Makin' them dry bones dance
Dr Orange and the Dictionary of New Zealand Biography.
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Probing the depths for climate clues
Oceans cover 70 per cent of the Earth's surface. Ocean-based ecosystems are a major food source, ocean seafloors are expected to be the major source of new resources needed in the new millennium, and ocean chemistry and current systems are as important as the atmosphere in controlling the world's climate. Yet the oceans, particularly the ocean depths, are the least known part of our world. The following two articles offer glimpses into research being conducted to improve our understanding of planet Earth.
Taking the ocean's temperature
It is now well established that the Earth's climate and weather are controlled by the interplay between the atmosphere and oceans. We know, for example, that a redistribution of heat in the oceans of the tropical Pacific during an El Nifio Southern Oscillation (or ENSO) event—or its opposite twin, La Nifia—affects the weather and climate of the entire planet. Much of our improved understanding of ocean-atmosphere interactions results from new observation systems, especially those provided by satellites. To this end, the present generation of NOAA (National Oceanic and Atmospheric Administration) polar orbiting satellites has been continuously monitoring our atmospheric and ocean environments since 1979. These satellites orbit 850 km above the Earth, measuring the radiation emitted by atmospheric gases such as carbon dioxide, oxygen, ozone, and water vapour, as well as reflections of sunlight and emissions of heat from cloud, land and ocean. It is these measurements that are leading to advances in today's, and tomorrow's, weather and climate forecasting systems. Scientists at the National Institute of Water and Atmospheric Research (NIWA) are using data from these same satellites to measure the characteristics of New Zealand's ocean areas. Each day about 1.6 gigabytes of data (sufficient to fill about 1200 floppy discs) from three NOAA satellites flow into NIWA computers. These data are then used to derive analyses of cloud cover and sea surface temperature (SST) over our region. For the first time, the sea surface temperature of every square kilometre in an area that stretches from Fiji to 60 degrees south and from Australia to a third of the way across the Pacific is being monitored up to six times daily. These data have revealed that the ocean environment around the New Zealand region during the El Nino summer of 1997/ 98 was very different from that observed for any previous El Nino. Direct local measurements of SST have also played a part in solving the El Nifio puzzle. Such readings have been taken at the Leigh Marine Laboratory since 1967, and have shown that sea surface temperatures in the New Zealand region have always been colder than normal (by about 1 degree) during El Ninos, and, conversely, warmer than normal during La Ninas. In 1998 that pattern changed, as can be seen from Figure 1, which shows the mean sea surface temperature in the New Zealand region during February. Although the satellite measures the radiation emitted from just the top few microns (1000 microns equals one mm) of the ocean, these measurements reveal much about the oceanography of our region. The southward flow of warm water down the east coast of Australia, the East Australian Current, is clearly visible as are the warm southward-flowing currents (the East Auckland and East Cape currents) east of the North Island, and the warm northward-flowing Southland Current just east of the South Island. The eastward flowing Antarctic Circumpolar Current is just visible at the southern edge of the map. The difference (or anomaly) between the February 1998 sea surface temperatures and the longterm mean for February was as much as +4° C around much of the North Island, which is nearly half the normal annual difference between winter (August) and summer (February) sea surface temperatures. In a normal year, the 20° isotherm east of New Zealand is found near East Cape in February. In 1998, 20° waters reached as far south as Cape Palliser. However, despite this very large positive anomaly, east of the North Island and shoreward of the 1000 m colder than normal. This was because the East Auckland Current was flowing strongly during the summer months, leading to a nearshore upwelling of cold, nutrient-rich bottom waters. Upon meeting sunlight in the euphotic zone, this water generated nearshore algal blooms, thereby supporting an extraordinarily productive marine environment. The spectacular warm anomaly had other effects too: warm-water fish were carried much further south than normal—marlin were even caught off the Wairarapa coast—while subtropical species were found off Northland. Also, as a result of this large anomaly, summer air temperatures were around 3° warmer than normal in Auckland. In a normal El Nino, air temperatures in the New Zealand region tend to be near normal, or a little cooler than normal, but apart from the West Coast of the South Island, air temperatures were warmer than normal over much of the country, and in February the anomaly was of the order of 2 to 3° everywhere. So why were the SSTs around New Zealand so warm in 1998? It is not possible to give a definitive answer, but we do know that the East Australian Current, which is fed from the South Pacific Gyre, a flow that encircles the whole South Pacific, has been transporting more warm tropical water than normal into the Tasman Sea since late 1996. This probably explains why the whole Tasman Sea was anomalously warm in 1998. And the prospects for the 1998/99 summer? Figure 2 shows the mean SST anomalies over a region that includes the Tasman Sea and New Zealand waters as far east as the Chatham Islands. While the very strong positive anomaly that was present in February 1998 decayed rapidly, it has not returned to zero. Instead, it is clear that the region is again warming. This is typical of La Nina conditions, which have always been associated with positive anomalies in the New Zealand region. So it looks as though it is going to be another summer of warm sea temperatures, although they are unlikely to reach the extremes of last February. We may also expect more harmful algal blooms, as in the last La Nina summer of 1995.
Something evil this way comes?
In 1993, when New Zealand Geographic was celebrating five years of publication, the magazine produced a lengthy feature on Pinus radiata, "the prince of pines." Among the many issues covered was a consideration of the pine "monoculture" that makes up most of this country's forestry stands. Critics such as Albany nurseryman Graeme Platt denounced our reliance on a single species as a dangerous practice but, by and large, any perils were played down by the forestry industry. Hadn't pines survived attack by the wood-boring wasp Sirex in 1946, and the pine needle blight Dothistroma pini, which arrived in 1962? Couldn't our new clones of genetically superior trees beat anything else that might be out there? We may yet have the opportunity to find out, for a fresh threat to the pine hegemony has emerged. While it is still distant from these shores—as far as we know—it may prove hard to keep out. What we term sap or resin, the Americans call pitch, and a disease named pitch canker has been known from the south-eastern US since 1946. There the fungus Fusarium subglutinans pini infects several species of pine, including slash and loblolly pines. Infected trees develop lesions on shoots, cones, bark and roots. On shoots and branches, needles beyond the lesion die, and when bark is removed from the canker, the underlying wood is found to be soaked with resin. If a number of branches are infected, much of the crown of the tree may die. Infected cones often abort without maturing. On the trunk of the tree, lesions may reach 30 cm in diameter, and resin may dribble down the bark for a metre, but bole lesions are usually a late stage in the disease. Young trees, up to three or four years old, may get a single infection at soil level which kills the whole tree. Many trees die completely, others linger deformed and debilitated. Seedling mortality is extensive, with root rot and other rather nonspecific symptoms. In the warm, wet south-east (a climate not dissimilar to New Zealand's) the disease is largely spread by rain splattering infectious propagules into the air and the wind ferrying them from tree to tree, but the fungus also seems to require some sort of wound to gain entry into the tree. In 1986, Pinus radiata infected with pitch canker were found in Santa Cruz County, California, about 120 km south of San Francisco. The disease has since spread in coastal California from San Diego to north of San Francisco, and is expected to go further north. San Francisco is at the same latitude as Hamilton. Pinus radiata has turned out to be particularly susceptible to the disease, but 40 other species of pine occurring in California have either been found naturally infected or have been experimentally infected. Some of these species are of European origin, and it is thought that probably no species of pine is immune to the disease. A few Douglas fir have been attacked, although that species is neither generally nor seriously affected. No other species of conifer is affected. In California, the fungus seems to be spread in a different manner from in the south-east. There it has been isolated from a number of insect species which live around and in susceptible trees, including moths, bark beetles, cone and twig beetles, weevils and possibly aphids. Experimental contamination of some of these insects has led to their infecting plants, and insects are now implicated as major vectors in the spread of the disease. When insects burrow into or feed from infected plants they pick up spores, which they then carry to healthy trees and infect as they feed upon them. Seeds from infected trees are also frequently infected, probably reducing rates of regeneration, and there is a suspicion that even pollen could carry the disease. In California, Pinus radiata is not much regarded as a timber species (they say it has too many pests), but it is grown in plantations as a Christmas tree—often from seed purchased from New Zealand—and is widely planted as an amenity tree along highways, in parks and public gardens, etc. Because lesions develop within a month or so of infection, the Christmas-tree business is literally wilting, and the transportation of infected Christmas trees around the state is thought to have contributed to the spread of the disease. Many disfigured and dying amenity trees have been felled, and the State Senate has approved the expenditure of several million dollars to fund research into the disease. There is serious concern that pitch canker will travel inland into the large commercially important pine forests of the Sierra Nevada, although lower temperatures at higher altitudes may impede its spread. In the laboratory, infections have not established at temperatures lower than 10°C, but in summer even the mountains are a lot warmer than this. New Zealand-sourced Pinus radiata have proved just as susceptible to pitch canker as the Californian material, and Fletcher Challenge Forests is now preparing to test the susceptibility of 80 of its New Zealand clones in California. Once a tree is infected, nothing can be done to cure it. Reports from California indicate that no fungicides or insecticides are effective against the disease, and lopping off infected branches is of little value. However—a ray of hope—even in areas where the disease is well established, a few Pinus radiata—less than 5 per cent—seem to be unaffected. Perhaps a small minority of trees are naturally resistant; this is certainly the hope behind the Fletcher Challenge trials. Needless to say, pitch canker could devastate New Zealand's forestry industry, since more than 90 per cent of our forests consist of Pinus radiata, with Douglas fir the second most important species. While we lack the exact insect species that are implicated as vectors in California, the wide range of insects involved there suggests that we would have a good chance of having local equivalents. It is not even certain that insects would be required to spread the disease here, as our wet climate is more akin to the south-eastern US, where insects seem of little importance. Our practice of extensively pruning young trees produces an abundance of major wounds which would provide ideal entry points for this disease. How good are our chances of keeping the fungus at bay? Pine pitch canker has spread in the past decade to South Africa, Japan and Spain, which does not auger well for us, and it also occurs in the Caribbean. For several years we have had restrictions on imports of conifer seeds from the US, and our port and airport interception services are vigilant. But fungal propagules are invisible and long-lived, and our success at intercepting even insect pests has been limited. A succession of serious insect pests on eucalypts have established here in recent years, and tussock moth and Mediterranean fruit fly were eliminated only with great effort, and only after getting through the net. Recently, examples of Monterey pine aphid (Monterey pine is what Americans call radiata) were found at Sydney airport on a shipment of avocados from New Zealand. This pest was not known from New Zealand, but a search of pines around the orchard the avocado came from yielded many aphids. This pest has now been found in pine forests throughout the North Island, and we didn't even know it had arrived! It could possibly serve as a vector for the canker fungus. Another possible avenue for the disease to reach here is via soil—an unnoticed passenger on many a campervan, tent, item of used logging equipment or simply on a car. Most used camping gear brought into the country has been found to have plant debris and probably soil adhering to it. Used logging equipment has been imported from the US in recent years. And remember that Japan, source of more than a few used cars, has this pest now. Wood can also carry the disease, and although we import no pine from the US, there is at least a possibility that lumber from some of the dying trees in California might be used in packing crates and the like. Infected beetles could also arrive here in the wood of packing cases. Early symptoms of the disease are not especially distinctive, and in California it is thought that the canker may have been present in some areas of spread for a couple of years before it was spotted. By then it was well established and impossible to stop. A group from the New Zealand Farm Forestry Association recently visited North America and described stands of Pinus radiata infected with pitch canker as looking like Chernobyl. Some of the party were so afraid of bringing the disease back to New Zealand that they left their boots in California. How many tourists would be prepared to follow their example?
Vitam impendere vero
I came across this Latin phrase in 1995, when the magazine was preparing to publish a story on the life of William Herbert GuthrieSmith—Hawkes Bay sheep farmer, naturalist, writer of the acclaimed Tutira, voice for the land. The words were part of a coat of arms imprinted on a piece of Guthrie-Smith's crockery. They mean "To spend one's life for truth," or "A life devoted to truth." I found the motto inspiring then, and I do now. Considered along with the photographs we published—of Guthrie-Smith writing up field notes in a but on some offshore island, of G.-S. regarding a native pigeon with affection and solicitude—the words speak of a man for whom knowledge was a lifelong journey. And such is the journey of New Zealand Geographic. We have chosen to celebrate our 10th anniversary year with the words "A decade of discovery." We use "discovery" in a broad sense. We are not often in a position to announce great scientific revelations in our pages; our discoveries are often more akin to those T S. Eliot alluded to in his lines: "We shall not cease from exploration And the end of all our exploring Will be to arrive where we started And know the place for the first time." It is these personal moments of discovery—what someone has called the "Aha!" factor—that New Zealand Geographic seeks to provide. Discovery in our pages may take the form of looking at the familiar but seeing it in a fresh way. Or it may mean finding out about a fragment of history and watching it click into place with other pieces like a jigsaw. It may take the form of armchair travel with a writer and photographer whose skills are the loom on which our own impressions are woven. When I explain to people that New Zealand Geographic is a "knowledge publication" I sometimes feel the need to jazz up the comment with examples of particularly heroic exploration or daring adventure. I shouldn't feel so constrained. The "increase and diffusion of knowledge" is a goal our magazine shares with such august bodies as the Smithsonian Institution and the National Geographic Society. It's just that knowledge doesn't seem like much of a reward these days, when "info" usually has to have "tainment" after it to be deemed palatable. Yet for those who choose to "spend their life for truth," the acquisition of knowledge is every bit as exhilarating as scaling a peak or winning a lottery. "The person who collects knowledge will seldom be downhearted and never be bored," was the recent comment of a woman who had amassed a huge collection of American folk art. It seemed to me a very Guthrie-Smith thing to say. And, I'd like to think, a very New Zealand Geographic sort of statement, too. You are holding the first issue of the magazine to exceed 128 pages. Think of the extra pages as our "thank you" for your support. To those who have been with the Geographic for a while (how gratifying it is to pick up the telephone and hear a person announce themselves as a "proud member since the first issue"), we salute you. For those who are new to the magazine, welcome to the journey and to the quest for vitam impendere vero.
Trending
His excellency
Wildfire
A place to stand
Fungi of Aotearoa: A curious forager’s field guide
A dissection
Lego man overboard
A custom-built life
Rock hounds
Beyond the Bermuda Triangle: The Devil’s Sea
K' Road
Archive
Timeless huts, priceless heritage
The explorers who set out to conquer Antarctica at the beginning of this century didn't know that it was the highest, coldest, driest and windiest continent on Earth—just that it was the last great frontier, and likely to test the mettle of any man courageous (or foolhardy) enough to venture upon its icy domain. When horses and dogs died and machinery froze up, or the ice just got too rough, men settled into the traces—as here, during Scott's push for the Pole. Bare wooden huts, shuttered and wired to the ground, were their havens from the unforgiving elements. Today the three that were erected on Ross Island offer mute testimony to this age of heroism.
Ten years of change
From a meteorologist's point of view, the most significant change in the past 10 years has undoubtedly been the way technology has increased the amount of data available for describing the state of the atmosphere, with a corresponding increase in our power to predict what the weather will do next. Weather satellites now transmit images not only of clouds but also of high-level water vapour, highlighting areas where cloud has not yet formed but is likely to do so. Calculations of high-level wind speeds are made on the basis of cloud displacements from one photo to the next, and these are routinely fed into computers which calculate the future state of the atmosphere. Satellite instruments can also measure air temperature at different altitudes in the atmosphere over the vast areas of ocean that surround New Zealand, from which we have traditionally received only a handful of weather-balloon measurements of the upper atmosphere. Satellites can also measure surface wind speeds over the ocean by transmitting pulses of microwave energy down to the sea surface and measuring the amount of that energy that is scattered back up to them. The stronger the wind, the rougher the sea surface and the greater the amount of microwave energy returned this development has proved useful in mapping some of the narrow, elongated rivers of strong wind that develop in New Zealand's coastal waters near the ends of our mountain ranges. Although the automation of lighthouses in the 1980s meant a loss of human observation from these remote sites, this has mostly been compensated for by automatic weather stations that report every hour, day and night. These stations are particularly useful for keeping track of rainfall and following wind changes as they sweep across the country. However, they are unable to describe sea conditions or weather in the distance in the way a human observer can. The lack of surface observations over the Great Southern Ocean has always been a problem for forecasters trying to create a picture of the weather approaching New Zealand. Now there is an international programme to release drifting buoys that report via satellite every few hours, providing measurements of surface pressure from areas where there may be no other surface observation for thousands of kilometres. Weather-radar coverage of New Zealand has increased, too, and radar itself has become sufficiently sophisticated to measure the movement of raindrops within a storm and so determine its characteristic wind patterns. And, of course, computers have steadily grown more powerful, and are capable of handling more sophisticated models of the atmosphere, describing it in greater detail and predicting changes in it further into the future. The result of all these developments is more accurate forecasts several days in advance. The past decade has also seen progress made in seasonal forecasting. In particular, we have a much improved understanding of the phenomenon known as El Nino. Detailed measurements are now taken of ocean temperatures and currents, both at the sea surface and below, by dozens of tethered buoys spread across the tropical Pacific Ocean. Fed into sophisticated computer models, these helped to predict the dramatic El Nino event of last summer many months before it happened. Our knowledge of climate change has also advanced, and especially the impact of climate change on history. A core taken recently from the floor of the Gulf of Oman was found to contain a thick layer of dust, indicative of drought, that has been dated to around 2200 BC. This was the time of the collapse of the Akkadian Empire in Mesopotamia, which stretched 1300 km from the Persian Gulf to the headwaters of the Euphrates in present-day Turkey and is regarded as the world's first empire. Isotope analysis of radioactive strontium and neodymium in the dust layer showed that much of the dust came from Mesopotamia, blown 2000 km down the valley of the Tigris and Euphrates Rivers to the gulf by the north‑west wind known today as the Shamal. Analysis of the rest of the core indicated that this drought lasted almost 300 years and was the most severe of the past 10,000 years. Evidence that this drought may have been a worldwide event has come from investigations in the United States and Peru. A dust layer dated to the same period has been found at the bottom of Elk Lake in Minnesota. Three times as much dust settled in the lake each year during the 100 years of the drought there as in each year of the infamous Dust Bowl period in the 1930s. In Peru, an ice core from a mountain glacier contains a dust spike indicative of a major drought in the Amazon basin about 2200 BC that appears to be the largest such event of the past 17,000 years. Dust may not only be a consequence of climate change, it may also be a cause. A sea-floor core from the Atlantic has shown peaks in the concentration of helium 3, a marker for the interplanetary dust that swirls around the solar system. These peaks tend to occur every 100,000 years and correspond with the major fluctuations of temperature during the last million years of the Ice Age. It is thought that increased amounts of extraterrestrial dust in the upper atmosphere blocked a proportion of the incoming sunlight, thus reducing air temperatures in the lower atmosphere. Some scientists, however, have argued that the amounts of dust concerned are too small to have had a significant effect, and claim that the coincidence with the 100,000-year cycle of lower temperatures is the result of regular small variations in the Earth's orbit. Interplanetary dust particles can also be used to measure the amount of oxygen in the atmosphere more than a billion years ago. As such particles enter the atmosphere at tens of kilometres per second, friction causes most to vaporise. But a few flash-melt at temperatures above 1500°C, interact with gases in the atmosphere in the few seconds they are molten, then solidify and fall to Earth. With present levels of atmospheric oxygen, the iron and nickel in these particles—known as spherulesare totally oxidised, forming the oxides magnetite and wustite. In earlier times, when atmospheric oxygen was less abundant, only a portion of the iron and nickel was oxidised, so giving a measure of just how much oxygen there was. Although spherules are usually badly affected by chemical weathering, some excellently preserved samples have been found in sandstone deposits in Finland formed 1.4 billion years ago. On average about 40,000 tonnes of interplanetary dust hits the Earth each year, but the amount can increase when the planet travels through the orbit of a comet. When it passed through the orbit of Tempel-Tuttle in November 1998, there was a spectacular sky display in Asia, although not much could be seen from New Zealand. When the same thing happened in 1966, the United States got the best view, with 5000 shooting stars in a period of 20 minutes. Astronomers have calculated that these displays would have been even more dramatic around 4000 years ago, and perhaps left their mark on early religions, many of which relate battles between sky gods. A folk memory of these events survives in the fire festivals many cultures still celebrate on the dates when the Earth encounters high dust levels in the orbits of a number of major comets. Guy Fawkes Day is one example, the origins of which long predate the attempt by Catholic dissidents to blow up the English Parliament. Equally intriguing is new evidence from Namibia supporting the theory that the Earth was like a giant snowball about 700 million years ago, with sea ice or glaciers stretching from pole to pole. Part of the evidence for this is a big shift in the relative proportions of two isotopes of carbon found in sea-floor sediments. Photosynthetic organisms living in the seas before the glaciers developed took up carbon-12 from the water as they grew. This caused the ratio of carbon-13 to carbon-12 in the sea water to increase. On the other hand, precipitation of dissolved carbonate onto the sea floor takes place in equal proportion, thereby preserving the ratio of the carbon isotopes so it can be measured today. This ratio shows a steady decline as the glaciers are thought to have grown, indicating life in the sea was gradually being snuffed out as the ice spread across the oceans, cutting off the supply of sunlight to the organisms. Once formed, the Earth's icy coating kept it cold by reflecting most incoming sunlight back out to space. This ice age is estimated to have lasted around 10 million years, until volcanic carbon dioxide, gradually oozing from inside the Earth, created a strong greenhouse effect that eventually broke the ice's stranglehold. The atmospheric carbon dioxide level is calculated to have been 350 times as high as today's, causing a characteristic cap layer of carbonate to be deposited on the sea floor. As the ice retreated, life slowly returned to the oceans and the ratio of carbon-13 to carbon-12 gradually rose again. We live in changing times, no doubt, but the record contained in the Earth's ancient rocks shows it went through some pretty big changes long before we arrived on the scene.
High over New Zealand
"What one can see from above, one can't see from below."
The long pathway
I patted a Buttress on that stout little tub of concrete, the Cape Reinga lighthouse, and moved off. It was just coming on light—time to go. Miriam and I walked up the hill to the collection of huts at the top. We stopped at the beginning of the trail that leads away behind the loos, the post office and the generator hut. The sign said:
Harold Wellman and the Alpine Fault
Drenching rain, lush forests, rivers that regularly inundate the land, even sandflies and that fierce human independence bred by isolation—all that is the West Coast can be traced ultimately to the towering presence of the Southern Alps. Yet from a geological perspective these mountains are mere outward symptoms of greater things happening beneath the ground, where two of the world's tectonic plates collide along one of Earth's greatest fault lines, dubbed the Alpine Fault. Geologists Harold Wellman was the first to recognise this vast structure, a discovery that helped revolutionise the way we see the Earth.
Takahe - the bird that came back from the dead
When Dr Walter Mantell formally described a large, attractively-plumaged new species of rail in 1851 from only the second specimen captured, he wrote: "It is unlikely that any further living specimens will be found." Indeed, only two further individuals were taken last century, and the bird was officially considered extinct for 50 years—until an Invercargill GP filmed birds in Fiordland in 1948. Yet despite 50 years of careful management since, the species is probably scarcer now than when it was rediscovered.
