Really quickly. I think that global warming is a real thing. I have no idea how it is impacting worldwide weather. Since it is driven by the physics of a massive system, and follows the laws of thermodynamics in particular, weather is a statistical science.
Strong hurricanes occur, not because of “global warming”, but because they are bound to occur occasionally. Only with vast quantities of data can one discuss anything related to causality. These days, however, when there is an increase in severe weather, people tend to attribute it to Global Warming. There may be some truth in that – more heat means more energy, more energy, one might think, means more high energy storms, like hurricanes and tornadoes. Without getting too much into it (I only go so deep on the topic), there is a lot more to it than a simple 0.5 degrees = 8% more tornadoes. For instance, a warmer arctic means less cold air to mix with the warm air from the gulf, leading to less tornadoes. Or, changes in global temperatures might change global wind patterns. These wind patterns may increase the wind shear over the tropical Atlantic. It is possible that global warming might even decrease the total number of hurricanes – a prediction that has been made by some.
A few quick topics.
1) Never say that a single event is caused by global warming. The world’s most powerful tropical system occurred in 1979, when everyone was talking about global cooling (Typhoon Tip). The 1930s had the most drastic drought in recent history for the United States – to blame Texas droughts on global warming is scientifically irresponsible. If we had 1000 years of data, we could say that “droughts are more likely to happen when the global temperatures are warmer”, but that’s about it. No single event is ever “caused” by global warming. It’s far too complicated a system for that.
2) The event that I’ve heard most often as associated with global warming is extreme rainfall events. Scientists that that global warming will increase the number of flooding rains. Interestingly enough, people attribute major snow falls to global warming as well – the principle is the same, more moisture is evaporated, and it’s still cold enough to fall as snow.
3) Here’s a chart of strong tornado frequency as a function of year. You’ll see that it doesn’t change much. If anything it has decreased. This year will be a major spike in the graph, but it is not attributable to global warming.
4) Here’s a chart of hurricane frequency as a function of year. You cannot trust the total numbers of hurricanes on those charts prior to the 1960s. Before satellite, a storm that was a minimal hurricane for a day in the central Atlantic was not tallied. As we change the way that we capture the data, the numbers are bound to change as well. I believe that “intense” hurricanes (Cat 3 or greater) are more reliable, as they were unmistakably big events in the olden days as well. It seems as though the number of intense hurricanes has increased slightly, as predicted by global climate models. This chart came from here if you want a scale.
I still really don’t trust hurricane numbers from the olden days very much, even big ones.
All of this to say: the tornadoes this year may, statistically, have been exacerbated by global warming. We can speculate that, but the evidence cannot possibly exist to show us that. They were not caused by global warming. This would have been a major outbreak in 1850 as well.
However…
Just because it’s impossible to have enough data to make a claim that the weather has changed for the worse because of global warming doesn’t mean we should ignore it until the results are in. I honestly don’t believe we’ll have enough data for that for another 200 years. It’s WAY too long to wait to do something. I support global warming initiatives because common sense says that polluting less is better than polluting more. The burning of fossil fuels has been around for a while – as a society, we tend to advance our technologies as time passes.
And so on, I have to go back to work.
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