Tornadoes and climate change

I’m sure you’ve already seen the sad news about the tornado in Oklahoma - it looks like it has done a lot of damage and claimed a lot of lives.

Tornadoes are not uncommon in that area and it is almost impossible to make good forecasts of where they will hit as they are too small for computer forecast models to capture. Even the scientific understanding of how they form is not great as it’s really hard to get good measurements of them in their destructive phase.

I’m sure that the discussion will now turn to the role of climate change in this particular event but, as usual, that’s a very difficult question to ask despite recent efforts on this front. At one level it’s quite easy to speculate that if the warm air heading north from the Gulf of Mexico that fed the storm that spawned the tornado was warmer than it otherwise would have been then, yes: climate change could have made this event more likely and/or stronger.

But the atmosphere doesn’t really work like that and the number of complex factors required to produce any specific tornado makes the cause and effect arguments that are wrapped up in the  ”link to climate change” question very, very difficult.

But perhaps we think about this more statistically and ask whether tornadoes will get stronger and/or more likely in a warmer future climate.

Again, this is really difficult because climate models certainly don’t have the power (i.e. high enough resolution) to represent tornadoes. So you can’t just go through climate model data and count the tornadoes that it thinks will occur.

If we think statistically again, though, we can look for the change in larger scale conditions that usually produce tornadoes.

Unfortunately, this isn’t particularly clear either.

Whilst the increased warmth and moisture predicted by climate models will mean more energy would be available to developing tornadoes, the climate projections also show a decrease in the occurrence of the wind patterns that are needed to form tornadoes.

Nonetheless, one thing that does seem likely is that we can still reduce the likelihood of a stormier future world. If you compare the storminess of climate simulations with, say, ”medium” and “high” greenhouse gas concentrations (as done here) then the “medium” case looks better than the “high”.

More on Antarctic sea ice

I wrote a post recently on Antarctic sea ice where I only included sea ice extent at minimum month, mostly because it was a nice figure.

Anyway, I just noticed this nicer figure from a new paper in the International Journal of Climatology (Tareghian and Rasmussen, 2013):

Quantile regressions (20th, 50th, and 80th percentiles) and standard linear regression of monthly sea ice extent (1979–2010) for (a) the Northern Hemisphere and (b) the Southern Hemisphere from Tareghian and Rasmussen (2013)

This shows the difference in the annual trends as well as the seasonal ones.

Reference

Tareghian, R. and Rasmussen, P. (2013), Analysis of Arctic and Antarctic sea ice extent using quantile regression. Int. J. Climatol., 33: 1079–1086.

Climate quick fix! (But please sign this disclaimer first.)

Geoengineering sometimes looks like a good option: international agreements on greenhouse gas emission reductions don’t seem to be going anywhere so having a back-up plan to deal with global temperatures would be useful.

However, there are potentially big problems with tinkering with the climate system more than we already have.

Haywood et al. outline one of these problems in a new Nature Climate Change paper that was published this week.

They look at the response of the climate in models when you add aerosol particles to the stratosphere – this will reduce the amount of energy entering the climate system by reflecting some of it away.

The unintended consequences, however, are not good: global rainfall patterns change as a result of the intervention and could lead to droughts in some areas e.g. the Sahel. (These outcomes are sensitive to where the aerosol is added and, of course, are subject to all the usual model uncertainties.)

So it would seem that geoengineering might only be useful if there are international agreements on who takes responsibility for the outcomes. Best get those negotiations started ASAP then!

There’s some more comment in The Gaurdian.

Antarctic sea-ice growth in Nature Geoscience

There’s a new paper on Antarctic sea-ice in Nature Geoscience so I thought it might be a good time to have a quick look at how this story has developed recently. (The short version: the small increase in Antarctic sea ice is most likely a result of a complicated coruination of: density changes in the surface layer of the Southern Ocean (a result of temperature and salinity changes), which stops warm deep water reaching the surface and melting the sea ice; changing wind patterns (partially a result of ozone depletion) that leads to ice drift increase and increased sea ice extent; and melting from the bottom of ice shelves adding cool water to the ocean surface layer that further reduces deeper warm water reaching the surface and reducing sea ice melt.)

Firstly, though, why does anyone care about Antarctic sea-ice? Well, it’s been increasing a little recently. This isn’t quite what you’d expect in a changing climate where the change is being driven by an increase in energy being retained in the system by an increase in greenhouse gases in the atmosphere.

In contrast, we often hear about sea-ice loss in the Arctic, which is often linked with climate change. However, if we compare the Arctic loss with the Antarctic gain you can see that one is clearly more of an issue than the other:

Sea ice extent for the month when its at its minimum (i.e. the end of local summer) Source: James Hansen

Nonetheless, its still interesting to think about why Antarctic sea ice is increasing.

The best theory around five years ago (Zhang 2007) was that the surface layer of the Southern Ocean was changing density and that this stops the warmer water below getting to the surface and melting the sea ice. The change in density itself is driven by a couple of factors, such as increased evaporation from warmer Southern waters that increases rainfall in the seas around Antarctica and freshens the water and changes in salinity driven by the sea ice changes themselves (sea ice rejects salt as it forms).

Last year, the big advance was the use of satellite observations to show that changing wind patterns in the Southern Hemisphere (which I’ve written about here) were driving the sea ice extent increase via increased ice drift (Holland and Kwok 2012).

The new paper (Bintanja et al. 2013) shows that melting from the bottom of ice shelves – where the Antarctic glaciers flow out over the ocean – produces a layer of cold water that stops warmer water below reaching the surface and slowing sea-ice growth. Although,  Holland (of Holland and Kwok) isn’t convinced that the experiments are a good demonstration of the mechanism.

So this is quite a complicated situation to understand. However, the ocean and air temperatures around Antarctica aren’t decreasing so that isn’t the reason for the sea ice increase, even though it may seem like the most obvious. To find out the real reason you need to dig a little deeper.

In the immortal words of Father Jack Hackett…

“Award! Award! Award!”

To be more specific: I found out a few weeks ago that I’ve been awarded the Royal Meteorological Society‘s (RMetS) Michael Hunt Award, which is “for excellence in increasing the understanding of meteorology or its applied disciplines among members of the general public”. Get me!

And don’t worry, I’m sure it wasn’t given to me for this blog, which has only rarely been updated in the last year or so – I blame having kids and my change from postdoc to lecturer, which have occurred since I started blogging. I also do other outreach/public engagement things like school visits, Skeptics in the Pub talks, science festival events and wotnot. It’s usually a lot of fun and to get an award for doing it is great!

Oddly enough, though, my previous post on this blog was slightly critical of a recent RMetS Meeting on climate change communication; I’m glad that they didn’t hold that against me!

So, to continue that theme, I thought I’d make another couple of points about RMetS and how it communicates with the outside world…

Most of RMetS’ effort goes into their meetings and publications, which are excellent for academics but what about everyone else?

I know that they run events in schools and at science festivals, which is great.

The previous RMetS Chief Exec had a blog for a while (it was quite fun, I enjoyed the posts about his watch) and it’s now become a more general society blog but I think that there’s still room in the weather and climate blogosphere (ugh, never though I use that word seriously) for coverage of big issues. For example, The Carbon Brief has only been going since 2011ish and it has become an excellent resource. Whilst I suspect that RMetS want to keep it a bit more light-hearted, there’s still some low hanging fruit here that I’m sure RMetS could grab. Even the columns in the (recently departed) “theWeather” magazine would have made excellent blog posts that I’m sure would get widely read but they were never (as far as I know) made available online.

I loved “theWeather” magazine and it even won an award or two but, given the way that publishing and reading habits are changing, perhaps it wasn’t the time to launch a subscription only print magazine.

I just hope that the RMetS can find more of a place online where most people do their communicating these days, particularly in terms of climate change. (Whether that’s a good thing is another matter!)

What I would do is set up a network of early career meteorologists, climatologists, oceanographers etc. to run a collaborative blog on the RMetS website. One of the most interesting and exciting things I’ve done outreach-wise was the EPSRC-funded (now EPSRC-non-funded) NOISEmakers ambassadors scheme. It was great meeting up with scientists that you wouldn’t normally work with and discuss ideas (perhaps a little bit like the JASONs but not as serious!) In my case, this led to writing some nice general audience pieces, starting my own blog, networking with other people about communication and even working on papers and research proposals with people I met through NOISEmakers.

Finally, I also thought I should find out who Michael Hunt was and found this clip on youtube, you can see Hunt at 3.39, he’s got a good look!

Communicating Climate Science (but don’t mention the b-word)

Blog.

There, I said it.

Which, as far as I can remember, is more than it was mentioned in the 7 talks or during the panel discussion at yesterday’s RMetS meeting on Communicating Climate Science.

Just to re-iterate, in a 3 hour meeting about Communicating Climate Science I don’t remember anyone saying the word “blog”.

Also to be clear, I thought the meeting was really interesting and well worth going to to. But, looking back on the event, I’m amazed that I don’t think anyone mentioned the impact of blogging on climate science communication, how it could be used better by the community or even that it exists.

Which is odd because two of the speakers are very good bloggers (Alice Bell and Adam Corner) and I noticed a few in the audience (e.g. Tamsin Edwards and Bob Ward, who seems like a blogger without a blog, unless I’ve missed it!)

So, did anyone else notice this or did I just nod off at the wrong moment?

How much does Antarctica contribute to sea level rise? (And how should that be communicated?)

There’s an interesting new paper in Nature (King et al.) this week that looks at how much the Antarctic continental ice contributes to sea level changes. It initially caught my eye as it uses data from the GRACE satellites, which are very cool! They are twin satellites that can detect tiny changes in the distance between one another. These distance changes are driven by changes in the gravity field so it is then possible to work out how that relates to changes in mass at Earth’s surface.

King et al. aren’t the first to use GRACE to look at Antarctic mass change but they have used a new model of the way ice sheets affect the Earth’s surface. When this new model is used, you get quite a low number for the contribution of Antarctic mass loss to global sea level: 0.19mm ± 0.05mm (this is less than half of previous GRACE estimates of Antarctic mass loss to global sea level).

The first result I found for global average sea level rise for 1993-2009 was: 3.3 ± 0.4 mm per year (thanks wikipedia!) so you can see that it is a small contribution.

Anyway, I tweeted a link to this paper from my @Antarctic_news twitter account and then noticed a story about the paper in the Sydney Morning Herald and tweeted a link to that as well.

Someone quickly pointed out that the headline in the SMH was wrong – it said Antarctica was contributing 1mm to global sea level when it should be less than that (0.19mm ± 0.05mm). It turned out that Ben Cubby, who wrote the SMH article, had already noticed the mistake (and our tweets) and the headline was corrected by the next day. This is why the article has a rather clumsy headline now!

But the chat on twitter didn’t end there. Quite a few tweets were exchanged between myself, Ben and Barry Woods, who felt that Ben should have said ~0.2mm per year in his article rather than “less than a millimetre per year”, which is what he did say (and was probably why the sub-editor made a mistake with the headline).

Personally, I feel that either (~0.2mm or less than 1mm) would have been ok so tried to defend Ben’s choice of words. Both options sound quite small and, without the context of average global sea level change (which I doubt many people hold in their head), the more accurate figure doesn’t really add much. Moreover, the full passage that includes the “less than a millimetre per year” bit gives some important qualitative information that does contextualise the result:

While the continent contains enough frozen water to raise global sea levels by 59 metres should it ever all melt, the findings show it is currently contributing less than a millimetre per year. Professor King said the findings showed that sea levels had already been rising faster than they had for centuries without much extra water from the Antarctic ice sheet.

That last bit, which I’ve emboldened, seems to convey that the Antarctic contribution is small in comparison to global changes without using either of the numbers (i.e. 0.19mm ± 0.05mm and 3.3 ± 0.4 mm per year).

Someone else suggested that is was in the interest of “environmental activists” to maximise the contribution of Antarctica to sea level rise but I’m not sure that even makes sense: the view from King et al. seems even more worrying i.e. sea levels are rising without a large contribution from Antarctica.

So what was the point of this blog post? Maybe it was so that I could articulate my thoughts without twitter’s 140 character limit but I was also wondering what other people thought about how to communicate findings like this. Should journalists always use the figures straight from papers or are phrases like “less than a millimetre” ok if they make the article more accessible?

King MA, Bingham RJ, Moore P, Whitehouse PL, Bentley MJ, & Milne GA (2012). Lower satellite-gravimetry estimates of Antarctic sea-level contribution. Nature PMID: 23086145

Excellence all round!

Some sort of measure of relative “excellence” (top 0.1% in terms of citations) amongst a group of leading research nations.

I guess everyone would like to be excellent but that’s not possible unless everyone was average. But that would be pretty boring, right?

Anyway, we had an EPSRC person visit Brunel last week and they gave a talk on the EPSRC strategy. The main thing I remember is that they’re very interested in “excellence” and, if I recall correctly, they’d like to focus more of their funding on the excellent people.

And it turns out that we’re quite good at being excellent in the UK – if you have a look at the plot to the right, which featured in the talk, then you’ll see that we’re second only to the USA in terms of share of the top 0.1% of papers ranked in terms of citations. (As an example, the department I work in is doing pretty well in terms of citations in environment sciences.)

Well, good for us!

But it got me thinking. How did the excellent people become excellent? I would guess that it comes from giving quite a few people the opportunity to prove themselves, which probably requires some funding, and the excellent (or the lucky, right place, right time) people rise to the top. I’m not suggesting that mediocre ideas should be funded just that focussing funding on the already excellent end might be a bit short-sighted.

Ideally, what I would like to see is that scientific proposals were double blind reviewed (where authors and referees are anonymous) for scientific excellence so that excellent ideas can be identified without bias towards people who’d previously done excellent work. Obviously track record should also be considered but I see no reason why this can’t be done separately from the the assessment of excellence.

That sounds like an excellent system to me!

Stormy weather ahead? at @ScienceLondon SciBar

I gave a little talk last night at the SciBar in London. It was a lot of fun and hope people enjoyed it! I’d recommend that you go along to one of their future events.

So I was talking about some of my current research on future storminess. This was kind of based on a post I wrote for the Nature Soapbox Science blog a few months ago (and then re-posted here).

One of the issues with looking at convective storms, or thunderstorms, in computer climate models is the resolution of the model i.e. the size of the boxes that the model splits the atmosphere up into. Ideally you’d have very small boxes so that you can “build” the storms in the model. But that isn’t possible given current computing power.

To demonstrate the importance of this at the SciBar I brought along some lego, duplo and a cube and asked people to make the best storm they could (see picture). I hope that this worked!

How different models might see a thunderstorm, like the one in the picture at the top. So, from left to right, the lego model is how a quite high resolution weather model would see the cloud, the duplo cloud in the middle is how a low resolution weather model would build the cloud and, on the right, is how a climate model would see the cloud i.e. it doesn’t. Just to clarify, the butterfly and pig would not be included in the climate model

What do other people think about this method of explaining the effect of model resolution? I guess someone’s used it before but I quite liked it all the same.

(By the way, sorry I didn’t have any results to show at the talk! Keep an eye out here and I’ll post something when it’s ready to roll.)

Book review: Teaching What You Don’t Know by Therese Huston

Click to find it on Amazon

Short version

Brilliant, even if you know what you’re talking about. Loads of ideas for making university teaching and learning far more enjoyable for everyone.

Long version

So, the first module that I’ve had to coordinate on my own turned out to be something that only overlaps slightly with my research area – I got the Sustainable Development module. In this respect, the title of TWYDK jumped out at me as a potentially useful resource. UPDATE (28/03/2012): when I first posted this I didn’t mention that the book is based on American universities – I am assuming that analysis and ideas equally applicable elsewhere.

I suppose I could’ve just shown the brilliant xkcd comic on this topic (see below) and called it a day but I’m not sure that the students would have appreciated that.

Joking aside, the prevalence of academics teaching at university level on subjects that they have little or no expertise is something that Huston discusses at length from the perspective of the teacher and the student. The argument that I most associated with was that for “survey courses” or “cutting edge courses” (which I hope my SD module was) the experts are many different people for different topics and these topics develop very fast. In that respect, having a module led by someone with only limited experience in the area is not much of a problem.

Structure

I decided quite early on to go down the Problem Based Learning route for my module as I’d helped teach on a module at the University of Manchester that used the PBL model and I’d seen many of the students really engage with it. Huston also recommends this as a useful method of delivery for “content novices” as the key is defining interesting and relevant questions rather than compiling hours of lecture material.

As I’m now approaching the end of my module for the first year I’ve run it, I’m glad I did it this way and definitely feel that TWYDK gave me a bit more confidence to try something beyond a standard “Module = 12 x lectures + 1 coursework + 1 exam” model. I think that most of the students have taken to it as well and I’ve jotted down more ideas from TWYDK to improve the module again next year.

More than just TWYDK

Whilst going through the book, however, I started to pick up ideas for other lectures I give on topics that I do know well. In some cases these were very simple ideas but maybe being a “content expert” means that you ignore the little tricks to try to get the students to actually “learn” in favour of just delivering all your hard-earned wisdom.

I suspect that I engaged with this book because it tackled a specific problem but, in the process of reading it, made me think about more general teaching points. This is probably where TWYDK is such a success where more textbook-like higher education manuals barely get opened (you know, like that one with the blue stripe across the middle of the cover and pristine spine that you see in most lecturers’ offices, mine included).

Things I wasn’t so keen on…

Well, most of the book is based on a series of interviews with university teachers, I think Huston says that it’s around 20 interviews, I could be wrong. Whilst this set off my anecdote vs. data alarm bells I suppose a good teaching idea is still a good teaching idea so I’m willing to let it go! And other parts of the book are based on more robust stats so that made me happy.

My only other point of concern is that the book just kind of ends. In the introduction Huston suggests dipping in and out of chapters as you need to know stuff but I found that it flowed quite well and read it cover-to-cover. The only disappointment with this is that there isn’t a chapter bringing it all together. (In fact, the final chapter is advice for administrators, which I still read and found useful as it gave me a different perspective on my contribution to the department teaching load.) Still, who am I to talk? I couldn’t be bothered to think up a decent end to this blog post.

Details

Hardcover
Pages: 330
Publisher: Harvard University Press
ISBN-10: 0674035801