# Extreme weather events – what last year tells us

[See my first part]

by USDAgov

Last year in the US, there were 14 ‘billion dollar’ events related to the weather, the most recorded in one year.  They cost us \$60 billion — all the costs are converted into 2012 dollars so they can be compared.

Since 1980, 133 such events have been recorded.

Since 1980, almost \$900 billion dollars has been lost to these weather disasters.

Here is a little math. It is not the strongest possible because we are dealing with only 31 years of data — and I am making a lot of  simplifying assumptions. I am sure I am overanalyzing it but it is indicative of the fact that the weather has become more extreme lately.

What was once very rare is now becoming common place. We are loading the climate dice to only come up hot.

Here we have the set of data for billion dollar disasters related to the weather.

For the first decade of measurements (1980-1989), there were on average 2 ± 1.7 such events a year. From 1990-1999, there were about 4.7 ± 1.8 such events per year.

For the last decade, there have been about 6.2 events a year — three times the average seen only 25 years ago — with a standard deviation over 3.

This means that whereas 25 years ago we could expect anywhere from 0 to 4 events a year, now we can expect from anywhere from 3 to 9.

Last year we had 14 events. With a mean of 2 and a standard deviation of 1.7, we can easily see that 14 events falls just outside 7 standard deviations from the average — 2+ 1.7+1.7+1.7+1.7+1.7+1.7+1.7 = 2+11.9=13.9.

Statistically, this means that we would expect this to happen – 14 events in one year — less than once every  400 billion years. Since the Earth is only 4.5 billion years old, we can safely say that it would never happen.

So, based on the average we saw from 1980 to 1989, we would never expect to see a year with 14 ‘events costing over \$1 billion each.

How about on the average we saw from 1990-1999? Fourteen is a little over 5 standard deviations out.  Then  the number of events seen in 2011 would happen every about every 2 million years. This is over 200,000 times more frequent than seen in the first ten years but still not something we would every expect to  live to see.

Now, based on the last decade, how often would we expect to see 14 events in one year? Once in a hundred.

The number of events seen in 2011 which we would have expected to happen once every 400 billion years just a generation ago, now happens 1% of the time – 400 billion times more often than just a generation ago.

This is what we mean by warmer climate affecting extreme events. From a statistical viewpoint it is a certainty each of us will live to see one. Which we have.

And ten percent of all the extreme weather events over the last 30 years happened just last year.

Through June of 2012, we have had seven events costing more than \$1 billion, with another 2 likely to be added from July. Looks like another really bad year.

These extreme events certainly appear to be the result of global warming. We have painted too many sides of the climate dice red and now when they get rolled, only more heat comes up.

And this is now costing us at least \$30-70 billion a year to deal with. Money we really do not have. How much would it cost to fix this global warming in the US instead of spending money to clean up after it? About \$50 billion a year.

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