Tally: Annual BAMS "Explaining Extreme Events" attribution reports that identify climate change signals in heat events
Explaining Extreme Events of...
...from a climate perspective
Every year since 2012, the Bulletin of the American Meteorological Society has published an annual report of studies looking for the signal of climate change in extreme events from the previous year. All 11 heat-related studies from the most recent report, published in December 2016 on the extreme events of 2015, found that the heat-related event studied was made more intense or likely due to human-induced climate change. Since the first report, 32 out of 33 heat-related attribution studies implicated climate change. Below is a complete list of all these studies, categorized by event-year.
The studies presented in the BAMS reports do not necessarily reflect a representative sample, hence summarizing across this particular group of studies does not necessarily reflect changes in events collectively. However, this pattern is consistent with the results of individual global studies that have found the fingerprint of global warming in the overwhelming share of extreme heat events globally.
Without exception, all the heat-related events studied in this year’s report were found to have been made more intense or likely due to human-induced climate change, and this was discernible even for those events strongly influenced by the 2015 El Niño. Furthermore, many papers in this year’s report demonstrate that attribution science is capable of separating the effects of natural drivers including the strong 2015 El Niño from the influences of long-term human-induced climate change.
- MULTIMODEL ASSESSMENT OF ANTHROPOGENIC INFLUENCE ON RECORD GLOBAL AND REGIONAL WARMTH DURING 2015
- "In 2015, record warm surface temperatures were observed for the global mean, India, and the equatorial central Pacific. CMIP5 simulations suggest that for the globe and India, anthropogenic warming was largely to blame."
- THE ROLE OF ANTHROPOGENIC WARMING IN 2015 CENTRAL EUROPEAN HEAT WAVES
- "Station-based observations and bias-corrected model simulations show that the frequency of short-term heat waves in central Europe has increased, albeit quantitative estimates of risk ratios differ considerably between methods."
- THE 2015 EUROPEAN HEAT WAVE
- "A heat wave swept across central Europe in summer 2015. Model experiments suggest that anthropogenic forcings were a major factor in setting the conditions for the development of the 2015 heat wave."
- HUMAN INFLUENCES ON HEAT-RELATED HEALTH INDICATORS DURING THE 2015 EGYPTIAN HEAT WAVE
- "A combined modeling and observational assessment of the 2015 heat wave in Egypt found that human discomfort increased due to anthropogenic climate change."
- THE DEADLY COMBINATION OF HEAT AND HUMIDITY IN INDIA AND PAKISTAN IN SUMMER 2015
- "We find that the deadly heat waves in India and Pakistan in 2015 were exacerbated by anthropogenic climate change. Although the impacts of both events were severe, the events themselves were not connected to each other."
- RECORD-BREAKING HEAT IN NORTHWEST CHINA IN JULY 2015: ANALYSIS OF THE SEVERITY AND UNDERLYING CAUSES
- "The record-breaking heat over northwest China in July 2015 was linked directly to atmospheric general circulation indices and anthropogenic forcing. The latter increased the risk of extreme heat by three-fold."
- HUMAN INFLUENCE ON THE 2015 EXTREME HIGH TEMPERATURE EVENTS IN WESTERN CHINA
- "Human influence has very likely increased the probability of occurrence of the 2015 western China extreme summer temperature events by at least 3-fold and 42-fold for the highest daily maximum and minimum temperatures, respectively." 
- A PERSISTENT JAPANESE HEAT WAVE IN EARLY AUGUST 2015: ROLES OF NATURAL VARIABILITY AND HUMAN-INDUCED WARMING
- "The persistent Japanese heat wave that occurred in early August 2015 was mainly attributed to intraseasonal disturbances including tropical cyclones. Anthropogenic warming contributed to an increase in the probability of occurrence."
- CLIMATE CHANGE AND EL NIÑO INCREASE LIKELIHOOD OF INDONESIAN HEAT AND DROUGHT
- "El Niño and human-induced climate change have substantially increased the likelihood of rainfall deficits and high temperatures, respectively, in Indonesia such as those experienced in the drought conditions of July–October 2015."
- SOUTHERN AUSTRALIA’S WARMEST OCTOBER ON RECORD: THE ROLE OF ENSO AND CLIMATE CHANGE
- "Anthropogenic climate change was found to have a substantial influence on southern Australia’s extreme heat in October 2015. The relative influence of El Niño conditions was less clear."
- WHAT CAUSED THE RECORD-BREAKING HEAT ACROSS AUSTRALIA IN OCTOBER 2015?
- "Using a seasonal forecasting framework for attribution, we find that half of the record heat anomaly across Australia in October 2015 can be attributed to increasing CO2, with much of the rest due to internal atmospheric variability."
A number of this year’s studies indicate that human-caused climate change greatly increased the likelihood and intensity for extreme heat waves in 2014 over various regions.
- CAUSAL INFLUENCE OF ANTHROPOGENIC FORCINGS ON THE ARGENTINIAN HEAT WAVE OF DECEMBER 2013
- "The Argentinian heat wave of December 2013 was likely caused in part by anthropogenic forcings. These forcings have increased the risk of such an event occurring by a factor of five."
- RECORD ANNUAL MEAN WARMTH OVER EUROPE, THE NORTHEAST PACIFIC, AND THE NORTHWEST ATLANTIC DURING 2014: ASSESSMENT OF ANTHROPOGENIC INFLUENCE
- "According to CMIP5 models, the risk of record annual mean warmth in European, northeast Pacific, and northwest Atlantic regions—as occurred in 2014—has been greatly increased by anthropogenic climate change."
- ANTHROPOGENIC INFLUENCE ON THE 2014 RECORD-HOT SPRING IN KOREA
- "A comparison of observations and multiple global climate models indicates human influence has increased the chance of extreme hot springs in Korea such as the 2014 event by two to three times."
- ROLE OF ANTHROPOGENIC FORCING IN 2014 HOT SPRING IN NORTHERN CHINA
- "Anthropogenic forcing may have contributed to an 11-fold increase in the chance of the 2014 hot spring in northern China."
- INCREASED LIKELIHOOD OF BRISBANE, AUSTRALIA, G20 HEAT EVENT DUE TO ANTHROPOGENIC CLIMATE CHANGE
- "Climate model simulations for 2014 indicate anthropogenic climate change very likely increased the likelihood of hot and very hot November days in Brisbane by at least 25% and 44% respectively."
- THE CONTRIBUTION OF ANTHROPOGENIC FORCING TO THE ADELAIDE AND MELBOURNE, AUSTRALIA, HEAT WAVES OF JANUARY 2014
- "Anthropogenic climate change very likely increased the likelihood of prolonged heat waves like that experienced in Adelaide in January 2014 by at least 16%. The influence for Melbourne is less clear."
- CONTRIBUTORS TO THE RECORD HIGH TEMPERATURES ACROSS AUSTRALIA IN LATE SPRING 2014
- "The record warm Australian spring of 2014 would likely not have occurred without increases in CO2 over the last 50 years working in concert with an upper-level wave train."
- INCREASED RISK OF THE 2014 AUSTRALIAN MAY HEATWAVE DUE TO ANTHROPOGENIC ACTIVITY
Attribution of extreme events is a challenging science and one that is currently undergoing considerable evolution. In this paper, 20 different research groups explored the causes of 16 different events that occurred in 2013. The findings indicate that human-caused climate change greatly increased the risk for the extreme heat waves assessed in this report.
- THE ROLE OF ANTHROPOGENIC FORCING IN THE RECORD 2013 AUSTRALIA-WIDE ANNUAL AND SPRING TEMPERATURES
- "Anthropogenic climate change has caused a very large increase in the likelihood of extreme events such as the record Australia-wide average temperatures in September, spring, and the 2013 calendar year."
- INCREASED SIMULATED RISK OF THE HOT AUSTRALIAN SUMMER OF 2012/13 DUE TO ANTHROPOGENIC ACTIVITY AS MEASURED BY HEAT WAVE FREQUENCY AND INTENSITY
- "Human activity has increased the risk of experiencing the hot Australian summer of 2012/13, as measured by simulated heat wave frequency and intensity, by two- and three-fold, respectively."
- UNDERSTANDING AUSTRALIA’S HOTTEST SEPTEMBER ON RECORD
- "Record high September maximum temperatures over Australia arose from a combination of a strongly anomalous atmospheric circulation pattern, background warming, and dry and warm antecedent land-surface conditions."
- CLIMATE CHANGE TURNS AUSTRALIA'S 2013 BIG DRY INTO A YEAR OF RECORD-BREAKING HEAT
- "The record heat of 2013 across inland eastern Australia was caused by a combination of anthropogenic warming and extreme drought."
- ASSESSING HUMAN CONTRIBUTION TO THE SUMMER 2013 KOREAN HEAT WAVE
- "A comparison of observations and multiple global climate model simulations indicates that extreme hot summer temperatures in Korea have become 10 times more likely due to human influence."
- THE CONTRIBUTION OF ANTHROPOGENIC FORCING TO THE JAPANESE HEAT WAVES OF 2013
- "Anthropogenic climate change played a significant role in increasing the probability of events such as the heat wave in Japan in 2013."
- UNDERSTANDING A HOT SUMMER IN CENTRAL EASTERN CHINA: SUMMER 2013 IN CONTEXT OF MULTIMODEL TREND ANALYSIS
- "July–August 2013 was the warmest such period in central eastern China since 1951. Comparison based on Coupled Model Intercomparison Project Phase 5 (CMIP5) models suggest a discernible impact of anthropogenic forcing, with internal variability also being important."
- THE 2013 HOT, DRY SUMMER IN WESTERN EUROPE
Extreme events, by definition, can be both rare at any given location and common in a global sense. In any one place, the chance of a once in a 100–year heat extreme is so rare that, in principle, it only occurs, on average, once every 100–years. This also means that, on average and with a stationary climate, every year one percent of the world would be expected to experience a once in a 100–year heat extreme and one percent a cold extreme...The fact that “The Extreme March–May 2012 Warm Anomaly over the Eastern United States: Global Context and Multimodel Trend Analysis” (in this report) found 15.3% of the world experiencing its first, second, or third warmest year, while no grid box experienced their first, second, or third coldest year implies that expectations based on the assumption of a stationary climate may no longer be fully applicable.
- LIKELIHOOD OF JULY 2012 U.S. TEMPERATURES IN PREINDUSTRIAL AND CURRENT FORCING REGIMES
- "The mean occurrence of 2012-magnitude temperatures is more than four times as frequent over the north-central and northeastern United States in the current forcing."
- U.S. HEAT WAVES OF SPRING AND SUMMER 2012 FROM THE FLOW-ANALOGUE PERSPECTIVE
- "The record hot spring of 2012 over the eastern United States can be mainly explained by atmospheric dynamics...The contribution of potential changes in circulation to the recent long-term warming in the United States, therefore, requires further research."
- THE EXTREME MARCH–MAY 2012 WARM ANOMALY OVER THE EASTERN UNITED STATES: GLOBAL CONTEXT AND MULTIMODEL TREND ANALYSIS
Changes in extreme temperature and the intensification of extreme precipitation events are expected consequences of a warming climate. A warmer climate would be expected to have more intense warm temperature extremes, including longer and more intense heat waves and more frequent record-breaking high temperatures than expected without warming. It would also be expected to show less intense cold temperature extremes and fewer record-breaking low temperatures than expected before. Both of these expected changes in the occurrence of record-breaking temperatures have indeed been observed.
- DID HUMAN INFLUENCE ON CLIMATE MAKE THE 2011 TEXAS DROUGHT MORE PROBABLE?
- "The heatwave that affected Texas has become distinctly more likely than 40 years ago."
- CONTRIBUTION OF ATMOSPHERIC CIRCULATION TO REMARKABLE EUROPEAN TEMPERATURES OF 2011
- "Europe's record warm temperatures would probably not have been as unusual if the high temperatures had been caused only by the atmospheric flow regime without any long-term warming."
- HAVE THE ODDS OF WARM NOVEMBER TEMPERATURES AND OF COLD DECEMBER TEMPERATURES IN CENTRAL ENGLAND CHANGED?
- "The likelihood of very warm November temperatures in the UK has increased substantially since the 1960s."