The main purpose of this ongoing blog will be to track global extreme or record temperatures related to climate change. Any reports I see of ETs will be listed below the main topic of the day. I’ll refer to extreme or record temperatures as ETs (not extraterrestrials).😉
Main Topic: Focus on Tropical Cyclone Gabrielle and a Very Wet New Zealand
Dear Diary. New Zealand, which is located southeast of its much larger neighbor of Australia, has a cool climate with moderate rainfall. I wish that I had visited there once in my life, looking at its snowcapped mountains and vast green meadows. It’s a country famous for its sheep and wool. Unfortunately, due to climate change, this pristine land is changing.
This year my buddy Maximiliano Herrera has been reporting record rainfall at Aukland this summer in the Southern Hemisphere along with occasional record warmth being reported there and elsewhere across New Zealand. Could New Zealand become tropical in nature as we head closer to the 22nd century?
One big hint of change is a strong tropical cyclone that is forecast to get very close to Aukland over this weekend:
For more on Gabrielle, here is a Climate Connections writeup from Dr. Jeff Masters and Bob Henson:
Auckland just had its wettest month in over 170 years, and more rain is on the way
Just days after its worst flood disaster on record, New Zealand braces for Tropical Cyclone Gabrielle.
by BOB HENSON and JEFF MASTERS FEBRUARY 9, 2023
Workers work to clear belongings on Jan. 29, 2023, from a property in the Remuera section of Auckland, New Zealand. A man was found dead in the home after a landslide struck following record rainfall. (Image credit: Hannah Peters/Getty Images)
New Zealand’s largest city, Auckland — renowned for its typically tranquil climate — is now gasping its way through a flood-soaked southern summer that won’t quit. Having endured its wettest month and wettest single day on record, Auckland is now looking warily to its northwest as Tropical Cyclone Gabrielle gathers steam. Gabrielle is likely to bring yet another punishing round of heavy rain to New Zealand’s North Island early next week.
Climate change is exacerbating the wet setup, as a freight train of rainmaking systems from the tropical western Pacific draws on unusually high sea surface temperatures (up to six degrees Celsius or 11 degrees Fahrenheit above average near the South Island) associated with a marine heat wave. Intensified short-term rains and warming oceans are two of the most clearly established effects of a human-warmed planet.
Read: Why is it raining so hard? Global warming is delivering heavier downpours
Auckland had already racked up one of its wettest months in 170 years of record-keeping before an especially intense round of rain on Jan. 28 triggered particularly severe flooding. The month’s final total of 539 millimeters (21.22 inches) was more than 25% higher than any other month going back to 1853, including the old record of 420 mm (16.54 inches) set in February 1869, according to NIWA, New Zealand’s National Institute of Water and Atmospheric Research/Taihoro Nukarangi.
Insured damage for New Zealand’s resulting January floods could hit $630 million USD, according to one estimate, which would make it the nation’s costliest flood on record by far. At least four deaths have been reported. According to EM-DAT, the international disaster database, New Zealand’s previous costliest flood was a summer 2004 flash flood that cost $310 million (2023 USD).
New Zealand’s only billion-dollar weather disaster on record (adjusted for inflation) was a 2013 drought that cost $1.1 billion.
Figure 1. Rainfall totals for each month in Auckland, New Zealand, as measured since 1853. (Image credit: NIWA)
The band of culprits putting Auckland underwater
La Niña, the cooling of the eastern Pacific that’s been in control since late 2020 and is expected to wrap up early this year, tends to generate warming in the western Pacific. It often leads to tropical cyclones rolling their way from the Coral Sea southeast toward New Zealand. However, most such cyclones angle away from the island nation or weaken before reaching it.
This summer in the southwest Pacific, La Niña has had unusually juicy air to work with. One analysis from NOAA and the University of Wisconsin, Madison, found that precipitable water (the amount of moisture in a column above the surface) was running up to twice its usual values for the region within an atmospheric river in late January.
The atmospheric river was funneled toward New Zealand by a tropical low (the remnants of Tropical Cyclone 10P), and the moisture was squeezed out across the North Island, particularly the Auckland area.
“Converging moisture with origins from the tropics almost always produces extreme precipitation downstream,” tweeted Sheldon Kusselson, a retired satellite meteorologist from NOAA.
Figure 2. A channel of moisture with precipitable water values exceeding 45 millimeters (1.77 inches) extended from the deep tropics into northern New Zealand on Jan. 29, 2023.
(Image credit: NOAA/NESDIS via Sheldon Kusselson)
On Jan. 28, Auckland’s Albert Park reported an unprecedented 280 mm of rain (11.02 inches), including 211 mm (8.31 inches) in just six hours.
“The Earth has warmed by about 1.1°C already because of human activity and this extra heat gives more power to extreme rainfall. All other things being equal, we would expect climate change to contribute between 10-20% more rain in the most intense part of this storm,” said climate scientist Sam Dean in a NIWA media release.
Another factor: water infrastructure that hasn’t kept up with a growing city. “Many parts of the network are aging and under increasing pressure from continued urbanization and greater rainfall intensity,” said NIWA urban aquatic scientist Annette Semadeni-Davies in the media release.
“Nature-based solutions, such as infiltration basins, ponds, and wetlands, have been put forward as additions to our current pipe-based systems for flood protection. However, these alone won’t be enough. We also need to explore low-risk infrastructure that diverts and stores water more effectively, introduce managed retreat for vulnerable areas, and continued maintenance and upgrades to our existing drain network.”
Kevin Trenberth, a senior scientist emeritus and expert on global water and climate change long based at the U.S. National Center for Atmospheric Research, is now living in his native New Zealand near Auckland.
“Recently, as part of a team of international scientists that just published a paper on ocean changes, I’ve been commenting on the fact that the [global] oceans are at their warmest state ever and that it has consequences,” Trenberth wrote in an essay on Jan. 29.
“While the recent flood disasters are not directly caused by climate change, the warming climate contributes substantially to making all extremes more so, and the damage increases exponentially.”
“Nature-based solutions, such as infiltration basins, ponds, and wetlands, have been put forward as additions to our current pipe-based systems for flood protection. However, these alone won’t be enough. We also need to explore low-risk infrastructure that diverts and stores water more effectively, introduce managed retreat for vulnerable areas, and continued maintenance and upgrades to our existing drain network.”
Kevin Trenberth, a senior scientist emeritus and expert on global water and climate change long based at the U.S. National Center for Atmospheric Research, is now living in his native New Zealand near Auckland.
“Recently, as part of a team of international scientists that just published a paper on ocean changes, I’ve been commenting on the fact that the [global] oceans are at their warmest state ever and that it has consequences,” Trenberth wrote in an essay on Jan. 29.
“While the recent flood disasters are not directly caused by climate change, the warming climate contributes substantially to making all extremes more so, and the damage increases exponentially.”
Gabrielle gathers strength en route to New Zealand
Tropical Cyclone Gabrielle will add to the woes of northern New Zealand over the next few days. Because it originated from a large monsoonal low, Gabrielle has been slow to organize. The flip side is that Gabrielle is an unusually large tropical cyclone already packing immense amounts of water vapor. Gabrielle’s sustained winds as of 7 a.m. EST Thursday were 80 mph.
Gabrielle is predicted to head on a straightforward southeast track over the next several days, peaking as a high-end category 1 hurricane with 90 mph winds on Friday morning (U.S. EST). By late in the weekend, Gabrielle should hook southward just as it nears the North Island, likely going through post-tropical transition around this time, and Gabrielle may be subtropical or extratropical when it makes its closest approach to New Zealand. Tropical cyclones are uncommon in New Zealand; NOAA’s historical hurricane database shows only two hurricane-force storms have ever hit the island, Tropical Cyclone Gisele (1968) and Tropical Cyclone Alison (1975).
Regardless of how the storm is classified, the predicted motion would allow Gabrielle’s clockwise circulation to fling a large field of deep tropical moisture across the North Island. Ensemble output from the GFS model (GEFS) indicates that the Auckland area could easily pick up four inches or more of rainfall on Sunday and Monday, with even heavier amounts possible across east-facing slopes. Falling on saturated soils, the heavy rain could lead to serious flooding. High winds from Gabrielle could bring down trees and power lines.
Because of Gabrielle’s large area of tropical-storm-force winds, coastal damage from several feet of storm surge is also a danger.
Figure 3. Fewer tropical cyclones have been affecting Australia’s east and west coasts, and New Zealand, in recent years (blue areas on map). White dots show where these trends are statistically significant. (Image credit: Murakami et al., 2020, “Detected climatic change in global distribution of tropical cyclones,” PNAS May 19, 2020, 117:20, 10706-10714)
Australia has seen a decrease in tropical cyclones in recent years
Even as New Zealand will have suffered through the impacts of two tropical cyclones this year, Australia — which is historically more prone than New Zealand to catastrophic impacts from tropical cyclones — has enjoyed yet another relatively tranquil cyclone season thus far.
Natural variability and climate change have caused significant changes in the distribution of tropical cyclones in recent decades, and Australia has been the beneficiary of a reduced incidence of landfalling tropical cyclones (Figure 3).
According to statistics from EM-DAT, Australia has suffered seven billion-dollar tropical cyclones since 1974. Just one of these storms, Tropical Cyclone Debbie of 2017, occurred in the past 10 years. However, some islands of the Southeast Pacific to the east of Australia, such as Tonga and Samoa, have seen an increase in tropical cyclones.
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BOB HENSON
Bob Henson is a meteorologist and journalist based in Boulder, Colorado. He has written on weather and climate for the National Center for Atmospheric Research, Weather Underground, and many freelance… More by Bob Henson
JEFF MASTERS
Jeff Masters, Ph.D., worked as a hurricane scientist with the NOAA Hurricane Hunters from 1986-1990. After a near-fatal flight into category 5 Hurricane Hugo, he left the Hurricane Hunters to pursue a… More by Jeff Masters
Dr. Jeff Master’s and Bob Henson’s Auckland just had its wettest month in over 170 years, and more rain is on the way was first published on Yale Climate Connections, a program of the Yale School of the Environment, available at: http://yaleclimateconnections.org. This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 2.5 license (CC BY-NC-ND 2.5).
More featuring insights by Kevin Trenberth:
Here are some “ET’s” recorded from around the planet the last couple of days, their consequences, and some extreme temperature outlooks, as well as any extreme precipitation reports:
Here is some more new January 2023 climatology:
Here is more climate and weather news from Friday:
(As usual, this will be a fluid post in which more information gets added during the day as it crosses my radar, crediting all who have put it on-line. Items will be archived on this site for posterity. In most instances click on the pictures of each tweet to see each article. The most noteworthy items will be listed first.)
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Guy Walton… “The Climate Guy”