Wednesday, November 13, 2013

I Can’t Say Haiyan Was Caused By Climate Change, But …….

I am NOT writing this because I am establishing an argument that Supertyphoon Haiyan was caused by climate change. Many that have followed my previous writings know that I am quite averse to the media or public question, “Did climate change cause Storm X?” It is an ill-posed question in my view (more on this later).

In the wake of  Superstorm Sandy, my colleague John Knox and I took a more measured perspective on the Sandy-Climate Change discussion with a firm anchor in the peer-reviewed science (

As someone that is asked about these topics often, it is important to capture a realistic, peer-reviewed science based perspective without a hostile or confrontational tone. The last statement is particularly important to me because there are people that disagree with me, at times, that I still consider friends or valued colleagues. Folks, we can disagree and be civil!

I am not shy about weighing in on these questions because I believe science literacy is critical.  There will be perspectives from all sides that will rush in to fill the vacuum.  Today, many get their science and context from the University of Wikipedia, Twitter  Tech, and Blog State University (the irony as I write this blog :)).

While I am not some “Random Joe” writing from my basement while munching on Gummy Bears (Black Forest please :)), there are people that know waaaaay more about hurricanes and climate processes than I do. However, I have published peer-reviewed papers on various hurricane topics (Knutson and Shepherd (2005), Shepherd et al. (2007), Anderson and Shepherd (2013).

Typhoon Haiyan challenged the all-time lowest record pressure recorded on the planet (e.g. by Typhoon Tip in 1979,   A humbling and disturbing fact is that my colleagues and I knew from various weather satellite signatures and intensity measures that it was going to be bad for the Philippines. Really Bad. First, the storm was a category 4-5 class storm. Second, it was affecting a socio-economically and place-based vulnerable population (KC and Shepherd 2013). Increasingly, as we saw with Sandy, it doesn’t even take a “major” hurricane to affect people and infrastructure. I recommend very good reads on storm surge by Jason Samenow ( of Capital Weather Gang and disaster vulnerability by Tim Kovach (

A friend of mine that always "cuts to the chase", Deke Arndt, has pointed out that the poor and least informed (i.e., most vulnerable) are often victimized the most by events like Haiyan. I still remember images from Katrina that reaffirm this point. Vulnerability is a function of exposure to the event, sensitivity to the event, and the ability to respond/adapt to the event.  Therefore, I strongly resonate with what Samenow and Kovach have written. Going forward, we have to focus not just on the storm, but the population characteristics in its path.

One other human dimension facet that I find interesting is a CNN report that suggested people would have responded with more urgency if “tsunami” warnings had been issued. Culturally, citizens in the Philippines were more heighted to “tsunami” warnings than “storm surge” warnings. This highlights the increasingly important recognition that communication/perception is as important as the “fancy” satellite and model technologies that have emerged for folks like me.

First or Accurate?

Unfortunately, the death toll numbers are now being estimated in the 4 to 5-figure range (and counting). Some initial media reports suggested that the Philippines dodged the “proverbial” bullet, but those reports were premature and even misleading to loved ones that had family in harms way (different discussion for a different day). In the rush to be first, we saw an information flow that was deceptive and counter to the “meteorological common sense” that many of us could see from the scale and intensity of the storm.

As I recall, we saw this with Hurricane Katrina in the United States. Newsflash, often in a storm of this magnitude, “no news” doesn’t mean things are ok, it probably means communications lines are down or people are getting their bearings straight. After seeing preliminary images, it is not surprising that information was slow to materialize.

Typhoons happen...

From a meteorological perspective, typhoons happen and tend to be stronger, on average, relative to their Atlantic brethren. There are “meteorological and oceanographic” reasons for this. October and November have been active in the typhoon basis. In the U.S., Atlantic Basin has been relatively quiet. The Earth doesn’t know the difference in basins and which is most active, it just generates “storms” in a quest to put the Earth on a “heat diet”. Earth has weather, ocean currents, and hurricanes because the tropics amass extra heat. The Earth attempts to transport that heat poleward and that is partially manifested in weather circulations, currents, and even hurricanes/typhoons.

There will be research to determine factors that led to Haiyan and other typhoons this season and why the Atlantic hurricanes never came. I am not going to speculate here.

Matt Daniel offers a nice discussion of why and how Haiyan may have been so strong at ( Capital Weather Gang explores the Atlantic season at (

Let’s allow the research to play out on both of them.

Bigger picture and climate context

I want to focus on the bigger picture for a moment.

A relative asked, “we’ve had strong storms in the past, right? I remember Camille. Are these different because of climate change or is there a hype factor?”

As noted earlier, I am not a big fan of the "Did Climate Change Cause Haiyan or Sandy?”  I believe there is a more appropriate why to frame that discussion. And to be clear, yes and there is still uncertainty with climate-hurricane linkages relative to other things (e.g., drought, heatwaves, etc.).

For me, one of the "success stories" in research comes from hurricane-climate change discourse. Colleagues, once in conflict on this topic, came together with an important paper on the role of natural and human-affected climate change on hurricane activity (see Knutson et al. 2011,  They generally suggested that the science is not as clear on frequency but warming climate would lead to more intense tropical systems, on average. The recent IPCC AR5 report, forthcoming National Climate Assessment Report, and other reports echo the findings of this paper too. Scientifically, we understand what this means but the public (and some scientists) will tend to watch "every storm or season" and evaluate this result against them. You just can’t do that. I can’t look at my stocks today and draw a conclusion about the year. I can’t conclude, because my son misses 2 free throws in a row, that I should encourage him to take up tennis rather than basketball. Understanding statistics and probability (mean, variance, and distributions) is critical. Yet, to be honest, many in the public (and many experts too as a forthcoming UGA study by John Knox and colleagues found) don’t even know what “40% chance of rainfall means.”

I am the first to frown when people make too much of an “active" or “quiet" tropical season in a climate context (either way) or narrowly focus on the Atlantic.

What's the Big Deal Now?, We Had Camille

Even before the "Steroid Era", Major League Baseball (MLB) players could hit home runs (i.e., there was a natural component to home runs in baseball in the same way that we had storms like Camille), but MLB also noticed more and longer homeruns too. So, they asked questions and found a steroid or performance enhancing drug issue. It is ok to ask questions, and I think that is what scientists have done and will do related to extreme events and climate change going forward. Attribution studies are challenging, but some progress is being made, see

I still cringe at the “one event” or “one new study” cycle that currently exists in our society. This cycle can really mislead the public and policymakers.

Science is a careful process that must be verified and vetted. It is not inherently tailor-made for the 24-hour news cycle and social media world. Concepts of the scientific method, experimentation, and uncertainty just don't grab headlines. They can even mislead the public. For example, uncertainty means "bad or lack of knowledge" to the public but to scientists, uncertainty means something different. In fact, the public consumes "uncertain" information every day.

Asking questions and research will help parse out the natural and human contributions. It is not an either/or, but likely both (e.g.,  I can't say for certain which specific home run was caused by a "pill or injection" in Major League Baseball, but I certainly know that, on average, something was different during the steroids era. I have continually been baffled by the quest to frame climate change as human or natural.  I study urban climate. I know that on a given morning in the Atlanta area, we will see temperature variability because of the natural weather variability and the human-contributed urban heat island.

I also cringe at those that immediately challenge the notion that storms like Sandy/Haiyan should not be questioned or researched from the perspective of a changing climate system. Again, please capture the nuance of what I wrote. I reject the  immediate notion of saying “Haiyan” was caused by climate change. However, I also reject the immediate notion of immediate skepticism for asking questions.  As I have noted many times, skepticism is inherent and vital in good science. But if skepticism is only directed in one direction, is it skepticism or bias?

I am not a confrontational person by nature, and I do not expect people to agree with every viewpoint that I hold. We have to get back to a place where science can play out without the vitriol, “slash and burn” tactics, and name-calling every time this type of event happens.

I participated in a study for the U.S. Navy by the National Academy of Science. In this report, we warned about vulnerabilities to climate change and potential climate refugees being a source of conflict and instability. We also warned that U.S. military assets would be stretched to the limited by humanitarian and disaster response. The report can be found at .

Admiral Locklear, the U.S. Pacific Commander, probably was thinking along such lines when he said, “ the biggest long-term security threat in the Pacific region is climate change.” (

I am not writing this to determine whether your ideology, belief system, or data lines up with Locklear’s statement.  I wrote this because I am heartbroken at the images that I continue to see, and I wanted to offer what I believe is reasonable, fair context, irrespective of your viewpoint.

Praying for 2 things as I write this: the victims of the Haiyan and spirited, respectful science discourse.


  1. I'll be very interested to see what comes out of the studies of this storm.

  2. Marshall, I respectfully disagree the science points to a role for climate change in Haiyam. I outline my reasons here:

    The IPCC report is quite definitive: At present, there is no increase in numbers or intensity of hurricanes. Ryan Maue's index shows neither a high value at present nor an upward trend.

    If you would like to explain how I have the science wrong, I am open to it provided it is science-based rather than opinion-based.

  3. Mike, I agree, I am not sure the Science points to anything related to Haiyan. So we actually agree. I was hopeful that this point would come forth in the blog. I think on Haiyan we are closer perhaps than apart...

  4. The exact reason I wrote this is because I was bothered by people saying Haiyan was caused by climate change. As I said today in the media, this storm would and could happen in a typhoon season irrespective of warming climate....

  5. My reference to IPCC is related to projections going forth and I tried to use language in the blog that states that there is less confidence in hurricane studies. Thanks for taking the time to read the blog and of course you know that you are one of the people I was referring to that may occasionally disagree but that I respect to the utmost :)

  6. Marshall, I have tremendous respect for you. Believe it or not (I'll email you the item privately if you wish), this column has been used to bolster "Haiyam caused by global warming" case.

    I posted to try to clarify the state of the science. In no way did I intend to criticize you. Mike

    1. I think the relevant quote from this blog post is, "I reject the immediate notion of saying 'Haiyan' was caused by climate change."

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  8. Hi Mike, I totally knew where you were coming from and didn't take it as criticism. Thanks for weighing in. As I shared, our discourse can and should be a model. Hope all is well.....I owe you Maggiano's soon :)

  9. In some respects the most telling quote is: "This highlights the increasingly important recognition that communication/perception is as important as the “fancy” satellite and model technologies that have emerged for folks like me". Perhaps we are at the point where investments in NWP are yielding diminishing returns, at least if we compare those potential returns made possible by sharpening resolution or tweaking the dynamic core to the potentially much greater effect of forecasts communicated in a way that will make decision-makers take appropriate, proactive measures. Only improved meteorological risk-based communication will allow us to make the most of the huge global investment in modeling and infrastructure. Up until now we've been content to put the warnings out there and hope that the correct decisions were taken. Clearly, more often than not, the inevitable aftermath is rescue and funerals. Which begs the question: what part of Cat-5 do decision makers not understand? Perhaps, as a community, its time we took on the challenge of making our work more effective. Budding meteorologists should have communicating risk as part of their mandatory studies. And we need to really promote the growing trend (at least in the West) of co-locating weather and emergency response officials in their operating locations. That breeds the familiarity that leads to trust. We're inclined to take advice from someone we trust, after all.