It’s another scorcher!

Kirsti: Having endured the past week, you might not be surprised to know that this time last year was also hot. It reached almost 50^oC in Moomba, South Australia in January 2013, and in Narrabri NSW – where we were driving a fortnight ago –  it reached almost 48^oC. In fact, have a browse of the daily extreme temperatures during January yourself – WA and QLD peeps are cooking eggs on car bonnets every day!

But this is not a post about climate change, even though it is contributing to these hot summers. It is about localised heatwaves, which are heralded if the temperature has been extreme for 3 days in a row; ‘extreme’ is relative to the time of year. You can check if there has been a heatwave in your area on an amazing website called Scorcher too, but it doesn’t tell you why it has occurred.

The thing is, heatwaves are caused by a complex combination of long- and short-term factors. Uber-long-term factors include global warming, both natural and man-made. Australia has warmed steadily since the 1940’s. But medium- to short-term factors are what interest me most at the moment. Warm winters preceding summer can increase temperatures across the continent, and high pressure systems (characterised by clear dry days) are also responsible for the local warming of air. Dry soils do not absorb heat as effectively as those holding water, which can act to heat the localised above ground air. But probably the most important is the fact that it is warmer more often and for longer periods of time. Recent heatwaves in Australia are essentially an extension of the preceding record breaking hot days, even months, exacerbated because it is mid-summer.

I would advise at this point to check the forecast and consider the previous month’s temperatures before embarking on a roadtrip into western NSW and southward.  Our two kids, trailer and 1996 Nissan Patrol can attest to it being one hot and sweaty trip spotting willy-willies, wheat and windmills!

NB: Image is a digital alteration of one of my own photos. 

[disclaimer: the heat + travelling in the heat is why I’ve been absent from here too!]

Bone picking

Sarah: After approximately ten years of summers and Easters and long weekends spent at the southern end of Yorke Peninsula, I am now finally the happiest amateur naturalist alive. With my trusty A Guide to Squid, Cuttlefish and Octopuses of Australasia (thanks to redmap), I can finally identify the two species of cuttlefish ‘bones’ (actually internal shells used to aid buoyancy) that wash up on ‘our beach’ at Marion Bay.

The bone shown above  – collected on the beach this afternoon, and photographed on my coffee table – are approximately 10 cms long. On the right is the bone from a Giant Australian Cuttlefish (Sepia apama), famous for its incredible colour and textural displays and mating aggregations in the waters of South Australia (although recent data suggest numbers are declining).

The bone on the left belongs to the Knifebone Cuttlefish (Sepia cultrata), a less common and deeper water species found in waters stretching from Queensland to Western Australia.

No longer will I wander the beaches in ignorance of these chalky cuttle remnants discarded on the high tide line.

Now I can sleep at night.

 

Day 202. Garden update

My garden has somehow survived the hottest summer on record.

Although my two basil varieties are now going to seed (‘Italian’ and ‘Asian’, shown above), the quinces are nearly ready to pick, I hold high hopes for a singleton pumpkin and a new crop of figs ripens each day.

My mouth is watering at the thought of a new mandarins, which have just started to turn slightly orange.

Day 189. Blue-green algae

Today was damned hot in Adelaide: the maximum reached 39 degrees Celcius.

My decision to go for a run along the River Torrens was not a good one, given that (a) the sun was already fierce and temperature high, although only 8am and (b) the water-way was a stinking, stagnant mess.

This shot shows blue-green algae just near the Adelaide Zoo-section of the river.

Blue-green algae is a misnomer: the growing mass is actually comprised of a type of bacteria called cyanobacteria. Although a natural part of the freshwater environment, according to the Murray-Darling Basin Authority,

“If conditions are favourable, they reproduce at very high rates to form ‘blooms’ – explosions in growth that dominate the aquatic environment, forming unpleasant and sometimes toxic scums.”

Blooms arise when non-flowing pools of water collect in sunny, protected areas: this in turn allows a layer of warm, sun-drenched water to sit at the surface and create perfect conditions for the cyanobacteria colonies to multiply. Like plants, the bacteria generate their own source of energy by photosynthesis.

Water containing blue-green blooms is not fit for swimming or consumption due to the toxins produced by the bacteria. Amazingly, today I saw two little water birds paddling about in the scum shown in the image. I hope their health is still good.

Blooms in the River Torrens have been triggered by recent hot weather combined with low rainfall in South Australia: what we need now is a little rain and a drop in temperature to clear it up.

Tommorow’s forecast is minimum 27 degrees, maximum 39 again.