Posted by: maximos62 | February 13, 2014

How many swallows, or when can we talk about #climate change?

When I coined this heading I hadn’t realised that, in a sense, I’d been trumped by The Guardian but I’ll press on, regardless.

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Recently I took up residence in Singapore. Visiting first in 1972 and returning briefly in early 1973, I remember of Singapore as a green wet place.  I enjoyed the rain.  So, when I knew I’d be arriving about the same time of year 42 years later, I was well prepared, but Singapore is dry.  The monsoon forest trees planted out in parts of the city are shedding their leaves, epiphytes are drooping, otherwise green lawns in the botanical gardens look more like Australian parks in summer and cracks have appeared in the earth as remaining moisture evaporates.

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While rain finally fell over parts of the island last weekend there have been no good rains since December and the National Environment Agency (NEA) says the dry spell could remain until late February of early March.

A Meteorological Service Singapore spokesman said of the present weather: “Spatially, the current dry spell this year has been more widespread compared with the dry spells in 2009 and 2011.” [1]

Assistant Professor Winston Chow from the Department of Geography at National University of Singapore said this year’s dry period reached our sunny island earlier, most likely due to the colder and drier than normal air from the origin of the monsoon in China. [2]

Here is the present situation viewed from the Japanese geostationary meteorological satellite.

http://www.jma.go.jp/en/gms/smallc.html?area=6&element=0&time=201402130400

Full Disc, infrared, colour. 0400UTC February, 2004.
http://www.jma.go.jp/en/gms/smallc.html?area=6&element=0&time=201402130400

So the key to this longer than usual dry spell seems to be colder and drier than normal air from the origin of the monsoon in China. As a geographer, this makes perfect sense to me. There are predictable cycles of weather and weather related events. Colder in Central Asia or China doesn’t mean that global warming is unimportant either.  Warming refers to increasing average global temperatures.

I have an obvious question, one I’ve been asking for some time.

How many of these out of the average weather events must occur before we can begin to talk about climate change?

Some are already assessing the impact of climate change on the frequency and magnitude of extreme weather events.  Scientists have a hunch rising temperatures due to human activity are making fire and flood more likely.

Certainly, in Australia, recent attempts to suggested that climate change might be playing a role in weather related events have been denied  by those with an interest in taking little if any action on climate change.

Prime Minister Tony Abbott has dismissed the comments of a senior UN official who said there was a clear link between bushfires and climate change, arguing ”fire is a part of the Australian experience”. [3]

The Commonwealth Scientific and Industrial Research Organisation (CSIRO) observed in State of the Climate – 2012

http://www.csiro.au/Outcomes/Climate/Understanding/State-of-the-Climate-2012/Temperature.aspx

Number of hottest-day-of-the-month (highest maximum) records at 43 Australian climate reference stations with daily data from 1910; for each year (orange line) and each decade (grey boxes), and the 11-year average (black line). The average for the most recent 10-year period (2002-2011) is in darker grey.

  • Each decade has been warmer than the previous decade since the 1950s.
  • Australian annual average daily maximum temperatures have increased by 0.75 °C since 1910.
  • Australian annual average daily mean temperatures have increased by 0.9°C since 1910.
  • Australian annual average overnight minimum temperatures have warmed by more than 1.1 °C since 1910.
  • 2010 and 2011 were Australia’s coolest years recorded since 2001 due to two consecutive La Niña events.

Sadly, sceptics searching for solace, might cite the last of these bullet points to suggest that global warming, as the principal feature of climate change, is a non-event, but trends are certainly not consistent with denialist dreams.

The Australian Bureau of Meteorology went on to report, in late 2013 that:

The mean temperature for Australia, averaged over the 12 months from October 2012 to September 2013, was 1.25 °C above the long-term average. This was also 0.17 °C warmer than any 12-month period prior to 2013.

October 2012 to September 2013 mean temperature deciles for Australia showing 12-month temperatures were the highest on record for 39% of Australia.

October 2012 to September 2013 mean temperature deciles for Australia showing 12-month temperatures were the highest on record for 39% of Australia.

So, it was the hottest 12 months on record and just happened to correspond with one of the earliest starts to the bushfire season on record.

Rising sea levels and Cyclonic Disturbances

The World Meteorological Organisation’s Michel Jarraud says Australia’s record-breaking summer helped push average global temperatures higher this year, and rising sea levels worsened the situation in the Philippines.

In early November I met a Filipino man at Sydney’s Kingsford Smith Airport.  He was on his way home.  We both sat and watched early news reports of Typhoon Haiyan. At the time neither of us could have known the extent of the damage and loss of life that followed.

It was atypical as typhoons go.

“The impact of this cyclone was definitely significantly more than what it would have been 100 years ago because of the simple mechanical fact that the sea level is higher,” Mr Jarraud said.

So, climate change is also something that affects oceans.  Thermal expansion of oceans and the gradual melting of the Greenland ice cap are just two impacts of climate change on the marine environment.  Rising sea levels makes the storm surges associated with tropical cyclones worse, extending the impact of storm wave damage to coastal areas. Warm oceans also establish the preconditions for cyclonic uplift of atmosphere, the warmer the ocean the more efficient the uplift.

In this UK weather animation it’s quite obvious that massive cyclonic disturbances have been the trigger for the extensive flooding and coastal damage affecting large parts of Britain. As reports have come in about the extent of these floods, I’ve been thinking of droughts and bush fires, then I came across a clever image from Climate Outreach. It makes an important point.

When will it be politically correct to talk about any one of these events being rendered more severe by climate change?

Since the initial publication of this post the Australian Climate Council has published its latest report.  It confirms that heatwave conditions in Sydney, Melbourne and Adelaide have already reached levels initially predicted for 2030.  You can download the full report here:

https://www.dropbox.com/s/wed2eic23m6hr43/cc.heatwave.report.web4-small.pdf


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