Sunday, July 05, 2009

As the world wobbles

The issue of increased damage from extreme weather driven disasters as a result of climate change is attracts the same polemic that the gallery previously observed about climate change and global warming.

  1. Starting Position: It ain't happening
  2. Fallback Position: It has noting to do with the enhanced greenhouse effect
  3. Fallfurtherback Position: There is no scientific proof, we need more research
  4. Fallmuchfurtherback Position: If the local left (relatively) party didn't insist on building on the coast or in flood planes there would not be a problem.
  5. Fallwayfurtherback Position: What have the Bangladeshi's ever done for us?
In many ways this resembles the progression we have seen throughout the history of climate change, and the answers given by the IPCC (and previous reports).
FAR: The unequivocal detection of the enhanced greenhouse effect is not likely for a decade or more.

SAR: The balance of evidence suggests a discernible human influence on global climate (considerable progress since the 1990 report in distinguishing between natural and anthropogenic influences on climate, because of: including aerosols; coupled models; pattern-based studies)

TAR: There is new and stronger evidence that most of the warming observed over the past 50 years is attributable to human activities

AR4: Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely (> 90% certainty) due to the observed increase in anthropogenic (human) greenhouse gas concentrations.
The state of the art can be found in a new paper by Schmidt, Klemper and Hoeppe that was previously commented on at Rabett Run. Particularly interesting is the correlation between sea surface temperature and tropical cyclone damage.

The bars in the figure to the right shows adjusted losses for tropical cyclones that made landfall in the US. The adjustments take account of socio-economic changes. The black line is a ten year smoothed average. The red line is the smoothed North Atlantic sea surface temperature. The good correlation of the losses with the sea surface temperature provide a cleft stick to hoist DenialCON 2 position holders on, leaving them the oxymoric position of asserting that sea surface temperature is independent of global warming. Eli is confident that they will be up to it tho.

As Chris pointed out, the conclusion brings us pretty close to having to invoke DenialCon 4.
annual adjusted losses since the beginning of the last cold phase (1971) show a positive trend, with an average annual rise of 4% that cannot be explained by socio-economic components. This increase can at least be interpreted as a climate variability impact. There is no evidence yet of any trend in tropical cyclone losses that can be attributed directly to anthropogenic climate change. But we advance the premise that if losses are affected by natural climate fluctuations, they are also likely to be affected by additional global warming due to anthropogenic climate change. This premise is supported by indications that the intensity of tropical cyclones is affected by anthropogenic climate change."
An objection to this has been raised on the basis that the trends do not extend back to the 1950s. File that one in the wishful thinking category given the physical correlation between global warming, sea surface temperature, and tropical cyclone intensity.

See Harold, not once was the name of the The Talented mentioned or even linked to.



Simon D said...


I like the DenialCon analogy. A new report questioning the link between fertilizer use (on corn) and hypoxia in the Gulf of Mexico, the National Corn Growers Association takes a novel approach to denial of science. Rather than take one position (no hypoxia, nitrogen is not to blame, corn is not to blame for the nitrogen, etc.) the report invokes all five DenialCon stages. I suppose the same can be said for Heartland's
"non-IPCC" reports

Nick Barnes said...

Two things about the chart:

1. Please explain the right-hand axis.

2. I have to say, it doesn't eyeball as very correlated. The red line maybe has an upward trend from the mid 80s. The blue (and therefore black) data is all over the place, with a crazy 2005 outlier (Katrina, I assume). Let's see a scatter-plot.

CapitalClimate said...

Since there are so many stronger pieces of evidence, why focus on the one atmospheric effect which is probably the most tenuous? Doesn't that just give the deniers a free strawman to beat up on? As Landsea and other tropical skeptics are fond of pointing out, SST is a necessary condition for cyclone development, but it is hardly sufficient. Wind shear, both horizontal and vertical, is extremely important, and it is influenced in complex ways by large-scale circulation responses to the balance of various forcings. Throwing landfall probability and damage impacts into the chain of evidence muddies the water even further.

Anonymous said...

Nick looks like your scatterplot can be found on p. 550 here:

From text:

"Figures 5.2.7a and 5.2.7b shows the lack of meaningful relationship between normalized U.S. hurricane damages (NHC data, transformed with the natural log) and North Atlantic sea surface
temperatures 1950-2005 and 1950-2004.47 The r-squared values are low with or without 2005
included, and the regression results are not statistically significant (p = 0.28 and 0.69 respectively).

There is consequently no systematic evidence that higher SSTs are systematically associated with larger losses."

chris colose said...

I'm very skeptical. Isolating natural hurricane losses, anthropogenic hurricane losses (or maybe something in the middle, i.e., hurricanes that would have happened anyway but were a few percent more intense), fully accounting for losses in the early part of the time series record, as well as increases in socio-economic infrastructure in vulnerable areas is pretty sketchy business...this is a new approach and something which should be investigated much further.

CoRev said...

CoRev also agrees that this correlation is at best forced. SST and land falling hurricane/typhoons and then into a densely populated area with high value structures gets just a little tenuous. At least for me.

CapitalClimate said...

Andrew caused historically high damage in a year (1992) with only 6 Atlantic storms.

Anonymous said...

Kerry Emanuel, among others has pointed out that there have been just too few hurricanes that have made landfall in the US to support the claim of increased damages due to global warming. he thinks it will be about 2050 or so before the statistics can say anything about such a claim, one way or the other.

"Thus while we can already detect trends in data for global hurricane activity considering the whole life of each storm, we estimate that it would take at least another 50 years to detect any long-term trend in U.S. landfalling hurricane statistics, so powerful is the role of chance in these numbers." -- Kerry Emanuel

The problem is actually very similar to trying to nail down the temperature trend over the short term with sparse data. Random fluctuation just plays too big a role to say anything with any great certainty.

The logic makes sense (increased SST's increase hurricane intensity which increases damages from any given storm), but logic is not the same as scientific evidence.

For example, other things may come into play. What if global warming also leads to increased wind shear which tends to limit storms?

Also, if it turns out that global warming produces stronger storms but fewer storms overall (as some scientists think may be the case), the collective damage might actually decrease, even though each bigger storm produces more damage than it would have in the absence of warming.

EliRabett said...

Hurricanes are tropical cyclones, not all tropical cyclones are hurricanes. Sometimes you see interesting parsing on this point.

However, who here believes that warmer sea surface temperatures won't lead to stronger tropical cyclones?

Anonymous said...

It is possible that "warmer sea surface temperatures will lead to stronger tropical cyclones" will turn out to be true for some regions of the globe, but not others.

"Global Warming Increases Wind Shear, Reduces Hurricanes, Climate Model Shows"

"Wind shear is one of the dominant controls to hurricane activity, and the models project substantial increases in the Atlantic," said Gabriel Vecchi, lead author of the paper and a research oceanographer at GFDL. "Based on historical relationships, the impact on hurricane activity of the projected shear change could be as large -- and in the opposite sense -- as that of the warming oceans."

"While other studies have linked global warming to an increase in hurricane intensity, this study is the first to identify changes in wind shear that could counteract these effects. "The environmental changes found here do not suggest a strong increase in tropical Atlantic hurricane activity during the 21st century," said Brian Soden, Rosenstiel School associate professor of meteorology and physical oceanography and the paper's co-author. However, the study does identify other regions, such as the western tropical Pacific, where global warming does cause the environment to become more favorable for hurricanes."

CapitalClimate said...

Here's another example of why the obvious ain't necessarily so:
Modiki El Niños and Atlantic hurricane activity
And hot may also be not.