Canadian Underwriter
News

New report finds human-caused climate change increased the severity of many extreme events in 2014


November 6, 2015   by Canadian Underwriter


Print this page Share

Human activities, such as greenhouse gas emissions and land use, influenced specific extreme weather and climate events in 2014, including flooding in the Canadian Prairie provinces, according to a new report released on Thursday.

A long exposure image shows the El Portal Fire burning near Yosemite National Park, California in late July 2014. On the morning of July 28, the fire had burned more than 2,500 acres and was just five percent contained. More than 400 firefighters and several helicopters battled the flames. (Credit: Stuart Palley, EPA)A long exposure image shows the El Portal Fire burning near Yosemite National Park, California in late July 2014. On the morning of July 28, the fire had burned more than 2,500 acres and was just five percent contained. More than 400 firefighters and several helicopters battled the flames. (Credit: Stuart Palley, EPA)

The report, titled Explaining Extreme Events of 2014 from a Climate Perspective, published by the Bulletin of the American Meteorological Society, addresses the natural and human causes of individual extreme events from around the world in 2014, including North America, South America, Europe, the Middle East and Africa, Asia, Australia and Antarctica. Scientists from the National Oceanic and Atmospheric Administration (NOAA) served as three of the five lead editors on the report.

The report found that human activities influenced such events as tropical cyclones in the central Pacific, heavy rainfall in Europe, drought in East Africa, and stifling heat waves in Australia, Asia, and South America. The flooding in the Canadian prairies was found to be more likely because of human land-use changes that affect drainage mechanisms.

In this year’s report, 32 groups of scientists from around the world investigated 28 individual extreme events in 2014 and broke out various factors that led to the extreme events, including the degree to which natural variability and human-induced climate change played a role, NOAA said in a statement. When human influence for an event cannot be conclusively identified with the scientific tools available today, this means that if there is a human contribution, it cannot be distinguished from natural climate variability.

The report this year added analysis on new types of events, including wildfires and Antarctic sea ice extent, and in one case looked at how land use patterns may influence the impacts and severity from precipitation.

“For each of the past four years, this report has demonstrated that individual events, like temperature extremes, have often been shown to be linked to additional atmospheric greenhouse gases caused by human activities, while other extremes, such as those that are precipitation related, are less likely to be convincingly linked to human activities,” said Thomas R. Karl, director of NOAA’s National Centers for Environmental Information, in the statement. “As the science of event attribution continues to advance, so too will our ability to detect and distinguish the effects of long-term climate change and natural variability on individual extreme events. Until this is fully realized, communities would be well-served to look beyond the range of past extreme events to guide future resiliency efforts.” [click image below to enlarge]

Location and type of events analyzed in Explaining Extreme Events of 2014 from a Climate Prospective. (Credit: BAMS)

In North America, the report found that:

• The overall probability of California wildfires has increased due to human-induced climate change, however, no specific link could be made for the 2014 fire event;

• Though cold winters still occur in the upper Midwest, they are less likely due to climate change;

• Cold temperatures along the eastern U.S. were not influenced by climate change, and eastern U.S. winter temperatures are becoming less variable;

• Tropical cyclones that hit Hawaii were “substantially more likely” because of human-induced climate change; and

• The extreme 2013-14 winter storm season over much of North America was driven mainly by natural variability and not human-caused climate change.

“Understanding our influence on specific extreme weather events is ground-breaking science that will help us adapt to climate change,” said Stephanie C. Herring, lead editor for the report at NOAA’s National Centers for Environmental Information. “As the field of climate attribution science grows, resource managers, the insurance industry, and many others can use the information more effectively for improved decision making and to help communities better prepare for future extreme events.”

The report was edited by Herring, along with Martin P. Hoerling, NOAA’s Earth System Research Laboratory; James Kossin, NOAA’s National Centers for Environmental Information; Thomas Peterson, World Meteorological Organization’s Commission for Climatology and formerly with NOAA’s National Centers for Environmental Information; and Peter A. Stott, UK Met Office Hadley Centre.