FELICITY CAMPBELL
Whanganui
Extreme weather more common
Rob Thomson (Letters, June 17) queries a Chronicle editorial that blamed the recent Canterbury floods on global warming. He wants to know what causes extreme weather events, what evidence there is for these events occurring more frequently, and how they can cause more droughts.
The Chronicle was quite correct in stating that extreme events are becoming more common. Between 1980 and 1999, the United Nations recorded 3656 disastrous floods, storms, heatwaves, droughts and forest fires around the world. But, between 2000 and 2019, there were 6681 climate-related disasters. (tinyurl.com/parawhenua).
Nasa and NOAA have just reported they found Earth retained twice as much of the sun's energy in 2019 than it did in 2005, partially due to a temporary El Nino event and partly the result of an increase in anthropogenic greenhouse gases returning more solar radiation back to Earth's surface. This raised seawater temperatures, causing more water vapour to rise into the atmosphere. (tinyurl.com/huarua).
Excessive amounts of lightweight humid air rising up from the oceans cause deluges, high winds, tornadoes and cyclones, so the more water vapour that rises from the warming-up oceans around us, the heavier will be the deluges on Taihape and Parapara hills.
During a Beef + Lamb woolshed meeting at Bell's Junction about 10 years ago, a Niwa climate expert told us to expect warmer and more-frequent westerlies creating "rain events" dumping 50 per cent more water on our hills than past cloudbursts did, while East Coast farmers could expect worse droughts because they are in our rain shadow.
A MAF farm expert suggested local farmers could prepare for these events by planting more hillside trees and by moving tracks and farm sheds further away from the rivers. It is good to see many of them have now taken these precautions.
Hopefully, this answers Mr Thomson's questions.
JOHN ARCHER
Ohakune