Three other scientists testified at the briefing, but I am not interested in what they had to say. Shepherd's remarks are of interest because he is the President of a major scientific society. He was not at the briefing to present his personal opinions, but rather in his role as a leader and representative of the scientific community. Thus, in my view of the obligations of such a role, he had a duty to play it straight.
Unfortunately, as is so often a case when leaders in the climate science community find themselves before an audience of policy makers, on extreme events they go rogue, saying all sorts of things with little or no scientific basis. Even if the scientist includes many accurate statements in his/her remarks (such as the reality of significant risks of human-caused climate change), the presence of horsemeat ruins the lasagne.
Let's take a step back. The science on climate change, extreme events and disaster costs is clear and unambiguous. You don't need to take my word for it, you can find the science well summarized in the IPCC SREX. And if you don't like the IPCC you can find an array of peer-reviewed literature. I am happy to debate this topic with all comers as the data and analyses overwhelming support the claims below.
In a nutshell here is the state of the science (here I focus on the US as Shepherd did):
- US floods have not increased over a century or longer (same globally).
- US hurricane landfall frequency or intensity have not increased (in US for over a century or longer).
- US intense hurricane landfalls are currently in the longest drought (7 years+) ever documented.
- US tornadoes, especially the strongest ones, have not increased since at least 1950.
- US drought has decreased since the middle of the past century.
- US East Cost Winter Storms show no trends (here also).
- Disaster losses normalized for societal changes show no residual trends (US, other regions or globally).
- Trends in the costs of disasters are not a proxy for trends in climate phenomena.
What did Shepherd say in his briefing?
- He said his spouse can see the impacts of recent extremes
- Weather is now on steroids, like baseball players
- Weather is like your mood, climate is like your personality
- He cites two scientists quoted in The Guardian saying that all weather is affected by climate change
- The impact of climate change can be seen in the price of Cheerios
- The recent Northeast blizzard is related to climate change
- Suggests that climate change is "loading the dice for extremes"
As President of the AMS Shepherd does not have the luxury of using that platform to share his personal opinions on climate science that may diverge from that of the community which he represents, much less stretch or misrepresent broader findings. Leaders of important institutions of science -- like the AMS -- speak for more than themselves when presenting science in public fora. They also represent the credibility of their institution and climate science more generally.
In formal settings such as the briefing yesterday where experts meet politicians, I fully expect Democrats and Republicans to cherrypick experts convenient to the arguments they wish to see made. That is politics as usual. Leading scientific institutions play that same game with some considerable risk to their credibility.
My advice? On extreme events, please, just play it straight.