The Climate Chap: Understanding our Ice Age

THE CLIMATE CHAP

27 Feb, 2023

We take ice for granted, after all it’s only frozen water. Chances are that you frequently make and store ice in your own fridge and use it liberally in your drinks and applied to black eyes and strained calf muscles from time to time.

Need it in volume? Then almost every dairy, gas station and bottle shop will sell you bags, and we have a wonderful local business making and delivering the stuff.

Back in New York before everyone had a fridge, ice-men would deliver huge slabs of ice to your home to refrigerate food during the summer months and then switch to delivering firewood in the winter.

Ice also facilitates sports, be it ice skating, skiing, curling or ice hockey.

Geographically ice covers some of the largest land masses on the planet, especially Antarctica and Greenland (not named after me!) and also form glaciers in many of the world’s mountainous regions, including our wonderful Southern Alps. Glaciers are defined as moving bodies of snow and ice that are larger than 25 acres. Indeed Fox, Franz Joseph, and Murchison Glaciers are spectacular and form the basis of a valuable tourism industry.

However, the National Institute of Water and Atmospheric Research (NIWA) estimates that over the past 45 years more than a third of the ice volume has been lost from the Southern Alps, and potentially many of our glaciers could disappear in the next decade.

Why are glaciers so important? Naturally for tourism, but more important as a vital store of fresh water with their seasonal melt into rivers supporting irrigation of farmland and hydropower schemes, and acting as a buffer against drought.

Whether in your G&T or in the Southern Alps, ice melts, and with global warming the melting is accelerating. Recently this has caused major flooding in highly populated regions with glaciers melting in the Himalayas.

Ironically Glacier National Park in Trumpland might soon be in need of a more relevant name. The park, which was once home to 37 of the 39 named glaciers in Montana, could run out of glaciers within the next few decades. Since 1966, 11 have vanished completely, while those that remain have shrunk by as much as 85 per cent due to global warming. In the late 19th century, 150 glaciers covered the region.

So how does this impact Mangawhai? On the one hand not at all. We have no glaciers and would need to visit Ruapehu to see one. However, as snow and ice continue to melt there is a direct relationship between global warming and the rise in sea levels and quality of the water.

I am certainly not a scientist, but our marine life is already being negatively affected by warmer seas, and therefore the potential of fishing along coastal Mangawhai being restricted by the reduced availability of fish and increased legislation to establish more zones where fishing may be banned or restricted.

Much has been written about the potential rise in sea levels and the resulting impact on coastal communities. Climate change is one of the main causes of sea level rise.
Our greenhouse emissions warm the atmosphere. More than 90 per cent of this heat is then absorbed by the ocean. As seawater warms it expands. Because of the overall warming of the climate, ice sheets and glaciers are now melting into the ocean. The expansion of water and the melting of land-based ice cause sea levels to rise.

In just 25 years Aotearoa’s mean sea level has risen by more than 7 centimetres, around 3 inches. This is almost half of the total sea level rise since the start of the 20th century. At the same time our coastal land is sinking therefore increasing the perceived rise in sea levels. Add the occasional king tide and low-lying neighbourhoods may experience increasing floods, but hard to imagine sea water rising to levels where evacuation or relocation of coastal properties is deemed vital.

But what if – courtesy of climate change – all the ice melted away? There is still some uncertainty about the full volume of glaciers and ice caps on earth, but if all of them were to melt, global sea level would rise approximately 70 meters, flooding every coastal community on the planet. Not great news for our Polynesian neighbours!

NIWA estimates that over the past 45 years, more than a third of the ice volume has been lost from the Southern Alps, and potentially many of our glaciers could disappear in the next decade. PHOTO/WIKIPEDIA