Friday, July 20, 2012

Left Side of the Aisle #66 - Part 4

Global warming: Drought, storms, and ever-increasing data

Global warming is back in the news. The US is seeing wildfires, freak storms, thousands of temperature records being broken. The last 12 months in the US made up the hottest 12-month stretch on record; the first 6 months of 2012 were the hottest consecutive 6 months on record.

The average US temperature for each of the last 13 months has ranked in the top third of its historical distribution. In other words, June 2011 was in the top third of hottest Junes on record, as was July 2011, and August 2011, and September, and so on. This is the first time that has happened in the recorded history of weather data. According to the National Oceanic and Atmospheric Administration, or NOAA, the odds of this occurring randomly are 1 in 1.6 million.

In fact, it's been so hot that we even had events like the one in the picture, with a jet getting trapped at Reagan airport outside DC because it had been so hot that that the tarmac softened and the plane sank four inches down. It had to be towed out of the depression before it could take off.

We're also had the worst droughts in over 50 years, as the map below shows. Some 56% of the land surface of the continental US was designated to be in some form of drought at the end of June. Now, to be fair, I have to note that this is not as bad as dust bowl of '30s but again, it is the worst in over 50 years - and it ain't over yet.

According to a Washington Post-Stanford University Poll in June, over three-fourths of Americans now accept that human activity is at least partly responsible for the rising temperatures and yes, something needs to be done about it, a finding echoed by an editorial in the Sat Lake City Tribune, headlined "A hotter West: Climate change effects undeniable."

Now, as I've said many times before, one hot spell no more proves global warming than one cold snap disproves it. Assigning a particular weather event to global warming is problematic at best. But what we're seeing here is not a single event but an increasingly long string of a variety of events. Each on them on its own proves nothing - but taken together, they make up a massive amount of data persistently, consistently, insistently, pointing in the same direction: We are screwing with the climate to our own pain and harm.

What's more, the latest State of the Climate report out of NOAA notes that scientists are increasingly able to assign probabilities to weather events, that is, not to say "yes this weather event would have happened even without global warming" or "no it wouldn't have happened except for global warming," but to express how likely that event would be. For example, a La Niña year can produce a heat wave in Texas. Now, due to climate change, such a La Niña-driven heat wave is 20 times more likely than it was 50 years ago. Unusually warm Novembers in Great Britain are now 60 times more likely than they would have been 50 years ago, while cold Decembers are half as likely.

Take another look at that drought map. Again, this is not the worst drought on record - but droughts like this, of this severity, are now much more likely than they were 50 years ago. We simply are more likely to experience more droughts, more freak storms, and more record high temperatures than we have been in the recorded history of weather data.

As Deputy NOAA Administrator Kathryn Sullivan said when releasing the new State of the Climate report, “Every weather event that happens now takes place in the context of a changing global environment."

That report, by the way, used 43 separate climate indicators to track and identify changes and trends in global climate. Each indicator includes thousands of measurements from multiple independent datasets and was compiled by 378 scientists from 48 countries around the world. Think about the weight of that data and that range of expertise the next time some nanny-nanny naysayer wants to go on about something they read somewhere on the Internet.

And that report, that State of the Climate report, does cover the world. And in fact, worldwide, 2011 was the coolest year since 2008, with temperatures held in check by back-to-back La Niñas, which produce cooler-than-average water temperatures in the eastern equatorial Pacific and so bring cooler temperatures to various regions. Despite that double dip cool-it-down effect, temperatures worldwide remained above the the 1981–2010 average and 2011 was among the 15 warmest years on record.

One last thing to give you some bad dreams. Even with La Niña conditions occurring during most of the year, the 2011 global sea surface temperature was among the 12 highest years on record. Ocean heat content, measured from the surface to 2,300 feet deep, continued to rise since records began in 1993 and was at a record high.

Why are the air and surface temps not even higher than they are? Because, as the graph to the right shows, most of the warming has gone into the world's largest heat sink: the oceans. At some point - and some fear it is fast approaching - the oceans will have absorbed all they can. Future warming will then go into the land surface and the air, having nowhere else to go. And then you will see the temps really climb.


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