When it comes to hurricanes, climate change effects may be 'a wash'

In some ways, hurricane season 2011, which ended Wednesday, seems to fit right in with the wild weather wreaking havoc in recent years - a string of severe floods, droughts and heat waves that the world's top climate scientists recently warned will likely worsen with global warming.

The tropics churned out 18 named storms, a number that tied for sixth place in 160 years of record-keeping and continued a hyperactive hurricane period going back more than a decade. Florida escaped unscathed for the sixth straight year, but much of the Atlantic coast was not so lucky. and Tropical Storm Lee combined to kill 58 people and cause an estimated $8 billion in damage from North Carolina to Maine.

That frightening destructive power has made hurricanes a symbol of the perils of global warming, with the image of a whirling eye spewed from a smoke stack adorning posters for Al Gore's ground-breaking and Oscar-winning 2006 documentary, "An Inconvenient Truth."

But a new report on from the United Nations-led Intergovernmental Panel on , released last month, suggests that for hurricanes at least, the effects of global warming remain uncertain and likely so incremental that it might be difficult to even measure them. Some storms might grow slightly more intense, the report concludes, but there might be fewer of them - at least over the next century.

"That's kind of a wash in my book,'' said Chris Landsea, science and operations officer at the National Hurricane Center in Miami-Dade.

The report, the first from the IPCC to focus on extreme weather, concludes the impacts of climate change - fueled by increasing greenhouse gases generated by humans - won't necessarily be uniform but could be both dangerous and costly in some places.

It's almost certain that global warming is behind soaring, record-setting high temperatures around the world. The world is also likely to see more droughts like one searing Texas, and the unprecedented flooding that has hit Russia, Thailand and Australia also will likely be more common, the report concludes.

David Easterling, chief of global climate applications at the National Climactic Data Center in North Carolina and one of the authors, called the findings "a wake-up call.''

But when it comes to hurricanes and their Pacific cousins known as typhoons, the alarm is considerably more muted. That's a significant shift from positions argued by some IPCC scientists in the past, who viewed the decade-long increase in storm numbers as compelling evidence of climate change at work. Some studies have suggested that rising sea temperatures could perhaps double the number of storms in the future.

The IPCC's official, more cautious position reflects both scientific consensus and new research into historic hurricane patterns, said Easterling. The report isn't ruling out impacts, he said, but "the bottom line is there is probably less confidence in the long-term increase in hurricanes than were reported earlier.''

The report amounts to vindication for the hurricane center's Landsea, who resigned from the IPCC in 2005, contending a fellow scientist had made "scientifically unsound'' statements linking global warming to increased hurricane formation.

By one measure, the number of named storms, the last decade has seen an unprecedented explosion of tropical cyclones. Including 2011, nine of the 15 busiest storm seasons have occurred since 2000, with activity peaking with 28 hurricanes and tropical storms in 2005. 

But Easterling and Landsea said the number of named storms has been skewed upward by advances in radar and other technology capable of detecting storms that were virtually invisible even a few decades ago. Landsea estimates some 240 storms may have been uncounted since 1851, when the official record book begins, including "shorties'' that last only a day or two and often spin harmlessly in the open Atlantic.

Toss out those shorties, Landsea said, and the trend line turns nearly flat. Other measures, including landfalls and intense storms, also haven't changed significantly over the last century, he said.

Instead, the numbers have swung from decade to decade, with hurricane development likely driven by other global weather patterns - among them La Nina, El Nino and the Atlantic Multidecadal Oscillation, a pattern of ocean temperature shifts that can last 20 to 40 years. Warm phases like the current one, in its 17th year, tend to produce more storms.

The IPCC does find it "likely" that climate change could increase both rainfall and average intensity but Landsea said computer models have estimated that wind speeds would rise only 1 to 3 percent. On a major Category 3 storm, that could ramp up winds an extra 1 to 5 mph.

"That's so small we can't even measure it,'' Landsea said.

There's little doubt rising sea temperature will provide hurricanes with more starting fuel but computer models also suggest formation may be blunted by more moisture in the overall atmosphere and increased windshear, which can shred developing storms. By Landsea's estimate, that could result in up to 25 percent fewer storms by century's end.

None of the findings, unfortunately, suggest hurricanes will become any less of a threat. Public safety concerns and economic losses are more likely to continue to soar, the IPCC finds, with rising sea levels and populations increasing along vulnerable coastlines - though those risks could be reduced by tougher building codes and restrictions on coastal building.

Some global-warming skeptics have pointed to Landsea's resignation from the IPCC, delivered in an open letter to , as evidence that the threat of climate change has been exaggerated.

The National Hurricane Center doesn't have an official position on climate change. Landsea does have a personal opinion: There is, he said, "quite a bit of evidence'' that manmade is real and poses an array of uncertain risks, including to hurricanes.

"We are doing an experiment with the atmosphere. We're adding all these and we're not sure what is going to happen,'' he said. "That makes me a little nervous.''

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Study: Warming to bring stronger hurricanes

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Dec 01, 2011
"The number of hurricanes that develop each year has more than doubled over the past century, an increase tied to global warming, according to a study released Sunday."
"Research Meteorologists See More Severe Storms Ahead: The Culprit -- Global Warming"
So why should anyone believe AGWites?

Dec 01, 2011
"According to Emanuel, on a global scale, the strength of storms corresponds with ocean temperatures: It goes up when temperatures go up, down when temperatures goes down.

Most scientists say the rise in sea surface temperature in the last 30 to 50 years is a signal of global warming.

"That's their conclusion, not mine," Emanuel said. "[But] it would follow reasonably well from this metric that the upswing [in intensity] is a result of global warming." "

Dec 01, 2011
This isn't surprising.
Hurricanes are infrequent rare events and the small number that occur per year makes tracking any trend over periods as short as decades, very problematic.
Imagine if you select 6 people who walk through a doorway over a year, and do so for 10 years. Would you be able to determine from the data any statistically significant change in height in the general population over that time?

No, I wouldn't. In fact, it would make me worry! Why ARE there so few? At some point in global warming do we hit a tipping point that is catastrophic? An increase so great & powerful that was predicted by something minor that we missed until it was too late. We really do need 2 put this one 2 rest. Network, all our supercomputers, all of them, & run projections through models of El Nino & La Nina & try to figure out where this is going & what 2 do about it. we should do this before Mother Nature has her own Black Friday & these storms start bringing their relatives

Dec 01, 2011

In a global warming scenario, it's not just the maximum water temperature that increases, but the AREA over which water temperatures in the 26.5c range exist. The isotherm moves northward as the poles and temperate zones heat faster than the equator and tropics. So the equator will heat by maybe 0.5c, while 30N heats by 1C, and 40N heats maybe 2 or 3C.

So the RANGE of hurricanes is likely to extend greatly to the North AND East into Europe in the atlantic basin, and possibly into California in the Pacific basin.

The intensity is limited not just by sea surface temps, but by lower stratosphere temps, of which the CO2 component of the greenhouse effect is theorized to actually COOL the lower stratosphere proportional to the tropospheric warming: Thus increasing the temperature difference further.

If your stratosphere cools maybe 5 or 10c, and your ocean warms 1 or 2c in the tropics and temperate zone, then max potential actually goes up about a full category.

Dec 01, 2011
But basicly, get a SST map from the SSD site of NOAA for August and September.

Take all the temperature lines Near 30N and add 1C.

Take all the temperature lines near or above 40N and add 2 or 3C, since the poles and temperate zones will heat more than the tropics.

the gulf hurricanes will only get slightly stronger, but the East Coast hurricanes will cover a much larger area of landfalls at any given intensity, and will probably be a full category stronger average max intensity by the time these conditions occur.


I'm not sure on the data for the northern oceans, but the Southern Ocean is currently heating by an average of 0.2C per decade, and that is the entire 4km deep water collumn.

Cyclones may become common in the South Atlantic and Southeast Pacific, rather than a "once per decade" event...

Again, it's not just the max temps. It's the range of 26.5c temps over a wider area, and changes in wind shear that matters

Dec 01, 2011
@ nanobanano

So my friend, are you of the opinion that the tracking, mapping, and projection data for the thermal, ocean-warming effects/footprint of El Nino and La Nina, will not be sufficient to measure both 'greatness' and power of the future Hurricanes??
I just cannot think of anything else powerful enough to effect the seas and oceans that is from this planet.
please enlighten...

Dec 02, 2011
This story buries the lead. Dr. Landsea resigned from the IPCC 4th assessment report because fellow scientists were claiming that there would be more hurricanes because of global warming. The news here proves Landsea was right, and the IPCC wrong. Objective measures of weather, sea level, ice packs, etc., show that IPCC predictions of catastrophe or significant problems are all wrong. Conditions are in fact well within historic norms. Temperature especially is normal, even below normal, when you look at the 10,000 year record since the last ice age. The IPCC is a fear generator, like all greenie operations.

Dec 02, 2011
Temperature especially is normal, even below normal, when you look at the 10,000 year record since the last ice age. The IPCC is a fear generator, like all greenie operations.

Can I say that's a lie?

Just now saw an update on Wunderground today, and most states in the United States had their top 5 or top 10 hottest summer on record, several had their all time hottest summer on record.

Most states in the united states have had their 10 hottest years on record all within the past 15 to 25 years.


Where? One or two isolated regions?

Much of Asia was actually 10f to 20f above normal through much of the summer this year.

The temperature is definitely higher now than it has been in at least 600 years, and ice levels in the arctic and in ice caps and other glaciers is lower than it has ever been in recorded history.

Dec 02, 2011
WE just set an ALL TIME record low annual maximum for world wide Sea Ice extent and beat the previous record low minimum arctic sea ice VOLUME by a factor of 10%...


Don't know where you got your "facts", but it's BS...

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