I'm Kate Calvin, NASA's
chief scientist and senior climate advisor.
Hi. My name is Doctor Kate Calvin.
I'm NASA's chief scientist and senior climate advisor.
And I'm going to answer some of the top questions
that we're getting from users like you about climate
Well, what we're seeing over time is more and more,
hot years, hot months, hot days, because of climate change.
So temperatures are rising overall.
And with that brings impacts to people and ecosystems all around the world.
And while sometimes these numbers may seem small, our ecosystems and our and
our people are adapted to the temperatures that we've experienced in the past.
And when we have these increasing temperatures, we're seeing these impacts
like extreme events, melting of ice sheets, sea level
rise, changes in the water cycle that affect precipitation.
And we're seeing all of these impacts all around the world.
With climate change, we're seeing more hottest years, hottest months,
hottest days.
These are driven by increases in greenhouse gases
and they're impacting in these changes in temperature.
These extreme heat events are impacting people and ecosystems all around
the world.
We're seeing changes in impacts like, more extreme events.
We're seeing declines in Arctic sea ice, increases in sea level
changes in the water cycle.
And these types of impacts are happening in different parts of the world.
And they're impacting people, where they live.
So with these increases in temperature
and with climate change, we're seeing impacts all around the world.
And those impacts include
things like declines in Arctic sea ice, increases in sea level.
We're seeing changes in extreme events like heatwaves and wildfires.
We also see changes in the water cycle that can lead to more heavy
precipitation events, and in some regions, more droughts.
These numbers look modest on paper,
One thing that's
important to keep in mind we often talk about global average temperature.
But the temperatures you experience are different where you live.
And what we see are more temperature rise over land and over ocean.
More at higher latitudes and lower latitudes.
And each of these even small changes can impact, other parts of our Earth
system in ecosystem like changes in, in water cycle
or extreme events
about this?
One of NASA's most important missions is our home planet.
so we have been studying the Earth for decades, helping to understand
how it's changed what it looks like today and provide that information to people.
And one of the ways that we study the planet is through our Earth
observing satellites.
So we have more than two dozen satellites and instruments in orbit
that are continuously monitoring our planet.
And they can show us things like vegetation, sea level rise,
carbon dioxide, changes in the mass of ice sheets, and much more.
in addition to our satellites, we also use surface
and airborne observations to complement those satellite records.
And one of the things we do is we take the surface
measurements of temperature and construct a global temperature record.
And that's how we understand whether a month is the hottest month
on record or a year is the hottest year on record, is by using that surface data
and constructing this global temperature record.
More than 70% of the Earth's surface is ocean.
And we're also seeing record warming over oceans.
the oceans play a really important role in our Earth system.
So they absorb heat and carbon dioxide.
and some of that heat, you know, by absorbing it in the ocean,
it's not in the atmosphere.
So heat comes in from the sun.
Some of that heat is reflected back into space.
how much is reflected?
Depends on the color of the of the Earth's surface.
It depends on the aerosols in the atmosphere.
It depends on clouds.
Some of that heat, though, is absorbed by the oceans.
so the surface of the oceans absorb heat, and then they mix, taking the heat down
into the depths of the ocean.
And then the surface can absorb more.
But some of that heat remains in the atmosphere.
And that's what we're experiencing.
As increases in temperature is this heat that's remaining.
And it's affecting people and ecosystems and causing impacts all around the world.
Perfect.
this.
El Nino is a natural cycle that affects
temperatures and and weather around the world.
El Nino years tend to be warmer on average than others.
La Nina years tend to be cooler on average.
But with climate change, what we're seeing is an overall trend in warming.
So our La Nina years are also getting warmer, as well as our El Nino years.
And so we see an overall trend in warming, but we're still seeing
individual years that are warmer or cooler than the previous year
because of El Nino and La Nina.
Yeah.
So 2022 was a long any year on average.
La Nina years are cooler than other years.
But 2022 was the hottest la Nina year on record.
2023 was an El Nino year.
We moved into El Nino, and as a result, 2023.
The combination of climate change, El Nino and other factors mean that 2023
was the hottest year on record.
So scientists have been studying our planet for more than a century,
and we have different ways of looking at Earth
and measuring it and understanding what's happening.
So we have observations, and so we can look at temperature records
dating back to the late 1800s and see that temperatures are rising.
We have observations of carbon dioxide, a greenhouse gas
that's driving that warming.
And we can look at how carbon dioxide has risen.
We have laboratory experiments dating back to the 1850s
that tell us that carbon dioxide traps heat and warms temperatures.
We have models.
These are computer programs
that capture our understanding of physics and how the Earth works.
And from those models, we can see that the only way to replicate recent
warming is to include carbon dioxide and greenhouse gases.
And last, we can look at what we what scientists call fingerprints.
So these are how exactly, climate change
is affecting or or how temperatures are changing.
And that gives us information about the drivers.
So we can look at temperature in different parts of the atmosphere.
And what you see
is that the upper atmosphere is cooling and the lower atmosphere is warming.
And that's consistent
with with, greenhouse gas effect, where heat is being trapped.
If we had more incoming sunlight, you would expect all of the atmosphere
to warm with greenhouse gases. You don't have,
that you have trap the heat at the lower part of the atmosphere.
So less is reflected back into space.
And that's what we're seeing.
So we can combine all of these different types
of information, observations, laboratory experiments, models,
and together that tells us both what is happening and also why.
So what we do at NASA is we're actually measuring
individual temperatures all around the world.
And we have different ways of doing this. One.
We use the surface temperature record.
That's the one we often talk about.
when we're talking about hottest year, hottest month
and what that surface temperature record,
it's a bunch of stations all around the world
that are measuring temperature at the surface of the Earth.
You might have one, you could have a temperature,
in your backyard or at an airport or in other parts of the world.
and we measure that at the surface, and then we can calculate the global
average temperature from that.
We at NASA also measure temperature from space.
So we have satellites that can measure temperature.
And what we see from those is we actually see the same trends
that we see with the surface temperature records.
So we can confirm those surface temperature measurements
by looking at satellite measurements of temperature.
But what we're measuring is local temperature.
And then calculating an average.
did we do this human activities in principle
through the release of greenhouse gases are warming our planet.
So we can look at changes over time and we can see an increase in greenhouse
gas emissions that are trapping heat, in the atmosphere
and warming our planet.
Is there hope?
Well, we know what's driving the warming on our planet.
We know it's driven by increases in greenhouse gases.
We also know, how to limit warming.
So we know that by reducing greenhouse gases and reaching,
we can reduce the rate of warming.
And there are options available today that can help us reduce greenhouse gases.
There's also people all around the world
that are working to better understand our planet, and to develop technologies
and understanding
that can help us address the changes that are happening where I live.
And there's people like you that are learning about this now
and can help us in the future.
That's
record?
Not necessarily.
So we're
seeing an overall trend in warming, but we might still see individual years
that are hotter or cooler than the previous,
and individual months that are hotter or cooler than the previous month.
So we are seeing an overall trend in warming, but that doesn't
necessarily mean every single month will be the hottest.
planets?
The sun is the source of heat for our planet and other planets.
And so we have incoming sunlight.
Some of that is reflected back into space.
Some of it is trapped as heat.
and increase in greenhouse gases in our atmosphere mean we're
trapping more heat on Earth, and it's warming the surface of our planet.
These are things
we can measure,
so we can look over time and see the change in the incoming sunlight.
We can see the change in the amount of heat going back into space and understand
what's what's happening and what's driving it, and so on Earth.
What we've seen is this increase in greenhouse
gases, is trapping more heat and warming our planet.
We can also look at other planets and see what's happening there.
So Venus
is slightly closer to the sun than Earth, so it's getting more sunlight coming in.
But it also has a much, much higher concentration of carbon dioxide
in its atmosphere.
So it's trapping a lot more heat, and it's hundreds of degrees warmer than Earth.
at the surface, because of both the closer to the sunlight,
but most importantly because it has a higher concentration
of greenhouse gases that are trapping heat.