It’s the bomb

A friend asks “So what is up with this bomb cyclone term? Is it just a blizzard with a more compelling name? Or is it something unique that I have not experienced before now? Is bomb cyclone a technical term?”

Answer: like “polar vortex”, “bomb” is a term that has been used by meteorologists for many years but is just now being brought into popular usage by weather media. It refers to a winter storm over the ocean that strengthens very rapidly – the technical requirement is that the minimum surface pressure drops by at least 24 hectopascals (hPa, also known as millibars, or mb) in 24 hours. The term was brought into the scientific literature by Fred Sanders and John Gyakum in a 1980 paper, here:

http://journals.ametsoc.org/…/1520-0493(1980)108%3C1589%3AS…

a less technical and more recent discussion is here:

https://www.fastcompany.com/…/is-bomb-cyclone-even-a-real-t…

a bit more history and some quotes from Gyakum:

https://www.huffingtonpost.com/…/bomb-cyclone-definition_us…

And if you want to know more about the polar vortex while you’re at it: Darryn Waugh, Lorenzo Polvani and I wrote an article about that term for the Bulletin of the American Meteorological Society that is a bit more scientific than what you’ll find in the mass (or social) media, but more accessible than a typical peer-reviewed research article:

http://journals.ametsoc.org/doi/pdf/10.1175/BAMS-D-15-00212.1

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The unbelievable coincidence of Cyclone Ockhi, Mumbai and me

On Monday evening, I will travel to Mumbai, India. I am going there for a research project in which we are trying to assess the risk that Mumbai might someday be hit by a tropical cyclone, particularly one strong enough to cause a significant storm surge and a major disaster for this low-lying coastal megacity. The problem is scientifically interesting – and difficult – precisely because such an event has not happened in modern history. So one can’t use historical data as a guide, although we know the risk is not zero – we believe that it has probably happened sometime, but it’s very rare our records are just not long enough. One has to use models of some kind to assess the risk, and our problem is to develop, evaluate, and use those models. (And climate change is most likely increasing the risk, but that’s another issue.)

Anyway, at this very moment there is a cyclone, named Ockhi, in the Arabian Sea. It is forecast to pass quite close to Mumbai on Tuesday evening, precisely when my flight (booked several weeks ago, and planned long before that) is due to arrive there!

ockhi_track_sunday_1130_est

While the storm is pretty powerful now, it is forecast to weaken a lot before landfall, so it will probably not cause a major disaster. And the models have it making landfall a bit to the north of Mumbai anyway (although with the uncertainty in the track forecast, a more direct hit is still possible). So this probably won’t be quite the disaster our project aims to address, but still, the coincidence is profoundly spooky. There are only 1-2 cyclones on average each year in the Arabian Sea, and most of those never come anywhere near this close to Mumbai. It’s an *extremely unusual* event, and it’s happening *precisely* as I’m coming to town to study it.

Harvey commentary

Some further commentary on Harvey. Mostly (but not all) about the climate connection.

Global Warming’s Role in Hurricane Harvey (The Takeaway, NPR)

Why Harvey’s devastation is so severe (CNN)

Climate Change Didn’t Cause Hurricane Harvey, but It Made It Worse (Fortune)

Commentary by Columbia Scholars (not just me)

Meanwhile, Hurricane Irma is breaking records and looking truly fearsome in the Atlantic.

December 2015’s crazy weather

I’m in Oregon, where December has broken rainfall records east of the Cascades, and the Cascades themselves are deep in snow. I got to see some of it up by Mt. Hood yesterday on a Christmas Day family cross-country ski outing.

hood_xmas_15

Though that was beautiful, I’m still sad to be missing the record-breaking warmth back east. (I like warm weather; it’s not an accident that most of my research over my career to date has been about tropical meteorology.) To help myself experience it vicariously, I wrote an op-ed piece for CNN about what the probable causes are. It has even been translated into Spanish.

Patricia’s ultra-fast intensification

I have a piece in CNN today about the incredibly fast jump that Hurricane Patricia made from tropical storm to what some people are saying should be called “category 7”. I point out that this case shows vividly why we need advances in the science of hurricane intensity prediction, at the same time as funding for this work was severely cut earlier this year. And, I compare Patricia to The Hulk.

Earlier, before landfall, Allison Wing and Chia-Ying Lee wrote an expert but accessible analysis of what the storm was doing and how the forecast models failed to capture it.

patricia-1530_custom-deef5f687ea6077b391eaa49719236b181dd7b05-s900-c85

Sudden excitement in the forecast

Update: Tropical Depression Eleven has already been upgraded and is now Tropical Storm Joaquin.

Some weather models shifted their predictions today from what they had been just before. Now New York City, along with much of the rest of the northeast US, is in the headlights of a weather event with some potential. We are now in the forecast cone of uncertainty of a tropical cyclone: currently it’s Tropical Depression Eleven, could intensify to become Tropical Storm Joaquin. Here is the track forecast map from the National Hurricane Center:

:210443W5_NL_sm

There is still quite a lot of uncertainty with this system, with the GFS model predicting it to be less likely than the ECMWF does that we’ll be hit by this storm. There are faint echoes of Sandy in that model disagreement – the EC predicted landfall earlier than GFS did then too. It doesn’t look like Eleven/Joaquin stands much chance of becoming an event of that magnitude, though, at least not as a wind or surge event (though never say never, or at least not yet).

There does seem to be good potential for heavy rain. Maybe very heavy, as tropical moisture funnels up from the south into a cold front that will be hanging around our region for a few days. NOAA’s precipitation forecast for the next five days puts over five inches of rain on a very large stretch of real estate from the Mid-Atlantic up to northern Maine:

p120i

Some model runs are producing numbers as high as double that – around ten inches – for NYC. This is perhaps unlikely, but possible.

The media is starting to pick up on this. Jason Samenow of the Capital Weather Gang has a nice summary; Weather.com has picked it up; and here is a local NYC TV take on it. From a quick scan, this coverage looks reasonable. It’s giving a sense of what the more extreme outcomes could be, while clearly stating that the uncertainties are still significant. This is as it should be. This is in the “stay tuned” category.

Urgency and Uncertainty in Rolling Stone

Eric Holthaus has a recent piece in Rolling Stone enitled “The Point of No Return: Climate Change Nightmares Are Already Here.” The subtitle is “The worst predicted impacts of climate change are starting to happen — and much faster than climate scientists expected.”

It’s a good article. But it highlights the difficulty of talking about current extreme weather events and their relation to human-induced climate change. On the one hand, the essential message of the piece is to communicate urgency on climate and need for action. This is right and appropriate. And sentence by sentence, the individual statements about specific weather and climate phenomena are accurate (at least those where I have adequate expertise to make an evaluation).

On the other hand, the piece implicitly attributes a lot of individual weather and climate events – all of those it mentions, really, which is a long list – to human induced climate change. Some of those attributions are justified, but others aren’t.

In the cases where the attribution isn’t justified, Holthaus doesn’t explicitly make it, not line-by-line in the sentences talking about those events. I couldn’t find anything outright wrong at that level. The piece was, clearly, researched and written quite carefully and with deep respect for the science. But the attribution is there implicitly, through the piece’s headline, its subtitle, and its overall framing.

I’ve added some annotations at the site Climate Feedback (my annotations and others’ on this piece are not visible yet, as far as I can tell; soon, I think), a new site designed for scientists to evaluate the science content in popular articles on climate. Two of my comments are about Holthaus’ discussion of the ongoing El Niño and positive phase of the Pacific Decadal Oscillation. These two are enough to make the point I’m interested in here.

These two climate phenomena, manifest by slow changes in the sea surface temperature in various parts of the Pacific ocean are indeed having major impacts, as described well in the article. But most climate scientists consider these phenomena to be essentially natural. We can’t be certain that the current instances of El Niño and the Pacific Decadal Oscillation aren’t in any way connected to human induced climate change, but there is no convincing evidence of such a connection, to my knowledge. Holthaus doesn’t say there is one, but to my eye it’s clearly implied. The title and subtitle, as well as the overall framing of the piece, say that it’s a list of impacts of “climate change” – which presumably most will understand to mean “human induced climate change”.

I’m being critical on this issue because it’s one I struggle with myself, and because Holthaus is a thoughtful, serious and committed writer on climate, one who actively seeks criticism from scientists (I understand that he asked Climate Feedback to evaluate his piece). And because while I read the piece as making some implied claims that are outside what science can justify, I agree completely with its bottom line, and appreciate the force with which it comes across.

Human-induced climate change is real, is a grave threat to human society, and is already having significant impacts now. Some of the events Holthaus describes almost certainly do have some imprint of human influence: heat waves and ocean acidification, for example. And natural and human influences can’t be completely untangled. While the heat, drought and wildfire in the west now are likely caused in large part by natural variations in the Pacific sea surface temperature (El Nino and Pacific Decadal Oscillation), greenhouse gas warming adds extra heat, making the impacts worse.

And regardless of the causes of individual extreme weather and climate events now, the disasters they cause still tell us something about our vulnerabilities, and that is relevant to the longer-term climate change question. The human influence will grow larger in the future, as warming proceeds. It will eventually make some kinds of extreme events significantly, detectably more frequent or more intense, even if we can’t clearly detect that influence in individual events of that type happening now. (Tropical cyclones are a good example of this.) The current events can rightly be seen as harbingers, if nothing else.

Holthaus writes quite a bit about the recent paper by James Hansen and colleagues, which warns that sea level rise may occur much sooner and more severely than most of us had thought. This paper is controversial, and not yet even through peer review. But in my view it deserves the coverage it gets, here and elsewhere – its predictions may or may not be right, but it seems pretty clear that we can’t rule them out. Contrary to denialist lines of argument, the uncertainties in climate projections should make us more worried, not less.

What if Holthaus had made a more concerted effort to avoid any implication of human influence on events to which it wasn’t justified? In a piece with the title and subtitle that this one has, the simplest way to do that would have been not to write about those events at all. That would have meant leaving out some of the most serious and visible disasters going on right now in the US, where the main readership for this piece presumably is. Alternatively, the piece could have had a different title and subtitle (my guess is that these were written by an editor rather than by Holthaus himself), one that communicated that the piece was about events of both natural and human origins. Either way, would the sense of urgency have been diluted?

Professional scientists are sometimes criticized for under-communicating the urgency and reality of climate change, especialy when we talk about current extreme events. This criticism is often fair in my view. We talk so much about the uncertainties that we leave nonscientist audiences with the feeling that we don’t know anything. We do this, I think, because we are used to talking to each other. Being clear about uncertainties is an inherent part of scientific practice. Also, our colleagues already share our knowledge and understanding of the big picture on climate change – the consensus is real – so we don’t feel a need to restate that. We fail to recognize that that underlying knowledge is not shared outside our professional circles, and that it’s often appropriate to emphasize what we do know more than what we don’t.

Journalists, on the other hand, are often criticized by scientists (and others) for overstating the connection of extreme events to climate change by glossing over uncertainties – as I have done here, in my first few paragraphs above. This is also often fair, and as with scientists, similarly traceable to the daily realities of their jobs. Journalists are under great pressure to make it current, make it exciting, keep it simple. It’s easy to see how that leads to a little exaggeration and overstatement, whether by implication or outright.

If there’s a perfect solution I don’t know it. I’m glad that writers like Holthaus (and many other good ones) are grappling with the science and doing their best to keep it accurate while still getting the essential message on climate into the popular press. I don’t love everything about this Rolling Stone piece but I think we need more like it anyway.

Full disclosure: Eric Holthaus is an alumnus of Columbia University, where I teach, though I didn’t teach him when he was here and haven’t met him in person to my knowledge. He has interviewed me a couple of times for other pieces he has written, though not for this one in Rolling Stone. He wrote a very kind review of my book when it came out last fall.

The extreme state of the Pacific climate

I have a post up at the Columbia Earth Institute State of the Planet via the Initiative for Extreme Weather and Climate, on the current El Nino event, recent Madden-Julian Oscillation, typhoons and hurricanes, and everything else going on in the tropical Pacific now, as well as its impacts on the US, and the ramifications (including some pretty speculative ones) for the global climate.