In my questioning at Senate Estimates the Bureau of Meteorology confirmed that we’ve had bigger floods before. Our recent weather has been severe and affected many people and my heart goes out to them. But greenies claiming that our recent weather is unprecedented are abusing these people’s grief for political gain.

Transcript

Senator ROBERTS: I’d like to ask some questions about the distressing floods, but first of all I want to commend you for admitting that you don’t know everything. That’s so refreshing to hear. I don’t know everything, and someone who’s talking about weather certainly doesn’t know everything. Nature’s highly variable, and natural variation is enormous. Coming to the floods, they’re very distressing for people and it’s important to give them the right information. According to the Bureau of Meteorology’s graphs, in the last 100 years there have been two major floods and in the previous 90 years there were 11 major floods.

Dr Johnson : Sorry, just to be clear, where are you talking about? In Brisbane?

Senator ROBERTS: Sorry, Brisbane, yes. In 1974, which is the highest recent flood in the last hundred years, the flood levels reached were much less than in 1893 and much, much less than in 1841.

Dr Johnson : Correct.

Senator ROBERTS: Has the government, state or federal, discussed anything about doing some research with regard to flood mitigation?

Dr Johnson : Maybe I can respond to the two parts of your question. You’re right, there have been bigger floods in Brisbane since records have been kept, and records have only been kept since the 1840s, so who knows how big the floods really get in Brisbane. When you look at the historical narratives, if you read George Somerset’s writings on where the traditional people of the Brisbane Valley used to have their summer camps, one could reasonably possibly reasonably draw a conclusion that flood levels have been even higher.

Senator ROBERTS: You’re familiar with where the university’s experimental mine is at Indooroopilly?

Dr Johnson : Yes.

Senator ROBERTS: Apparently, geologists say that the floods were five metres higher than the 1841 floods. That’s unfathomable.

Dr Johnson : All of these things are possible. But to correct the record, there have been 12 major floods in Brisbane since 1840 and three since 1970, including the most recent ones. We had the 1974, the 2010-11 and the one the other day, so three major floods in Brisbane since 1970. Certainly, of the most recent ones, the 1974 flood was the biggest.

Senator ROBERTS: I was going off the bureau’s graphs and it had lines across the major—

Dr Johnson : We probably haven’t put the line on for the one the other day yet, but—

Senator ROBERTS: No, it was on there.

Dr Johnson : Was it? But there are three: 1974, 2010-11 and 2022. For the record, that is the flood history in Brisbane. The second part of your question is about flood mitigation. That’s not a responsibility of the bureau. That’s the responsibility of state governments and local governments, indeed. As you know, obviously Wivenhoe Dam being put in, although its primary purpose is not for flood mitigation—it’s for water security—it does perform a flood mitigation function. The Brisbane City Council also undertakes significant flood mitigation works. As you’re probably aware, since the 2010-11 flood they’ve installed extensively throughout Brisbane engineering works to try to reduce the backflow of water from the river up into the suburb. It was one of the experiences from the 2010-11 flood that people were getting flooded through water coming back up through the stormwater system. The flood mitigation work is their responsibility. Certainly the flood mitigation works draw heavily on bureau historical data.

Senator ROBERTS: That’s what I was getting at: it’s not your responsibility to—

Dr Johnson : It’s not our responsibility to do the mitigation.

Senator ROBERTS: But they do consult with you?

Dr Johnson : Correct. And the state and local governments also heavily utilise not only their own in-house capability but also significant capability in the private sector. So we make all that data available. People are welcome to use it—and we hope they use it—to keep our community safer in the future.

Senator ROBERTS: My question wasn’t going to any attempt to pin you down and blame you for the floods—that’s ridiculous.

Dr Johnson : No, I wasn’t reading it that way.

Se nator ROBERTS: Good. But I can’t imagine that the bureau has any responsibility to correct politicians or media that produce stories saying the floods in 2022 were due to climate change caused by humans or anything like that. That’s their responsibility, not yours.

Dr Johnson : We just report what we see happening in the environment. We try to do so to the best of our abilities and as factually as we can. So we don’t choose to speculate on what we’ve said. What we’ve said very clearly is that, with climate change, we can expect the frequency of high-intensity rainfall events to increase—

Senator ROBERTS: Based on models?

Dr Johnson : Based on models and also based on our recent experience. What we can also see, just as a basic law of physics, is that, for every one degree the temperature rises, the atmosphere holds about seven per cent more water. The Australian temperature record is around 1.47—plus or minus 0.2—since records have been kept. I’m not an engineer like you are, Senator, but the atmosphere is holding roughly 10 per cent more water than it might have had in pre-industrial times. That water has got to go somewhere. It circulates around the planet as part of a mass balance with the oceans and the rivers. I think it’s absolutely reasonable to expect that, as the climate continues to change, the likelihood of high-intensity events like those we have seen will increase. And, all other things being equal, there will be an increased risk of flooding for those communities live on active flood plains. A lot of people live really close to rivers that are still very active—

Senator ROBERTS: And some people say that Brisbane is a city built in a river.

Dr Johnson : Indeed. I think the title of the book is A River with a City Problem.

Senator ROBERTS: That’s right.

Dr Johnson : I know the book you’re referring to.

Senator ROBERTS: Some argue—and there is a lot of conjecture about this—that an increase in water vapour in the atmosphere leads to a cooling effect, for all kinds of reasons. So there are a lot of uncertainties in forecasting the weather and forecasting the climate. I want to quote from the transcript from the Senate estimates in February. I asked whether the State of the Climate reports scientifically prove that carbon dioxide from human activity affects climate and needs to be cut. You responded: ‘I’ve got the report in front of me. I don’t believe there’s a section in there’—that’s right, it’s not the purpose of the report. I happen to agree with you. I’ve been through many of your reports. Later on, you said: ‘I think we made it really clear what the purpose of the document is. It’s to provide a synthesis of our observations of Australia’s climate and oceans.’ Previously you said: ‘I think it’s important for the record to note that none of the State of the Climate reports in any way whatsoever make statements with respect to global emissions.’ I compliment you on your clarity and I appreciate your clarity. It’s not the Bureau of Meteorology’s responsibility to correct politicians when they say that the state of the climate contains evidence of cause and effect, is it?

Dr Johnson : Certainly the bureau is not in the habit of making public comment around statements that our elected officials make. As you know, our job is to advise. Elected representatives are free to say whatever they wish to say. You, of everybody, would probably know that best. We provide our best scientific advice to you and you’ll form your own conclusions on that advice.

Senator ROBERTS: Thank you.