Climate & Climate Change

I’ve previously described 2006 as the year of climate change hysteria , but interestingly at least in Australia it wasn’t that warm.

While 2005 was the hottest on record, according to ABC Online quoting from the Australian Bureau of Meteorology last year, 2006, was the 9th warmest on record.

I’ve just received the report by email from the Bureau (7.30am, 3rd January) and they are now claiming last year was only the 11th warmest on record.

Here is the graph:

The report says:

“Data collected by the Bureau of Meteorology indicate that Australia’s annual mean temperature for 2006 was 0.47°C above the standard 1961-1990 average, making it the eleventh warmest year since comparable temperature observations became available in 1910.

“Despite record warm daytime temperatures in the drought-affected southeast, 2006 was cooler than the previous year when averaged across the whole country. This was largely due to a very active tropical wet season early in the year resulting in cooler temperatures through the north, and clear skies and low soil moisture associated with the drought resulting in cold overnight temperatures from April to July. The annual mean maximum temperature was 0.60°C above average (ninth highest), while the mean minimum temperature was 0.34°C above average (seventeenth highest). Temperature anomalies varied throughout the year but spring 2006 was particularly warm (+1.42°C), being Australia’s warmest spring season on record.”

And the 9 warmest years span an appromiate 26 year period.
That would mean last year was about the coolest year that we have had in Australia for about 26 years.

The full report is apparently due out tomorrow. I will update this post once it is available online at the Bureau.

The Queensland Premier, Peter Beattie, yesterday announced that $7.6 million will be provided over four years to evaluate the effectiveness of cloud seeding in increasing rainfall in Queensland, Australia.

Mr Beattie said beginning next year (2007) a pilot project would be conducted in south-east Queensland using new “warm cloud” seeding processes.

The pilot project will be in collaboration with the Bureau of Meteorology and the United States National Centre for Atmospheric Research.

Interestingly China already has a $50 million a year weather-modification program with the aim of increasing rainfall by up to 15 percent.

Indeed when the Chinese government’s 11th Five Year Plan kicked off earlier this year it included provision for the creation of 48 billion to 60 billion cubic meters of artificial rain annually. How many gigalitres is that?

So what about techno-fixes for global warming too? We could fertilize the ocean making more algae which sequester carbon? We could put sulfur particles into the stratosphere to cool the earth?

I can hear an environmental fundamentalists shout, “DON’T MESS with the climate!” But we already have?

Following is the text* from a ‘Special Climate Statement’ entitled ‘Climate conditions preceding the December 2006 southeast Australian bushfires’. The statement was issued on 19th December 2006 by the National Climate Centre.

Introduction

Southeast Australia has experienced highly unusual widespread bushfire activity in December 2006. These fires were preceded by exceptionally dry conditions, over both the short and long term, in all of the major fire regions (Victorian Alps, Tumut, and eastern Tasmania). In the two mainland regions, exceptionally high daytime temperatures also occurred during the months leading up to the fires. This statement describes the antecedent climatic conditions in the fire-affected regions.

Severe and extensive bushfires in southeast Australia are usually a result of an extended drought which leads to the drying of forests and grasslands. In most summers, there are a number of days on which high temperatures combine with low humidity and high winds to produce dangerous fire weather conditions. When combined with ignition, the antecedent dry and extreme weather set the stage for potentially severe bushfires.

The short-term weather conditions during the fire period itself are not within the scope of this statement, and will likely to form part of a separate report on meteorological aspects of the fires to be released at a later date.

Most of the affected areas are mountainous, with relatively sparse meteorological station networks. In addition, the networks in the affected regions have changed substantially over time, with a number of automatic weather stations recently being installed at high elevations. The changes in the station network mean that the gridded analyses are likely to underestimate the severity of the current dry period at high elevations, while the shorter-duration station records miss some previous exceptional drought episodes (such as 1902 and 1914). For these reasons, this report uses a mix of station and gridded data sets. The gridded datasets are the Bureau’s operational 0.25 degree (~25 km) resolution analyses dating back to 1900 and experimental new 0.05 degree (~5 km)
analyses which currently extend back to 1941.

Long-term rainfall deficits in SE Australia

Rainfall has been generally below normal in most of south-eastern Australia (including Tasmania) for the 10-year period starting late 1996 (see Special Climate Statement 9). An analysis of rainfall deciles for the 10 years ending November 2006 shows that a number of areas have experienced their driest 10-year period on record, including the area east of Melbourne, around Tumut, and in parts of eastern Tasmania. Virtually all of southeast Australia has experienced its driest 10-year period since at least the 1940s.

Over most of the region, mean annual rainfall since 1996 has been 10-20% below the long-term average, with anomalies exceeding 20% over areas east of Melbourne.

Acute shorter-term rainfall deficits and depleted snow cover in 2006

After near average rainfall during 2005, acute drought conditions began across southeast Australia in January 2006. Over the period from January to November 2006, rainfall has been at or near record low levels over most of the area of interest, both on the mainland and in Tasmania. At some locations in the core of the alpine region, including Cabramurra, Harrietville, Mount Buffalo, and Dartmouth Dam, as well as sites in or near the Melbourne water supply catchments such as O’Shannassy and Marysville, the January-November 2006 rainfall has broken previous records (many set in 1967) by a substantial 80-200 millimetres.

At most mainland locations, January-November 2006 rainfall has been 50-65% below normal. The anomalies have been particularly acute at most of the higher-elevation stations, with Mount Buffalo and Charlotte Pass 66% below normal, and Cabramurra 65% below normal. In the vicinity of St. Marys (Tasmania) January-November rainfall has been generally near 50% below normal. We note that the streamflows across this region have been at record low levels, in many cases far below previously observed lows, indicating the severity of the current drought episode.

For instance, winter inflows to the Murray River system were around 100 GL per month below that of the previously lowest inflows, which occurred in the Federation drought of 1902. (Further details are available from the Murray-Darling Basin Commission website, www.mbdc.gov.au).

Rainfall anomalies have been less extreme on the Gippsland side of the Victorian fire region, although January-November 2006 is still in the driest 10% of years (i.e., decile 1) at most locations, with many areas 35-50% below the 1961-90 average.

Snow cover was also abnormally light throughout south-eastern Australia during winter 2006. Reliable long-term snow cover data are only available from the NSW Snowy Mountains. These data indicate that the peak depth of the 2006 snowpack was the lowest recorded in the 50 years (all records) since records began at the three major Snowy Hydro monitoring sites (Spencers Creek, Deep Creek and Three Mile Dam), although the snow cover during the early part of the season was not as light as it was in 1973 and 1982. Virtually all snow had melted or sublimated by the first week of October, not only indicative of the warm spring, but also suggesting a longer period of exposure for alpine grasses. Whilst no long-term objective data exist for the Victorian snowfields, anecdotal reports indicate that similar snowpack anomalies occurred there. For instance, the ski resort of Mt Baw Baw experienced a maximum natural snow depth of 15 cm during winter.

Exceptionally high mainland temperatures, August-November 2006

After a relatively cool autumn and early winter, daytime maximum temperatures were well above average over most of the south-eastern mainland from August onwards. August-November maximum temperatures were 2-4°C above normal over most mainland fire regions, and were the highest on record over almost all of this region.

The temperatures were particularly exceptional at the high-elevation alpine sites. Mount Buller, Mount Hotham and Cabramurra all set record high mean maximum temperatures for the August-November period by between 1.4 and 1.8°C. Whilst these sites (except for Cabramurra) only have data for relatively short periods, all were operating in 2002 when temperatures at longer-term lowelevation stations were near record levels, and therefore it is likely that the 2006 temperatures are extremely unusual in the context of the last century. The warm temperatures of 2006 are consistent with the long-term warming trend over Australia. In addition the lack of snow cover
during spring 2006 provided a positive feedback to maximum temperatures at the higher-elevation sites.

Abnormal warmth was not such a significant feature of the Tasmanian fire regions. August-November maxima were generally 0 to 1°C above normal and did not approach record levels.

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The text was supported in the original statement by various tables and graphs which have not been reproduced here.

I received the following note* from Vincent Gray. He began by wishing us all “the compliments of the season” and then lauched into a discussion of mean global surface temperature records:

The theory that “Climate Change” is caused by increases in carbon dioxide stands or falls on the reliability of the “mean global surface temperature record” as compiled by the three compilers, Hadley Centre (UK) , GISS (Goddard Institute of Space Studies), USA, and GHCN (Global Historic Climatology Network), USA.

But how reliable is it?

There are enormous changes in the numbers of weather stations used for compilation of the “suface record” at different periods. In 1900 there were 1500, in 1980 there were 6000 and in 1998 there were 2700.

The averages are taken from “grid boxes” made up of 5ºx5º latitude/longitude squares on a Mercator map. Out of a possible total of 2,592 grid boxes, there were 300 available In 1900, 850 in 1980 and 500 in 1998. However, these were not distributed uniformly. There was a high density in the USA and in Western Europe and vast gaps in Africa, South America, India and Siberia. Antarctica had none until fairly recently.

Then there is the reliability for individual weather stations to record temperature trends.

The following website gives photographs of a large number of official weather stations, all of which are obviously unsuitable for recording long term trends. One is even on top of a building:

http://climatesci.atmos.colostate.edu/2006/12/12/new-evidence-of-temperature-observing-sites-which-are-poorly-sited-with-resepct-to-the-construction-of-global-average-land-surface-temperature-trends/ .

Cheers, Vincent Gray
New Zealand

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* I have shortened and edited ‘the note’.

Also by Vincent Grey:

“The Cause of Global Warming”, Energy and Environment 11 pages 613-629, 2000,
http://www.john-daly.com/cause/cause.htm), and

“Regional Climate Change” at http://www.john-daly.com/guests/regional.htm.

Hi Jennifer,

2006 might be regarded as the year of climate change hysteria or perhaps the year where we had to get serious about attribution and what is and is not global warming.

Certainly one could not help but notice various bouts of unseasonal cold weather this year with frosts affecting fruit crops in Tasmania, juxtaposed with record high temperatures of late in western Queensland and Russia.

Following a press release from the World Meteorological Society , a regular commentator at this blog Sid Reynolds questioned whether the WMO has infra-red rose coloured glasses and can only see when warm records are broken, having previously listed an impressive slew of recent record breaking cold events.

THE STATISTICS OF EXTREMES

There is a perception that the climate change story selects record breaking events to suit its argument and ignores the cold extremes.

So how do we view extreme events. What’s fair and what’s not?

Certainly global warming theory does not say all weather will be suspended and all temperatures from here on, everywhere in the world, will be always warmer every moment of every day.

It does not say there will never ever be another cold spell – or even a record-breaking cold event.

Realclimate gives a cold overview on record breaking events: “In statistics, there is a large volume of literature on record-breaking behaviour, and statistically stationary systems will produce new record-breaking events from time to time. On the other hand, one would expect to see more new record-breaking events in a changing climate: when the mean temperature level rises new temperatures will surpass past record-highs”.

In short, the probability of cold extreme events should decrease over time.

REGIONAL COLD ANOMALIES

Inner continental Antarctica has cooled compared with a warming on the Antarctica peninsula and surrounding ocean.

The issue is discussed in ‘Interpretation of Recent Southern Hemisphere Climate Change’ by Thompson and Solomon
in Science 3 May 2002: 895, DOI: 10.1126/science.1069270 .

For a graphic view of that trend visit http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=17257.

HISTORIC COLD ANOMALIES

What about periodic cold extremes in recent centuries?

A very recent study published in Nature shows how changes in the thermohaline circulation may have contributed to the Little Ice Age .

From around 1200 until 1850, during which average temperatures across the Northern Hemisphere dipped by around 1 °C, the strength of the Gulf Stream also slackened by up to 10%, oceanographers report. The Gulf Stream, which is part of a vast pattern of currents nicknamed the ocean conveyor belt, carries warm surface waters from the tropical Atlantic northeastwards towards Europe. The reduced flow that occurred during medieval times would have transported less heat, contributing to the icy conditions that persisted until Victorian times.

ICE AGE

The ultimate cold event in an ice age. Despite popular opinion the current orbital positions make that unlikely for millennia.

THE PRESENT DAY

What studies of extremes do we have of our contemporary climate? Anthropogenic global warming theory would indicate a reduction in the frequency of cold events (but not disappearance).

Where we have decent long term data this is exactly what’s been happening !

From: Frich, P., Alexander, L.V., Della-Marta, P., Gleason, B., Haylock, M., Klein Tank, A.M.G. and Peterson, T. (2002). Observed coherent changes in climatic extremes during the second half of the twentieth century. Climate Research, 19, 193-212. http://www.int-res.com/articles/cr2002/19/c019p193.pdf

From: Changes in Climate Extremes Over the Australian Region and New Zealand During the Twentieth Century.
http://www.springerlink.com/content/j488604372402531/

There has been another, more recent study, involving much of east Asia and Australasia also showing statistically reduced frequency of cold extremes: http://www3.interscience.wiley.com/cgi-bin/abstract/110573943/ABSTRACT .

THE FUTURE

What do state of the art climate models say about cold air outbreaks (CAOs) in a greenhouse world?

Various studies indicate that although in many areas CAOs will decrease, in some areas there will be little change. How counterintuitive. So the global atmosphere is a complex thing – local circulation changes may override as basic aspects of greenhouse forcing for some areas:

http://ams.confex.com/ams/87ANNUAL/techprogram/paper_117372.htm

http://www3.interscience.wiley.com/cgi-bin/abstract/112510787

http://igloo.atmos.uiuc.edu/CAO/

http://www.int-res.com/articles/cr2002/19/c019p193.pdf

Interestingly, temperatures are expected to warm over the source regions of the CAOs and the coverage of snow and ice are projected to correspondingly decrease. However, the models do not necessarily project a corresponding decrease in the number of cold air outbreaks in all regions.

From: Changes in Cold air outbreak days from a GCM ensemble run. The behavior of extreme cold-air outbreaks in a greenhouse-warmed world. Stephen J. Vavrus, University of Wisconsin, Madison, WI; and J. E. Walsh, D. Portis, and W. L. Chapman. http://igloo.atmos.uiuc.edu/CAO/mrcm.freq.abs.diff.gif

IN CONCLUSION

In conclusion, one still should expect to see periodic cold extreme events in a greenhouse world.

Exact climatology will vary from place to place depending on circulation patterns.

A simplistic assumption that cold extremes will disappear and be replaced with only hot extremes is not what the science is showing. However, in general, a greenhouse world should have a higher frequency of heatwave events compared to the current climate, and a reduction in the frequency of cold extremes would be expected. This seems to be already occurring.

Regards, Luke.

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This contribution from Luke has been significantly shortened. In particular I have deleted some of the technical argument/abstracts from technical paper to make the post more readable. I hope some of this information finds its way into the thread through comment and discussion.