Talking about tropical cyclones in Jeju: IWTC-VIII

I spent last week on Jeju Island, South Korea, for the Eighth International Workshop on Tropical Cyclones (IWTC-VIII) organized by the World Meteorological Organization (WMO). Every four years, the WMO convenes this meeting, which gets together forecasters and researchers from all over the world to review the last four years’ advances in the science of tropical cyclones (also known as hurricanes, typhoons etc.). It’s an invitation-only meeting, which reflects (or maybe is one of the causes of) the fact that tropical cyclone experts are a close-knit club. I had never been invited before, which I took to mean that I was not really part of the club. I guess I am now.

jungmun_basalt

View east along the south coast of Jeju Island, near Jungmun Beach. In the foreground are basalt columns formed by rapid cooling of lava.

In the months before the meeting, the scientists involved put together a report to the WMO summarizing the advances since the last meeting in both basic science and operational forecasting practices. The structure of the meeting reflects the structure of the report. There are five overarching topics, each of which is a chapter, and a session of the meeting: 1. Motion; 2. Cyclogenesis, intensity and intensity change; 3. Communication and effective warning systems; 4. Structure and structure change; 5. Beyond synoptic timescales. Each topic has multiple subtopics, each subtopic has a “rapporteur” (or sometimes two) who led a team of people in the writing of their part of the report; the overall topic has a “topic chair” who organizes all of the subtopic reports and writes an introduction to the whole chapter.

I was the topic chair for topic 5, “Beyond synoptic time scales”. The word “synoptic” here refers to the time scale of a typical tropical cyclone forecast, a few days. The subtopics were climate change, seasonal forecasting, and intraseasonal forecasting – in that order, decreasing the time horizon sequentially.Seasonal forecasts are forecasts of overall tropical cyclone activity (with no details about specific storms on specific dates) for a particular region, made months in advance. The most important phenomenon that controls TCs on this time scale and makes the forecasts possible is El Nino. The “intraseasonal” time scale, also known as “subseasonal”, covers everything shorter than that, but longer than the range of a typical weather forecast. So, about 10 days to a month or two. On this time scale, the most important single phenomenon (though not the only one) modulating TC activity is the Madden-Julian oscillation, or MJO (see also here, here, and here).

Although I wasn’t at previous IWTCs, my sense is that at the last few, climate change has been a contentious topic.  Around 2005, Katrina and the hyperactive Atlantic season of that year, combined with a couple of high-profile papers showing increasing trends in various measures of TC activity, caused a dramatic increase in the volume of research being done on the links between climate and TCs (and in the number of researchers doing it). Combined with some historical cultural differences between TC experts and climate scientists, this led to some growing pains in the field in the mid-late 2000s. A lot of that has been sorted out now. Not that we know everything or that everyone agrees on the fundamentals – far from it – but the field has advanced rapidly in a decade, and a lot of the early contention has shaken out. It’s much clearer what we know and what we don’t. So this part of the meeting, and the report, while not without debate, was actually relatively placid.

In my view the most exciting new developments have been in the intraseasonal arena. Just a few years ago – certainly a decade ago – weather forecast models could not predict the MJO to save their lives. The best ones have become dramatically better at it, and now show skill in MJO prediction out to as long as 4 weeks’ lead time. Since the MJO influences tropical cyclones, this – combined with broader overall improvement in the models – makes new kinds of forecasts possible, well beyond the 5-day time frame of current tropical cyclone forecasts.

Forecasts in this range, let’s say a week to 2-3 weeks, are just barely starting to come into view. They exist still mostly in research mode, and are mostly not yet issued to the public. There are a few exceptions; an example is the NOAA CPC Global Tropics Hazards and Benefits Outlook, a “climate-like” product which defines large areas in which things could happen in the next two weeks. Other, more weather forecast – like products are clearly possible, such as long-range forecasts of the track and intensity of a specific storm that are produced several days before it has formed (currently, no agency issues public track and intensity forecasts for a tropical cyclone before it actually exists) – such forecasts would not be highly accurate, but could give some indication of a threat to a broad region ten, or even 15-20 days in advance. The science and technology now exist, since just recently, to issue products with some skill in this range. But forecasters are conservative. Before they’ll issue such products, they need time to understand how good or bad these forecasts are, and to learn how to communicate them effectively so that users of the forecasts grasp the uncertainties.

hagupit

Typhoon Hagupit on December 4, 2014. Day-night visible image from the VIIRS sensor on the NPOESS satellite, from the CIRA TC web page.

Meanwhile, during the whole conference, Typhoon Hagupit was drawing closer to the Philippines. It was quite a fearsome storm at midweek, reaching Super Typhoon status. We had regular forecast briefings during the latter part of the conference, from the Japanese and Korean Meteorological Agencies. Thankfully the storm weakened quite a bit before landfall. Between that and better evacuations, it looks so far like it won’t be near the disaster that Haiyan was last year. But Hagpuit provided a constant vivid reminder, as one presenter said at the start of this talk, of “why we do this”.

US-China climate deal

I have an op-ed piece on CNN today about the new climate agreement between the US and China. The full piece is here, and the first three paragraphs below.

The agreement between President Obama and President Xi of China to reduce greenhouse gas emissions is the most important advance in the several decades-long history of international climate negotiations. It has been greeted with rage by those in Congress whose positions on the science are denialist or evasive (“I am not a scientist”). Their criticisms are specious and predictable.

But while most climate scientists I know are still sharing a period of joy following its announcement, some substantive criticisms of the agreement have also been raised. I want to address two of them here.

One is that the agreement doesn’t do enough to solve the problem of global warming. The other is that it doesn’t promise anything that wasn’t likely to happen anyway. Both of these criticisms have some truth, but neither diminishes the importance of what Presidents Obama and Xi have achieved.

Continue to full piece…

The size of it

What a day yesterday.

adam march photo

The organizers are saying 400,000 people. That is an astonishing number, but it did seem an endless throng. It didn’t move at all for the first couple of hours; we were wondering what was going on. Afterwards, I read somewhere that people filled the entire 4-mile length of the route, so some had to finish before others could start.

A friend who didn’t march said right after that she had thought she wouldn’t fit in because it was all “climate scientists and ex-hippies”. I said that wasn’t what I had seen. Ok, there were a few of both for sure, but you don’t get to 400K with just those factions. Most of the crowd looked pretty civilian to me.

I read a quote from someone today (can’t remember who now, nor find it) to the effect that this was the biggest political demonstration about anything in the USA in a very long time. True, no doubt; what came closest? Can’t have been anything more recent than the last Iraq war, if that. Certainly, I can remember no show of feet like this in my adult lifetime on any “environmental issue”, let alone climate.

The mass of the thing was profoundly heartening, because ignorance and denial still loom so large on this issue in this country, and nothing else seems able make a dent in the hard core of it. We know that facts from the mouths of scientists (or anyone) are not going to cut any ice with those who get their information from Fox News or the Wall Street Journal op-ed page – which unfortunately includes about half of Congress – because if they could, they would have by now. The only thing that will matter is sheer force of numbers. We showed that we had that.

On a much smaller scale, I carried an intentionally nerdy and obscure sign (thanks for the idea Michela) to create teachable moments. Indeed maybe half a dozen people asked me what it meant, allowing me to explain the mechanics of carbon emissions scenarios and IPCC assessments to interested citizens. Here’s a photo of me explaining it to one of New York’s finest:

nypd

We ended the day exhausted but happy. It was a privilege and a great thrill to have been able to march. We made the kids come, figuring that someday they’d appreciate  having been there. In the event, they seemed to appreciate it right then. There’s hope yet.

Back to school heat in NYC

In New York City, today’s temperature was forecast to be hotter than any yet this summer (though it hasn’t got there yet, there is still time). This is a little unusual since it is already September. I got an inquiry from a reporter today, containing the following questions:

“This summer’s seemingly mild weather was actually warmer than average.  Has climate change caused us to have a new normal?  And while  a 92 degree day on September 2nd is not unheard of, is there a larger case of climate change going on?”

Here is the answer I sent, edited and expanded a bit for this post:

Yes, there is certainly a new normal as far as temperature is concerned. It was a cool summer compared to recent decades, but those have been warm compared to the longer-term historical record, due in large part to human-induced global warming. Thus this summer was still warm compared to the long-term average (which means, since the mid-19th
century).

It’s worth also mentioning that the coolness this summer was limited to our half of the country; the west was extremely hot even compared to recent years, with bad forest fires in the Pacific NW, the drought in California etc.

One can’t assign the hot weather today to global warming though – at least not for the most part. It’s never a good idea to attribute a single day of weather to long-term trends, because the natural day-to-day (and even month-to-month or year-to-year) fluctuations are large. On the other hand, it is safe to say that global warming will mean more 92-degree days after Labor Day in years to come, compared to the past.

Because of natural variability, some summers are a little warmer, some are a little cooler. But global warming keeps continuously pushing them all warmer. So by sometime in mid-century, the coolest summer in any given decade is still very likely to be hotter than even the hottest summer that anyone alive now (or their parents, grandparents etc.) has yet experienced.

Climate Central did a nice piece recently which includes an online form allowing you to see how this summer stacked up against the historical record for many US cities. Here is the image I got by selecting San Francisco, where this summer broke the all-time record according to the graph – I’m not sure why the title is just “Near Record Warmth”. The bars are the different years ranked by their average temperature.

2014SummerWrapUp_sanfrancisco