Climate change brings more spring frosts
A common theme of climate change is the greater number of spring frosts, challenging growers in both the northern and southern hemispheres. Whilst average temperatures are rising, there are greater extremes in terms of hot and cold events.
Winegrowers in some regions are reporting a turbulent start to the new grape growing season, with frost-fighting efforts already well up on last year.
In an MPI Technical Paper by Prof Andrew Sturman et al the authors conclude, “it is evident from analysis of observed temperature trends in New Zealand vineyard regions since 1940 that there are significant regional differences, with Marlborough showing virtually no warming trend in mean annual temperatures, but instead a trend of increasing daily temperature range and frost occurrence over recent decades.”
Over the past year, Master of Environmental Studies student Alyssa Ryan asked more than 500 wineries about their climate change beliefs, knowledge and information sources, and their plans to adapt to climate change. She then conducted more in-depth interviews with some of them.
The wineries she interviewed reported an increase in frost and wind, as well as a lack of water. However, many wineries have no plans to adapt to climate change, citing a lack of data and budget constraints.
Ryan’s goal is to make sure New Zealand wineries have access to this data. She will be making her Master’s research available to the wineries that took part and hopes to continue on to a PhD where she can complete some specific regional climate modeling for the industry.
Stu Powell from Climate Consulting regularly provides advice and wind machine placement for large growers in New Zealand and Australia. Decisions concerning frost protection can be made scientifically. The expansion of orchards and vineyards into increasingly challenging environments places a greater emphasis on quantifying risk before you develop and ensuring frost mitigation is positioned correctly and is reliable.
Climate Consulting has been delivering site-specific detailed reports to clients in New Zealand and Australia for over 18 years. Stu insists that implementing the most effective method of frost protection together with correct placement saves clients substantial money and anxiety.
Early last year, New Zealand Frost Fans launched an online tool which allows growers to run their own numbers to calculate the Return on Investment from installing frost fan/s.
The Bureau of Meteorology in Australia has released the first 20 Regional Weather and Climate Guides, which will give growers the best possible guide in terms of climate risk and opportunities. This includes frost risk as well as rainfall and temperature trends.
The reports show that in the last 30 years, spring frosts have been more common and occurring later in the NSW Murray and Riverina regions as well as the Victorian Mallee region. Inland parts of south-east South Australia have also experienced more frosts.
More frosty nights tend to occur through dry winter and spring periods when soil moisture is low and cloud cover infrequent.
Researcher Patrick Fresne recently published an article on climate change and its effects on the Australian almond growing industry. He observes that despite the warming trend, the minimum temperatures recorded in Riverina weather stations for the month of August seems to be falling ever lower with the passing of the years. In both 2017 and 2018, unusually cold late August conditions resulted in significant damage to the crop of many almond growers around Griffith and Hillston.
In a paper published by CSIRO – “Recent changes in southern Australian frost occurrence: implications for wheat production risk” – the researchers’ analysis uses Stevenson screen temperature thresholds of 28ºC or below as an indicator of frost at ground level; this demonstrates that across southern Australia, despite a warming trend of 0.178ºC per decade since 1960, ‘frost season’ length has increased, on average, by 26 days across the whole southern portion of Australia compared with the 1960–1990 long-term mean. Some areas of south-eastern Australia now experience their last frost an average 4 weeks later than during the 1960s.
Analysis of the observed minimum temperature record has revealed that over the last six decades, the frequency of minimum temperature events below 2ºC has increased and the period between the first and last minimum temperature at or below 2ºC has broadened.
Another paper – “An investigation of some unexpected frost day increases in southern Australia” – concludes “frost days have increased in May in south-eastern Australia as well as in spring in some locations over the period from 1980 to 2011. The south-eastern Australian frost increases are strongly linked to a decrease in the number of wet days in the area. These results confirm that the recent drying trend in south-eastern Australia has resulted in more frequent very cold nights and more frost days. In south-west Western Australia, frost days have increased in late winter and spring.
In the northern hemisphere, global warming has cost the Champagne region over 10% of its potential harvest this year. Whilst the principal damage was caused by a heatwave in June and July, the Champagne Bureau reported “periods of frost in spring did destroy a proportion of buds.”
Loncel frost fan monitoring
As a sister business to New Zealand Frost Fans and Australian Frost Fans, Loncel is the market leader in frost fan monitoring across Australia and New Zealand. By far the majority of frost fans installed by New Zealand Frost Fans and Australian Frost Fans are specified with Loncel’s monitoring option. Using any internet-connected device, growers can access real-time data from their fans, together with text alarms and historical data and graphs on temperature, run-hours and machine performance.
Loncel is continually improving its monitoring software and has recently added a regional reporting tool. Powerful insights are now available at a regional, site-specific and individual machine level. The tool allows users to see historical and real-time data on the number of fans running, the duration of frost events and tower and canopy temperatures (temperature inversion).
Regional data is not only useful for existing users but also for growers looking at acquiring land for development. By talking to [New Zealand Frost Fans/Australian Frost Fans] as early as possible, they can provide insights into the number of frost events and the requirement for frost protection. In addition to assisting with due diligence, they can help with suggested fan layouts and consent applications (if required) through to after-sales service.
For more information visit:
www.nzfrostfans.com – supply and installation of FrostBoss frost fans and monitoring hardware in New Zealand.
www.aussiefrostfans.com - supply and installation of FrostBoss frost fans and monitoring hardware in Australia.
www.loncel.com - frost fan monitoring
Links and references