Worldwide, extreme weather was abundant in 2012. To name only a few of the events occurring in the first half of the year: 50 wildfires in Chile from high winds and dry conditions in January; a severe cold snap lasting three weeks in Central and Eastern Europe through mid-February; heavy rainfall and flooding in Queensland, New South Wales, and Victoria, Australia in March; severe thunderstorms and tornadoes in northern Texas in April; two tropical storms in the Atlantic, Alberto and Beryl, that kicked off the hurricane season in May; and record-low Arctic sea-ice cover attributed to high temperatures in June. See also: Forest fire; Hurricane; Sea ice; Thunderstorm; Tornado
For 2012, the National Oceanic and Atmospheric Administration (NOAA) National Climatic Data Center (NCDC) reported 11 weather or climate events in the United States that resulted in disasters costing over one billion dollars. Topping the list were Hurricane Sandy, which inflicted $62 billion in damage on Northeastern states, and the Midwest drought, which cost $35 billion in crop losses alone.
With atmospheric carbon dioxide concentrations, ocean heat content, and global temperature all on the rise, one cannot help but wonder if extreme weather events, such as heavy rainfall, heat waves, and drought, are also on the rise because of climate modification. The problem for scientists is they cannot say for sure whether a specific extreme weather event occurred because of climate change or was instead simply the result of natural climate variability or a weather anomaly. As a result, scientists are trying to determine the likelihood (odds) of an extreme event occurring. See also: Climate modification; Drought
The Intergovernmental Panel on Climate Change (IPCC) of the United Nations, representing the scientific consensus on climate change, in March 2012 published a special report, Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation (SREX). The report characterized scientific confidence that climate change had caused increases in monsoons, tropical cyclone activity, and the extent of flooding worldwide as low (the equivalent of maybe not), in some drought patterns as medium (maybe), and in changes in precipitation and snowmelt causing flooding as medium to high (likely). See also: Global climate change; Hydrological consequences of global warming
Also in 2012, some climate scientists reported evidence for global warming being a likely cause of some extreme weather events. In a paper published in the journal Proceedings of the National Academy of Sciences, NASA scientist James Hanson and colleagues argued that the extent and severity of recent extreme hot temperatures were statistically more likely to have been caused by global warming than by natural variability. In another paper published in the journal Nature Climate Change, climatologists Dim Coumou and Stefan Rahmstorf report that a review of the scientific evidence indicates that heat waves and precipitation extremes likely have increased because of global warming. They also expect the number of such extreme weather events to increase in a warming climate.