Winemakers must prepare for temperature extremes

Rates of climate change may have slowed, but winemakers must prepare themselves for increased warming and greater extremes, warned viticultural research climatologist, Professor Gregory Jones.

Jones, who holds the position of research climatologist in the Department of Environmental Studies at Southern Oregon University, specialises in the study of the influence of climate variability and change on grapevine growth, wine production and quality.

Speaking at May’s Masters of Wine symposium, which welcomed 450 wine professionals to Florence, he remarked that “much has been said about the slowdown in warming,” while admitting that “it’s true, we thought there would be a greater rate of change this decade.”

However, he said that the wine world should expect the rate of change to accelerate in the future.

“It has been shown that the Pacific Ocean is absorbing much of the warmth to a great depth, and once it has done doing that, temperatures could shoot up.”

He also recorded, “Globally, 2013 was the fourth warmest year since records began in 1880 and only one year in the twentieth century, 1998, was warmer than 2013.” Then he stated, “All 13 years in the 21^st century rank among the 14 warmest.”

Considering his home country in particular, he added, “The USA in the last five years has seen more records in climate extremes that it has seen in the last 25 years.”

Speaking about the nature of climate change, he said that there has been “little cold season warming” but “significant warm season warming with greater extremes”.

He observed that no part of the wine growing world has seen growing seasons shorten, and while he said that shorter, warmer dormant periods have led to reduced freeze and frost damage, it has also meant that vines are losing their resistance to temperatures below 0 degrees Celsius.

“The vines gets used to it, so when frost does happen, it’s more problematic,” he explained.

He also stated that with every 1 degrees Celsius warming, plants respond 5-10 days earlier.

According to Jones, other implications from climate change on viticulture include a heightened disease threat, as well a change in the timing and severity of pests, drier and more saline soils, as well as greater rates of soil erosion from heavy rain events.

When responding to such developments, Jones said that the vine has a “large genetic potential for adaption”, but also said that producers can alter training systems, optimise canopy geometry, use shading materials, as well as change the scion-rootstock combination.

He said that an additional threat to viticulture will be warming soil temperatures, which follow the rise in air temperatures, while asking, “Do we know enough about the upper temperature limit for varieties?”

Remarking that “the issue of climate change is so difficult because it is slow and kind of fuzzy,” he added that this gives wine producers “time to adapt”.

Nevertheless, he said that measures for reducing the impact of climate change on wine production must be developed immediately.

“Research, innovation and technology must be employed to minismize vulnerability,” he stated.