Haven't heard of Palmyra before? That's probably because no one lives there, at least not all the time - Palmyra is a "US Affiliated Pacific Island" managed by The Nature Conservancy, and is 'inhabited' by a rotating crew of TNC staff, US Fish and Wildlife Service personnel, and visiting scientists.
Even though Palmyra has never been permanently settled by humans, it has a very cool history: it's named for an American sailing ship, the USS Palmyra, which ran aground there in 1802. Throughout the 1800s it was annexed a variety of times: by the US government, by the Kingdom of Hawaii, then by the US again (when the US took over Hawaii - for a while there Palmyra was actually part of Hawaii!). Then in the early 1900s it was bought by a wealthy judge, and has been privately owned ever since... with the exception of a few years during World War II when it was used as a naval base by the US. The Nature Conservancy bought Palmyra in 2000 and sold part of it to the Fish and Wildlife service, and now it's maintained as a wildlife refuge.
Palmyra has an amazing variety of marine life, and one of the healthiest coral reef ecosystems in the world. It's common to see all sorts of sharks, rays, whales, and (it seems like) any other tropical fish you can think of - this makes it a very valuable destination for marine ecologists, who can actually study the ecosystem there without worrying about all the ways people have screwed it up! But none of that is the reason why we're headed out there. No, we are a physical oceanography team, and we'll be deploying instruments on Palmyra's reefs to measure the temperature, salinity, and currents around the island - and the isotopic composition (relative amounts of oxygen-18 and oxygen-16) of the sea and rain waters as well.
Why are we doing this? Well, to explain that I need to explain something else: El Nino. Not this one:
This one:
That last picture is a satellite image of sea surface temperature (SST) anomalies during the last really big El Nino event, in 1997-98.
El Nino events (and their sisters the La Ninas) happen when the trade winds that blow from east to west along the equator become either much weaker or much stronger than normal. When that happens, all the warm water that sits along the equator either 'sloshes' over to the east (El Nino) or gets pushed over into the west (La Nina). They both have dramatic impacts around the world, on weather, fisheries, and many other things: so we'd like to have an idea of how often they happen and how strong they tend to be, not to mention figuring out how they might change in the future! But the problem is that we've only been observing the oceans in enough detail for about 30 years, and El Nino/La Ninas only happen every 3-4 years, and that adds up to not enough events to get a good sense of what 'normal' is like.
One way we can get around this problem is using paleoclimate data to reconstruct what past El Nino/La Nina events were like. Paleoclimate data is basically any naturally occurring object that is sensitive to climate and accumulates fast enough to record changes in climate. On land, people use tree rings, ice cores and other things... but in the tropical oceans, coral reefs are the name of the game. Corals grow very quickly, like trees, and changes in the seawater around them affect the proportion of isotopes of oxygen that get incorporated into their skeletons. Islands in the central Pacific, like Palmyra and its neighbor Christmas Island, are excellent sites for collecting coral data since they're right where we expect the biggest effects of El Nino to be. But we still don't have good measurements of exactly how you translate between isotopes of oxygen in corals and what a particular set of El Nino events looked like, since there aren't very many measurements from right next to the reefs during their entire 'life cycle'. I've been working on using model simulations to understand the physics of how you go from El Nino to coral isotopes, but of course having more data would always be helpful.
Cue the 2014 El Nino! ...hopefully... Earlier this year, it looked like we might be in for the biggest El Nino since the one that inspired the Chris Farley video above. So my collaborators (Kim Cobb, Mark Merrifield, and Brian Powell) and I put in for a small grant to actually go down and put instruments near the reefs at Palmyra so we could watch how the event affected conditions near the shore! In a companion grant, Kim is also collaborating with coral ecologists to look at the impacts of this El Nino on coral ecology. She has a blog here:
Coral reef impacts of the 2014/15 El Nino event
Since we received our funding, the El Nino forecast got downgraded a bit, and it looks like any event we get won't be nearly as big as the 1997-98 one. But regardless of how big this El Nino turns out to be, the data we gather in the next week or so will be critical for understanding how these events are recorded by corals.
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