Fri Nov 19th, 2010 at 05:24:01 AM EST
In a diary a few weeks ago I indicated that the exaggeration of hurricane science, in the wake of the active 2005-2006 hurricane seasons and hurricane Katrina, didn't do harm to risk assessment and (re)insurance companies. I also indicated that science behind the 5-year projections of risk assessment companies have been shown to be flawed (and that, unsurprisingly, 5-year projections are horribly failing).
While commenting in said diary, I hit upon a feature that drew my interest: how much the world's largest reinsurance company just doesn't care about science, and continues to propagate nonsense, despite knowing better. You know, claims like these:
Munich Re - Two months to Cancún climate summit / Large number of weather extremes as strong indication of climate change
Munich Re's natural catastrophe database, the most comprehensive of its kind in the world, shows a marked increase in the number of weather-related events. For instance, globally there has been a more than threefold increase in loss-related floods since 1980 and more than double the number of windstorm natural catastrophes, with particularly heavy losses as a result of Atlantic hurricanes.
The rise in natural catastrophe losses is primarily due to socio-economic factors. In many countries, populations are rising, and more and more people moving into exposed areas. At the same time, greater prosperity is leading to higher property values. Nevertheless, it would seem that the only plausible explanation for the rise in weather-related catastrophes is climate change.
Except that increasing flood, windstorm and hurricane losses have not been attributed to global warming / climate change so far.
Meet Munich Re: the world's leading reinsurance company, based in Munich, Germany, and serial offender in communicating doom. This was the snippet that grabbed my attention:
ABC The Drum - Bookies buying into climate change race
Mr Rauch's original expertise was in earthquakes, but following devastating losses for the insurance industry from a series of storms in the European winter of 1990, his area of responsibility shifted to the analysis and modelling of meteorological risks.
And the verdict?
"Climate change, we believe, is a fact."
His pockets are already hurting.
"Based on our own loss experience, climate change we believe is a fact. It triggers natural disasters, atmospheric natural disasters, and the number of these natural disasters worldwide has more than doubled since the 1980s, driven by atmospheric perils, not by earthquakes or volcanic eruptions," Mr Rauch said.
"If we look at the sheer number of losses from natural catastrophes worldwide since the 1980s, more than $US1,600 billion in losses have occured. Most of them were actually weather-related, not earthquakes, not geophysical events."
Or here. Or here.
First of, I do applaud companies speaking out for initiatives to curb anthropogenic greenhouse gas emissions, which Munich Re and other important companies in the reinsurance branch (like the competing Swiss Re) do prominently. Unfortunately, Munich Re seems to frequently suffer from cognitive dissonance between their PR department and their own considerably qualified science group. Let me explain what I mean with that.
Starting with tropical cyclones, that proud icon of climate change, first a backtrack to 2005, when two prominent publications gained wider traction in the public domain. Both articles were released briefly after hurricane Katrina had struck New Orleans, and many people on the world were wondering if climate change had anything to do with that catastrophe.
The Webster et al. (2005) article argued that there were appearing more tropical cyclones in the Atlantic Basin, in short, the frequency was increasing (but the same article also argued against a global increase). On top of that, the Nature paper by Emanuel that had been released shortly before, argued that particularly for the Atlantic Basin, hurricanes were becoming increasingly more violent, that is, an increasing intensity, beyond the scale of natural variation. All of that sounded indeed disconcerting, but the hurricane scientists were heavily divided over these announced results, particularly by how these scientists had gotten their results. Nevertheless, both papers became cornerstones for the conclusions of the IPCC 2007 report on tropical cyclones, summarising them as following:
While other basins do not show overall increases in activity,
observations based on satellite observations of intensity (which start in the 1970s) suggest a shift in the proportion of tropical cyclones that reached the higher intensity (CAT 4 and CAT 5) from close to 20% of the total in the 1970s rising to 35% since the 1990s (Webster et al., 2005). Although challenged by some climatologists based on arguments of observational consistency, as quoted fromTrenberth et al., (2007) Section 3.8.3) "the trends found by Emanuel (2005) and Webster et al. (2005) appear to be robust in strong association with higher SSTs".
While being perfect fodder for Munich Re's press releases, the papers exacerbated divisions in the hurricane science community, with a classic divide running between modellers and data scrutinizers. Yet, unlike the Climate Wars over temperature proxies, experts kept talking and discussing with each other. And the result? An authoritative, key paper in Nature Geosciences published early this year, written by hurricane experts encompassing several camps, including Emanuel. So what does it read?
Tropical cyclones and climate change : Abstract : Nature Geoscience
Large amplitude fluctuations in the frequency and intensity of tropical cyclones greatly complicate both the detection of long-term trends and their attribution to rising levels of atmospheric greenhouse gases. Trend detection is further impeded by substantial limitations in the availability and quality of global historical records of tropical cyclones. Therefore, it remains uncertain whether past changes in tropical cyclone activity have exceeded the variability expected from natural causes.
Emphasis mine. That single sentence negates Webster et al. for the time being. How does it work out for Emanuel's paper?
The most significant cyclone intensity increases are found for the Atlantic Ocean basin, but the relative contributions to this increase from multidecadal variability (whether internal or aerosol forced) versus greenhouse-forced warming cannot yet be confidently determined.
And with one stroke, the IPCC chapter on tropical cyclones needs to be rewritten.
But wait! If we actually can't observe a global warming trend in tropical cyclones, how do we attribute a global warming signal to damage losses from Atlantic hurricanes - as Munich Re blithely announces? Well. We can't. And even before the recent Nature paper, damage losses from hurricanes in the Atlantic Basin had been analysed at least twice, with identical results:
Pielke et al. (2008):
[T]here is no remaining trend of increasing absolute damage in the data set, which follows the lack of trends in landfall frequency or intensity observed over the twentieth century.
Schmidt et al. (2009):
There is no evidence yet of any trend in tropical cyclone losses that can be attributed directly to anthropogenic climate change.
That last paper was actually written by scientists working for Munich Re... That's what I'd call cognitive dissonance - although the authors do stress that there is a higher chance climate change is playing a part in tropical cyclone losses. Except: it can't be shown.
Right, increasing hurricane damage for the USA can't be contributed just yet to climate change. Can happen. But USA is only a country. Doesn't say anything about the rest of the world! And I didn't even mention floods so far.
The analysis of twenty-two disaster loss studies shows that economic losses from various weather related natural hazards, such as storms, tropical cyclones, floods, and small-scale weather events such as wildfires and hailstorms, have increased around the globe. The 10 studies show no trends in losses, corrected for changes (increases) in population and capital at risk, that could be attributed to anthropogenic climate change. Therefore it can be concluded that anthropogenic climate change so far has not had a significant impact on losses from natural disasters.
You know, I could next point everyone to this study on flood losses in Europe showing no correlation between increased flood damage and climate change, based on data amongst others from Munich Re but I think the point I wanted to make is clear by now.
All listed studies are prominent, solid science publications, all available in the public domain. I will post a diary the moment I find studies that conclusively show a linkage between climate change and catastrophe losses. Promise. Because, in all fairness, that there will be increasing (normalised) catastrophe losses with increasing global temperatures does look guaranteed - except that this is a long term prediction. But it's simply not the reality of today: in terms of major catastrophes losses, a climate change signal has not be attributed so far by scientific research. The subjects are complex, many factors contribute, the variability in the data has been too large so far to determine a trend.
Yet, incredibly convenient, unsubstantiated doom is sold by the world's leading company selling reinsurance. Whom would you believe?