I. Identifying Links Between Climate Change and Tornadoes?
The outbreak of recent killer weather events including US tornadoes hitting Joplin, Missouri and Tuscaloosa, Alabama has everyone asking whether there is a link between tornadoes and human-induced climate change. In this writer’s experience when US TV or radio weathermen are asked about the cause of recent strong tornadoes, they most always ignore climate change as a potential cause and point to a cyclical ocean circulation event known as La Niña as the cause of recent tornadoes if they comment on causation at all.
Rarely is human-induced climate change mentioned as a cause or contributing factor in the recent outbreak of sever tornadoes although questions about causation are becoming more frequent on TV and newspapers in this writer’s experience.
This post argues that ethics requires acknowledging the links between tornadoes and climate change despite scientific uncertainties about increased frequency and intensity of tornadoes in a warming world. However, because there are also scientific reasons to doubt that tornado propagation and intensity will increase in a warming world, as we shall see, care is necessary about how we should discuss these risks.
As we shall see there are certain aspects of atmospheric conditions necessary to produce violent tornadoes that climate change is enhancing while there are other atmospheric conditions necessary to form tornadoes about which scientists are uncertain exactly how a warming world will affect them. To figure out whether climate change will cause more intense and frequent tornadoes requires asking lots of smaller questions about the atmospheric conditions necessary to produce tornadoes and to determine how climate change will affect each of these various atmospheric conditions that combine to propagate tornadoes.
Before discussing tornadoes, it is important to note that it is scientifically uncontroversial to conclude that climate change is causing more violent weather particularly in the form of: (a) more damaging thunder storms, (b) the kind of devastating flooding we have seen this year in Australia, Pakistan, Brazil, Columbia, Venezuela, along the Mississippi and the Tennessee valleys, and (c) more severe droughts such as those experienced this year in China, Brazil, and Texas. Similarly more intense hurricanes have been linked to climate change although it is still uncertain whether global warming will increase hurricane frequency. (Emanuel, 2005)
Most climate scientists agree that future weather will be characterized by far more chaotic weather causing greater damage to human life, health and ecological systems and so tornadoes are not the only intense weather events that could be enhanced by climate change and that will likely cause increased damage and suffering. .
It also can be said that in one way climate change is already changing all global weather including tornadoes. This is so because climate change has already caused changes to the global climate system such as raising ocean temperatures and increasing the amount of water in the atmosphere. Increased ocean temperatures and the water content of air have an effect on the amount and timing of precipitation that is being experienced in any one location. And so a strong claim can be made that climate change is now at least partially responsible for all global weather although the part played by climate change could be small for any individual climate event relative to other causes such as normal ocean circulation patterns. Yet, no tornado or hurricane experienced recently would likely be the same without some contribution from climate change. That is no tornado would appear at the same place, the same time, with the same wind speed without changes to the climate system that have been caused by human impacts on climate And so every tornado is very likely affected somewhat by climate change. That is although strong tornadoes have occurred before recent human-induced climate change, no recent tornado is likely to have happened in the same way at the same place in the absence of global warming.
This is not to say, however, that the intensity and frequency of tornadoes will surely increase in the years ahead.. Yet, although it is not clear that climate change will be responsible for more tornado caused damages, other kinds of storm damages are virtually certain to increase.
This post, however, looks at links between tornado intensity and frequency and climate change and what ethics requires when discussing these links. That is, this post does not examine other links between climate change and damaging weather.