On Sunday the temperature at Penrith hit 47.3 degrees Celsius, making it the hottest place on Earth during that 24-hour period. Meanwhile, on the other side of the world, extreme cold and snow penetrated deep into the south-east United States. In normally sub-tropical Florida, frozen iguanas were falling out of trees from the extreme cold. "Give us a bit of that 'global warming'," President Trump thundered sarcastically.
Terms like "global warming" and the mental images they trigger can be misleading when people attempt to understand what is happening to the climate. A far better term is "climate disruption", which captures the real nature of the vast array of changes, many of them abrupt and unexpected, that are occurring.
In New Hampshire, boiling water turns to snow
Weather observers atop the Northeast's highest peak say the temperature has hit a record negative 34 degrees. Adam Gill of the Mount Washington Observatory in New Hampshire says the previous record of negative 31 degrees was set in 1933.
"Climate disruption" was often used by Professor John Holdren, science adviser to former US president Barack Obama, to emphasise that a 1 or 2 degree increase in global average temperature does not simply translate into modest, uniform warming but rather triggers surprisingly sharp changes in extreme weather and disrupts longer-term weather and climate patterns.
The world's ecosystems and critical human systems, such as agriculture, are adapted to the relatively stable climatic conditions of the past 12,000 years. These include not only temperature, but also the circulation patterns of the atmosphere and the oceans that move heat and moisture around the planet and deliver the seasonal and geographical patterns of rainfall, heat and storms that we consider normal. These normal patterns are increasingly being disrupted by what is often termed "climate change".
The climate disruption we are increasingly experiencing is not natural. It is caused by the heat-trapping gases we humans are pouring into the atmosphere primarily by the burning of coal, oil and gas.
This enormous increase in energy in the atmosphere is disrupting normal circulation patterns. In the northern hemisphere, the exceptional heating around the north pole – twice the global average – is breaking down circumpolar air flows that normally keep the cold air around the north pole and more temperate air to the south. Now icy polar air is penetrating as far south as Florida while balmy conditions linger north of Finland.
Southern hemisphere circulation is also being disrupted, although not so dramatically yet. The cool-season frontal systems that normally bring rain to southern Australia are slipping southwards, leading to long-term drying trends in both the south-west and south-east of the country.
Many animals and natural ecosystems are being hammered by climate disruption. Florida's iguanas are not the only creatures dropping dead from trees. In Western Australia over 200 endangered Carnaby's black cockatoos were killed by extreme heat in 2010. More than 45,000 flying foxes were killed on one unusually hot day in south-east Queensland in 2014.
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An iguana that froze lies near a pool after falling from a tree in Boca Raton, Florida, on Thursday. Photo: Frank Cerabino
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Human systems are also at risk. The world's major agricultural zones have been developed around areas of good soils and predictable, stable climate patterns. These patterns are shifting as we continue to pour greenhouse gases into the atmosphere. The north-east China food bowl is experiencing long-term drying while more erratic heat, rainfall/drought and storm patterns hit the central US.
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| A man cools off in the Nepean River in Penrith on Sunday. Photo: Brook Mitchell |
Climate disruption brings growing risks of large-scale migration and conflict as people, particularly the most vulnerable, are forced to deal with increasingly difficult conditions where they live. Some security analysts warn that climate disruption will dwarf terrorism and other conventional threats if present trends continue or worsen.
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| Fans were left high, dry and hot at the Sydney International as organisers ordered players off the court due to extreme heat. Photo: AAP |
*Will Steffen is a Climate Council of Australia councillor.
Links
- Will Steffen
- Climate Council
- Records topple in 2017 heat
- Southern Storms: Climate change and extreme weather events
- Critical Decade 2017: Accelerating Climate Action
- Making sense of the Australian government’s data dump: Carbon pollution and climate review
- Earlier, More Frequent, More Dangerous: Bushfires in NSW
- Sydney was the hottest place on Earth on Sunday
- SCG Sunday roast: Blistering heat tests players and 33,285 fans
- Not a record, but mighty hot: Sydney weather reaches 47 degrees
- How hot was your suburb? Sydney's scorching Sunday
- Australia Swelters Through Third Warmest Year On Record
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