The brave prediction, “Sydney’s climate to ‘become like Brisbane’s'” for 2100 by staff at James Cook University means that Sydney Airport will warm by ~2.75 degrees C relative to Brisbane Airport (based on 1961-1990 averages) for this prediction to come true. It is obvious that the Sydney Urban Heat Island (UHI) has already notionally moved Sydney north but we will all be departed when it falls due to adjudicate on this claim by JCU staff in 90 odd years time.
However the review paper that this prediction was extracted from is titled, “Expansion of the tropics”. The authors do not seem to present evidence directly themselves, preferring to cherry pick quotes from a wide range of IPCC compliant literature.
I just want to point out that whatever merits this concept of the “expanding tropics” might have, the tropics are only warming slightly. According to 30 years of temperature trends in the lower troposphere generated by NASA satellites and calculated by the University of Alabama at Huntsville, the tropics are warming at about 0.05 C per decade. That trend is partly driven by cooling due to volcanoes early in the 30 year period then warming from the huge El Nino in 1998 – cooling early in the 30 years and warming late in the 30 years forms a couple which to some extent inserts a warming trend into the data.
However one hopes that none of the papers reviewed and relied upon by our JCU academics are quoting the authoritative (much IPCC quoted) HadCRUT3 land sea gridded temperature data compiled by the University of Norwich, Climate Research Unit, Dr. P. D. Jones and the UK Met. Office Hadley Centre.
This graphic shows that for a huge region of tropical Africa the HadCRUT3 data has errors of about 0.8 degrees C over the 30 odd years.
And world leaders are discussing huge changes to our economies assuming all the science is settled.
I should have said I got my data from the The Royal Netherlands Meteorological Institute useful website Climate Explorer. Follow the Monthly observations link on the right.