Wellington will get significantly warmer, new climate change report shows

Wellington city will have warmer autumns, almost a month of days over 25°C and up to 10 per cent more winter rain by 2090, according to a new NIWA climate report.

The Climate Change Report for Wellington Region has just been released that shows specific weather changes for the capital, Kapiti Coast, Hutt Valley and Wairarapa for the first time.

One of the most startling projections shows an increase for Wellington city from six hot days (over 25°C) a year now to 26 days by 2090. In the Wairarapa, that figure goes from 24 days now, to  94 in just over 70 years.

Te report highlights significant impacts and implications with more floods and droughts, and increasing coastal inundation and coastal erosion due to sea level rise.

Other report findings on the future of the Wellington region’s climate include:

• Autumn is the season likely to warm the most
• Annual temperatures will increase by 1°C by 2040 and up to 3°C by 2090
• Frosts in the high elevations of the Tararua Ranges likely to disappear
• Spring rainfall will reduce by up to 15%  in eastern areas by 2090
• Up to 15% more winter rainfall along the west coast by 2090
• The risk of drought will increase significantly in the Wairarapa
• More extreme rainfall events

The report was written for the Greater Wellington Regional Council (GWRC) by a team at NIWA led by climate scientist Petra Pearce. She says the climate is warming with New Zealand warming about 1°C since 1909 with more heat waves, fewer frosts, more rain and in the south and west, less in the north and east and rise in sea level of about 1.7mm per year since the 1900s.

"The Wellington region is likely to warm significantly in the future. This has a number of implications and opportunities including the possibility of growing different crops, an increase in droughts that may limit pasture production and crop growth and pressure going on water supply," Ms Pearce said.

The report takes into account inherent uncertainty in climate projections due to likely fluctuations in future greenhouse gas emissions. It also outlines a number of implications and opportunities for New Zealand including:

• Sowing crops earlier in the growing season and seeing them mature faster due to higher temperatures
• "Sleeper" pests affecting primary industries due to changes in the climate
• Increased susceptibility of cattle to heat stress

"This report is the latest in a series of reports commissioned by regional councils. It contains high resolution climate change projection maps which will be useful for Greater Wellington Regional Council's decision making and communication with stakeholders about the potential future impacts of climate change," Ms Pearce said.

GWRC chairman Chris Laidlaw says the council has a strategy in place to ensure it is doing everything it can to future proof the region's communities and infrastructure.

"The reality of climate change is taken into account in every decision taken by council. The information in this NIWA report is key to understanding the magnitude of the changes."

Mr Laidlaw said the worst impact of climate change can be avoided but only if communities around the world act to reduce their emissions.

"Our strategy contains a number of specific actions that will ensure our organisation reduces its own emissions - and to influence the transition to a low carbon economy around the region."