Tuesday, June 05, 2007

No More Drought - no more GW?

We previously suggested that the south Australian drought is now over, with the past 4 months all having greater than normal rainfall than expected both in Victoria and south eastern Australia.

Now we can add May to the list:

Given below is the expected and actual rainfall in south eastern Australia

Expected Actual
Jan 45.0 41.6
Feb 40.8 41.4
Mar 38.3 37.3
Apr 39.9 52.0
May 54.9 64.0
Total 218.9 236.4

So we have a 8.0% increase in rainfall than the norm.

Also in Victoria:

Expected Actual
Jan 37.0 55.7
Feb 36.6 31.1
Mar 40.2 38.5
Apr 46.5 42.4
May 58.7 71.0
Total 219.0 238.7

A 9.0% increase in rainfall since the start of the year.

So once again all the signs are that the drought it over. Phew. I guess global warming isn't having an effect now....or is it?

Despite all the good news, nothing to be worried about stuff - the Australian Bureau of Meteorology still paints an ugly picture.

Autumn rainfall was average to above average over much of inland NSW, northern and western Victoria, Tasmania and southern South Australia, thereby providing some short-term relief to many agricultural systems and an easing of the severe drought caused in part by the 2006/07 El Niño event.

Short Term Relief = almost half a year. And note that the drought was caused, in part, by El Niño - hmm..what else are they insinuating here?

Interesting that despite it admitting that Australia has seen higher than average rainfall over the past month, it continues to talk about every possible place that has severe deficiencies (bad news). More than likely, there would be more places that would have severe efficiencies (good news!), but none of these are mentioned.

Whilst they point you in the direction of the rainfall deficiencies (a good map that shows you when you look back on a longer period of time, that the rainfall problem is almost becoming non existant), a better example would be their one which shows the efficiencies as well like here.

Obviously in any given month or 3 months or whatever, there will be places with lower than normal rainfall. Just like there should be places with higher than normal rainfall. And if these are similar, and Australia has not been decreasing in rainfall (which it hasn't), then why all the global warming scare about droughts?

I guess now that the drought has gone in south eastern Australia (remember global warming only effected south eastern Australia), global warming is not having its effect - or maybe - it's just a little bit of natural variation.


Anonymous said...

Nice stats, and encouraging signs for the future, Jonathan. I also believe it is natural variation that drives our cycles. I still think your idea of how drought is broken is a bit sketchy, however, and will try to illustrate why. I will use your 8%/6 months values.
The upper catchment where I live (Central Qld) is approx 61,000 hectares. Our long term average is around 830mm per year. Our last 5 years of rainfall, '02-'06, have been 476,982,768,631 and 549mm, for a 5 year average of 744mm.
In an 830mm year, our upper catchment would receive roughly 506.3 Gigalitres. Every 100mm you drop is a loss of some 61 gigs to the catchment. By your standards of drought-breaking, if the first 6 months of '07 were 8% above the long-term average, everything should be back to normal..drought broken. Jan to June rainfall would normally average 353mm, adding the 8% would mean a 6 month total of 381mm. After 3 out of 5 years of drought rain, the catchment has received 744mm less rainfall than it would normally expect in that 5 year period. About 453 Gigalitres less water. The 8% (28.24mm) increase over average falls in 6 months means it has recovered 17.2 Gigalites of that missing 453. There would be nice grass, but the goundwater/creeks/river would still be very stressed. In drought, you might say. If the rainfall stayed at 8% above average, it would take just over 25 years to balance the drought losses from the previous 5 year period. In reality, we have actually received 273mm for the year up til today, including 85mm from the recent upper-level system. Also, isn't Jan-June your dry season down there? Sometimes we get more rain than average in the dry season during an El Nino, but due to wet season shortfalls, really lose out. I hope the trend continues through your wet season, where the extra volume will make more of a difference. Apologies if I have made errors in the maths. Stu F.

Warwick Hughes said...

I tend to agree broadly with Jonathon here Stu.
Since the 2002 drought, which could have been termed "Great West Queensland Drought of 2002",
the Nation has been subjected to a constant stream of deceptive media articles about rainfall. I do not think that is overstating things.
Also see, Are Martians growing Australian wheat ?
If you reply with a few localities near your property I will see about putting together a long term rainfall history for you.

I live near Perth and since our moderate dry year of 2001 when dam levels went under 20% the Govt & Water authorities have made slanted statements "denigrating" rainfall. I have a recent page trying to put the current position in perspective,
Note that the Premiers paranormal statement was made last month when in fact near average rain fell in Perth supply catchments. Weird, bizarre, are terms not too strong.

When I read Jonathons post and what he says about the BoM, it all rings so true to what I have observed over years. My take is that the BoM in 2002 was attracted to the idea of going along with or remaining silent when false claims were made about rainfall / drought. They saw it advantageous to have the Greenhouse link made, must have seen it as too hard to state the correct position which is,
[long term high quality rain data show the current dryer period to be cyclic and no statistically significant claims can be made that large regions of Australia are in the "worst drought ever", or "worst drought in a hundred years".]
Utterly shameful for our peak Met org.
But then this is the same BoM who every month promulgate their "totally uselss" rainfall & temperature Outlooks.
Sorry to rave on so long,
Warwick Hughes

Anonymous said...

Thankyou for taking the time to type your considered reply, Warwick. 99% of what you and Jonathan say I would broadly agree with, and yes, the claims made by media are rubbish. The 1000 year drought comment is a great example. I also get uncomfortable with many assertions the BOM and Governments from time to time trot out.

Also thankyou for the kind offer of searching up long term stats for me. We actually have official records for 2 local properties dating back to 1906 and 1909. BOM Sites 039061 and 039020. We used to be the observers for 039061. When the family moved in 1993 the BOM opened a new site at 039334 where we live now. It is about 500m from the site 039020. I used 039020 for the long term median which the BOM collated, and the last 5 years of our ROT obs at 039334. The BOM is yet to transfer paper data to their stats area online. I would be very happy to copy and scan the collations they sent us, however, if you would like them.

I do not disagree with Jonathan's take on rainfall patterns/stats. He is dead right, the falls for the areas he states are above average. They do show a "break" away from drought falls.

It is his assertion that such 5 or 6 months of 8% above average rainfall actually busts a drought on the ground (or catchment) that I have a problem with. I am no expert and made some errors, the main was stating our current 5 year average at 039334 as 744mm. It should read 681mm. Perhaps it would be better if you or Jonathan did the maths. Our long term annual average is around 830mm. 61,000 hectares is the catchment area, also approx. The totals '02 through to '06 at site 039334 are 476mm, 982mm, 768mm, 631mm and 549mm.

My point is that 5 or 6 months of 8% above av rainfall would not address the shortfalls of 60 months of falls around 18% below the average in my area. The groundwater situation would still be very crook. Low bore levels, and greatly reduced flows. The condition of both at the moment are worse than at any time in my grandfather's or father's memory. Great-grandfather had diary records of the federation drought here at 039334, which I am keen to locate.

I stress that I only use my area that I know first hand as an example. Quite frankly, the last 30-odd years of cycle here has been enough to take in, without trying to research droughts elsewhere. Having had the drought declared "over" before on many occasions in this area has left me quite sensitive to declarations of "drought gone". As I guess many farmers are.

Sorry if my reply is long-winded, and thankyou again for taking the time to read my thoughts. Stu F

Jonathan Lowe said...

Thanks Stu,
I'm meery trying to point out that the rainfall that we have had in the last 6 moths and in the last 5 years is far from extraordinary. Whilst many people have blamed global warming for the lack of recent rain, a close view of the data suggest it is nothing much more than natural variation.

Anonymous said...

No arguments from me at all on the natural variation score, Jonathan.

I take on board what both you and Warwick have posted. It suits some to exaggerate the situation in certain areas where rainfall has been short, to fit the AGW theory and advance the public's acceptance of it.

No doubt, when natural variation returns us to a few years of extra cyclones/rain depressions and heathy storms/upper systems those same people will try to paint it as "bad" or "extreme" weather and lay it at the feet of AGW as well.

I had been of the impression that you had meant SE Australia had not been in drought. Or that if it had, the last 5 months had solved the problem completely,not just grass but stream/groundwater and storages.

I guess I took it overall as saying that all you need to break a real long-term drought was a 6 month period of average or just above rainfall. 8% above is not much above, and 8% below would not be much of a drought either, by the same token.

Refuting that specific notion is why I put forward our catchment case, where even on 8% above average rainfall, it would take 4 years to make up for our 34% drop last year, let alone the 5-year av shortfall of 18% per year. I believe the figures qualify as drought.

Sorry if I took your post the wrong way. If you ever get up to CQ, I would be happy to tour you around the catchment. Keep up the important work. Stu F