Friday, November 15, 2013

Christian und Haiyan

In den letzten 2 Wochen gab es zwei sehr schwere Stürme mit erheblichen Schäden - in Nordeuropa "Christian" und im Westpazifik "Haiyan". In unmittelbarer Nähe von COP 19 überrascht es nicht, dass in den Medien ein definitiver Zusammenhang mit dem menschgemachten Klimawandel hergestellt wurde (etwa hier im  Morgenmagazin von ZDF und ARD.

Inzwischen hat das Seewetteramt des Deutschen Weterdienstes Stellung bezogen zu beiden Ereignissen - Christian und Haiyan.

1 comment:

@ReinerGrundmann said...

Roger Pielke Jr has a couple of useful posts up on his blog:

For an alternative view, see Dana Nucitelli in the Guardian:

In this piece we some interesting rhetoric at work which tries to get around the IPCC wisdom on this matter. The author introduces the piece as follows:

'Climate scientists are confident in three ways that climate change will make the impacts of hurricanes worse. First, global warming causes sea level rise, which amplifies storm surges and flooding associated with hurricanes. As a paper published in the Proceedings of the National Academy of Sciences by Aslak Grinsted and colleagues concluded,

"we have probably crossed the threshold where Katrina magnitude hurricane surges are more likely caused by global warming than not."

Second, as climate scientist Kevin Trenberth has noted, global warming has also increased the amount of moisture in the air, causing more rainfall and amplifying flooding during hurricanes.

Third, warmer oceans are fuel for hurricanes. Research has shown that the strongest hurricanes have grown stronger in most ocean basins around the world over the past several decades, and climate models consistently project that this trend will continue.'

Further down in the article the author makes reference to the IPCC as follows:

'Chapter 2.6.3 of the 2013 IPCC report notes,

"Time series of cyclone indices such as power dissipation ... show upward trends in the North Atlantic and weaker upward trends in the western North Pacific since the late 1970s"

The hurricane intensity trend in the western North Pacific (where the Philippines are located) isn't crystal clear. One recent paper finds that over the past few decades their intensity has slightly fallen (but has grown for the planet as a whole), while others suggest it's slightly risen, or that there are fewer but stronger hurricanes in that western North Pacific region.

However, a paper published earlier this year in the Proceedings of the National Academy of Sciences by MIT hurricane expert Kerry Emanuel found that future "Increases in tropical cyclone activity are most prominent in the western North Pacific." So while we're not certain about the trend over the past few decades, the evidence indicates that hurricanes near the Philippines will both become stronger and form more frequently in a warmer world.'

One might think this is cherry picking. So did I and asked the author via Twitter if there were other studies.

Me: "Interesting Q is if there were other studies that found otherwise than Emanuel. Genuinely interested."

DN: "depends if you're talking present or future trends. I ref'd Kossins & Elsner on the former."

Someone else chips in:

"They both find trends globally, but not in all basins. Is that right?"

DN: "Yes, positive trends globally & in most basins. See my post today."

If true this would mean that IPCC would need to revise its recent assessment.