We just returned from our 10 day expedition to collect coral samples from Islas Wolf and Darwin. The journey to these northern islands is ~24 hours there, and as much as 40 hours back on our vessel the “Queen Mabel.” Long stretches of nothing but blue on the horizon emphasize the vast expanse of ocean and the extremely remote nature of this field expedition.
|The Queen Mabel anchored at our destination. Photo credit: Stephan Hlohowskyj|
This remote, the rules of field work are particularly critical. “Adventure” after “adventure” was continually thrown at us, and we continued moving forward (albeit sometimes very slowly), and with no whining. Even when it was, in fact, justified. Because unfortunately, one of Darwin’s many angry moray eels decided to break our amended rule #5 (no maiming, no death). And poor Gloria is left with a very bad wound on her thumb and is undergoing hyperbaric chamber treatment in town over the next few days.
But I’ll let her tell that story. Over the next few days, as Stephan and I get back on a boat, this time heading to Genovesa and Bainbridge for lake work, I will post a series of blogs recounting our adventures at Darwin and Wolf.
But first if you’ve gotten past the jealousy, you might be wondering why on earth I keep going back to the Galapagos for work. What exactly is it that we’re doing here? And why so many trips, and can I take you with me next time?
The Galapagos are a hotspot for year-to-year changes in climate. Normally within the tropical Pacific Ocean, strong trade winds blowing from the east drive strong upwelling in the eastern Pacific, bringing cold, nutrient rich water to the surface around the Galapagos Islands. We can thank these nutrient rich waters for one of the world’s most productive fisheries.
But every few years, these trade winds weaken, and less deep water is brought to the surface in the eastern Pacific and local fisheries crash. Because this phenomenon happens around Christmas time, locals dubbed it “El Nino” (the boy). The Galapagos is located pretty much smack dab in the center of most El Nino events.
These El Nino events not only drive warm, nutrient depleted conditions in the eastern Pacific Ocean around the Galapagos, but they also change climate patterns globally. For instance, much of California and the western US experiences extremely high rainfall and flooding during El Nino events. Other areas, like much of the Australian continent, experience severe droughts during El Ninos.
Because of their global influence on climate, it is critical that we understand how the strength and frequency of these events may change in the future as the world warms. Unfortunately, we have very limited historical ocean observations in the vast tropical Pacific, and climate models disagree regarding changes in El Nino into the future. So we still do not have a very good understanding of how this extremely important climate phenomenon may change in the future.
That’s where we (my colleagues and I) come in. As paleoclimatologists, we study past climate changes to improve our understanding of the range of potential climate scenarios we may see into the future. To do this, we use natural archives of climate as windows into the past. For example, the rings of trees may tell a story of past changes in rainfall at a particular site, while bubbles trapped in ice sheets show how the composition of our atmosphere has changed through time.
To study past changes in El Nino, we capitalize on two of Galapagos treasures: it’s coral reefs, and it’s crater lakes.
Corals, like trees, grow in annual layers. Much like the rings of trees tell a story of past rainfall changes, the chemistry of layers of the coral’s skeleton paint a picture of past ocean conditions. Their skeletons tell us about the temperature, salinity, upwelling strength and even wind at the time the coral grew. From this, we can learn about the strength and frequency of El Nino events that happened before historical records were made.
|Drilling a coral sample from Wolf Island in 2010|
But unfortunately for us (and the coral, of course), most corals only live to be a couple hundred years old. So even the largest, oldest corals we take samples show us a glimpse into the past few hundred years. Corals that long since died, either submerged or tossed up onto the beach, can give us windows into the distant past, but many such corals are needed to try to piece together the history of climate changes.
But that’s where the Galapagos crater lakes come in: volcanic craters that are filled with very very saline water (2-3 x the salinity of the ocean!). Sediments accumulating at the bottom of these lakes also tell a story of past El Nino, this time through their impact on local rainfall. During El Nino events, the Galapagos experiences heavy rainfall, which washes in material from the crater walls and changes the chemistry of the lake. These changes are recorded in the sediments accumulating at the bottom of the lake.
|Sarah Truebe and I at Genovesa Crater Lake|
Together, these corals and lake sediments tell us a story about the history of El Ninos. From this story, we gain a better understanding of how the strength and frequency of these important events has changed as the Earth’s climate has changed in the past (as a result of changes in input from the sun and the number of volcanic eruptions, for example).
The primary goals of this trip are twofold:
1) Collect additional coral samples from the northern islands
2) Maintenance and redeploy instruments recording the local climate at our lake sites
I’ll update the blog with our successes, and of course “adventures” along the way.