Climate scientists attack criticism

16:00, Nov 26 2009

New Zealand climate scientists wonder where the next attack on their work will come from in the lead-up to the Copenhagen climate talks.

Scientists yesterday rubbished claims from New Zealand climate-change sceptics that temperature data from around the country had been deliberately tampered with to show a higher degree of warming.

The suggestion from the New Zealand Climate Science Coalition and the Climate Conversation Group comes just days after "Climategate", in which thousands of emails and documents sent between scientists were hacked from the University of East Anglia's Climate Research Unit and leaked on the internet.

Sceptics have been selecting out comments from the emails and saying they are evidence of selective science and even collusion in preparing reports for the Intergovernmental Panel on Climate Change.

National Institute of Water and Atmospheric Research (Niwa) principal climate scientist James Renwick , sacked Niwa scientist Jim Salinger and commentator Gareth Renowden say the timing of the attacks is no coincidence.

The Climate Conversation Group (CCG) and the Climate Science Coalition have released their own analysis showing that unadjusted temperature readings from seven weather stations with 100-year-plus records – Auckland, Masterton, Wellington, Hokitika, Nelson, Lincoln and Dunedin – were stable and did not create the warming trend that Niwa's adjusted figures did.


CCG convener Richard Treadgold claimed the results were "shocking".

Niwa's adjustment of early temperatures down by up to 1.3 degrees Celsius had introduced a "false warming", allowing the graph to climb to the present day.

"It's a disgrace," Treadgold said.

Renwick, Salinger and Niwa chief climate scientist David Wratt hit back at the claims of manipulation.

Wratt said Niwa climate scientists had previously explained to members of the coalition why such corrections had to be made. He was disappointed they continued to ignore that and present misleading analyses.

Salinger said adjustments were made for legitimate reasons, such as changes of site.

"I haven't seen this work but it will be b......., because I have worked on this for many years.

"When I was doing my PhD, looking at the record up to 1975, there were at least 50 to 60 climate stations started in the 1930s that, before we did anything, 90 per cent of them showed warming."

Renwick said there were several reasons for adjusting the temperature record, including introducing new thermometers or sensors to a weather site, and changes to its exposure caused by growing vegetation or urbanisation.

For example, the Wellington figures had to be adjusted down when the official weather site moved from the Thorndon waterfront to Kelburn.

"That's a move up of about 120 metres – that is the equivalent of a degree of cooling."

The claims were "more of the same" with Copenhagen only 10 days away.

"This implies that people such as myself have some agenda and we're deliberately trying to do something funny and we are going to profit from it. I'd actually just like to get on with my work."

Renowden, of blog site Hot Topic, said the timing was deliberate.

"I have no doubt that all of this is part of a concerted campaign to discredit climate science and prevent action on reducing emissions.

"I don't believe New Zealand's climate sceptics are necessarily part of an American PR campaign, but I do think they play along with it."

The temperature analysis had "zero credibility", he said.

The Press