Wet La Nina winter shifting, to a stormy summer?

Hawai`i’s wettish winter could continue, as the current La Nina climate cycle is expected to last through the winter.

That’s the latest assessment (January 11, 2018) from NOAA’s Climate Prediction Center and the International Research Institute for Climate and Society.

Long-term prediction of climate cycles is problematic, but most climate models seem to suggest that we could shift into El Nino by mid-summer. If that holds true, it could result an more tropical storms and hurricanes later this year than normal.

La Nina and El Nino are two major climate cycles affecting weather conditions in the Pacific. La Nina has cooler water in the equatorial central Pacific and El Nino has warmer waters.

Generally, for Hawaiian islands, El Nino conditions are associated with dry winters and stronger and more frequent hurricanes June to November. La Nina—which we’re now in—tend to have fewer storms from June to November and wetter winters.

Have you noticed a lot of strong tradewinds recently? La Nina conditions are also associated with stronger low-level tradewinds.

The new report suggests that La Nina conditions continued through the end of 2017 and are expected to persist through the rest of the winter, while weakening. After that, conditions should drift toward a neutral condition for the spring. And the models seem to indicate a continued shift toward El Nino as the summer progresses.

El Nino/La Nina conditions don’t only impact the climate of the Pacific, but are also associated with rainfall and temperature patterns on the Mainland.

Based on the latest climate models, “The outlooks generally favor above-average temperatures and below-median precipitation across the southern tier of the United States, and below-average temperatures and above-median precipitation across the northern tier of the United States.”

Since central Pacific ocean water temperatures are a key indicator of El Nino and La Nina cycles, the climate agencies have computerized models that track where they think water temperature is going. There are many such models, but as shown below, most of them are showing water warming into the summer months.

The bottom line shows months in three-month periods. The dynamic average shifts from negative to positive temperatures in May-June-July (MJJ)

Forecasts of sea surface temperature (SST) anomalies for the Niño 3.4 region (5°N-5°S, 120°W-170°W). Figure updated 18 December 2017. Credit: NOAA.

© Jan TenBruggencate 2018

Figure 6. Forecasts of sea surface temperature (SST) anomalies for the Niño 3.4 region (5°N-5°S, 120°W-170°W). Figure updated 18 December 2017.

Figure 6. Forecasts of sea surface temperature (SST) anomalies for the Niño 3.4 region (5°N-5°S, 120°W-170°W). Figure updated 18 December 2017.

Rats detected at Lehua, four months after major eradication effort

Rat control team on Lehua. Credit: DLNR

Rats are back at Lehua, or more likely, a few Pacific rats survive after a major effort to eradicate them during the late summer.

Wildlife management teams were on the island yesterday to better understand the extent of the rat presence and to establish extensive bait and trapping measures in the area where they were seen. They have not abandoned efforts to completely eradicate invasive rats from the small island.

The Lehua rat control project is designed to remove a major predator of the many species of seabirds that nest on the small island north of Ni`ihau. The island has been populated by Pacific rats at least for the past century. It is a state seabird sanctuary.

Pacific rats prey on eggs and chicks of many species, and they also damage the environment by eating seeds and seedlings of plants that otherwise would provide cover and nesting habitat for the birds.

This statement about the rat control project was released yesterday by the state Department of Land and Natural Resources:

Lehua's steep terrain. Credit: DLNR

“The invasive Pacific rat is a voracious predator on the eggs, chicks and even adult birds that currently breed and nest on remote Lehua. The restoration project team has stated repeatedly that the project will not be considered a success unless every invasive rat is removed from the ecosystem, and that will take a full year after the final application to say for sure. The goal of the Lehua Island Restoration Project is to provide safe, predator-free breeding habitat for native seabirds and other species so they may thrive again.”

Numerous motion detection cameras and human surveys of the island after the final delivery of diphacinone rat bait in September 2017 detected no rat presence. But camera memory cards collected in December revealed at least two rats near the summit of the island in late November.

The rats spotted on the camera cards are believed to be Pacific rats, the species that was abundant on the island before the eradication effort in August and September, although a positive identification from fuzzy black and white photos was not possible.

The team sent to the island yesterday included members from Island Conservation (IC), the state Division of Forestry and Wildlife and the Kaua‘i Endangered Seabird Recovery Project (KESRP.) 

The teams have installed a range of measures to attempt to assess whether there are more of the predators present on the island. A total of 134 monitoring devices have been placed on the island, including traps, tracking tunnels with ink pads to detect footprints, wax chewing blocks, bait stations and motion-detection cameras.

Many of the cameras are aimed specifically at seabird nests and burrows as part of the KESRP program, but will identify rat presence as well.

Rats have been eradicated from dozens of islands around the globe, and most eradications work the first time. However, a significant percentage has required repeat control efforts. In the case of Lehua, one theory was that winds at the top of Lehua blew rodenticide pellets away from the top of the ridge, allowing a few rats to survive there, while rodents elsewhere on the island were controlled.

“After seeing these two rats on camera, we collected, immediately reviewed, and noted locations of any additional images the cameras may have picked up,” said Mele Khalsa, of Island Conservation. A review of all other camera records identified no other rat photos.

“While we are clearly disappointed to see evidence of two rats on the island, we are very lucky our partners (KESRP) were able to detect them. We knew from the beginning there was the possibility that a few rats could linger. Now it’s important to address this,” said Suzanne Case, chair of the state Board of Land and Natural Resources.

The rat eradication program has been intensely controversial, largely over the fear that toxic baits could impact the marine environment. Tests on fish found around the island immediately after the bait distribution could not show that the rodenticide was an issue, and tests on the livers of pilot whales that stranded on Kaua`i a month later showed no presence of diphacinone.

Since the two rat detections were in the central part of the island, the current effort should not impact the coastline of Lehua.

© Jan TenBruggencate 2017