Sealevel rise predictions are defended

STATEMENTS by Prof Tim Naish and others regarding the Antarctic melting and subsequent sealevel rise (TVNZ 1, 1 News) are not supported by evidence obtained by direct measurement. Even Nasa tells us that ice accumulation exceeds ice losses by an amount that should lower sea levels by 0.28mm/ year.

The alarmist drum has been beaten regularly for 30 years now, but the Otago Harbour tide gauge has yet to register any increase in rate of sealevel rise. Prof Naish’s alarmism is about securing funding for their research. Peter Foster

Merton [Prof Tim Naish replies: ‘‘As an expert on ice sheets and global sealevel, it gives me no pleasure highlighting the consequences of future sealevel rise for New Zealand, but to be forewarned is to be forearmed.

‘‘The climate science communicated by my colleagues and I to the public and decisionmakers is published in the world’s leading scientific journals and is rigorously peerreviewed. It’s based on multiple lines of evidence, assessed with the appropriate acknowledgement of uncertainty through the Intergovernmental Panel on Climate Change process.

‘‘Global mean sealevel rise has accelerated in the last 50 years and is now at 3.3mm/year. Nasa’s Grace satellite measurements show that the Antarctic ice mass is decreasing by 125 billion tonnes per year and this is accelerating. Global mean sealevel by the year 2100 is predicted to be between 50 and 100cm above present.

‘‘The latest scientific evidence on the Antarctic ice sheets suggests the sealevel will be even higher, if carbon dioxide emissions are not reduced.’’]