The Earth is
the most
important planet that we study,
at least in my opinion.
And the work that we do from space
is incredibly valuable
in giving that this global vantage point,
the ability to see everything,
It's like going to the world,
you know, the top of a big hill
and you get to look down
and see everything,
but there's no place we can do that.
What we're actually
on the surface of the earth.
And so the work that NASA does
in exploring space
and finding new ways
to get instruments
that look back at Earth
have given us this
incredibly rich dataset
that help us understand
the world
and how it's changing over
the course of multiple decades now
you know, when NASA's first started
sending people up into space,
they would look down at the Earth
and they would see things
that we see from the ground.
But this whole different
perspective, right?
They could see the movement
of these big clouds and weather systems.
They could see lights at night. Right.
And so over time,
that guided
the development of instruments
that we've sent into space
that look back at our planet,
that are able to monitor
weather systems,
that are able to monitor human activity.
So now those data sets have provided
this foundation of understand
how the Earth functions as a planet
over the course of the
past several decades.
Studying the Earth as a
system is incredibly important
because the more we look
at individual variables
like rainfall or air
pollutants or temperature,
we realize how interconnected
the Earth is as a planet, as a system,
right when we warm the planet,
when we increase temperatures,
we don't just get warmth
and balmy days, right?
We get changes in weather systems.
We get changes
in the acuteness of pollution episodes
that send people to the hospital.
We change the frequency
and the patterns of wildfires
so understanding
all those different variables
and how connected they are,
that's one of the most special things
that we get
from this record of Earth observations
and this really impressive
global perspective
that NASA's satellites give us
as Earth scientists
It's incredibly important for us to study
how the planet's changing.
Our observations helped us understand
how the planet functions.
But we also know we want to know
how that's going to evolve
in coming decades, coming centuries.
So really understanding the climate
that we have today
and how that's changing, that's
providing this really important
benchmark to understand
how extremes might be changing
and also to understand how the efforts
that we're all taking to mitigate
climate change
are having a positive effect
both now and in the future.
So atmospheric chemistry is a
lot like the chemistry
that you probably learned
about in high school.
But when we talk about
atmospheric chemistry,
we're talking about the way
that that molecules in the form of gases
react with each other
to form new molecules,
many of them
in very small concentrations.
But those can be incredibly important
and affecting things like air quality
pollution and public health
and the evolution of climate change
setting.
Atmospheric chemistry
is really, really important for us
in order to be able to understand
and predict
things like air pollution
episodes, the concentrations
of greenhouse gases,
the rates at which
some of these reactions
occur are driven by the concentrations
of different gases in the atmosphere.
But they can also be affected
by things like changes in humidity,
changes in temperature.
So when we study atmospheric chemistry,
we're not just looking at
how are those processes occurring now,
but how are those going to change
with climate change.
How sensitive
are some of those types of reactions
to a world that's getting warmer and in
a lot of cases more moist?
So greenhouse gases are this
really important type of gas
that's present in the atmosphere
in really, really small concentrations.
But it's important
because they're very,
very efficient
at trapping
long wave heat
that's emitted from the Earth's surface.
And they can do this
because greenhouse gases
are comprised of more than two atoms.
That means structurally
they have a little bit
more ability to move
and they can absorb that energy
through rotational
translational vibrational motion.
So some of the most important
greenhouse gases
that are influenced by
human activities are carbon
dioxide or CO2,
as you may have heard of, called methane,
nitrous oxide or N2O
and also water vapor.
Now, water vapor obviously occurs
naturally in the atmosphere.
That's important for
for sustaining life
sustaining precipitation.
But as the planet warms,
the concentration of water
vapor can increase.
So you have this positive feedback,
as scientists call it, where water vapor
is contributing to climate change,
even though it's there
naturally in the atmosphere.
So methane is really powerful.
Greenhouse gas
is actually more powerful
on a molecule by molecule
basis than carbon dioxide,
even though it's
present in the atmosphere
in much smaller concentrations.
Now, methane is emitted
by a number of both human
and natural sources.
So things like oil
and natural gas production, landfills,
wastewater treatment facilities, it's
also emitted by natural sources
like wetlands.
About 30% of the budget is wetlands.
By many estimates,
that's really important
because in some cases, it's harder
for us to manage and control
those diffuse natural sources.
And another reason
scientists are really concerned
about what's happening
with methane right now
is that methane emissions from places
like wetlands are temperature sensitive,
meaning they can accelerate
in a warming world.
And we want to make sure we understand
how wetlands are changing,
how those human and natural components to
methane emissions are changing as climate
change progresses.
So another reason that methane
is really important right now
is that
policymakers are targeting
methane emissions as a
as a major effort to reduce
emissions from methane in the near term.
They hope that that buys us some time
to bring down carbon
dioxide concentrations in the future.
So things like trying to reduce
fugitive emissions from oil,
natural gas is getting a lot of attention
because the hope is that
that can give us some time, both
because methane is a very powerful gas
and because there's a lot of agreement
from both policymakers, industry
and the general public
that we have places
to reduce those emissions
that'll make life a little bit safer
and help us reduce
climate change at the same time.
So greenhouse gases are really effective
at trapping heat.
We know that.
And most of the warming
is due to CO2 or carbon dioxide,
which is built up in the atmosphere
over the past hundred 50 years.
And so that's the main driver
trapping heat
in the Earth's system
and causing a lot of the changes
we associate with climate change.
So the 1880s is important
in terms of general dates.
The technology
to measure temperature pressure, rainfall
was being distributed
in communicated more broadly.
And so that's one of those
early dates in history
where scientists were able to gather
enough information
to have a reliable picture
of global temperature
in a global sense
to understand how things are changing.
So trace
gases are really important
in raising global temperatures.
Most of the atmosphere
is into and out to atoms,
and they don't have a lot of flexibility
to absorb energy. Right.
But when you have these
special greenhouse gases
that have at least three atoms,
they have more capacity
to absorb energy and absorb
that in the molecular bonds
between those atoms.
That means that
even though they're present
in the atmosphere,
only in very,
very small concentrations,
they have this outsized impact
on the temperature budget
in being able
to very efficiently
trap energy that's emitted
back to space from the Earth's surface.
So the way that heat is
expressed throughout the planet
when it's trapped by
these greenhouse gases
is is really diverse. Right,
We see all of these different impacts
for example,
we see changes in ocean temperatures
that can affect ocean biology.
It also affects ocean currents,
the presence of ice
at the high and low latitudes.
But we also see changes on land.
We see changes in ecosystems,
changes in growing
season, changes in the frequency
and severity of droughts
that can affect the risk of fires.
We see changes in life.
We see changes in the migration
patterns of birds and fish.
And so these are some of the ways
that the planet is interconnected.
And when we trap heat,
that's not just
expressing itself
as this change
in the daily temperature value,
it's expressing itself
in all of these fundamental ways
that our lives
are influenced day after day.
This is something
people ask a lot, right?
And early
on, people use to focus on
global warming, global warming.
And I think as scientists,
we say climate change more frequently
because global warming
is really only talking
about one part of the problem,
the fact that greenhouse gases trap heat,
and that's expressed
in global temperature increases.
When we talk about climate change,
we're talking about these really complex
interactive effects, things
like changes in vegetation
changes and fires, changes in air
pollution, ocean circulation,
really something as fundamental
as temperature can't change in a vacuum
without affecting
literally every aspect
of the earth as a planet.
And so that's why we like to call it
climate change,
to just make sure
we're encompassing
the full range of effects
that are happening across the planet.
So scientists, policymakers and citizens
all across
the world are working
really hard
to get us to net zero emissions,
to bring us down to a point where
we're not emitting a net amount of carbon
that that
the emissions are balanced by by natural
and imposed things. Right.
But one thing
that's really important
for people to know is, one, it's
going to take us some time to get there.
That's not going to happen overnight.
It's going to happen
over the course of decades.
And even when we get to net zero,
that doesn't mean
that carbon dioxide
concentrations, greenhouse
gas concentrations
fall back
to pre-industrial levels overnight.
We've been emitting these things
for well over a hundred years.
We've been perturbing these cycles
and it's going to take time.
We expect over the course of decades
to even over a century,
to see those decreases in greenhouse
gas concentrations
continue as carbon is absorbed
into natural reservoirs.
And you see more of that balance return.
So that's one thing
that is important for people to note.
Net zero doesn't mean an immediate
end to global climate change.
So scientists look at a
range of explanations for everything.
It's important for people to think
we don't just jump to conclusions.
So we look at all of these explanations
to understand
what are the drivers of climate change,
things like changes
in the solar radiation
cycles, volcanoes that
that erupt and change
atmospheric composition naturally.
And when we do computer simulations,
none of these things can explain
the dramatic changes
that we're seeing in global temperature,
which occur at the same time
as greenhouse gases.
Really only the system makes sense
with the warming
that we know happens
as a result of greenhouse gases.
In addition, people should know that
the imprint of climate change from humans
has a really distinct signature
in terms of temperature.
When you have this warming
for greenhouse gases that traps heat
throughout the atmosphere,
it acts as a blanket
that warms the surface,
but it makes the top of the atmosphere
a little bit colder.
And we can actually see
in the records of observations
that we have
that this fingerprint, this unique
trapping of heat
from greenhouse gases
is occurring at the same time
temperatures are warming.
So that's a really dead giveaway
that this isn't some natural cycle.
This is warming
that's caused by absorption
from greenhouse gases.
So we talk about models.
You probably hear about this a lot.
Models are really just a set of equations
that describe
our best understanding
of the way some system functions.
It can be a lot of equations.
They can be very long and complicated.
They can be solved by supercomputers
and on a grid,
which is actually how
weather and climate models work.
But at the end of the day,
they're really just our best
understanding, encapsulated
in a mathematical form
that help us
integrate and predict into the future.
So the weather and climate models
that we use
to study things like climate change
are made up of these sets of equations.
They're being solved on supercomputers.
But one thing
that's really important to know
is that we don't just make up
these equations, right?
We develop equations
and we refined them over time
using a combination
of satellite data, of ground based data.
So that helps us make and test
the best equations over time.
We're also continually
evaluating those models
with a combination of data to ensure
we know what they do well,
where they can use improvement.
We also use data sets to initialize
predictions, right?
So when we make a weather forecast
that's actually taking data
from satellites,
from ground
based networks,
even from from airplanes,
passenger airplanes
that people fly on every day
and using that
to give us a reliable picture
of what's happening
with today's conditions
so we can make a reliable prediction
into the future
to inform people all over the world
how weather is changing.
And we do the same thing
for seasonal predictions.
So we can predict things
nine months into the future
and give people some sense
of how seasonal temperatures
might evolve.
So one thing that's really
exciting about models
is the whole landscape of models
has changed, both with the availability
of high performance
computing supercomputers
and the availability of satellite data.
So some of the things
that we're able to do with models
we couldn't do five
even ten years ago,
things like running models
and much finer
spatial scales to understand
how conditions
are changing in local areas, urban areas,
even within neighborhoods.
The other thing that's really changing
is the complexity of processes
and models.
Used to be that we had one model
that would tell us about weather,
and then we had to take that data,
plug it into a separate model
that would tell us about greenhouse gases
and air quality.
Today's models include
all of those processes at the same time.
That's important
for having the most accuracy
and being able
to provide the best
and most integrated information
that helps policymakers
navigate a number of climate
related challenges all at once.
So models are an incredibly
important component
of helping us understand and navigate
a warming climate.
But I want people to understand that
when we talk about temperature
change, global temperature
changes over the past 250 years,
that knowledge is grounded
in observations taking at ground stations
across the world, in some cases
satellite data as well.
But really
the observations
are the basis of understanding
and documenting
how the planet has changed.
Now, using those observations,
we create better models.
Those models can help us understand
things that we can't observe directly,
like why the climate is changing,
what are the relative
contributions of natural factors
and human factors.
And really importantly,
given an amount of warming,
how is that going to change
the trajectory of the planet in
coming decades and centuries?
know, it's really tricky.
We have computer models
and in a lot of cases
we know a lot more in terms of science
and we can actually write
and solve in terms of these equations
because it's a lot of compute power,
a lot of energy to make those models go.
Some of the things that we know
we want to understand
and increase the complexity
of in these projection
models
are the interactions between
tiny particles
called aerosols
and clouds,
because those are really important
in changing
how clouds either
trap or reflect radiation.
So it really affects the way
that climate change
progresses, also affects things
like the formation of storms.
Another area
where we would like to have
a lot more information
is the way
that the natural sinks of carbon
dioxide on the land in
the ocean are affected by climate change.
So right now,
trees and the world's oceans
absorb about half
of our pollution of carbon dioxide,
and it's giving us a huge assist
in terms of climate change.
But one of the things
that's a big source of uncertainty
is how long that can continue
and how are things like fires
and droughts and more stress
on vegetation
influencing that ability to absorb
and help us out with climate change.
So one thing that's really
important for people to understand
when we talk about
global temperature rise
is that we're talking about the increase
in global mean temperature,
but that doesn't mean you're
not going to have an extreme winter.
It doesn't mean
you might not have a big snowstorm
in your area. Right.
Because that means that temperatures
across the world
as an aggregate
are getting warmer
and marching steadily upwards.
But still,
there's natural variability
from year to year, season to season.
There's spatial variability
with warming,
concentrating in some areas
like the higher latitudes
of the northern hemisphere
that are warming
more rapidly than others.
So there's all this complexity
from different regions
that are experiencing
climate change in different ways.
And some people confuse that with
the idea that global
temperature isn't increasing.
So that's an important thing
for people to understand and relating
what might be happening
in your own environment
with what's happening to the planet
as a whole.
You know, when people ask questions
like this,
I think it's important
to understand
that everybody has individual answers
and everybody is experiencing
climate change from a different lens.
It's affected by where you live.
It's affected by
just the way that you tackle problems.
But for me,
I tend to look at the positives
and I see a lot of attention.
I see a lot of people
working hard and understanding
that climate change is serious
and that we have to do something
about it,
you know, 5
to 10 years ago
when I used to do interviews,
people would say, Is climate change real?
And I don't get that reaction
very much anymore.
I get the question, is it too late?
What can I do?
How do I team up with my neighbors
to help?
And so that gives me some hope
that people are taking this seriously.
I think we see evidence of that
in some of the
the emissions reduction measures
that are being imposed
across the world
and the actions that are being taken
not just at large
administrative countries scales,
but within communities within cities.
Some of the cities are around the world.
Are the leaders
in reducing greenhouse gases,
working to reduce them even more quickly
than the countries that they're parts of?
Right.
So you see these smaller
collective actions
that can add up
to a really big difference.
And those are some of the reasons
that even though yeah, we have to admit
that this is a serious problem
and we have to tackle it,
I am hopeful and I do see change.