Thursday, August 24, 2017

Archipelago-building volcanic hot spots moving scarcely if at all.

New scientific research suggests that volcanic hot spots—like the one that created the Hawaiian Archipelago—are far more stable than previously believed.

Stable, as in, they don’t move much on their own.

(Image: The line of volcanoes forming the 80-million-year-old Hawaiian-Emperor Chain. The bend is at 45 million years. Credit: NOAA.)

Hot spots are those plumes of molten rock that punch through the Earth’s crust from the mantle. They tend to create lines of islands or mountains as the crust moves across them.

The Hawaiian hot spot is believed to have been responsible for the Hawaiian-Emperor chain of islands and undersea volcanic peaks, which runs from Lo`ihi and Hawai`i Islands to the southeast, up to the Aleutians in the northwest.

It has been assumed that both the hot spot and the crust are in movement, but a team of researchers from Rice University’s Department of Earth Science, say their study suggests hot spots move very little, and often not at all.

Their paper in the journal Geophysical Research Letters is “Bounds on geologically current rates of motion of groups of hot spots.” In it, lead author Chengzu Wang and his collaborators, say “the rate of hot spot motion perpendicular to the direction of absolute plate motion…differs significantly from zero for only 3 of 10 plates and then” by very little.

What that means is that it is safe to use hot spot volcano progression as a way of calculating the historic movement of the tectonic plates that make up the planet’s crust, they say.

Rice University’s press release on the paper, headlined “Hot Spot at Hawaii: Not So Fast,” starts with the line, “Through analysis of volcanic tracks, Rice University geophysicists have concluded that hot spots like those that formed the Hawaiian Islands aren’t moving as fast as recently thought,”

Our previous coverage of scientific work suggesting that the hot spot is, in fact, doing a lot of moing, is here. 

For more on Hawaiian hot spot activity, see RaisingIslands articles on hot spot depth here. 

On the mysterious bend in the Hawaiian-Emperor chain here and here.

On the relationship of KÄ«lauea, Mauna Kea and Mauna Loa here

Clearly, this is dynamic stuff, but slow-moving.

© Jan TenBruggencate 2017

Monday, August 14, 2017

Lehua rat removal: risk minimal, benefits huge.

Wedgetailed Shearwater chick early August.
There are times when doing nothing is the worst alternative.

We have the opportunity, the technology and the funding to remove aggressive, invasive, non-native rats from the Lehua island bird reserve. We should do it.

What a tragedy for ourselves and our descendants—not to mention the native wildlife, if we did nothing.

The state Department of Land and Natural Resources is proposing addressing the issue this summer, when rat populations are seasonally low and rat food supplies are low—so they are more susceptible to attractant bait.

(Images: A wedgetailed shearwater chick on Lehua in early August. The same chick, dead and partly eaten, presumably by rats. Credit: Island Conservation.)

The agency proposes using techniques that have been deployed successfully on hundreds of oceanic islands around the world, including several in the Hawaiian archipelago. It is the aerial application of rat bait containing the anticoagulant diphacinone

And while there are risks, those risks seem minimal. There have not been problems with injury to other species when rats were removed from Mokoli`i off O`ahu, from Mokapu off Molokai, from Kure Atoll’s Green Island or from Midway Atoll.

Lehua, a volcanic tuff cone islet north of Ni`ihau, is a bird refuge, but one severely compromised by Pacific rats, which have been there for decades. A dense environmental assessment for the Lehua  rat removal project is available here.

Same chick, killed and partly eaten by rats.
There have been angry arguments against the project, which minimize the actual damage done by rats, and seem strongly driven by the anti-pesticide movement. Take a look here.

Some Kaua`i residents at recent public meetings have expressed concern over the use of rat bait near the coastline. It is a valid concern, but there is ample evidence from previous eradication programs that the bait breaks up in minutes in the water, and sampling has shown no active chemical remnant in the water just days after the application.

There is no evidence of fish kills or detectable toxicity at previous rat eradication efforts on small islets around Hawai`i.

Tests at Palmyra Atoll, which has a robust coral reef system, showed no impact on corals from a much more dense application of rat pellets than proposed for Lehua. A small number of shorebirds could be impacted, but that has not been the case in previous Hawai`i eradications.

So there is a small relative risk. What’s the benefit?

Here is a paper from 2014 on the impact of rats on small tropical islands around the world. 

Rats are a problem everywhere they exist. On Lehua, swarms of rats eat seabird eggs. They kill chicks. And they attack nesting adults. By limiting seabird populations, they reduce the size of oceanic bird flocks that trollers use to identify schools of fish. They even go down to the nearshore rocks and prey on crabs and `opihi.

Rats also feed on native trees and their seeds, and are partly responsible for the loss of Lehua’s native dryland forest. That lack of vegetation promotes sediment runoff from the island into nearshore waters. And they eat the insects on the island, including native insects.

And there is a long-term positive impact not only to the environment of Lehua itself, but addressing the larger global issues facing nesting seabird species.

One of the great benefits of promoting Lehua’s safety for nesting seabirds is that it is a high island, and in an era of climate change and sea level rise, it will provide nesting habitat when the low bird islands of the Northwestern Hawaiian Islands are drowned.

This seems to be a well-thought-out project using a mature technology, with minimal risk, and one that addresses a real environmental threat.

It is reasonable to be concerned about risks, but it is not reasonable to refuse to act when the benefits far outweigh any theoretical risks.

© Jan TenBruggencate 2017

Saturday, August 5, 2017

Duck and cover. Climate catastrophe now probably inevitable

The climate chickens are coming home to roost, and the news for farmers, coastal cities, wildlife, people who don’t live in high-elevation bunkers and humans who drink water—they are now likely to be disastrous.

And that’s the best case scenario, according to a new study in Nature Climate Change.

The scary thing about changing climate is how intertwined it is with everything in our lives. As the Hawai`i Climate Adaptation logo suggest, Pili na mea a pau: All things are related.

The only way to avoid it being even worse is with herculean effort. Far more effort than is now being engaged. And nobody’s likely to be putting out that kind of effort—especially not our country, which just walked away from the Paris climate accords.

The latest predictions of climate warming suggest that by the end of this century, there’s a 90 percent chance the earth will be significantly hotter than the disastrous 2 degree rise that folks have been predicting.

There’s a small chance that it will stay as low as 2-degree rise, and a small chance of as much as a 5-degree rise. The median rise is now estimated to be 3.2 degrees, according to authors of a new paper in Nature Climate Change.

We are already so far down the climate change turnpike that even really strong measures would only keep the warming to 2 degrees, said the paper’s lead author, Adrian Raftery, a University of Washington statistician.

"Our analysis shows that the goal of 2 degrees is very much a best-case scenario. It is achievable, but only with major, sustained effort on all fronts over the next 80 years," he said in a Eurekalert article.

Scientists have long known it could be that bad, but the International Panel on Climate Change and others have downplayed the worst case scenarios, in part because they are so horrific as to be easily rejected. Imagine cities under water. Farmlands poisoned by saltwater intrusion. Coastal resorts washed away. Flooding in dry areas and drought in our breadbaskets. Storms. Massive wildlife losses.

“Damages from heat extremes, drought, extreme weather and sea level rise will be much more severe if 2 degrees C or higher temperature rise is allowed. Our results show that an abrupt change of course is needed to achieve these goals." said one of the paper’s co-authors, Dargan Frierson, a University of Washington associate professor of atmospheric sciences.

The study was a detailed review of climate data, country by country.

"This is a high-tech statistical model that looks at what has happened to per-capita output in each country, to carbon intensity in each country, and to population in each country. What we find is that there is a wide range of what could happen, but unfortunately the bottom end of the range is still fairly bad, and the top end of the range is catastrophic," said another of the paper’s co-authors, University of California at Santa Barbara economist Dick Startz.

"Our predictions assume that carbon intensity is going to continue to trend downward, as it has been. That still leaves us in a mess. The only thing that is going to get us out of it is finding a way to make carbon intensity fall much more quickly than it has been," Startz said.

He said it is difficult but possible to envision a global initiative that could keep the temperature rise within some limits, using major advances in energy technology, but he’s not hopeful. Carbon intensity as been declining, but not nearly fast enough to make a significant impact.

"We can hope for some magic breakthrough or we can do the unpleasant task of charging more when we're polluting. But even that might not be enough," Startz said.

California already has a sense of how bad it could be in terms of sea level rise, as the state earlier this year released a major report on the subject. It’s available here.

California, as Hawai`i is, is already seeing some of the early effects, the report said: 

“Coastal California is already experiencing the early impacts of a rising sea level, including more extensive coastal flooding during storms, periodic tidal flooding, and increased coastal erosion.”

Much of the sea level change in recent decades has been from thermal expansion of ocean water, glacier melting and ice cap melting. But the planet is moving into a new phase in which there is melting of the massive ice sheets of Greenland and Antarctica.

California’s take on the most likely sea level rise by 2100 without significant mitigation? That would be 1.6 to 3.4 feet.

Worst case? Ten feet.

Hawai`i's efforts to understand the local impacts of climate and related changes are being overseen by the state's Interagency Climate Adaptation Committee, which has a website here

© Jan TenBruggencate 2017