I am wondering at what point extreme weather events are going to be seen as harbingers of climate change.Climate scientists have for some time noted that Anthropogenic Global Warming will produce extreme weather events The question is how do we establish that a pattern of extreme weather events is a product of AGW? AGW skeptics can rightly point out that we had extreme weather events before atmospheric CO2 began to increase. Thus extreme climate events are not in themselves evidence that climate change is happening.

What may begin to tip the scales toward acknowledgement of climate change is not the extremity of weather events but their number. If it becomes evident that the number of extreme weather events is increasing, the case for climate change will grow stronger. During the last few years wide scale flooding often accompanied by unusual rain events has appeared to increase. There have been large scale floods in Pakistan, Australia, Europe, and the United States, during the last couple of years. Currently the Mississippi River is flooding and the flood is either the largest in recorded history or the second largest. In addition, in 2010 an extreme rain event (a thousand year Rain event) triggered flooding in Nashville, Tennessee, and in 2009 an even more unusual rain event (a 10,000 year rain event) triggered flooding in Atlanta, Georgia.
In addition to flooding and rain events, there has been an unusual number of Tornadoes. As of May 23, there have been 1,170 tornadoes reported in the US in 2011. This number includes at several confirmed rare F 5 tornadoes. Three confirmed F 5 tornados occurred on April 27th 2011:
* From Smithville, MS to Shottsville, AL along a 32 mile path
* From Hackleburg, AL to Huntland, TN along a 132 mile path
* In or near Philadelphia, Mississippi along a 29 mile path
Monstrous F 4 or F 5 storms which devastated Tuscaloosa, Alabama, and Joplin, Missouri also occurred during the Spring of 2011.
In addition to extreme rain events, floods and tornadoes, we need to consider droughts and heat waves. In 2007 the Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC, 2007) noted,
Since 1950, the number of heat waves has increased and widespread increases have occurred in the numbers of warm nights. The extent of regions affected by droughts has also increased as precipitation over land has marginally decreased while evaporation has increased due to warmer conditions. Generally, numbers of heavy daily precipitation events that lead to flooding have increased, but not everywhere. Tropical storm and hurricane frequencies vary considerably from year to year, but evidence suggests substantial increases in intensity and duration since the 1970s.In the extratropics, variations in tracks and intensity of storms reflect variations in major features of the atmospheric circulation, such a
Not only did the IPCC note an increase in the number of extreme weather and climate events during the last 60 years, but foresaw a continuation of this pattern for the rest of this century.
The IPCC forecasts extreme rain and flood events due to increased precipitation that will cause:
* Damage to crops; soil erosion, inability to cultivate land, water logging of soils
* Adverse effects on quality of surface and groundwater; contamination of water supply
* Deaths, injuries, infectious diseases, allergies and dermatitis from floods and landslides
* Disruption of settlements, commerce, transport and societies due to flooding; pressures on urban and rural infrastructures
We cannot be sure yet that the IPCC forecast is coming to pass, but the evidence from the last couple of years strongly suggests that it is. If this pattern continues it is only a matter of time before the public recognizes the full implication of what is happening. At that point even the extreme political right may start indulging in climate alarmism. The real Joplin tragedy may turn out to be that we are not without responsibility for the disaster, yet unwilling to acknowledge our responsibility for it. The time is coming when we will acknowledge it.
Photo by Saiuri