'Spectacular' insights into past climate change from Timaru's Dashing Rocks
Timaru's Dashing Rocks area offers a spectacular storybook into the recent past climate history and should be treasured according to a paleo climate expert. Dr Peter Almond, a soil and physical sciences associate professor at Lincoln University, told Stuff that former Timaru Herald editor (1908-1910), and geologist John Hardcastle did pioneering work on loess (sediment) layers at Dashing Rocks which reveal past climate changes. Loess may comprise dust through wind; and particles of fossils, shells, pollen, grains and seeds that has accumulated over time through wind which enable scientists to piece together past climate changes. Almond, who researches the earth surface processes, biogeochemistry, natural hazards and paleoclimate, was in Timaru for an Insights into Climate Change from Loess presentation at an event organised by the Canterbury branch of the Royal Society of New Zealand and South Canterbury Museum. READ MORE: * How wind changes around Zealandia may have 'far-reaching consequences for global climate' * Doug Edmeades: No need for methane in the ETS * Tom O'Connor: There is no escaping climate change He said Hardcastle came across a concentration of crop stones at the top of the loess which moa had engorged adding great historical value to his research. Dashing Rocks is a spectacular storybook into the recent past climate history and should be treasured, as well as the field grounds. Hardcastle did globally important work. The last glacial maximum was 20,000 years ago when South Canterbury and the rest of New Zealand would have been mostly tussock and shrubs with very little forest remnants. The mean temperature would have been about 5 or 6 degrees Celsius lower than it is now, Almond said. Which means if Timarus mean temperature is now 11 degrees then it would have gone down to about minus 10 degrees then. He said plants have a threshold for survival depending on the number of hours they were in certain temperatures which could affect their growth and reproduction. As temperatures warmed forests grew again. Almonds interest in soil was piqued when he was working on a dairy farm during the holidays in his home town of Whanganui while studying his favourite topics physics, chemistry and mathematics at Massey University but unsure what career direction he was heading in. A man who represented a fertiliser company visited the farm and dug a few holes and talked about the loam and crumb structure and how important it was for soil nutrition and animal health and I thought I need to know more about this ... so picked up studying earth and soil science. He went on to gain a PhD and later work with international paleoclimate scientists on the Australasian Integration of Ice-core, Marine and Terrestrial Records (Intimate) project trying to understand the climate history of New Zealand in detail over the last 30 years. That was a highlight. When it comes to global warming Almond said in the past volcanoes have caused high CO2 levels and there is also methane on the ocean floor from decaying algae under sediment which affects temperatures. But looking at the broad pattern he is in no doubt greenhouse gases and the increase in CO2 concentration is from human activity. In the last two million years the amount of CO2 varied between 180 parts (air) per million and 280 parts per million now it is at 417 parts per million. To predict what will happen to ice sheets in the future we have to go further back in time to 3 million or 15 million to find a time when CO2 levels were at the same level. Almond said globally the climate is strongly dependent on the Southern Hemispheres westerly winds. Because most of the heat in the planet is in the oceans, shifting winds can reconfigure and influence ocean circulation creating the heat differences. In the glacial period 20,000 years ago, the westerly winds were further north, at lower latitudes than now, bringing with them sub Antarctic water. Southern westerly winds are contracting towards Antarctica and bring warm tropical oceans to extend further into the Southern Hemisphere and oddly enough into the Northern Hemisphere. The rate of CO2 increase is slowing but not decreasing. We are still putting more C02 into the atmosphere than we are taking out. During the Covid-19 lockdowns there was about an 8 per cent decrease in the amount of CO2, due to fewer flights and less use of fossil fuels through lack of traffic and industry. Globally we need to eat less meat, waste less food, preserve carbon sinks like the Amazon and change hydrology (study of management, movement and distribution of water). Almond believes there is hope for humankind and the planet if every individual and nation gets serious about making changes.