An Application Of The Use Of The Historical Climate Record To Assess Extreme Events By John Neilsen-Gammon

From Climate Abyss

In our papers and posts (e.g. see) we have urged

“There are 5 broad areas that we can use to define the need for vulnerability assessments : water, food, energy, [human] health and ecosystem function. Each area has societally critical resources. The vulnerability concept requires the determination of the major threats to these resources from climate, but also from other social and environmental issues. After these threats are identified for each resource, then the relative risk from natural- and human-caused climate change [from] (estimated from the GCM projections, but also the historical [record], paleo-record and worst case sequences of events) can be compared with other risks in order to adopt the optimal mitigation/adaptation strategy.”

There is an excellent example of the approach of using  “the historical” record to assess risk to these resources which has appeared on John Neilsen-Gammon weblog Climate Abyss titled

Texas Drought: A Fingerprint

As John writes

“2011 is not the low mark just at 7 months.  It also takes the record for the following durations ending in July: 2 months, 3 months, 5 months, 6 months, 8 months, 9 months, 10 months, 11 months, and 12 months. Everything from 5 to 10 months breaks the record by a large margin.  In fact, everything from 8 to 10 months breaks the record for consecutive months, no matter the ending month.

So we now have a dry outlier that’s even more an outlier than the wet outlier of 2007.  What are the odds of such an event occurring?  I had them at about 1 in 250.  What about you?

Whatever the exact value, it’s obvious that Texas is living through a very unusual weather event.  I don’t consider it to be the worst drought on record, because the 1950s drought lasted for seven years, and 1956 alone gives 2011 a run for its money.  But, combine it with July being the warmest month on record for Texas, and it probably becomes the most unbearable.  It may well be the worst drought on record for agriculture.”

He also reports that

“Maybe you’d like to take climate change into account.  Precipitation in Texas has been increasing over the long-term, and you can see that the highest graphs tend to be more recent than the lowest graphs.  That would make a dry event less likely.  Conversely, climate models project a slow decrease in precipitation: is a dry event more likely?”

I recommend reading the entire post. It provides real world information on the risks that Texas faces with respect to climate. These need to be responded to for the future irrespective of how humans are altering the climate system, as these events have actually occurred. Relying on unverifiable multi-decadal climate model predictions is not an effective way to develop measures of this risk.

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