Log in | Jump |

CEJournal

News & Perspective from the Center for Environmental Journalism
This item was posted on January 15, 2011, and it was categorized as Climate Change, climate change coverage, extreme weather.
You can follow comments through the RSS 2.0 feed. Both comments and trackbacks are closed.

Were they linked to global warming? Two news outlets offer different answers

Update: After reading this post, some readers might conclude that I think we should wait to take action to reduce our vulnerability to climate change. Nothing is further from the truth. I believe we have enough knowledge right now to justify reducing carbon emissions, and taking action to adapt to climatic disruptions — which are obviously occurring, right now.

Have a look at the ABC News evening news broadcast above, and the network’s more in-depth article here. It’s extraordinary these days for American television news to cover climate change in any way, as the recent analysis by Robert Brulle of Drexel University has shown. So it’s heartening to see at least one network news division wake up again to what still is a huge story.

That said,, the broadcast unequivocally tied the flooding in Australia, as well as in Brazil and Sri Lanka, to global warming. And in its headline on the web, ABC also made no bones about it:”Raging Waters in Australia and Brazil Product of Global Warming.” That’s as strong a cause and effect statement as you could make.

Reuters wouldn’t go quite so far, as this dispatch carried by MSNBC on the web shows:

SINGAPORE — Climate change has likely intensified the monsoon rains that have triggered record floods in Australia’s Queensland state, scientists said on Wednesday, with several months of heavy rain and storms still to come.

But while scientists say a warmer world is predicted to lead to more intense droughts and floods, it wasn’t yet possible to say if climate change would trigger stronger La Niña and El Niño weather patterns that can cause weather chaos across the globe.

Which story is more accurate?

The evidence for a link between a warming globe and extreme rainfall events like we’ve been seeing is supported by the last IPCC report, which stated:

The frequency of heavy precipitation events has increased over most land areas, consistent with warming and observed increases of atmospheric water vapour.

Those words, “consistent with,” are key. Scientists have used the same words in interviews with me, saying that extreme rainfall events are “consistent with” a revved up hydrological cycle in a warming world.

But “consistent with” is is not dispositive. So to what degree does the evidence justify going as far as ABC’s statement of cause and effect?

The severity of the Brisbane floods played a significant part in the case ABC made for their being caused by global warming.  Yet it doesn’t seem that they explored whether there was something about this event that has broken significantly with the past history of flooding in the region.

My colleague here at the University of Colorado, Roger Pielke, Jr., has examined this issue, and in this post he produced the following graph examining the incidence of floods in the Brisbane area going back to 1841:

It’s obvious that this flood is by no means unprecedented. Flooding in 1974 was even worse, and moderate to major flooding was far more common prior to 1900.

In fact, 1893 saw at least three floods, with two of them peaking at more than 30 feet above flood stage (9.51 meters for the first, and 9.24 meters for the second, with another flood in between at 3.29 meters).

The article at right from the Feb. 21, 1893 edition of the Brisbane Courier tells the story of receding waters from one of the two larger floods. Click on it, and a larger version will open in a new window. (It’s from “Trove”, a marvelous resource of digitized materials  such as newspapers, music, pictures, and video from the National Library of Australia).

Based on the history of flooding in the Brisbane area, Anthony Watts concluded that ABC’s story was “ridiculous,” and Richard Somerville, a scientific source in ABC’s story, needed a “swift kick in the butt style reality-check” [sic].

Other climate change contrarians are going even further, claiming that “warmists” are actually to blame for the floods. Their logic: Because the Queensland government was worried about drought due to global warming, it allowed the Wivenhoe dam upstream of Brisbane to get “dangerously full,” as one commentator put it at the Telegraph in the U.K.

According to the Austrailian, part of the devastation wrought by the flooding in Brisbane was in fact caused by “sudden releases this week of massive volumes of water from Wivenhoe Dam.” The dam was built after the 1974 flood to provide drinking water and to mitigate flooding during heavy rains.

Did operation of the dam actually contribute to the flooding? Or conversely, was the flooding actually less intense because of the dam, and perhaps others that have been constructed in the watershed since the period of frequent and intense flooding in the 1800s?

If you want to know just how unusual this flood was in the historical context, these questions merit investigation. As far as I can tell, neither ABC nor Reuters examined this issue.

The massive 1974 flood provides another clue that can help us arrive at the best way of characterizing a possible link to global warming. It occurred during a particularly strong La Niña episode — similar to the  strong La Niña we’re experiencing right now.

Here’s what the Australian Bureau of Meteorology says about the impacts of La Niña on the country:

La Niña periods are generally associated with above normal winter, spring and summer rainfall, particularly over eastern and northern Australia.The current event has contributed to 2010 being Australia’s third wettest year on record, and Queensland having its wettest December on record.

Based on the cool conditions in the central equatorial Pacific Ocean associated with La Niña, this was the bureau’s precipitation forecast for January to March 2011, published on Dec. 17:

Brisbane is located near the 70% label. And so it’s obvious that heavier than normal precipitation was expected, thanks to the strong La Niña now underway.

But that does not rule out a role for global warming. Far from it.

Purely from a logical perspective, it is entirely possible that warming has conspired with a strong La Niña to make the rains in Australia even more intense than they would have been.

And that is precisely the case made in the Reuters story:

“I think people will end up concluding that at least some of the intensity of the monsoon in Queensland can be attributed to climate change,” said Matthew England of the Climate Change Research Center at the University of New South Wales in Sydney.

“The waters off Australia are the warmest ever measured and those waters provide moisture to the atmosphere for the Queensland and northern Australia monsoon,” he told Reuters.

And this from David Jones, head of climate monitoring and prediction at the Australia Bureau of Meteorology:

“The first thing we can say with La Niña and El Niño is it [sic] is now happening in a hotter world,” he told Reuters, adding that meant more evaporation from land and oceans, more moisture in the atmosphere and stronger weather patterns.

“So the El Niño droughts would be expected to be exacerbated and also La Niña floods because rainfall would be exacerbated,” he said, though adding it would be some years before any climate change impact on both phenomena might become clear.

And that last caveat is key, I think. Scientists can’t say for sure yet whether climate change has been making those  La Niña floods more severe.

Of course the flooding in Australia is not happening in a vacuum. There is also catastrophic flooding in Brazil and Sri Lanka. And along the U.S. Northeast Coast, records were recently set for snowfall.

Moreover, in April of last year, 11 inches of rain fell in Rio de Janiero in 24 hours, the heaviest rainfall event in 48 years. (Meanwhile, to the north, parts of Amazonia experienced the worst drought in 40 years.)

After having experienced its second driest April since 1901 (behind 2007), Germany was hit by its wettest August since the same year.

Of course there was the astonishingly massive flooding in Pakistan last summer. And a host of other unusual rainfall events around the world during 2010 as well, as documented by the National Oceanic and Atmospheric Administration a few days ago.

And last but not least, 2010 was the wettest year globally on record, by NOAA’s accounting.

It seems obvious to me as a science journalist that there’s something happening here, and while it may not yet be exactly clear  (apologies to Buffalo Springfield), both ABC News and Reuters were right to pursue this story aggressively. I only wish other news outlets, particularly national television news, would follow their lead.

But in my opinion, ABC went too far in declaring cause and effect, whereas the Reuters story was more accurate, thanks to the caveats and greater scientific nuance.

Oh, one other thing: ABC spelled Richard Somerville’s name incorrectly. (It’s one ‘m’ guys, not two.)

Share
This item was posted by .


You can follow comments through the RSS 2.0 feed. Both comments and trackbacks are closed.

This thing has 14 Comments

  1. spyder
    Posted January 15, 2011 at 5:26 pm | Permalink

    and while it may not yet be exactly clear

    Well, i, for one, hope that when it starts to become exactly clear, it is not too late.

  2. Posted January 15, 2011 at 5:30 pm | Permalink

    Sypder: Good point! I’m going to add something to the story making the point that we don’t need to wait to prove cause and effect before taking action, both to reduce emissions and to adapt to changes that climate disruptions that are already occurring!

  3. Posted January 16, 2011 at 10:27 am | Permalink

    Hi Tom,

    Nice post. We published a story at Climate Central that honed in on the links between record high sea surface temps (due to La Nina and manmade climate change) and the heavy rainfall. We did not go as far as ABC did, and I am glad we didn’t, considering such direct attribution cannot be made until studies are conducted etc.

    http://www.climatecentral.org/blog/climate-change-connection-to-australian-flooding/

    Cheers,

    -Andrew

  4. Posted January 16, 2011 at 11:15 am | Permalink

    Spyder:

    Timing is, in my opinion, the most inconvenient of all truths regarding our climate situation. We keep ratcheting up the atmospheric level of CO2, which commits us to decades of ever greater levels of warming and disruption of the water cycle, among other nasty effects. But until we have a collective awakening to the urgency of the situation, we won’t do nearly enough about it.

    I’ve been involved in many of these “what will it take” discussions, and I’m not at all confident that it’s possible for a single, big event to change our world view. The 2003 EU heat wave, New Orleans in 2005, numerous US-state-size icebergs/shelves breaking up, Moscow and Pakistan in 2010, etc., are all seen as singular events, just horrible noise in the system and not part of a trend.

    I hate to be crass, but I think it will take something massive, with a very high body count and costs in the hundreds of billions to trillions of dollars, coupled with scientists who are confident enough in their conclusions to step forward and say, “We did this to ourselves with our emissions.” If we’re “lucky” that will happen soon, before we lock in too much more warming and damage.

  5. Steve Bloom
    Posted January 16, 2011 at 12:47 pm | Permalink

    Tom, that RP Jr.-provided graph doesn’t show what you seem to think it shows. Note that it’s a measure of river height at a specific point in Brisbane, which you conflate with flooding in the Brisbane area. This is SOP for RP Jr., but you need to try a little harder not to be sucked in.

    People in Qld are well aware that the max level at the Brisbane gauge was about a meter short of the 1974 flood, and yet:

    ANNIE GUEST: The three week flood crisis engulfing Queensland has been given its place in history by the Premier Anna Bligh.

    ANNA BLIGH: The worst natural disaster in our history and possibly in the history of our nation.

    Re the dam release business, are you serious? Do you know what can happen to dams that are allowed to overtop? FYI the dam in question had several such forced releases over the period in question (and BTW was built in response to the ’74 event, another reason why RP Jr.’s comparison is junk).

    On the main point, I think you should have a conversation with Kevin Trenberth about this. The key point is that starting with the detection of a global warming signal twenty or so years ago, every weather event has components of both natural and anthropogenic causation, and this will continue to be the case.

    So the question ought to be about the relative size of the components. It can’t be answered with any precision, but I think RS was entirely correct to make the point he did given the context of a) the *observed* substantial expansion of the tropics and resultant poleward shifts of the Hadley cells, b) a year of record SSTs leading to a major increase in water vapor available for the Qld storms and c) (most important to drawing the conclusion) the sheer quantity of these events. Read the piece Jeff Masters just posted.

    (BTW, if I had to point to one overwhelming failure in the media’s coverage of climate chnage, it would be the story of those observed atmospheric and oceanic circulation changes. They quite literally change everything, and not in small ways, which we know from paleoclimate data.)

    Also, I think this passage from the MSNBC story –

    But while scientists say a warmer world is predicted to lead to more intense droughts and floods, it wasn’t yet possible to say if climate change would trigger stronger La Niña and El Niño weather patterns that can cause weather chaos across the globe.

    – doesn’t mean what you seemed to have thought it did. It sounds to me like a sloppy answer to a poorly-framed question. I don’t know what changes are predicted for La Nina, but in any case they haven’t been detected yet. The better question: Are current high SSTs anthropogenically driven, do they make major precipitation events stronger, and is that what happened in Qld (and elsewhere)? Yes to all of that. Of course changes in La Nina would also have an effect.

    Thanks for the added clarification.

  6. Steve Bloom
    Posted January 16, 2011 at 12:49 pm | Permalink

    Link for the Bligh quote.

  7. Steve Bloom
    Posted January 16, 2011 at 12:50 pm | Permalink

    Hmm, it’s stripping the html. Here it is raw:

    http://www.abc.net.au/pm/content/2011/s3112389.htm

  8. Steve Bloom
    Posted January 16, 2011 at 12:54 pm | Permalink

    Andrew, the kind of direct single-event attribution you seem to want can’t *ever* be made, even in a much warmer world. As Trenberth says, it’s the answer to the wrong question.

  9. spyder
    Posted January 16, 2011 at 3:37 pm | Permalink

    And just to add a new flavor to the mix, the USGS released a study this past week on predictions of catastrophic flooding “superstorms” in CA. I suppose the longterm consequences of global climate change may impact these giant storms as well:
    http://www.nytimes.com/2011/01/16/science/earth/16flood.html

  10. Steve Bloom
    Posted January 16, 2011 at 4:39 pm | Permalink

    Thanks, spyder. Now if you close your eyes for a few decades you might miss the public policy response to this information. Or not.

    On a related topic, I see it’s been shown that most coastal marshes will disappear this century with sea level rises in the 1 meter range, although they’ll do badly even at much lower levels. Take that, seafood! (Despite the huge implications, AFAICT there wasn’t a peep about this in the media. A possible more positive note is that mangrove marshes will be more resilient, but there’s no guarantee of that, plus of course there are extensive ongoing losses of mangroves due to coastal development.)

  11. Steve Bloom
    Posted January 16, 2011 at 4:47 pm | Permalink

    Yet another one I missed last year (title/abstract):

    Changing structure of European precipitation: Longer wet periods leading to more abundant rainfalls

    Analysis of the duration of wet spells (consequent days with significant precipitation) in Europe and associated precipitation is performed over the period 1950–2008 using daily rain gauge data. During the last 60 years wet periods have become longer over most of Europe by about 15–20%. The lengthening of wet periods was not caused by an increase of the total number of wet days. Becoming longer, wet periods in Europe are now characterized by more abundant precipitation. Heavy precipitation events during the last two decades have become much more frequently associated with longer wet spells and intensified in comparison with 1950s and 1960s. The changes in the distribution of temporal characteristics of precipitation towards longer events and higher intensities should have a significant impact on the terrestrial hydrologic cycle including subsurface hydrodynamics, surface runoff and European flooding.

    But hey, this *still* doesn’t prove anything about any particular event.

  12. Steve Bloom
    Posted January 17, 2011 at 12:15 am | Permalink

    Here’s a map showing the amazing extent of record rainfall levels in eastern Oz from October through December. It had already been raining a lot before the really nasty stuff hit.

  13. Steve Bloom
    Posted January 17, 2011 at 10:01 pm | Permalink

    KT has a new (draft, I think) commentary for the AMS. The whole thing is worth aread, but relvant to this discussion he writes in part:

    So we frequently hear that “while this event is consistent with what we expect from climate change, no single event can be attributed to human induced global warming”. Such murky statements should be abolished. On the contrary, the odds have changed to make certain kinds of events more likely. For precipitation, the pervasive increase in water vapor changes precipitation events with no doubt whatsoever. Yes, all events! Even if temperatures or sea surface temperatures are below normal, they are still higher than they would have been, and so too is the atmospheric water vapor amount and thus the moisture available for storms. Granted, the climate deals with averages. However, those averages are made up of specific events of all shapes and sizes now operating in a different environment. It is not a well posed question to ask “Is it caused by global warming?” Or “Is it caused by natural variability?” Because it is always both. It is worth considering whether the odds of the particular event have changed sufficiently that one can make the alternative statement “It is unlikely that this event would have occurred without global warming.” For instance, this probably applies to the extremes that occurred in the summer of 2010: the floods in Pakistan, India, and China and the drought, heat waves and wild fires in Russia. It likely also applies to the flooding in Queensland, Australia In January 2011. (emphasis added)

  14. JCH
    Posted January 19, 2011 at 7:48 am | Permalink

    I read last night that the Wivenhoe Dam does not have a spillway that reaches low enough to release its 1.16 million ML drinking water component. If true, this would be a very pertinent fact as there would be no way for SEQ Water, and any timely manner, to increase the dam’s flood-mitigation component by reducing its drinking water storage component.

    On the dangers of overtopping an earthen dam, when I was in college I had a summer job nearby a tiny earthen dam that gave way during a deluge. The flooding resulting from the deluge and the broken dam killed more people than have died in Queensland. Risking the Wivenhoe is incomprehensible. It has fuse plugs to avert such an emergency. That had to release that water.

Comments are currently closed