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New Zealand is drying out, and here’s why
No full textOver 2012 and 2013, parts of New Zealand experienced their worst drought in nearly 70 years. Drought is the costliest climate extreme in New Zealand; the 2012-2013 event depressed the country’s GDP by 0.7-0.9%.
The drought of 1988-1989 affected 5,500 farms, pushing some farmers to the wall. But what does a climate-changed future hold?
Recent evidence confirms that New Zealand on the whole is getting dryer. And we’re beginning to understand why — increasing greenhouse and ozone-depleting gases are driving changes in the atmosphere, with impacts far beyond New Zealand.
A history of drought
Agricultural drought is occurs when there is not enough moisture in the soil available to support crop and pasture growth. It is usually fairly extensive over significant parts of the country.
In March this year we reported that there is distinct trend towards increased agricultural drought since 1941, in four (80%) out of the five agricultural drought regions. There is a trend toward a summer drying in all of these regions except the west of the North Island. The overall trend for New Zealand agricultural drought is shown in the diagram below.
New Zealand agricultural drought index 1941-2013 averaged over the country. The bars represent individual years, and the straight line shows the 72-year trend. Positive values mean a droughtier year, and negative values mean a wetter year for agriculture.
What’s causing the big dry?
Two recent reports shed light on why drought is increasing in New Zealand.
On 9 September the Geneva based World Meteorological Organization (WMO), a United Nations body, announced that the amount of greenhouse gases in the atmosphere reached a new record high in 2013, propelled by a surge in levels of carbon dioxide during between 2012 and 2013.
Last year the concentration of CO2 in the atmosphere reached 142% of the pre-industrial era (1750). Methane levels reached 253% and nitrous oxide 121%.
Between 1990 and 2013 there was a 34% increase in radiative forcing — the warming effect on our climate — because of long-lived greenhouse gases such as carbon dioxide (CO2), methane and nitrous oxide.
These have warmed the climate. Over the last 72 years mean annual global and New Zealand temperatures have increased by 0.6 and 0.7C respectively.
And on September 11 a new report, with Dr Olaf Morgenstern of the NZ National Institute of Water and Atmospheric Research as a reviewer recognised the role of ozone depletion in drying parts of southern Australia.
The same link has been established in New Zealand. Ozone depletion affects an atmospheric pattern known as the Southern Annular Mode, or SAM. These changes are particularly pertinent as the spring time stratospheric Antarctic ozone hole peaked this year at 24 million square kilometres on September 11.
SAM describes the movement of the westerly wind belt that circles the Southern Oceans between the South Island of New Zealand and Antarctica.
In its positive phase, SAM causes the belt of strong westerly winds to contract towards Antarctica. There are weaker westerly winds than normal over the South Island with higher pressures, and less cold fronts crossing New Zealand.
The opposite occurs in the negative phase of SAM with the westerly wind belt expanded north towards New Zealand and the passage of more westerly cold fronts.
The positive SAM has also been linked to decreasing rainfall in south western Australian, and the recent record-breaking expansion of Antarctic sea ice.
Index of the Southern Annular Mode, 1957 – 2013. Source: British Antarctic Survey, Cambridge, UK.
The graph of SAM over the last 56 years shows a trend towards a more positive index, averaging around -3 at the beginning of the record to +1 in recent years. Several researchers have now shown that this increase in SAM is strongly associated with stratospheric ozone depletion.
Less rain, more evaporation
Recent work has revealed that changes in SAM in New Zealand have resulted in a weakening of moisture laden westerly winds during the summer, and increased high pressures over the North Island with less rain.
The warming trend caused by increasing greenhouse gases has led to more moisture loss to the atmosphere from plants because of increased evapotranspiration. This is where plants “breathe out” into the air moisture that is stored in the soil.
The hotter it is, the more moisture plants pump out into the atmosphere. These two effects — less rainfall and more water loss from the soil have resulted in our climate becoming droughtier for agricultural activities.
Bringing back the rains
The stratospheric ozone layer is now protected by the Montreal Protocol — an international treaty to protect the ozone layer by phasing out production of ozone-depleting substances signed in 1989. Unfortunately it has not prevented some impacts on New Zealand climate — but at least these impacts will be slowed then reversed in coming decades. The Antarctic stratospheric ozone hole peaked in 2006 at around 30 million square kilometres.
However there is no such robust agreement to curb the growth of greenhouse gases in the atmosphere. The World Meteorological Organisation has called for even greater urgency for concerted international action against accelerating and potentially devastating climate change.
Any future New Zealand government must front up to New Zealand taking full leadership in any international agreements to rapidly halt and reverse the growth of greenhouse gases, as the country did with the Montreal Protection to protect the stratospheric ozone layer twenty five years ago.
After all, these trends are now affecting the country’s land-based industries vital for its wealth.
Jim Salinger does not work for, consult to, own shares in or receive funding from any company or organisation that would benefit from this article, and has no relevant affiliations.
This article was originally published on The Conversation. Read the original article.
Photo: Dave Young / Flick
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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