Tropical cloud-watching never gets old. Near the equator, the warm ocean generates a ton of fuel for cloud growth. Over the course of a few hours, you can watch a small cloud grow into a tower tens of thousands of feet tall. If you look at satellite images of the Pacific, you’ll often see a band of these clouds just north of the Equator. That band is called the Intertropical Convergence Zone (ITCZ), which I’ve discussed before, and is the pillar of global atmospheric circulation.
The seasonal movement of the ITCZ over the Marshalls provides the country’s drinking water. Needless to say, it’s pretty important; when it’s too far from the Marshalls, wells and catchments run dry. However, it’s hard to simulate the ITCZ accurately in climate models, which makes its future behavior difficult to predict. As a first step, though, we can look at how its location and strength has changed in the past.
Unfortunately, I haven’t found many good visualizations of the ITCZ through time, so I made my own. This video shows monthly precipitation from 1979 through 2016, from NOAA’s Global Precipitation Climatology Project (GPCP).
Brief rant: Mapping the Pacific is hell. Most files and programs pretend that the world ends at the International Date Line, which runs smack-dab down the middle of the Pacific. So, when I tried to map the Pacific Islands, everything beyond the date line simply didn’t exist, and it took nearly a week to fix it. The result, though, is worth it, because I can finally generate plots that show the outlines of the oft-ignored Pacific Islands and reefs!
Even though the rate changes, sea level is clearly rising. It’s already about a foot higher than in 1880, and is expected to rise by up to a meter by the end of the century (if melting of polar ice sheets accelerates, this number could be much higher). This figure was inspired by Dr. Ed Hawkins’ now-famous climate spiral, and took advice from this talk on making beautiful figures.
This flooding is part of a “king tide” – a tide higher than all others. When the sun, moon, and Earth are in alignment, and close to each other, the tides will have especially high amplitudes – that is, the highest high tides and the lowest low tides. If you want a general introduction to how tides work, check out this Crash Course Astronomy video.
So, with this week’s supermoon, the tides are especially strong – some of the strongest of the year. During high tide, salt water is sneaking through storm drains and spilling over seawalls all along our coasts.
This kind of flooding is often called “nuisance flooding” or “clear-day flooding” because it isn’t associated with storm surges or winds. But let’s be clear: this “nuisance flooding” is exactly how sea level rise works.
What’s more, these floods will become more common as sea level rises.
In the deserts of Arizona, I always talked about oceans the same way that we might talk about unicorns: It’d be nice to see one, but good luck with that.
Going to grad school in New England means I finally have an ocean within walking distance of my office. So, between SCUBA and oceanography courses, I’m taking every chance to learn more about the Atlantic.
Boston University has partnered with the Stellwagen Bank Marine Sanctuary to use the Research Vessel Auk to collect seawater and plankton data around the Sanctuary (a rectangular area stretching roughly from Cape Cod to Cape Ann). I know the phrase “collect data” can sound inherently boring, so here’s a whale picture to convince you that it’s actually fascinating:
I was (and am) an unabashed science fiction fan. As a kid, one of my favorite books was Jules Verne’s The Mysterious Island, which tells the tale of a motley group of Civil War survivors stranded on an unexplored Pacific Island. It’s not your typical Cast Away story of a bitter struggle against the elements. Instead, the novel is partly a how-to book: by combining the skills of an engineer, a freedman, two sailors, and a journalist, the group concocts nitroglycerin, erects a telegraph, and even builds a ship!
In other words, I’ve always been interested in how people can turn an inhospitable island into a home. So, like the castaways in The Mysterious Island, I’ve found my way to the scattered islands of the Pacific.
Last January was the hottest one on record, chasing the heels of the hottest year on record. This heat is impacting our coral reefs—the lifeblood of our oceans—and despite the promises of geoengineering and local conservation efforts, there’s no quick fix for these impacts.
These shattered records result from climate change fingerprinted onto a powerful El Niño, which warms the tropical Pacific Ocean and releases an unusual amount of heat into the atmosphere. This El Niño has changed patterns of temperature, drought, and floods across the world. It’s even been linked to the spread of mosquitoes that carry the Zika virus.
But, one of the biggest and most far-reaching impacts of El Niño lurks beneath the surface of our oceans: coral bleaching.
Coral bleaching often results from extreme ocean temperatures. Tiny algae live inside the tissue of the coral itself, generating nutrients from sunlight for its host. When the coral is “stressed” by high temperatures, it expels these algae, which turns the coral bone-white. While a coral can survive this bleaching for a few months, it’s starving, deprived of nutrients provided by its algae.
A bleached coral is more prone to disease and death. For example, heating of the tropical Atlantic in 2005 led to a bleaching event that killed nearly half of the Caribbean’s corals. Reefs are the foundation for healthy marine ecosystems. For example, they provide nurseries and breeding grounds for a quarter of the ocean’s fish, so the loss of these corals can decimate marine biodiversity.
Coral bleaching impacts humans as well. Reefs attract tourists, provide livelihoods for fishermen, and form living sea walls against erosion, generating an estimated $30 billion per year.
They’re also the sole subsistence for hundreds of thousands of Pacific Islanders. In the Marshall Islands of the western Pacific, reefs provide not only food, but also supply the coral sand that forms the islands themselves. Without its reefs, the entire nation will literally disappear. Researchers on a recent ecological survey of the Marshalls discovered the worst bleaching of its corals ever seen. It’s a foreboding finding for this fragile nation.
In short, the stakes are high.
The National Oceanic and Atmospheric Administration (NOAA) uses satellite measurements of ocean temperatures to predict bleaching. In 2014, it began monitoring an outbreak that escalated to the third-ever global coral bleaching event in October 2015. Reefs from Australia to Hawai’i to Florida turned white. El Niño is worsening and prolonging this problem. In fact, NOAA scientists just announced that this bleaching event is the longest one ever observed.
In the coming decades, ocean warming will usher in frequent, longer, and more severe bleaching, increasing coral death rates worldwide. This trend has led the Australian government to declare climate change the single biggest threat to its iconic Great Barrier Reef. That assessment likely holds for reefs worldwide.
So, what can we do to conserve our corals?
First, we have to recognize that temperature is not a reef’s only stressor. Runoff, chemical pollution, and invasive species can all decrease a coral’s ability to beat the heat. Maintaining clean oceans and limiting the spread of invasive species can encourage the growth of healthy corals. That’s been the management policy for the Great Barrier Reef, and it could work elsewhere.
While these actions could buy time for our reefs, they’re stop-gap solutions at best. Any attempt to minimize global coral bleaching has to address climate change. Because carbon dioxide also acidifies our oceans, solutions that cool the planet without cutting our carbon emissions won’t spare our reefs.
The Paris Climate Agreement is a step in the right direction. Now, it’s up to each nation to fulfill its commitment. As citizens, we must hold our government accountable to its promise to curb carbon emissions. It’s easy to fall into an “out of sight, out of mind” mentality, but ignoring the issue will only worsen it.
The solution won’t be easy, but without it, the future of our coral reefs will be far less colorful.
Fishermen off the coast of Peru have long noticed a warm current that appeared in the Pacific around Christmastime, and dubbed this phenomenon “El Niño,” after the young Christ. Today, “El Niño” refers to the pattern of unusually warm waters in the equatorial Pacific, which appears every 2-7 years and peaks in December.
Now, Christmas is almost upon us, and this year’s El Niño is expected to peak soon.
Surprise! Since then, the eastern Pacific has warmed even further, turning the 2015 El Niño into one of the strongest on record, second only to the one in 1997. You can explore current global ocean temperature anomalies at one of my favorite sites, here.
El Niño is changing temperature and precipitation patterns worldwide. In the next few months, El Niño is predicted to make the northern U.S. unusually warm (as my dad put it, “El Niño is bad news for northeast skiers”) and bring additional rainfall to the southern states. Check out the predicted impacts for your region here.
But El Niño impacts aren’t restricted to the U.S. In October, scientists at the National Oceanic and Atmospheric Administration declared the beginning of a global coral bleaching event, the third on record. Warm waters can stress corals, forcing out their symbiotic algae, bleaching the corals and effectively starving them. In 1997-1998, the largest El Niño on record caused a bleaching event that killed 16 percent of the world’s coral reefs. A similar event is now underway.
My time in Australia’s dry tropics amounts to three words: Fires. Fires everywhere. I’m sure the region has a certain amount of paranoia about this year’s growing El Nino, which brings droughts to the region, and the increased threat of wildfires. But, drought or no drought, controlled burns have been a traditional part of Australia’s ecological management for 40,000 years.