The state of the climate

Abstract

Context and purpose of the study – The climate has warmed over the past century or more bringing about changes in numerous aspects in both earth and human systems. One of these systems, agriculture, is strongly influenced by climate, which largely determines what type, where, and how crops can be grown. Within agriculture, growing grapes and wine production are a sensitive long‐lived specialty crop system where the environmental and economic sustainability of quality production is at risk from a changing climate. As such, this work examines the current state of the climate globally and within wine regions to provide a framework for these changes historically and into the future.

Material and methods – Summaries of global observations and climate model projections are utilized to provide a current state of the climate. Spatial climate data for 22 prominent wine regions worldwide are also used to assess characteristics and trends in annual and growing season temperature and precipitation.

Results – Growing season temperatures across the 22 regions for 1901‐2017 averaged 16.6°C, ranging from 13‐ 15°C in the cooler regions to 19‐21°C in the warmest regions. Over all 22 regions, the average decadal temperature trend during the growing season is 0.12°C while the average change over the entire time‐ period is 1.4°C. While some regions show higher interannual variability and more gradual warming trends, many regions show stronger trends and more rapid warming. Annual temperature changes closely mirror those during the growing season (not shown). For precipitation, the results detail a wide range in year‐to‐year variability in precipitation, with some regions experiencing consistent annual and growing season precipitation amounts while others are much more prone to extreme dry periods. The average percentage of growing season to annual precipitation across these regions is 45%, with those regions lower than average being predominately west coast regions and those with higher percentages being largely in continental climates with greater summertime thunderstorm activity or where greater oceanic influences exist. Precipitation trends for the 22 wine regions are few, following observations globally and in many other wine regions during the last 50 years