It took just under a month for 2011 to make the weather records, when, on 29 January, Cyclone Wilma brushed the North Island's east coast. Wilma drenched some regions with 400 per cent of their normal January rainfall, leaving a $24m cleanup bill behind.
Then, May wrote itself into the New Zealand record books as the warmest ever – a whopping 2.2ºC above average – but it wasn't all benign. Early that month, a tornado in Auckland killed construction worker Benedict Dacayan and flung cars into the air. Whakatane residents were later hit with 2.5 times their normal May rainfall, while Nelson homes were evacuated in the face of a deluge 3.5 times the region's monthly average.
In late April, warm, wet air was hemmed in by a blocking high off the Hawke's Bay coast on Anzac Day, and it wreaked havoc. Farmers lost hundreds of hectares of grazing as hills slipped into the creeks. Residents watched rivers of mud and backed-up sewage flow through their homes, leaving despair and $10m dollars' worth of damage.
In June, some Queens Birthday holidaymakers basked in another 21ºC record, but later that month, another deluge – this time at Ohope – took the life of teenager Hughie Biddle when a hillside behind his house collapsed. The next day, tornadoes struck again. This time, a swarm wreaked havoc in North Taranaki, hurling roofs into the air in New Plymouth.
Then, in August, the unthinkable: flakes of snow – more correctly, graupel – fell in Auckland, while heavy dumps closed businesses and paralysed traffic further south. It snowed at sea level in Wellington for the first time in 40 years.
2011 has so far been a big-ticket exercise; the Insurance Council of New Zealand says bad weather provisionally cost around $41.7m in claims in the first six months alone.
When people think of climate change, they often assume it simply means a warmer future, but warm air holds more moisture, carries more energy, than cool. That means we can expect more than just spikes in the mercury. As you'll read in this issue, Nature will deliver the weather with less routine and more force in future, and that has implications for us all.
New Zealand's average air temperature has warmed by around one degree Celsius over the last century, but we can't blame everything on climate change. It's not easy to unpick the tangle of influences – La Niña, El Niño, the IPO – that together decide our weather.
For Diane Tait, it hardly matters. She carried her two grandchildren through waist deep waters before a torrent of mud swept through their Waimarama home on Anzac night. She feared for her life that night, and all she knows is that life will be very different from now on. While some argue about the cause – even the very legitimacy – of climate change, as we seek to shift blame or responsibility, evade the costs or simply shoot the messenger – the weather keeps on coming.
We know that there is now more CO2 in the atmosphere than at any time in the last 420,000 years. It's a matter of record that 20 of the warmest known years globally happened in the last 25 years. Each of the past three decades has been warmer than the one before, and each closed by setting a record. The 2000s is the warmest decade yet, but as May pointed out, the trend may not stop there.
Di Tait's grandchildren will not thank us for prevaricating. They may well remember us as the generation that knew climate change was happening, that had the information, the opportunity and the technology to act, but did not. The compound interest on our deferred action will be theirs to pay, and Christiana Figueres, Executive Secretary of the UN Framework Convention on Climate Change, claimed early in June that every year of delay adds another trillion US dollars to the bill we leave behind.
Builder, banker or bus driver, a more volatile climate will affect us all: our economy, our society, our environment. As NIWA climate scientist Anthony Clark says in these pages: "normal is changing".
In this issue of Water & Atmosphere, you'll meet some of the people for whom New Zealand is already a different place. NIWA will continue to play its part, informing our collective response with the best of evidence-based environmental science.
John Morgan
Chief Executive, NIWA
