A follow up on the 'it was warmer in 1790 in Sydney' story

Readers may recall the story Global Warming?……. It was warmer in Sydney in 1790 by Craig Kelly, MP in NSW Australia in response to some of the recent alarmist caterwauling in the press about the hot summer in Australia being a sign of ‘global warming’. He writes in with an update regarding criticisms by Steven Mosher regarding instrument calibration.

Meteorological records for Port Jackson, New South Wales, compiled by Lieutenant William Dawes, 1788–91. The Royal Society.

Kelly writes:

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Hi Anthony,

I’ve done a bit more research on the temperature measurements recorded by Tench in 1790 that I thought you might be interested in.

Firstly, it appears the measurements were taken in a purpose built observatory which stood at location of the current pylons of the Sydney Harbor Bridge. The Observatory was built and run by William Dawes.

There is a detail description of the Observatory in letter sent back to England. The Observatory had two thermometers not one. These were loaned to the First Fleet by the Board of Longitude.

One was made by Nairne & Blunt and the other one by Ramsden.

When the First Fleet stopped at Cape Town on the way to Sydney, Dawes refers to calibrating the instruments. William Dawes’ journal actually mentions making a comparison between the two thermometers, noting;

‘‘I observe when the thermometers have been long at nearly the same height that they agree.’’

When both Dawes and Tench returned to England at the end of 1791 (after having their requests to stay denied) they took the thermometers with them and returned them to the Board of Longitude.

Both Tench and Dawes were remarkable men, they would have done everything in their power to ensure the measurements were as accurate a possible. Gergis et al. (2009) has stated that William Dawes’ data is commensurate with present-day meteorological measurements.

Add this to the numerous ancedotes of bird and bat deaths, and I think even the most skeptical would have to agree that records are quite accurate.

Regards,

Craig Kelly

Federal Member for Hughes

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Some additions by Anthony:

The abstract of Gergis et al 2009:

This study presents the first analysis of the weather conditions experienced at

Sydney Cove, New South Wales, during the earliest period of the European settlement

of Australia. A climate analysis is presented for January 1788 to December

1791 using daily temperature and barometric pressure observations recorded by

William Dawes in Sydney Cove and a temperature record kept by William Bradley

on board the HMS Sirius anchored in Port Jackson (Sydney Harbour) in the early

months of the First Fleet’s arrival in Australia. Remarkably, the records appear

comparable with modern day measurements taken from Sydney Observatory

Hill, displaying similar daily variability, a distinct seasonal cycle and considerable

inter-annual variability. To assess the reliability of these early weather data, they were cross-verified with other data sources, including anecdotal observations recorded in First Fleet documentary records and independent palaeoclimate reconstructions. Some biases in the temperature record, likely associated with the location of the thermometer, have been identified. Although the 1788–1791 period experienced a marked La Niña to El Niño fluctuation according to palaeoclimatic data, the cool and warm intervals in Sydney over this period cannot be conclusively linked to El Niño–Southern Oscillation (ENSO) conditions. This study demonstrates that there are excellent opportunities to expand our description of pre-20th century climate variability in Australia while contributing culturally significant material to the emerging field of Australian environmental history.

An account from Dawes journal extracted from Gergis et al 2009:

By September 1790, the settlers were fast realising just

how unpredictable Australia’s weather could be. Watkin

Tench remarks ‘it is changeable beyond any other I ever

heard of… clouds, storms and sunshine pass in rapid succession’.

But by the middle of 1790, Tench (1793) describes

the impact of dry conditions on the colony’s food supplies:

‘vegetables are scarce…owing to want of rain. I do not think

that all the showers of the last four months put together,

would make twenty-four hours rain. Our farms, what with

this and a poor soil, are in wretched condition. My winter

crop of potatoes, which I planted in days of despair (March

and April last), turned out very badly when I dug them about

two months back. Wheat returned so poorly last harvest’

(Tench 1793).

It appears that the summer of 1790–91 was a hot and dry

summer. Tench comments that, at times, it ‘felt like the blast

of a heated oven’. He goes on to describe the heat endured

during summer: ‘even [the] heat [of December 1790] was

judged to be far exceeded in the latter end of the following

February [1791], when the north-west wind again set in, and

blew with great violence for three days. At Sydney, it fell

short by one degree of [December 1790] but at Rose Hill [Parramatta],

it was allowed, by every person, to surpass all that

they had before felt, either there or in any other part of the

world…it must, however, have been intense, from the effects

it produced. An immense flight of bats driven before the

wind, covered all the trees around the settlement, whence

they every moment dropped dead or in a dying state, unable

longer to endure the burning state of the atmosphere. Nor

did the ‘perroquettes’, though tropical birds, bear it better.

The ground was strewn with them in the same condition as

the bats’ (Tench 1793).

Gosh, “climate disruption” in 1790? It’s worse than we thought!

List of Instruments proper for making astronomical Observations at Botany Bay

Other related items include two lists that detail the instruments Dawes needed for his colonial observatory. ‘List of Instruments proper for making astronomical Observations at Botany Bay’ contains a great many items, but as the Board of Longitude — of which Banks was an ex-officio member by virtue of his position as President of the Royal Society — did not have sufficient instruments on hand, most of these were eventually crossed out.

Note the “two thermometers” in the list above.

List of instruments to be lent by the Board of Longitude for making astronomical Observations at Botany Bay

The ‘List of instruments to be lent by the Board of Longitude for making astronomical Observations at Botany Bay’ is a much shorter list; it served as a clean copy of what was actually available from the Board of Longitude.