focused on the extent to which government regulations have restricted personal and business activity. Oxford University Blavatnik School of Government Here in New Zealand, the question of when to change Alert Levels dominated the media and Parliament, with some arguing that the highly-restrictive Levels 3 and 4 caused too much damage to the economy and employment. Others argue that the period in lockdown and the resulting elimination of community transmission will allow our economy to rebound more quickly than expected, now that New Zealand has one of the least restrictive environments in the world (as can be seen in this map). As this post was being written, governments in Victoria and the … Read More

The sun is setting on unsustainable long-haul, short-stay tourism — regional travel bubbles are the future - COVID-19

Jul 03, 2020

James Higham, University of Otago Unprecedented border closures and the domestic lockdown have paralysed New Zealand’s $40.9 billion a year tourism industry. In the process, the vulnerability of the sector to external shocks and the tenuous nature of tourism employment have been exposed. While New Zealand’s handling of the pandemic has been hailed as a global masterclass, and the prospect of travel bubbles promoted as a way to restart the tourism economy and save jobs, it is clear there is no quick fix. The inherent dangers of reinfection from travel to and from countries with uncontrolled community transition, and the challenge of protecting New Zealand’s borders, mean international tourism is grounded for the time being. Nevertheless, planning for recovery is underway. The United Nations World Tourism Organisation (UNWTO) wants to restore confidence and restart tourism without … Read More

Will the COVID-19 lockdown slow the effects of climate change? - Climate: Explained

Jul 03, 2020

Climate Explained is a collaboration between The Conversation, Stuff and the New Zealand Science Media Centre to answer your questions about climate change. If you have a question you’d like an expert to answer, please send it to Do you think the COVID-19 pandemic lockdown will slow or possibly reverse the effects of climate change (due to decreased air travel, cars, fossil fuels being emitted)? Simon Kingham, University of Canterbury The COVID-19 lockdown has affected the environment in a number of ways. The first is a reduction in air travel and associated emissions. Globally, air travel accounts for around 12% of the transport sector’s greenhouse gas emissions and this was predicted to rise. An ongoing reduction in air travel would lead to lower greenhouse gas emissions. The lockdown has also meant less travel by … Read More

Why long-term environmental observations are crucial for New Zealand’s water security challenges - Guest Work

Jun 24, 2020

Andrew Lorrey, National Institute of Water and Atmospheric Research; Ben Noll, National Institute of Water and Atmospheric Research, and Lauren Vargo, Te Herenga Waka — Victoria University of Wellington Brewster Glacier in New Zealand’s Southern Alps lost 13 million cubic metres of ice between March 2016 and March 2019 – almost the equivalent of the basic drinking water needs of all New Zealanders during that time. Climate and glacier scientists monitor New Zealand’s ice and snow. Video produced by Rebekah Parsons-King and Stuart MacKay. Simultaneously, seasonal extremes for Auckland – New Zealand’s largest city – swung from the wettest autumn on record to one of the most severe multi-season droughts. Water is arguably the most precious resource in New Zealand. These contrasting extreme events in two very different regions highlight the critical importance of long-term observations as we … Read More

What Earth would be like if we hadn’t pumped greenhouse gases into the atmosphere - Climate: Explained

Jun 24, 2020

Climate Explained is a collaboration between The Conversation, Stuff and the New Zealand Science Media Centre to answer your questions about climate change. If you have a question you’d like an expert to answer, please send it to This week, Climate Explained answers two similar questions. If humans had not contributed to greenhouses gases in any way at all, what would the global temperature be today, compared to the 1800s before industrialisation? and My question is what happens when all the greenhouse gases are eliminated? What keeps the planet from cooling past a point that is good? Laura Revell, University of Canterbury Earth’s atmosphere is a remarkably thin layer of gases that sustain life. The diameter of Earth is 12,742km and the atmosphere is about 100km thick. If you took a model globe and wrapped it … Read More

Two new COVID-19 cases in New Zealand, but elimination of community transmission still stands - COVID-19

Jun 17, 2020

Shaun Hendy; Alex James, University of Canterbury; Audrey Lustig, Manaaki Whenua – Landcare Research; Michael Plank, University of Canterbury; Nicholas Steyn, and Rachelle Binny, Manaaki Whenua – Landcare Research New Zealand is one of a handful of countries where community transmission of COVID-19 has been eliminated. But with two new cases announced yesterday (June 16), we have learned that elimination is not the end – rather, it’s the start of the next phase. Probability of elimination of COVID-19 community transmission. After 23 consecutive days with no new cases, today’s announcement that two people returning from overseas have tested positive does not mean New Zealand’s elimination strategy has failed. Just two weeks ago, we estimated we were likely to see one or two cases a week at New Zealand’s border. The two travellers in question came from the … Read More

Does your driving speed make any difference to your car’s emissions? - Climate: Explained

Jun 11, 2020

Climate Explained is a collaboration between The Conversation, Stuff and the New Zealand Science Media Centre to answer your questions about climate change. If you have a question you’d like an expert to answer, please send it to Does reducing speed reduce emissions from the average car? Ralph Sims, Massey University Every car has an optimal speed range that results in minimum fuel consumption, but this range differs between vehicle types, design and age. Typically it looks like this graph below: fuel consumption rises from about 80km/h, partly because air resistance increases. Author provided But speed is only one factor. No matter what car you are driving, you can reduce fuel consumption (and therefore emissions) by driving more smoothly. This includes anticipating corners and avoiding sudden braking, taking the foot off the accelerator just before reaching … Read More