Regarding The Weekend Sun letters from John Fairburn and Ken Jones (August 23) and Tony Wahren and Rob Colmore (August 30), don't forget it is scientists who discovered that Earth's climate has always changed (yes, with vineyards coming and going), its delicate balance easily disturbed by both natural influences and mankind. See the temperature chart accompanying Tony Wahren's letter representing the last 10,000 years up to 1950, derived from Greenland ice core GISP2. Since then average Arctic regional temperatures have risen a whopping 2.5 degrees to far exceed the Medieval Warming and about to surpass the Minoan Warming.

Meanwhile sea levels are indisputably rising due to thermal expansion and melting of the great ice sheets, recorded by multitudes of tide gauges and satellites. The average rate, both around NZ and worldwide, is currently about 3.4mm/year and increasing, but the rate between gauges varies due to tectonic and sea current changes – for example +5mm/yr recorded at Moturiki Island since 1998.

The declared climate emergency relates to the fast approaching ‘tipping point', beyond which time rising temperatures and sea levels will become unstoppable.

Our belated best efforts will then only buy our descendants more time to somehow prepare for the unimaginable consequences.

Peter Otway, Omokoroa