Californian wine grapes under climate threat

A recent report showed how California is becoming increasingly drier and hotter, and unless more is done to cut greenhouse gas emissions, heat waves will become more intense and crop irrigation will be disrupted.

Dr Chris Field, director of the Carnegie Institution’s Department of Global Ecology and lead author of the study, told edie that, if the current climate model continues, California’s grape production will come under serious threat.

“The quality of wine grapes tends to drop quite rapidly in warm climates, and the main concern is that warming will convert regions that currently produce high-quality grapes into low-quality producers,” Dr Field said. “Our data indicates that warming over the next few decades may be enough for this to occur, especially if it is driven by a high-emissions trajectory.”

The highest emissions forecast shows that carbon emissions would quadruple by the end of the century to around 28 billion tonnes. Under the lowest emissions forecast, they would simply stay at current levels of around seven billion tonnes.

Even in the best scenario heat waves in the region will increase in frequency and extremity by around four times, and mortality from heat exposure would double or triple. It will also lead to less high-quality grapes being produced, causing some damage to the US$3.2 billion industry.

Over the past 40 years, average temperatures have already increased in California by around 1 degree Celsius, according to Dr Field. Scientists have already warned that a constant global temperature increase of around 2 degrees Celsius could cause problems of catastrophic proportions (see related story).

Deductions by the team of interdisciplinary scientists that took part in the study showed that climate change in California and the severity of its impacts, including that on the wine industry, strongly depended on the levels of emissions from heat-trapping gases.

“We truly have a choice,” concluded Dr Field. “But I believe that a combination of aggressive investments in new energy technologies, investments in carbon sequestration and a person by person re-thinking of patterns of consumption can lead to a low emissions future that includes both a vibrant world economy and a sound environment.”

By Jane Kettle