More Frequent, Longer, and Hotter Heat Waves for Australia in the Twenty-First Century

Abstract

Extremes such as summer heat waves and winter warm spells have a significant impact on the climate of Australia, with many regions experiencing an increase in the frequency and duration of these events since the mid-twentieth century. With the availability of Coupled Model Intercomparison Project phase 5 (CMIP5) climate models, projected changes in heat waves and warm spells are investigated across Australia for two future emission scenarios. For the historical period encompassing the late twentieth century (1950–2005) an ensemble mean of 15 models is able to broadly capture the observed spatial distribution in the frequency and duration of summer heat waves, despite overestimating these metrics along coastal regions. The models achieve a better comparison to observations in their simulation of the temperature anomaly of the hottest heat waves. By the end of the twenty-first century, the model ensemble mean projects the largest increase in summer heat wave frequency and duration to occur across northern tropical regions, while projecting an increase of ~3°C in the maximum temperature of the hottest southern Australian heat waves. Model consensus suggests that future winter warm spells will increase in frequency and duration at a greater rate than summer heat waves, and that the hottest events will become increasingly hotter for both seasons by century’s end. Even when referenced to a warming mean state, increases in the temperature of the hottest events are projected for southern Australia. Results also suggest that following a strong mitigation pathway in the future is more effective in reducing the frequency and duration of heat waves and warm spells in the southern regions compared to the northern tropical regions.

Explaining Extreme Events of 2014 from a Climate Perspective

“…While impacts on human systems are likely minimal, anomalously warm events in cooler seasons can have vast impacts on agriculture (e.g., Lanning et al 2011), which currently contributes to 12% of Australia's gross domestic product. Moreover, increasingly frequent and elevated temperatures are expected throughout all times of the year, as anthropogenic influence on the climate continues to increase (Cowan et al 2014). This study employs the fraction of attributable risk (FAR) method (Stone and Allen 2005) to ascertain whether anthropogenic climate change has increased the likelihood of the 2014 Australian May heatwave.…”

Synoptic Conditions Generating Heat Waves and Warm Spells in Romania

“…In this line, we can talk about an abrupt warming in the region rather than of a simple linear warming trend. The HWs/WSs represent a characteristic of the temperature variability all over the year [69,82], but their concentration is higher during the warm period. This fact is caused especially by the higher variability of the temperature during this period of the year.…”

Co-occurrence of extremes in surface ozone, particulate matter, and temperature over eastern North America

“…In any case, the extremes often co-occur as a result of their shared underlying drivers, greatly increasing the risks to human health (14). The imperative to understand the co-occurrence of health extremes is driven in part by the recognition that episodes of extreme temperatures (15)(16)(17)(18) and poor air quality (19)(20)(21)(22)(23)(24) may become more frequent, longer lasting, and more intense in a warming climate, in which many climate-driven feedbacks can alter air quality independent of emissions (e.g., 8,10,25,26).…”