A 2012 climate study released Thursday as a special supplement to the Bulletin of the American Meteorological Society finds that anthropogenic climate change was a contributing factor to half of the extreme weather events that occurred last year. The study was conducted by scientists from 11 nations.

“The report shows that the effects of natural weather and climate functions played a key role in the intensity and evolution of the 2012 extreme events,” a report by the National Oceanic and Atmospheric Administration (NOAA), a contributor to the study, states.

The study includes 10 analyses by 18 different research groups, all using different methodologies to study the 12 extreme weather events of 2012. Scientists were able to use the study not only investigate the causes behind the extreme events, but also to compare and contrast strengths and weaknesses of their different methodologies.

Human-caused climate change was found to be a factor in the “magnitude of warmth” of the 2012 US spring and summer heat waves, and was found to have “affected the likelihood of such heat waves.”

According to NOAA’s summary, “High temperatures, such as those experienced in the U.S. in 2012 are now likely to occur four times as frequently due to human-induced climate change.”

In relation to Hurricane Sandy, both natural and human causes were given attribution. Researchers found that climate change-related increases in sea level have nearly doubled the probability of having more Sandy-level flooding, compared to 1950.

“Ongoing natural and human-induced forcing of sea level ensures that Sandy-level inundation events will occur more frequently in the future from storms with less intensity and lower storm surge than Sandy,” NOAA states.

“This report adds to a growing ability of climate science to untangle the complexities of understanding natural and human-induced factors contributing to specific extreme weather and climate events,” said Thomas R. Karl, LHD, director of NOAA’s National Climatic Data Center (NCDC).

The study’s summary states that researching climate and weather extremes and attributing their causes is critical to preparing for future events. Part of the goal is to contribute to the “information that governments, organizations, and individuals can use to manage climate risks and opportunities” in the future.

Alisha is a writer and researcher with Ring of Fire. Follow her on Twitter @childoftheearth.