La Niña, floods, mozzies & myxo. Neville Nicholls Monash University

Transcription

1 La Niña, floods, mozzies & myxo Neville Nicholls Monash University

2 Thousands homeless; deaths, loss in record flood. Dramatic stories from northern rivers, towns. RAAF Dakota planes and army ducks are being rushed to the assistance of more than 10,000 people rendered homeless in Northern NSW by the worst floods on record [Canberra Times, 26 June] Vast lake of flood. Scenes of desolation in 400-mile flight. From the air the Tweed River appears as a great, moving inland lake emptying into the Pacific Ocean, and isolating hundreds of farms from the rest of Australia The flood water in places is 40 miles wide and isolated within it are many small towns and hamlets. We flew over hundreds of homesteads deserted and with flood water lapping their roofs. Dead cattle and horses floated seaward in the swift current of the Richmond. [Courier-Mail, 26 June] Flood havoc on roads. Shires say repairs will take 6 months. Roads damaged by Queensland s six months of rain have almost dried out, but most of the devastation will not be repaired before February. Some of the damage will take two years to make good. One council faces a flood bill of nearly 40,000. [Courier-Mail, 9 September] 12 men now trapped in flood waters near Emerald. Eight men were thrown out of a rescue boat yesterday. They had gone out to rescue two of eight men capsized on Monday and marooned in a tree. Monday s boatload went out to rescue two wellsinkers. These two are still trapped on a mound. RAAF Lincoln bombers flew from Townsville in two mercy flights. They dropped dinghies and emergency food supplies to the trapped men. [Courier-Mail, 29 November]

3 Thousands homeless; deaths, loss in record flood. Dramatic stories from northern rivers, towns. RAAF Dakota planes and army ducks are being rushed to the assistance of more than 10,000 people rendered homeless in Northern NSW by the worst floods on record [Canberra Times, 26 June] Vast lake of flood. Scenes of desolation in 400-mile flight. From the air the Tweed River appears as a great, moving inland lake emptying into the Pacific Ocean, and isolating hundreds of farms from the rest of Australia The flood water in places is 40 miles wide and isolated within it are many small towns and hamlets. We flew over hundreds of homesteads deserted and with flood water lapping their roofs. Dead cattle and horses floated seaward in the swift current of the Richmond. [Courier-Mail, 26 June] Flood havoc on roads. Shires say repairs will take 6 months. Roads damaged by Queensland s six months of rain have almost dried out, but most of the devastation will not be repaired before February. Some of the damage will take two years to make good. One council faces a flood bill of nearly 40,000. [Courier-Mail, 9 September] 12 men now trapped in flood waters near Emerald. Eight men were thrown out of a rescue boat yesterday. They had gone out to rescue two of eight men capsized on Monday and marooned in a tree. Monday s boatload went out to rescue two wellsinkers. These two are still trapped on a mound. RAAF Lincoln bombers flew from Townsville in two mercy flights. They dropped dinghies and emergency food supplies to the trapped men. [Courier-Mail, 29 November]

4 East Australia spring rainfall and SOI Data: Bureau of Meteorology

5 East Australia spring rainfall and north Australia sea surface temperature Data: Bureau of Meteorology; Climate Explorer

6 Was 2010 wetter than is expected from a very strong La Niña event?

7 Was 2010 wetter than is expected from a very strong La Niña event? probably not

8 Spring rainfall and SOI Eastern Australia rainfall closely related to SOI Eastern Australia rainfall closely related to north Australia sea surface temperature No obvious trend in SOI No obvious trend in eastern Australian rainfall Strong increase in north Australia sea surface temperature

9 Conclusions Heavy rains and floods were caused by a very strong (natural) La Niña event Not by global warming Was the 2010/11 La Niña stronger because of global warming? No trend towards more/stronger La Niña events Models inconsistent in projections of ENSO Was the impact of the 2010/11 La Niña exacerbated by very warm SSTs or global warming? No rainfall trend, despite strong warming trend But were 2010 rains heavier than expected from strength of La Niña event? Any impact of global warming on the heavy rains/floods (and there must be an impact) is difficult to identify/quantify

10 Summer SOI and eastern Australia rainfall