PDSI Graph

Here is a graph. It is of yearly global average PDSI, which is a soil moisture index, from around 1890 to 2005. The graph was generated from NCAR/UCAR data through climate explorer, http://climexp.knmi.nl/select.cgi?id=someone@somewhere&field=pdsi

The lower the index, the drier the soil.

The dataset is owned/collated by Aiguo Dai. It can be downloaded here:
http://www.cgd.ucar.edu/cas/catalog/climind/pdsi.html

(This is more up-to-date, but I do not have the tools/skills/intelligence to get it into what would be a user-friendly format for me)

NCAR is the National Centre for Atmospheric Research.
UCAR is the University Corporation for Atmospheric Research.
Information on both can be found here:  https://www2.ucar.edu/about-us

What I believe that it shows is that the earth, on average, has been drying over the last three decades. What I am looking for in asking questions of lukewarmers and others is what kind of agreement we can come to on this drying and drying in the future.

I understand that the PDSI is not an absolute measure of dryness but a relative, so a wet area getting drier might be a good thing in agricultural terms, and that regardless we have much better technological and social solutions to drought now than we did in years past.

However, drought in crop-growing regions of the world still has major impacts for those who spend large portions of their income on food. This does not apply much to developed nations, but underdeveloped nations are vulnerable to shifts in global food prices.

I guess my first question would be: do you (and this question is directed at anyone interested) agree that the soils of the world appear to on average be getting drier?

We are the heroes who stopped climate change

We - you, me and everyone else reading this - are the heroes who stopped climate change. We saved the lives of millions of people. We prevented the extinction of thousands of species. We halted the acidification of the oceans and the collapse of global fish stocks, averting immense suffering. Thanks to us, wars that would have been fought over water never occurred. Thanks to us, the lives of every one of the billions of humans on this fragile and beautiful planet are better than they otherwise would have been. We are heroes.

It was not an easy battle. It cost money - large amounts of money. All of us sacrificed something. Our lifestyles altered. Our choices narrowed. Our lives were by some measures worse than they would have otherwise been. But we did this to make the lives of future generations better than they would have otherwise been; we gave up choices to allow our children more choices. And the alterations to our lifestyles, while difficult in the transition, became for us badges of honour and hope. We are heroes.

We made difficult political and personal decisions. We had the courage to research, refine and adopt nuclear power, overcoming our reservations in the face of the huge dangers that climate change presented. We had the vision to support the creation of solar and wind energy systems to run electric vehicles, moving completely away from fossil fuels - with which transport had seemed axiomatically and inextricably intertwined - in the course of a few short decades. We - sometimes reluctantly; sometimes disgruntledly - changed our eating habits. And came to realise that there were health benefits for us as well as for the planet. We are heroes.

Many things stood in our way; sometimes we stood in our own way. There were those who opposed us out of self-interest and those who opposed us out of honest disbelief. There were those who labelled us dupes or liars or simply wrong. And we were wrong on some things. We made mistakes. But we overcame. Our words were listened to and our deeds spoke for themselves. We are heroes.

As you look around today and see the world that we created, you will notice that it is not perfect; that it is not in all ways the way that you want it to be. But while there is still suffering, corruption, famine, conflict, disease, destruction - still many challenges to be overcome - there is far less of it thanks to you and I; thanks to all of us. Be proud. We are heroes.

note: this is an idea that I have for motivating people to take action on climate change

Return

I have been offline for eight months, with personal stuff happening. But I am back now.

The main thing to discuss is that we have had a fair bit of rain this year. :)

However, inflow has again not come close to matching historical averages.

In 2011, we received  577.7 mm of rainfall, with inflow of around 55,000 megalitres.

Thus far in 2012, we have received 495 mm, with inflow of around 45,000 megalitres. With an El Nino forecast for late spring/early summer, it is likely that we will get less than average rainfall. However, we should still get more than average for the year, given that we are only 120 mm or so short.

I will also discuss the state of the Arctic sea ice. At present, satellites are recording the lowest ice area on record, with ice extent in the bottom three (2007 and 2011 are the lowest and second lowest). Area and extent are two different but related ways of measuring the amount of sea ice. For a clear discussion on the difference, see here: http://nsidc.org/arcticseaicenews/faq/

With regard to volume, PIOMAS (http://psc.apl.washington.edu/wordpress/research/projects/arctic-sea-ice-volume-anomaly/) currently estimate that sea ice volume is the lowest for this date in the historical record, around 1,000 cubic kilometres below the previous record set last year. For context, last year's minimum was around 4,000 cubic kilometres. My own model predicts that this year's minimum will be 3,200 cubic kilometres. (This is up from the prediction made last year, because the PIOMAS model is now version 2). At present, the situation is tracking below that, but not too much below.

Weather over the next three months will determine if we set records. But the sea surface temperatures in the Arctic are three, four, five and more degrees above average in many areas, and significant melt is to be expected.

Weekend downpour and inflow update

On the weekend, 26-27 November, we received a very nice downpour of 53 mm. This has pushed November well above average in terms of rainfall. However, we have still had less than 500 mm of rainfall this year, which means that we need a wet Christmas to reach Canberra's average.

The inflow since the start of this year has been, by my calculations, 47,175 megalitres, with an error margin of 2,000 megalitres. The megalitre per millimetre ratio is around 98, but that should improve some as we are due more inflow from the downpour - probably 2,000 to 3,000 more.

If we have a few years without drought, it might be possible for us to return to something closer to the average megalitre per millimetre ratio of 300. But I do not think that we will ever get back to that level.

Oh, and a word on consumption: ACTEW releases annual figures, but for financial years. This financial year, we have used 17,142 megalitres thus far, an average of close to 3,500 per month. This points to another year of 40,000 megalitre consumption. This is good: lowest ever consumption was last year's 40,923 megalitres. While we get more than that on average, we will be fine.

Good rainfall to start November; la nina confirmed

We have had a good start to November, with 27 mm thus far, putting us on track for the average of around 60 mm. However, ACTEWAGL have been slow updating their dam level numbers and so I will have to estimate the inflow for the year thus far. My calculation put it around 44,000 megalitres, with probably a little more to come from last week's rain. However, we are having hot weather for November, which increases evaporation and transpiration, so there might not be much more to come. We will see.

La Nina has been confirmed as present in the Pacific, so above average rainfall is projected for the summer. If above average rainfall eventuates, it will be interesting to see the inflow figures. The heavy rainfall that we had from February 2010 and February 2011 did not bring us back to average inflow levels, but perhaps a few further months of good rain will go some way towards doing so.

Poor start to spring

Spring is when the rain should fall in Canberra, although in recent years the rain has been coming more in the summer months. Thus far this year, we have had below average rainfall for the first two months of the season. Our yearly total has not yet crested 400 mm, which means that in the last eight weeks or so  of the year we need more than 210 mm to reach the annual average.

The 13 months from February 2010 to February 2011 were months of extremely good rain. Since then, however, only around 210 mm have fallen, leaving the ground parched even though the dams are still full.  The megalitres per mm rate has dropped from a high of 120 early in the year (still low) to a low of 101. And in the past three months we have had less than 7,000 megalitres of runoff.

While I do not think that permanent drought will come upon Canberra in the next decade, which is what I was predicting previously, I think that we are heading in that direction. Large rainfall every few years may make us relatively secure, especially with the new dam. But I am still very concerned.

Rainfall and inflow update after a lengthy absence

I have been on my second teaching prac for a month and thus have not had time to keep this updated.

I overestimated the expected inflow from the good rain that we received in August. As of 19 September, we are only up to about 38,000 megalitres of inflow from yearly rain totalling close to 340 mm. Below average rainfall so far for this year and below average inflow. It does not appear that last year's huge amount of rain changed the dynamics significantly: megalitres per mm has dropped to 113.

La Nina has rolled in officially, so it is probable that we will get some good rain over the remaining four months of the year. We need it to push as to the average or above. I admit that I am concerned that we could be heading into another period of drought. At least our dams are full, though.