What ocean microbes reveal about the changing climate | Angelicque White

Translator: Joseph Geni Reviewer: Krystian Aparta

I'm a biological oceanographer.

I have the absolute privilege of studying microbial lives

in the Pacific Ocean.

So we'll talk about microbes in a minute,

but I first want to give you a sense of place,

a sense of scale.

The Pacific Ocean is our largest, deepest ocean basin.

It covers 60 million square miles.

If you took all the continents and you put them together

in a little Pangaea 2.0,

they'd fit snug inside the Pacific, with room to spare.

It's a massive ecosystem,

from the blues of the open ocean to the green of the continental margins.

In this place,

I get to study the base of the food web:

plankton.

Now, in my research,

and really in the field of microbial oceanography as a whole,

there's a theme that has emerged,

and that theme is "change."

These microbial ecosystems are changing in real and measurable ways,

and it is not that hard to see it.

Oceans cover 70 percent of our planet,

so ocean change is planetary change,

and it all starts with microbes.

Now, I have two vignettes to share with you,

and these are meant to be love stories to microbes.

But I'll be honest that there's an aspect of it

that's just a total bummer,

and, beware, focus on the love.

Right? That's where I'm coming from.

So the first thing to know

is that the forests of the sea are microbial.

And what I mean by that is that, by and large,

plants in the open ocean are microscopic,

and they are much more abundant than we realize.

So I'm going to show you some mug shots of these organisms

that I've collected over the years.

These are the lowest rungs of the ocean food web.

These are tiny plants and animals

that come in a variety of shapes and sizes and colors and metabolisms.

There are hundreds of thousands in a single milliliter of seawater.

You are definitely swimming with them when you're in the ocean.

They produce oxygen, they consume CO2,

and they form the base of the food web

on which every other form of ocean life is reliant.

Now, I've spent about 500 days of my scientific life at sea,

and a lot more in front of a computer or in the lab,

so I feel compelled to tell you some of their stories.

Let's start in the Pacific Northwest.

This place is green. It is beautiful.

These are blooms of phytoplankton that you can see from space

along the West Coast of the United States.

It's an incredibly productive ecosystem.

This is where you go to salmon fish, halibut fish, whale watch.

It's a beautiful part of our country.

And here, for 10 years, among other things,

I studied the uplifting topic of harmful algal blooms.

These are blooms of toxin-producing phytoplankton

that can contaminate food webs and accumulate in shellfish and fish

that are harvested for human consumption.

We were trying to understand why they bloom, where they bloom,

when they bloom,

so we could manage these harvests

and protect human health.

Now, the problem is the ocean's a moving target

and, much like some people in our lives, toxicity varies among the plankton.

(Laughter)

Alright?

So, to get around these challenges,

we combined satellite remote sensing

with drones and gliders,

regular sampling of the surf zone

and a lot of time at sea

in small boats off the Oregon coast.

And I don't know if many of you have had the opportunity to do that,

but it is not easy.

[Even oceanographers get seasick]

Here's some poor students.

(Laughter)

I've hidden their faces to protect their identities.

(Laughter)

This is a challenging place.

So this is hard-won data I'm about to talk about, OK?

(Laughter)

So by combining all of our data with our collaborators,

we had 20-year time series of toxins and phytoplankton cell counts.

And that allowed us to understand the patterns of these blooms

and to build models to predict them.

And what we found

was that the risk of harmful algal blooms was tightly linked to aspects of climate.

Now when I say "climate," I don't mean weather day-to-day,

I mean long-term changes.

These oscillations that you may have heard of --

the Pacific Decadal Oscillation, El Niño --

they usually bring warm, dry winters to this region,

but they also reduce the strength of the California Current,

which runs from the north to the south along the Pacific Northwest,

and they warm the coastal ocean.

These are the reds you're seeing in this plot,

warm anomalies,

strong positive indices of the PDO.

And when we have these changes in circulation

and changes in temperature,

the risk of harmful algal blooms is increased,

but also salmon recruitment has decreased,

and we see intrusions of invasive species like green crab.

So these are ecological and economic impacts of climate.

Now, if our models are right,

the frequency and severity of these events are only going to get worse,

right along with these warm anomalies.

And, to illustrate that,

2014 was probably one of the worst harmful algal blooms in Oregon history.

It was also the hottest year in the modern climate record at that time,

that is until 2015,

2016,

2017, 2018.

In fact, the five hottest years in the modern climate record

have been the last five.

That bodes really well for harmful algal blooms

and poorly for ecosystem health.

Now, you may not care about shellfish,

but these changes impact economically important fisheries,

like crab and salmon,

and they can impact the health of marine mammals like whales.

And that might matter a little bit more.

That might resonate.

So, there's your doomsday tale for the margins of the Pacific.

Actually, these are really resilient ecosystems.

They can absolutely bounce back if we give them a chance.

The point is not to ignore the changes that we're seeing,

which brings me to my second vignette.

I have since moved to the most remote island chain on our planet,

the Hawaiian Islands,

where I'm the new lead of a program called the Hawaiian Ocean Time-series.

And this is a program that for 31 years

has made this monthly pilgrimage to a spot called Station ALOHA.

It's in the middle of the Pacific Ocean,

in the center of this vast, swirling system of currents

that we call the North Pacific Subtropical Gyre.

It's our largest ocean ecosystem.

It's four times the size of the Amazon rain forest.

It is warm, in a good way.

It is blue water,

it's absolutely the type of place you want to dive in and swim.

You cannot do that off of research boats,

because, you know, sharks. Google it.

(Laughter)

This is a beautiful place.

And here, since October of 1988,

generations of researchers have made these monthly pilgrimages.

We study the biology, the chemistry, the physics of the open ocean.

We've measured the temperature from the surface to the seafloor.

We've tracked the currents, traced the waves.

People have discovered new organisms here.

People have created vast genomic libraries

that have revolutionized

what we think about the diversity of marine microorganisms.

It's not just a place of discovery,

but the important part about time series

are that they provide us a sense of history,

a sense of context.

And in 30 years of data,

it's allowed us to separate the seasonal change

and see the emergence of humanity's fingerprints

on the natural world.

There's another iconic time series in Hawaii,

and that is the Keeling Curve.

I hope you have all seen this.

This time series has documented the rapid increase in carbon dioxide

in the atmosphere.

It's not just the number, it's the rate of increase.

The rate of carbon dioxide increase in our atmosphere

is unprecedented for our planet.

And that has consequences for our oceans.

In fact, oceans absorb about 90 percent of the heat that's generated

by greenhouse gas emissions

and about 40 percent of the carbon dioxide.

And we have been able to measure that at Station ALOHA.

Each one of these dots is a cruise.

It represents people's lives over 30 years trying to make these measurements,

and it took 30 years to be able to see this.

CO2 rises in the atmosphere,

CO2 rises in the ocean.

That's the red line.

A consequence of that

is a fundamental change in the chemistry of seawater,

a decline in pH --

pH is on a log scale,

here's your blue line.

So we've seen a 30 percent decline in pH in the surface ocean

in this time series.

Now that has impacts for organisms that need to feed, build shells,

that changes growth rates, metabolic interactions,

and it doesn't just impact plankton --

it impacts ecosystems as large as coral reefs.

Now one of the things we've been able to show in this time series

is this is just skimming the surface.

Increases in CO2 and a decline in pH

are measured over the top 500 meters of the water column.

I really find that to be profound.

This is genuinely one of the most remote places on our planet,

and we've impacted the top 500 meters of the water column.

Now, these two things --

harmful algal blooms, ocean acidification --

that's not all, of course.

You've heard of the rest:

sea-level rise, eutrophication, melting of the polar ice caps,

expansion of oxygen minimum zones, pollution, loss of biodiversity,

overfishing.

It's hard for me to get a grad student --

you can see this pitch is a difficult one, right?

(Laughter)

(Sighs)

Again, I think these systems, these microbial ecosystems,

are immensely resilient.

We just cannot go too far down this path.

I personally believe that sustained observation of our oceans and our planet

is the moral imperative for our generation of scientists.

We are bearing witness

to the changes that are being inflicted upon our natural communities,

and by doing so,

it provides us the opportunity to adapt and enact global change,

if we're willing.

So the solutions to these problems are multitiered.

It involves a portfolio of solutions,

local change,

but all the way up to voting for people who will protect our environment

on a global scale.

(Applause)

Let's bring it back to the love.

(Laughter)

Microbes matter.

These organisms are small,

abundant, ancient,

and they are critical to sustaining our population and our planet.

Yet we are on track to double our carbon dioxide emissions

in the next 50 years,

so the analogy that I use for that

is like we are eating like we're still in our 20s,

assuming there will be no consequences --

but I'm a woman in her 40s,

I know there are consequences for my fuel consumption. Right?

(Laughter)

These oceans are very much alive.

These ecosystems have not collapsed.

Well, except for the Arctic, we can talk about that.

(Laughter)

But the sustained observations that I've shared with you today,

the work of generations of scientists,

are pointing us to take better care of our oceans

and to nurture the microbes that sustain us.

And on that note,

I want to end with a quote from one of my heroes,

Jane Lubchenco.

And this slide is appropriate.

Jane has said that the oceans are not too big to fail,

nor are they too big to fix,

but the oceans are too big to ignore.

Thank you.

(Applause)