Viewed
at just the right angle, and maybe with a bit of squinting — and
perhaps a little imagination — the natural stone formation resembled a
charging elephant, about 100 feet high and up to eight feet wide.
Elephant
Rock near Hopewell Cape, New Brunswick, was so well known and
frequently photographed that it appeared on the provincial health care
identification card.
But
like the Rockies and Gibraltar — as the Gershwins somewhat
simplistically put it — it’s only made of clay, and on Monday about half
of it collapsed.
The event, as far as anyone knows, went unwitnessed.
Hopewell Cape in the GeoGarage platform (CHS chart)
zoom on Hopewell Rocks with the GeoGarage platform (CHS chart)
Elephant Rock, or at least what remains of it, is one of the 17 Hopewell Rocks in the Bay of Fundy that become whimsical formations at low tide.
Yet
despite its importance as a tourist attraction and a provincial symbol,
some in New Brunswick see the demise of the elephant as inevitable as
the melting of an ice palace after a winter carnival.
“To
some degree, it’s the end of an era,” said Noël Hamann, the property
manager of the provincial park that includes the Hopewell Rocks.
“This
particular rock was iconic because it was on the health card, so
everyone in New Brunswick feels they have ownership of it,” he said.
“But the rocks are always changing.”
While
the most dramatic, Monday’s collapse was not the first recent act of
natural destruction visited upon Elephant Rock.
In 1997, a protrusion
that Mr. Hamann said resembled an elephant’s trunk snapped off.
Like
its neighbors, Elephant Rock is a mixture of sandstone and a soft rock
known as Hopewell Conglomerate.
This photo shows how drastic the difference is between high and low tide of the Bay of Fundy at the Hopewell Rocks.
(Kevin Snair)
The tides, which rise and fall 36 to 46
feet, helped create the rocks by carving them out of the shoreline and
also play a role in their destruction.
Interactive tides animation (click or tap on a photo below, then drag up & down) Remember, the real Bay of Fundy tides take about 6 hours to flow from low tide to high tide, so plan to stay long enough to witness this amazing phenomenon.
But Mr. Hamann said that major springtime collapses were the result of the same freeze-thaw cycle that creates potholes.
And, he added, all of the formations are ultimately doomed.
“People get attached, and they don’t like change,” Mr. Hamann said. “But the tide waits for no man or rock.”
Whales, the biggest animals on the
planet, are also among the hardest to find.
They spend most of their
time submerged and unseen.
But not unheard: Whales are noisy animals that flood the oceans with songs, clicks, moans, and calls.
And Purnima Ratilal from Northeastern University has developed a way of listening in on these calls
to instantly detect, find, and classify whales, over 100,000 square
kilometers of ocean—an area the size of Virginia or Iceland.
“The
conventional method for studying marine mammals is to go out on a boat,
dangle a hydrophone [an underwater microphone] off the side, and listen
for the sounds the animals make,” she says.
“Or you do visual surveys,
focused on one or two species and just a handful of individuals at a
time.”
By contrast, her technique uses 160 hydrophones to simultaneously map the presence of at least eight whale species, without ever needing to see a single fin.
Ratilal
started her scientific career studying military sonar and found that
fish would seriously clutter the rebounding signals.
That’s not great
for people trying to detect enemy craft but it’s perfect if you want to,
y’know, map fish.
Fishermen already use fish-finding sonar but it
typically uses very high frequencies and can only map the water column
directly beneath a boat.
By using lower frequencies, Ratilal could detect fish over thousands of square kilometers.
And a lot of fish, at that.
In September 2006, the team ventured out into the Gulf of Maine with
two ships: one that sent out sound waves and another that detected the
rebounding echoes with a string of 160 hydrophones. Together, they
visualized the movements of a quarter of a billion herring.
During the day, these fish stick to the ocean floor and largely keep
their distance.
But come sunset, they gather to spawn, rising to the
surface and aggregating into a kilometers-wide mega-orgy—a shoal of 250 million fish all busy creating millions more baby fish.
While working on the herring, the team kept on hearing whales in their recordings.
They initially focused on humpbacks, reputedly among the most vocal of
the whales.
“We were amazed at the quality of the data we got,” says
Ratilal.
“We found 2,000 calls from humpbacks each day.”
But even though
the herring were spawning throughout the gulf, the herring-eating
humpbacks were clustered in two separate locations.
Why weren’t they
going after the fish in the middle?
“We thought there might be other
whale species occupying the regions in between. And sure enough, we
found them.”
Each whale species calls within a certain frequency range and makes
its own distinctive repertoire of sounds.
Using this information, the
team could look at their recordings and extract the locations of five
huge filter-feeding species (the blue, fin, humpback, sei, and minke)
and three toothed ones (sperm, pilot, and killer).
The whales
seemed to divide the herring between them, with each species sticking to
its own particular part of the Gulf.
The blue whales stayed away from
the humpbacks, which swam apart from the minkes, which lived separately
from the seis.
“You find the same species in these same areas day after
day,” says Ratilal. “It’s quite stable.”
It’s possible that the
larger whales like blues stay away from shallower regions, leaving those
to the smaller minkes and pilots.
But in truth, no one knows why or how
the whales carve up the oceans between them.
It’s not surprising that
they do—you can see similar partitioning among, say, plant-eaters on the African grasslands—but it’s rare to see such
stark visual evidence of these divisions.
Check out Ratilal’s map:
that’s a huge body of water.
See those rings of color?
Those are the
territories of animals that are the size of ships.
Wang et al, 2016. Nature
“[Ours] is the only technique that can instantaneously monitor marine
mammal and fish populations over very large areas,” she says.
She calls
her technique Passive Ocean Acoustic Waveguide Remote Sensing (POAWRS),
and the “Passive” bit is important.
When the team studied the herring,
they found the fish by sending out sound waves and capturing the echoes.
But whales are so vocal that the first bit is unnecessary.
“We’re just
listening in,” says Ratilal.
She thinks that POAWRS can reveal not
just the distributions of whales and fish, but their interactions as
predators and prey.
For example, she says that humpbacks are ten times
more vocal at night than during the day, and suggests that they’re
making feeding calls while engulfing the amassed herring.
Likewise,
minke whales make buzzing sequences that have previously been
interpreted as mating calls. But the team found that they overlap with
the presence of herring.
“They’re probably an intricate part of the
minke feeding behavior,” says Ratilal.
But Jeremy Goldbogen
from Stanford University isn’t convinced.
He says that these large,
filter-feeding whales might make calls between bursts of foraging, but
tagging studies have shown that they don’t vocalize while feeding.
“This
demonstrates both the power and limitations of using acoustics to study
predator-prey interactions,” he says.
Sure, researchers can monitor
large swathes of ocean and find patterns that no one has seen before.
But they can only infer behavior through correlations, and they may do so wrongly.
When understanding what these animals are doing, rather than just working out where they are, you still need to see them.
Every year TeleGeography creates a new global undersea cable map.
TeleGeography's Submarine Cable Map 2015
was a particularly wonderful map.
The 2015 map was inspired by medieval
and renaissance cartography and featured some wonderful map border
illustrations and even a number of beautifully drawn sea monsters.
For the 2016 edition of its Submarine Cable Map
TeleGeography has designed a much more modern looking and information
rich map.
The main map shows 321 undersea cable systems around the
world, while a number of smaller inset maps depict some of the world's
busiest landing stations.
Locations of all copper telegraph cables around the world in 1877.
Countries on the map are colored to show how many submarine cable system
links are connected to each country.
Infographics along the bottom of
the map provide additional information on the capacity of the major
global cable routes around the world.
The Submarine Cable Map 2016 is certainly not as much fun as the 2015
edition.
However TeleGeography's latest map does provide a lot more
information about the world's submarine cable networks and is
consequently a lot more informative.
Hurricane Sandy's near-surface winds are visible in this NASA GEOS-5 global atmosphere model computer simulation that runs from Oct. 26 to Oct. 31, 2012.
When a hurricane, flood, heat wave, or other extreme weather event
strikes, reporters call scientists like me and ask us what human-induced
climate change had to do with this event.
Until recently, most of us
would say something like this: “Climate change is real. It alters the
broader patterns, the statistics of weather. But we can’t attribute any
single weather event to climate change.”
We are starting to
respond differently.
A new area of scientific research, known as
“extreme event attribution”, has emerged to provide more substantive and
quantitative answers.
Our science has reached the point where we can
look for the human influence on climate in single weather events, and
sometimes find it.
Today, the National Academy of Sciences released the report, “Attribution of extreme weather events in the context of climate change“,
which concludes it is now “often possible” to describe how
human-induced climate change altered the likelihood and/or intensity of a
specific extreme weather event.
The report was written by a panel of
climate scientists who have studied linkages between climate change and
extreme weather, in which I was honored to participate.
One
of the questions that motivated this report is: “Did climate change
cause this event?”
This is a question we hear frequently after
devastating instances of extreme weather.
We’ve never been able
to provide a satisfying answer and we still can’t because the question
is ill-posed.
No weather event has a single cause.
Each event has many
causes, and most of them are natural.
Climate change is one influence
among many, and it can be a subtle one.
But the report makes
clear that we now can begin to provide meaningful responses to the
following kinds of questions: “Did climate change make a heat wave like
this more likely to occur, and if so by how much?”
Or, “Given that a
storm like this occurred, did climate change make it more intense?”
Model simulations spanning 140 years show that warming from carbon dioxide will change the frequency that regions around the planet receive no rain (brown), moderate rain (tan), and very heavy rain (blue).
The occurrence of no rain and heavy rain will increase, while moderate rainfall will decrease.
Credit: NASA's
The answers can depend on how they are framed, as much as they depend
on the specifics of the event.
But at least in some cases, substantive,
quantitative answers to these questions are possible.
We obtain
those answers by comparing the event that just happened to a
reconstruction of what might have happened if humans hadn’t changed the
climate.
In one common method, scientists perform many realistic
computer model simulations, over long times (in computer years), of both
the present climate, and the climate of a hypothetical, cooler world
without human influence.
In each climate, they count how often events
occur that are similar to the one that happened in the real world.
If
they happen twice as often (say) in the simulated present climate as in
the hypothetical climate without humans, then we say that human-induced
climate change made the event twice as likely as it would have been
otherwise.
Of course, the results could also show that the event is
about equally likely in both climates, or less likely in the present
climate (as is generally true for extreme cold snaps).
Or the
results could be inconclusive.
Even the best model may not be good
enough to capture some events with sufficient accuracy, and then we just
can’t draw useful results about those events from it.
Or we may not
understand well enough how some kinds of extreme weather are influenced
by climate change, in which case we won’t trust what models tell us even
if it looks plausible otherwise.
The necessary understanding should
depend on multiple lines of evidence, including historical observations
and our knowledge of the basic physics of the events.
As a rule,
we can do better with the events that are the most directly related to
temperature, since then the chain of causality from global warming to
the event is shortest and simplest.
We can make the strongest
attribution statements about heat waves, in particular.
(National Academy of Sciences, 2016)
We can say very little (yet) about the climate change influence on
tornadoes, because our models don’t yet have enough resolution to
simulate them (like a digital camera with too few pixels to see
someone’s face from far away), their relation to temperature is
indirect, and not enough research has been done for us even to be sure
how they should be changing.
Other kinds of events – such as floods,
droughts, and hurricanes – are somewhere in between.
Though
attribution science is advancing quickly, it’s still new, and some
scientists are uneasy about it. Some are concerned that it politicizes
weather disasters by making them into climate change stories.
I have
been concerned, on the other hand, that stories focused on attribution
in the wake of weather disasters can send misleadingly skeptical
messages about climate change as a whole.
Climate science works best with patterns.
Determining climate
change’s role in a single event is usually more difficult than doing so
in global statistics.
It can be hard to be sure that exposure to small
amounts of a chemical caused cancer in a single patient, even when
studies of large populations prove that it is a carcinogen; similarly,
we often can’t make strong attribution statements about an individual
weather event, even when we have a lot of evidence that those kinds of
events overall are influenced by climate change, or will be in the
future.
So media coverage of attribution studies sometimes ends up
focusing more on what we don’t know than what we do.
That can leave the
impression that we know less than we really do, which is unhelpful in a
political climate which already doesn’t take the real one seriously
enough.
But attribution studies help to close the gap between the
widespread notion of climate change as distant and the real need for us
to act on it now.
Real extreme weather events get people’s attention.
Sometimes, some of that attention lands on broader issues around climate
change that are overdue for it.
When “Superstorm” Sandy struck, for
example, it started a critically important public conversation about sea
level rise and other climate change impacts on the New York
metropolitan area.
Now, some of the most important aspects of
this conversation don’t actually require us to say to what extent
climate change influenced Sandy.
(For the record, though,
climate-related sea level rise increased the depth of the flood waters
by about eight inches.)
We should be planning for climate change based
on our best projections of the future, and single events don’t change
those – the fact that Sandy occurred doesn’t change the probability of
the next one.
And even if the evidence doesn’t indicate a
significant human influence on a particular recent event, our lived
experience of that event can provide a needed vision of what changes may
be coming in the future, and an indication of our vulnerability to
those changes.
But it is natural to try to see climate change
through the lens of individual weather events, and to ask straight up
how they are related.
Our ability to answer is improving quickly,
allowing us to grasp more profoundly what is happening to our planet in
real time.
