Crikey



Hot enough for you? A meteorological explanation of the heatwave

hot

It’s too darn hot — and it’s going to get hotter. Get ready for the mercury to notch up a couple more degrees, with today on track to be the hottest day of the heatwave. Many towns and cities are set to break all-time records in what is now day four or five of sweltering conditions.

We are sweating through Australia’s second major heatwave for 2014 (and we’re just two weeks in). And it comes after the nation’s hottest year in over 100 years on records.

So why is it so bloody hot? From a weather perspective, it’s a pretty stock-standard scenario. From a climate perspective, it is anything but stock standard. The concern (and reality) is that this —  longer, hotter, more frequent heatwaves — are becoming stock standard. It is no longer a prediction. We are living in a changing, warming climate.

Weather-wise, one of the main culprits of the heatwave is a “blocking high” in the Tasman Sea that is churning hot northerly winds over south-east Australia. Normally, a high moves on after a couple of days, allowing cooler systems from the south carrying cold air to replace the heat and provide some relief. But this high isn’t moving on — not only is it deflecting cool changes, it is also the mechanism that is carrying hot air towards the south-east, day in day out.

Fortunately, it is moving  away later Friday, so after two more days of record-breaking heat, Adelaide is forecast to get a cool change late Friday afternoon and Melbourne late Friday evening.

Blocking highs are usually a primary cause of heatwaves. But what is extraordinary about this heatwave (and more recent ones) is how hot the heat source is and the fact that there isn’t a phenomena such as El Nino “pushing” the weather towards hotter conditions.

This record-breaking heat is occurring in “neutral” El Nino conditions. A quick refresh: during a strong El Nino we typically see our worst droughts/heatwaves in south-east Australia, and during a strong La Nina we typically see above-average rainfall and cooler temperatures over eastern Australia. So breaking heat records for duration and intensity in these current neutral El Nino conditions is like a race car driver recording his fastest speed in rain with poor tyres.

So what’s to come?

The frequency, duration and intensity of both heatwaves and hot days have increased in the last 30-40 years, and record hot days are outweighing record cold days by three to one. Australia’s longer, hotter and more frequent heatwaves are consistent with climate change predictions — and the trend is expected to continue. Of course, there will still be cold days and cold spells — that is just the weather — but the overall climate trend is one of warming.

*Magdalena Roze presents weather on Channel Ten news bulletins and tweets at @magdalena_roze

Tags: , , ,

Categories: Australia, ENVIRONMENT

32 Responses

Comments page: 1 |
  1. MR,so the frequency, duration and intensity of heatwaves has increased and this is consistent with climate change predictions so, then why do we have climate skeptics running this country ably supported by the gutter , and not so gutter, press such as recent SMH artcles by Tom Switzer.
    Thank you for an experts viewpoint, not just some LNP flunky pushing the carbon energy industry barrow.

    by MJPC on Jan 16, 2014 at 12:45 pm

  2. Sad isn’t it when we had such a vicious attack dog as opposition leader in Abbott who has gathered business druggies and pay members like Hunt who even denies the evidence of his own education, that the penny has not dropped for these self serving people. Abbott will be doing a lot of coughing into his hand if he ever allows the media to ask him why he is acting against the interest of humanity in not being a leader to tackle climate change.

    by K.D. Afford on Jan 16, 2014 at 12:49 pm

  3. Nice clear explanation MR. Thanks

    by paddy on Jan 16, 2014 at 1:02 pm

  4. I thought the government was taking “direct action” to stop this sort of thing happening? Maybe we are not being told what they are doing because of “operational” reasons. It certainly could not be the case that they are doing nothing, could it?

    by Stuart Coyle on Jan 16, 2014 at 1:15 pm

  5. In addition to El Niño/ENSO, Roze could also have mentioned the related Pacific Decadal Oscillation. That we are presently in a cool phase of the PDO has been recently identified as the main reason why global warming has slowed since 1998 (covered in the latest Nature, out today nature.com/news/climate-change-the-case-of-the-missing-heat-1.14525). It turns out the negative phase of the PDO that commenced in 1998 is the likely reason why increased heat has been going into the ocean instead of the atmosphere, accentuating the rain/bald tyres of Roze’s metaphor.

    The PDO reverses with a period of 15-30 years, i.e. it could do so at any time from now on. When it does, we will get more and stronger El Niños, and Australian temperature rise will increase rapidly.

    by Mark Duffett on Jan 16, 2014 at 1:56 pm

  6. Conservatives such as Abbott, Cardinal Pell, Tom Switzer, Rupert Murdoch et al will never, even in the face of glaring evidence, never admit that climate change has been brought about by human activity. Why? Because it plays into the hands of their political enemies, the progressives, and especially gives Greenies oxygen. Admitting that human based industrialisation caused this is a basic contraposition to conservative thinking.

    by Honest Johnny on Jan 16, 2014 at 2:16 pm

  7. If anyone thinks there is no global warming, they should try living here in Adelaide as we have all done this week. It is very hot and very uncomfortable. There has been a big increase in heat related health issues, especially for the elderly.
    To do nothing about the cause of these extreme temperatures is criminally negligent. I hope Abbott and his motley crew are proud of the increased suffering they are ignoring.
    Guess that’s okay, so long as their mates can continue to make squillions!

    by CML on Jan 16, 2014 at 3:29 pm

  8. Extreme heatwave? “Oh, we’ve had hot days in the past, and we’ll have them again.”

    Extreme cold snap? “Where’s your global warming now?”

    Extreme bushfires? “YOU’RE POLITICISING TRAGEDY!”

    by Charlie Maigne on Jan 16, 2014 at 4:25 pm

  9. What I really hate is those that say that the scientists are in it for the money. If they actually were, they’d be spouting whatever popped into the oil companies minds, as there’s orders of magnitude more to be made in non-renewables than there is in scientific grants.

    by Jimmyhaz on Jan 16, 2014 at 4:36 pm

  10. It won’t be long before TT & his Uglies declare a “war on science” - that way there will be no need for pressers or information as it would aid … errr.. the aahh.. atmospheric enemy.
    Cue Robbie Z - “Ya don’t need a Weatherman to know which way the wind blows”.

    by AR on Jan 16, 2014 at 6:14 pm

  11. @Stuart Coyle at 1:15 pm

    The guy who runs the government, chief sceptic himself PM Abbott, did take Direct
    Action over the sweltering Xmas: he took himself off, en famille, to a ski resort in the French Alps!
    It’s his Marie Antoinette moment: Let them go to a ski resort!

    by michael r james on Jan 16, 2014 at 7:42 pm

  12. With the recent cool spell in Melbourne, the high pressure systems were centered on the line of the South Australia/Northern Territory border bringing cool onshore winds. The high pressure system responsible for this extreme heat has its centre on the line of Hobart, directing winds over the hot & arid interior. The position of the high must be influenced by tropical dynamics & Kevin Long on his site ‘The Long View’ adds the effect of pollution from China as another dynamic influencing local weather. Worth a squiz.

    by Repete on Jan 17, 2014 at 1:36 pm

  13. Well some records are made to be broken.. What was going on in bloody 1939? - surely Adelaide deserves a new record after all that media hype.

    With the climateers willing more records to boost their case - surely they must need something after the Antarctic sea ice fiasco.

    A 0.2 degree hotter Mildura trumps a ship of fools stuck in the ice for 10 days where Mawson blissfully sailed free 100 years ago.

    by Ken Lambert on Jan 18, 2014 at 12:27 am

  14. @Ken Lambert at 12:27 am

    At the risk of feeding the troll, there was a cartoon in one of today’s weekend papers that has your name stamped on it. It shows a man, probably Maurice Newman, with his head plunged ostrich-like in the sand with the thought-bubble: Hmm, this sand is bloody hot!
    ………………………
    “Before the 2009 heatwave that primed Victoria for the Black Saturday bushfires, Melbourne had never recorded a day where the temperature averaged above 35 degrees. That event delivered two of them.
    This week’s heatwave …. delivered four days over 41 degrees — in a row.”

    And do you understand that warming means more and bigger lumps of ice breaking off Antarctica and floating into the Southern Ocean? (Though the reality is that it was the strong wind that forced the ice together that locked in those boats.)

    by michael r james on Jan 18, 2014 at 5:46 pm

  15. michael r james

    You really want to get your facts from somewhere other than the skeptical science blog.

    SIPEX will tell you what sea ice is: “Sea ice is frozen sea water that forms in the Arctic Ocean in the Northern Hemisphere, and in the Southern Ocean surrounding Antarctica in the Southern Hemisphere.”

    Frozen sea water is not a bunch of icebergs which calve off land glaciers. Ya don’t drive through icebergs with ice breakers - ya just avoid them bigtime.

    Where did you get this from: “Before the 2009 heatwave that primed Victoria for the Black Saturday bushfires, Melbourne had never recorded a day where the temperature averaged above 35 degrees.”

    Weatherzone and other sites say this: Record Maximums for and average number of days above 35 degC for Melbourne are:

    Maximums Average Days above 35 degC
    OCT: 36.9 degC 0.1
    NOV: 40.9 0.6
    DEC: 43.7 2.0
    JAN: 45.6 3.6
    FEB: 46.4 2.7
    MAR: 41.7 1.0

    Melbourne averages 9.8 days per year above 35 degC. This is from 158 years of records.

    Your Melbourne temperature statement is nonsense.

    by Ken Lambert on Jan 19, 2014 at 12:12 am

  16. michael r james seems to be correct. The MV Akademik Shokalskiy was trapped by icebergs broken off from the Mertz glacier, not by frozen seawater.

    But even if it had been sea ice, it’s easy to take a simplistic interpretation of events and scoff when someone tells you about regional effects and natural variability. But climate change is nothing if not complicated. The IPCC’s reports don’t take up thousands of pages just to say “everything is uniformly hot now”.

    You’ll notice that scientists and science reporters are very careful *not* to take the current heat waves as conclusive evidence of climate change, because they acknowledge that individual events (whether hot or cold) are statistically meaningless. Rather, they point out that the heat waves are representative of what we already know we can expect from climate change, based on aggregate data.

    by Dave C on Jan 19, 2014 at 3:20 am

  17. Dave C

    Have a look at this video and tell me how many icebergs you see?

    the white stuff around the ship is SEA ICE - kind of flat, cold and 1 or 2 metres thick - the sort of stuff you cn run around on while waiting for helicopter rescue.

    http://www.news.com.au/national/passengers-on-russian-mv-akademik-shokalskiy-ship-stranded-in-antarctic-to-be-airlifted/story-fncynjr2-1226793202950#ooid=NkdjQ5ajplEe6aVCkyehG718HOgxDbX7

    by Ken Lambert on Jan 19, 2014 at 10:34 am

  18. Ken Lambert

    I’m not sure how you think you can tell anything from that video. As I understand it, it had also been snowing.

    by Dave C on Jan 19, 2014 at 11:57 am

  19. Sorry for getting, erm, stranded a little off topic.

    Just thought I’d add this, for further reference:

    Turney later told FoxNews.com the ice surrounding his ship is old, rather than recently formed, and likely from a particular 75 mile-long iceberg [originally from the Mertz Glacier] that broke apart three years ago. Climate change may have prompted the iceberg to shatter and float into the previously open sea where the mostly Australian team finds itself stranded, Turney said.

    source

    by Dave C on Jan 19, 2014 at 1:14 pm

  20. @Ken Lambert Sunday, 19 January 2014 at 12:12 am

    Check out the use of the word “average” in context of “daily”. Sustained high temperature not some “Record Maximum” is what defines a heat wave.

    Must have too much sand in your eyes and ears, and probably suffering near heat-stroke too. Possibly CO2-toxosis too — unrelated to too much carbon in the atmosphere, just too much rebreathing in that enclosed bubble of yours, KL.

    by michael r james on Jan 19, 2014 at 3:03 pm

  21. Ken Lambert…
    http://seattletimes.com/html/photogalleries/living277/4.html

    by WelBil on Jan 19, 2014 at 4:34 pm

  22. Dave C

    Turney probably told FoxNews that in the certain knowledge that they would believe anything.

    by Ken Lambert on Jan 19, 2014 at 11:20 pm

  23. Dave C

    Its sea ice Dave C. Read all the repors. Look at the pictures - unless the Aurora Australia pic is a file photo it is definitely in sea ice 20 odd miles away from Turney.

    Are you seriously asking us to believe that a 75 mile long glacier ‘shatters’ due to global warming, lasts 3 years through 2 previous summers which were apparently pretty ice free in the waters in question, and ends up doing a great impersonation of sea ice around Mr Turney’s boat 3 years later?? 97% would not.

    by Ken Lambert on Jan 19, 2014 at 11:31 pm

  24. Ken Lambert

    I’m not asking you to believe *me*. What would I know about Antarctic maritime navigation?

    I’ve merely read three articles now asserting that the ship was trapped by ice from the Mertz Glacier (and none that seem to dispute this): number #2, and number #3.

    You’re welcome to jump in at any point and provide some evidence, beyond your own incredulity, cynicism and amateur ice sleuthing, that these accounts are incorrect.

    by Dave C on Jan 20, 2014 at 3:41 am

  25. Dave C

    Why don’t we pick a nice middle of the road newspaper like the SMH of the mildly pink Fairfax stable: This is a quote from Dr Rob Massom here:

    http://www.smh.com.au/travel/travel-incidents/third-vessel-heads-to-rescue-passengers-on-akademik-shokalskiy-trapped-in-antarctic-ice-20131229-301rp.html

    Rob Massom, an expert in sea ice at the Australian Antarctic Division and Climate Change and Ecosystems Co-operative Research Centre, said it was not unknown for sea ice to form into tight-packed ice very quickly.

    It formed from freezing of the surface of the ocean at minus 1.8 degrees, Dr Massom said.

    ”Although it’s summertime, the ice can blow around and the area can change very quickly, causing ships to get penned in the ice,” he said.

    Sea ice packs could also raft up on top of each other, doubling the thickness of the ice and forming pressure ridges several metres thick, he said. Sea ice could occur anywhere around the cost of Antarctica, but that particular area had changed due to the calving of icebergs - when icebergs break away from the land ice and float away.” endquote

    So the part played by icebergs is not to shatter into sea ice trapping Mr Turney’s boat, but to “change the area” which can only mean changing the circulation patterns of the wind and current driven sea ice.

    Make no mistake though - Dr Massom identifies clearly how sea ice forms from freezing sea water at -1.8 degC and can pack and ridge to trap a ship. No mention of Mr Turney’s shattered 3 year old land ice which came from the Mertz glacier.

    Turney’s assertion of being trapped in ice from old icebergs shattered by global warming is clearly designed to get a warmist angle on the farce playing out on the ship of fools.

    by Ken Lambert on Jan 21, 2014 at 12:18 am

  26. Ken Lambert

    I applaud your efforts to find an actual source, but it’s not exactly a smoking gun you’ve got there.

    It looks to me that Rob Massom is speculating about conditions rather than providing an account of what actually happened. You’ve read a lot into what he says about “changing the area”. Could he not, for instance, be referring to small icebergs frozen together? I don’t know, but that seems like a vaguely plausible interpretation to me, not being an expert myself.

    It’s a big leap of logic for you to say it “can only mean changing the circulation patterns of wind and current driven sea ice”.

    Why not entertain the testimony of someone — Turney — who was actually there? You have no reason to dismiss the man other than that his account of the facts, as an first-hand expert, was not to your liking as an armchair commentator.

    by Dave C on Jan 21, 2014 at 12:41 pm

  27. Dave C

    Could he not, for instance, be referring to small icebergs frozen together? I don’t know, but that seems like a vaguely plausible interpretation to me, not being an expert myself.”

    Vaguely plausible small icebergs frozen together but no sea ice? Is that the Turney explanation?

    How about lots of sea ice with a few icebergs of all shapes and sizes?

    by Ken Lambert on Jan 22, 2014 at 12:00 am

  28. Ken Lambert

    Has your point morphed from “the ship was trapped solely by the sea freezing around it” into “there must have been at least some frozen seawater”? Because yes, I’ll concede the latter is likely. Something was probably “gluing” the icebergs together, so to speak. But it’s still really the icebergs doing the trapping of the ship, isn’t it? One presumes it’s much easier for a ship to become stuck in ice if the major chunks of ice are already there.

    (And it’s really just the existence of the icebergs that provides the dreaded “warmist angle”.)

    For reference, there is a more detailed explanation of the circumstances of the Mertz Glacier and the nature of the ice on this page (and probably elsewhere as well). It seems it was frozen sea water after all (silly me)! But old, multi-year ice nonetheless, not new ice that just formed around the ship. This ice had been trapped by the Mertz Glacier Tongue, but set free when the tongue snapped off.

    I suspect the reported version of Turney’s remarks may have suffered from some imprecise (but innocent) paraphrasing and simplification by Fox News. Such things are known to happen in science reporting.

    by Dave C on Jan 22, 2014 at 1:21 am

  29. Dave C

    You say “For reference, there is a more detailed explanation of the circumstances of the Mertz Glacier and the nature of the ice on this page (and probably elsewhere as well). It seems it was frozen sea water after all (silly me)! But old, multi-year ice nonetheless, not new ice that just formed around the ship.”

    Indeed silly you. So it was sea ice, not shattered glacier ice (which is fresh frozen water from snow fall by the way). Nothing strange about glaciers calving ice bergs either. Thats what glaciers do.

    Multi year sea ice is good evidence that temperatures stayed low enough through more than one summer for it to survive.

    Hardly a good indicator of warming.

    Don’t forget that reduced multi year sea ice in the Arctic summer is heralded by the warmists as great evidence for human induced warming.

    Anyway Turney and his climateers are back in Hobart so he can explain his shattered ice berg/sea ice entrapment to a more educated audience.

    by Ken Lambert on Jan 23, 2014 at 12:14 am

  30. Ken Lambert

    I do believe we have established a set of shared facts! And they say Internet debates are futile.

    I’ll leave the interpretation of glacial calving and multi-year sea ice as an exercise for future debates, however, since I fear we may have overstayed our welcome in this thread…

    by Dave C on Jan 23, 2014 at 1:03 am

  31. Dave C

    Futile when you lose the debate.

    Your concession has been gracious Dave C - so hope to agree on more shared facts on climate change in the future.

    by Ken Lambert on Jan 23, 2014 at 11:00 am

  32. Ken Lambert

    Yes, Ken, you won the Internet. I bow before your imperviousness to first-hand expert opinion, your august insight into the motives of strangers, and your esteemed powers of logical inference that take you further than one could reasonably expect to go. Clap clap.

    by Dave C on Jan 23, 2014 at 12:41 pm

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