Close this search box.

Prof. Roger Pielke Jr. Answers AP’s Seth Borenstein’s questions on Typhoon Hiayan: ‘The scientific evidence does not presently support claims of attribution of the effects of greenhouse gas emissions on tropical cyclone behavior with respect to century-long trends ‘much less the behavior of individual storms’

Special to Climate Depot

Dr. Roger Pielke Jr., professor of environmental studies at the Center for Science and Technology Policy Research at the University of Colorado at Boulder. Also a Research Fellow, Risk Frontiers, Macquarie University

Dr. Pielke responded to questions about Typhoon Haiyan/Yolanda from Seth Borenstein of the Associated Press on November 11, 2013. 

Pielke Jr.: Seth Borenstein of AP sent me an email asking some questions, my quotes didn’t make it into his story, but here they are in 2 comments:

Here are ten questions:

1. What human factors do you see in play here in Typhoon Haiyan?

Roger Pielke Jr.: If you are referring to the physical qualities of Haiyan, then I will defer to the recent IPCC AR5: “In summary, this assessment does not revise the SREX conclusion of low confidence that any reported long-term (centennial) increases in tropical cyclone activity are robust, after accounting for past changes in observing capabilities.”

That means that the scientific evidence does not presently support claims of attribution of the effects of greenhouse gas emissions on tropical cyclone behavior with respect to century-long trends (much less the behavior of individual storms). The IPCC AR5 cites some of our peer-reviewed work in its report (Weinkle et al. 2012, Journal of Climate).

Our peer-reviewed work suggests that assuming model predictions for future changes in tropical cyclone behavior are perfectly accurate (for a range of models) that it will be many decades, even centuries, before such a signal can be detected in trend data. More generally, I have written: “In practical terms, on timescales of decision making a signal that cannot be seen is indistinguishable from a signal that does not exist”

Of course, there are scientists willing to go beyond what can be supported empirically to make claims at odds with the overwhelming scientific consensus on this subject — e.g., Mann, Francis, Masters are always good for inscrutable and unsupportable quotes. Such outlier views are welcomed, as help to push science forward. But they are also a minefield for journalists, politicians and activists who may cherry pick them as if they are somehow representative.

2. What about poverty and coastal development? How much of those were as factors?

RP: In general there is an inverse relationship between loss of life and property damage. The wealthier nations become the less loss of life in big disasters (again, in general). At the same time, more wealth also means more property damage.

While the details of Haiyan’s course of death and destruction will have to await post-disaster assessment, what we can say is that the development of warning systems and responses have led to a dramatic decrease in loss of life to tropical cyclones (and disasters generally) around the world. See:

Haiyan, and events like it, tell us that there is still much work to do in addressing vulnerability to disasters. The long-term trends tell us that we have a sense of what actions will be effective in that work.

3. How about construction quality or is this a case with winds (depending on who is measuring) of 150 or 200 mph, is construction no longer an issue?

RP: Construction quality, including standards, enforcement, etc. is always going to be important in locations exposed to high winds. When the intensity is such that it exceeds building capacity to withstand, then it is important to have plans in place for evacuation to safe zones or shelters. To suggest in any situation that “construction is no longer an issue” is probably the wrong way to think about the challenge – construction always matters.

4. What about disaster preparations, quality or lack thereof, as a factor?

RP: The Philippines have centuries of experience with typhoons and the tragedies that can result. The specific lessons from Haiyan (Yolanda there) should await a careful assessment of what worked well and what might be improved. It is premature to speculate.

5. What about sea level rise, especially that attributed to climate change?

RP: Sea level rise is inexorable and relatively slow in comparison to the surges associated with tropical cyclones. It is important to be aware of, especially in the context of long-term planning. It is not possible to identify a “sea level rise” signal in historical normalized losses from tropical cyclones, and of course, not a GHG-driven sea-level rise signal. More generally, when we are talking about 5 meter storm surges, I am not convinced that 3 mm/year of sea level rise is a big issue in the magnitude of disaster losses (because building and adaptation along the coast is continuous and in the context of where the sea is presently), even though sea level rise is (again) real and important to consider in long-term planning and will have economic and social consequences.

6. When you look at all the human factors and then look at all the natural factors, what percentage would you put at human-caused (including poverty, development, population, preparation, construction, and climate change related) and what part natural? And why?

RP: Sorry, I don’t understand this question? What part of what?

Disasters are well understood to be consequences of human development (As Gilbert White used to say, extremes are acts of God, disasters are acts of Man) — where we live, how we live, etc. So you could say that a disaster is 100% human caused. At the same time, without the extreme event there wouldn’t have been a disaster either. So you could say that the disaster was 100% natural caused. Not sure this is a useful question, though I do understand the urge to assign blame. A better question is, what actions can we be taken so that future storms have a lesser human impact?

7. This is an area that normally gets more tropical cyclones than anywhere else in the world and generally stronger ones. And the Philippines are 7000 islands smack in the middle, how much of this is unavoidable? And when we talk unavoidable, what about just avoiding living in dangerous places, does this count?

RP: The same question could be asked of Miami, San Francisco, Tokyo, or Boulder etc etc. As Dennis Mileti used to say, we cannot avoid disasters, but we can shape how we experience disasters. The Philippines are always going to experience tropical cyclones, some very extreme. Similarly, San Francisco is always going to experience earthquakes. The questions to be asked well before an event occurs (or in the aftermath of the most recent event) are how do we want to experience those disasters, and what can we do to shape those experiences via purpose action (which invokes issues of wealth, politics. capacity, etc.)?

8. There’s also a few human factors that lessen disasters _ warning, good construction, disaster preparations, etc. What were their roles here?

RP: Again, rather than speculate we should await rigorous post-disaster assessments. These are important questions that deserve thoughtful approaches.

9. In this case did human factors that lessen disasters outweigh or come close to outweighing human factors that exacerbate disasters? And why?

RP: Ill posed .. see #6.

10. In general, looking at the last decade of mega-disasters worldwide, are human factors worsening or lessening disaster effects? And why?

RP: Overall, globally and over decades, disasters from weather events are resulting in lower damages per unit of GDP and less loss of life. This is a sign that the world is collectively doing better. Events like Haiyan remind us that there is a lot of work still to do, and other very large, consequential disaster events (Japan and Boxing day tsunamis, etc.) also remind us that the human toll can still be very tragic. In this sense disasters are too important to merely serve as a talking point in the debate over climate change and greenhouse gas emissions.

Hope this helps, please follow up if anything is unclear etc.



Here is an exchange of letters in the FT on extremes, first I (Roger Pielke Jr.) wrote on 10/21:

October 21, 2013 12:27 am
Claims at odds with IPCC report
From Prof Roger Pielke Jr.

Sir, Julian Hunt and Johnny Chan write, in their article “We must face up to the rising threat from coastal storms” (October 17): “We
know that the frequency of heavy rain events, as well as rainfall intensity (amount of rain per unit of time), has already increased. This
has led to severe flooding becoming more frequent.”

This is factually incorrect. The Intergovernmental Panel on Climate Change concluded in its assessment report last month: “There
continues to be a lack of evidence and thus low confidence regarding the sign of trend in the magnitude and/or frequency of floods on a
global scale”.

Lord Hunt and Professor Chan also cite a 2010 WMO report to claim: “The World Meteorological Organisation’s committee on the
relationship between climate change and tropical cyclones expects global warming to cause the average intensity of tropical cyclones to
increase up to 11 per cent by 2100.”

This claim is also at odds with that of the recent IPCC report, which says: “ . . . it is likely that the global frequency of occurrence of
tropical cyclones will either decrease or remain essentially unchanged, concurrent with a likely increase in both global mean tropical
cyclone maximum wind speed and precipitation rates. The future influence of climate change on tropical cyclones is likely to vary by
region, but the specific characteristics of the changes are not yet well quantified and there is low confidence in region-specific
projections of frequency and intensity.”

While, in principle, there is no problem with scientists holding outlier views, in this case the authors have actually made errors in their
representation of the current state of the science.

Roger Pielke Jr, Professor and Director, Center for Science and Technology Policy Research, University of Colorado,
Boulder, CO, US


They respond today with this:

November 12, 2013 9:27 pm We have to keep examining data
From Lord Hunt and Prof Johnny Chan.

Sir, As meteorologists with some experience we were surprised by the accusation (Letters, October 21) by Professor Roger Pielke Jr (a
leading policy academic whose thesis about vulnerability we agree with) that our FT article “We must face up to the rising threat from
coastal storms” (October 17) was not based on good science, and contradicted the recent IPCC Working Group 1 Report.

Paragraph B1 of the report concludes that extreme weather events are likely to have become frequent, severe and last longer, with the
implication in other parts of the report (not stated very clearly) that these trends will continue, unless or until human influences on the
global climate are mitigated. The published data on extreme events mentioned in our article (some of which, although from highly
reputable institutions, had not been submitted or read by IPCC) provide details of where and how these events occur.

The IPCC Working Group 1 Report has done a fine job, but scientists need to keep looking at data and providing explanations about
trends in severe climatic and weather events, whether or not they coincide with the current IPCC consensus.

Julian Hunt, Former Director, British Meteorological Office; Johnny Chan, Chair, Tropical Cyclone Panel, World
Meteorological Organisation

Tue Nov 12, 02:49:00 PM MST