2012’s extreme events – what role did climate change play?
Climate change made some of 2012’s most devastating extreme events more likely, a new report suggests.
A close inspection of 12 major events that occurred last year shows climate change influenced certain droughts, heat waves and flood events, as greenhouse gases continue to rise.
Others, however, were more likely the result of natural fluctuations in the climate.
Natural, manmade or both?
The new peer-reviewed report focuses specifically on 12 extreme events during 2012, including droughts, heatwaves, hurricanes, heavy rain, the loss of Arctic sea ice and cold snaps.
Produced by scientists from the Met Office and America’s National Oceanic and Atmospheric Administration (NOAA), the report brings together the work of more than 70 scientists from 18 research groups worldwide.
It concludes that while events like these are a natural part of the climate system, on closer inspection, climate change made more than half of the 12 events indicated in the map above more likely.
‘Explaining Extreme Events of 2012 from a Climate Perspective’, is available in the Bulletin of the American Meteorological Society – but for a quick and easy summary of the studies contained in the report, here’s what you need to know.
Extreme events – the highlights
Heat waves
- Study 3: Stanford University scientists found evidence that high levels of atmospheric greenhouse gases have increased the likelihood of heat waves such as that experienced in the US last summer
- Study 5: Another study found the record temperatures seen March-May in the US are unlikely to be caused solely by natural fluctuations in the climate
Hurricanes
- Study 6: Scientists investigating floods associated with hurricanes found a storm like Sandy is likely to have resulted in greater destruction in 2012 than the same storm half a century earlier, when sea levels were lower
Drought
- Study 2: Scientists from the University of Oregon and the University of Oxford did not find evidence that droughts, such as the one experienced in the mainland United States during 2012, are made more likely by climate change
- Study 14: Another investigation by researchers from Spain, Portugal and the UK shows events such as the the winter drought in the Iberian Peninsula were made more likely as a result of rising greenhouse gases, with 25% less rainfall during winter months
Sea Ice
- Study 8: Scientists from the National Oceanographic and Atmospheric Administration 2012’s record low levels of Arctic sea ice are “extremely unlikely” to have occurred due to natural climate fluctuations alone
- Study 7: Barcelona University researchers similarly found that the 2012’s Arctic sea ice minimum could not have been reached without human influence
Cold snaps
- Study 9: Researchers from Holland discovered ice in lakes and canals was thinner during the winter of 2012 partly as a result of long term rising temperatures, but mainly because an insulating layer of snow had fallen
Heavy Rain
- Study 19: One investigation into heavy rain events in Australia during 2012 found humans’ influence on the climate increased the chances of above average rainfall, while another using a different method found no evidence greenhouse gas emissions had affected heavy precipitation events in the long run (Study 18).
- Study 20: Between one and five percent extra moisture was available during a major two day rainfall event in New Zealand as a result of human produced greenhouse gases.