Friday, March 08, 2013

Climate change: A glimpse of our future

Much of the North Island is in drought at the moment, meaning fire bans, water-restrictions, and flow-on effects for the wider economy. Writing in The Press, climatologist James Renwick warns us that this is a glimpse of our future under climate change:

Looking to the future, the risk of drought in New Zealand is on the rise. The persistent high pressure systems typical of the subtropics are already moving our way and this trend looks set to continue. The "subtropical high pressure belt" is where the world's deserts are located, and that belt is edging our way as the tropical region expands outwards under a warming climate.

Combine that with higher temperatures, increased evaporation, lower soil moisture, and we have a recipe for at least doubling the risk of drought in many of the drier parts of the country by late this century, possibly by mid-century in places. A recent report for the Ministry of Primary Industries projected an increase in drought occurrence for almost all of the country, even under an optimistic scenario for greenhouse gas emissions.

If emissions continue to run at the current high levels for too much longer, and we may be looking at a doubling of drought risk in the north and east by 2050, and a tripling (or more) of the drought risk in some regions by the end of this century.

What is quite a rare event for a farmer in Canterbury or Waikato today might be happening every few years when the farmer's grandchildren are running the property - drought is likely to become the "new normal" in some parts of eastern and northern New Zealand.

MPI's website doesn't offer direct links, but their report Drought in a changing climate can be accessed from here, and the NIWA ensemble study it is based on is here. Basically farmers can expect a lot more of this, particularly if they're in the east. Which means they are going to have to significantly change the way they do things. Sadly, this is probably going to mean more water-grabs for irrigation, rather than admitting that you simply cannot do dairy farming in Canterbury anymore and switching to something else.

It is also going to mean that we as a country will have to change. We can no longer rely on dairy farming as a source of future prosperity. Which means we will need to diversify our economy. Unfortunately, the current government does not seem to have grasped this.