1
00:00:01,835 --> 00:00:03,294
I'm Kate Calvin, NASA's

2
00:00:03,294 --> 00:00:06,297
chief scientist and senior
climate advisor.

3
00:00:07,173 --> 00:00:09,009
Hi. My name is Doctor Kate Calvin.

4
00:00:09,009 --> 00:00:12,012
I'm NASA's chief scientist and senior
climate advisor.

5
00:00:12,137 --> 00:00:14,180
And I'm going to answer
some of the top questions

6
00:00:14,180 --> 00:00:17,183
that we're getting from users like you
about climate

7
00:00:19,394 --> 00:00:21,855
Well, what we're seeing over
time is more and more,

8
00:00:21,855 --> 00:00:26,443
hot years, hot months, hot days,
because of climate change.

9
00:00:26,443 --> 00:00:28,570
So temperatures are rising overall.

10
00:00:28,570 --> 00:00:32,615
And with that brings impacts to people
and ecosystems all around the world.

11
00:00:32,991 --> 00:00:37,328
And while sometimes these numbers may seem
small, our ecosystems and our and

12
00:00:37,328 --> 00:00:41,124
our people are adapted to the temperatures
that we've experienced in the past.

13
00:00:41,374 --> 00:00:45,003
And when we have these increasing
temperatures, we're seeing these impacts

14
00:00:45,003 --> 00:00:48,256
like extreme events,
melting of ice sheets, sea level

15
00:00:48,256 --> 00:00:52,135
rise, changes in the water cycle
that affect precipitation.

16
00:00:52,343 --> 00:00:54,846
And we're seeing all of these
impacts all around the world.

17
00:00:57,098 --> 00:01:00,643
With climate change, we're
seeing more hottest years, hottest months,

18
00:01:00,643 --> 00:01:01,811
hottest days.

19
00:01:01,811 --> 00:01:04,564
These are driven by increases
in greenhouse gases

20
00:01:04,564 --> 00:01:07,067
and they're impacting in these changes
in temperature.

21
00:01:07,067 --> 00:01:11,196
These extreme heat events are impacting
people and ecosystems all around

22
00:01:11,196 --> 00:01:12,072
the world.

23
00:01:12,072 --> 00:01:16,034
We're seeing changes in impacts
like, more extreme events.

24
00:01:16,034 --> 00:01:19,621
We're seeing declines in Arctic sea
ice, increases in sea level

25
00:01:19,871 --> 00:01:21,706
changes in the water cycle.

26
00:01:21,706 --> 00:01:25,418
And these types of impacts are happening
in different parts of the world.

27
00:01:25,418 --> 00:01:28,379
And they're impacting people,
where they live.

28
00:01:31,007 --> 00:01:33,009
So with these increases in temperature

29
00:01:33,009 --> 00:01:36,221
and with climate change,
we're seeing impacts all around the world.

30
00:01:36,221 --> 00:01:37,514
And those impacts include

31
00:01:37,514 --> 00:01:41,935
things like declines in Arctic sea
ice, increases in sea level.

32
00:01:42,143 --> 00:01:45,980
We're seeing changes in extreme
events like heatwaves and wildfires.

33
00:01:46,147 --> 00:01:49,234
We also see changes in the water cycle
that can lead to more heavy

34
00:01:49,234 --> 00:01:52,403
precipitation events,
and in some regions, more droughts.

35
00:01:53,196 --> 00:01:54,781
These numbers look modest on paper,

36
00:01:56,658 --> 00:01:57,408
One thing that's

37
00:01:57,408 --> 00:02:00,662
important to keep in mind we often talk
about global average temperature.

38
00:02:00,662 --> 00:02:03,665
But the temperatures you experience
are different where you live.

39
00:02:03,832 --> 00:02:07,710
And what we see are more temperature rise
over land and over ocean.

40
00:02:07,877 --> 00:02:10,547
More at higher
latitudes and lower latitudes.

41
00:02:10,547 --> 00:02:15,093
And each of these even small changes
can impact, other parts of our Earth

42
00:02:15,093 --> 00:02:18,638
system in ecosystem like changes
in, in water cycle

43
00:02:18,638 --> 00:02:21,641
or extreme events

44
00:02:22,809 --> 00:02:23,726
about this?

45
00:02:23,726 --> 00:02:26,729
One of NASA's most important
missions is our home planet.

46
00:02:26,938 --> 00:02:30,775
so we have been studying the Earth
for decades, helping to understand

47
00:02:30,859 --> 00:02:35,446
how it's changed what it looks like today
and provide that information to people.

48
00:02:35,655 --> 00:02:38,741
And one of the ways that we study
the planet is through our Earth

49
00:02:38,741 --> 00:02:39,826
observing satellites.

50
00:02:39,826 --> 00:02:42,829
So we have more than two dozen
satellites and instruments in orbit

51
00:02:42,954 --> 00:02:45,540
that are continuously
monitoring our planet.

52
00:02:45,540 --> 00:02:49,669
And they can show us
things like vegetation, sea level rise,

53
00:02:49,669 --> 00:02:53,882
carbon dioxide, changes
in the mass of ice sheets, and much more.

54
00:02:56,426 --> 00:02:59,220
in addition to our satellites,
we also use surface

55
00:02:59,220 --> 00:03:02,974
and airborne observations to complement
those satellite records.

56
00:03:03,183 --> 00:03:05,476
And one of the things we do
is we take the surface

57
00:03:05,476 --> 00:03:09,314
measurements of temperature and construct
a global temperature record.

58
00:03:09,439 --> 00:03:12,734
And that's how we understand
whether a month is the hottest month

59
00:03:12,734 --> 00:03:17,071
on record or a year is the hottest year
on record, is by using that surface data

60
00:03:17,280 --> 00:03:20,241
and constructing this global temperature
record.

61
00:03:22,327 --> 00:03:24,954
More than 70% of the Earth's
surface is ocean.

62
00:03:24,954 --> 00:03:27,957
And we're also seeing record warming over
oceans.

63
00:03:28,208 --> 00:03:31,669
the oceans play a really important role
in our Earth system.

64
00:03:31,669 --> 00:03:34,130
So they absorb heat and carbon dioxide.

65
00:03:34,130 --> 00:03:37,008
and some of that heat, you know,
by absorbing it in the ocean,

66
00:03:37,008 --> 00:03:38,218
it's not in the atmosphere.

67
00:03:43,389 --> 00:03:45,892
So heat comes in from the sun.

68
00:03:45,892 --> 00:03:48,937
Some of that heat
is reflected back into space.

69
00:03:48,937 --> 00:03:50,521
how much is reflected?

70
00:03:50,521 --> 00:03:53,316
Depends on the color
of the of the Earth's surface.

71
00:03:53,316 --> 00:03:55,944
It depends on the aerosols
in the atmosphere.

72
00:03:55,944 --> 00:03:57,487
It depends on clouds.

73
00:03:57,487 --> 00:04:00,240
Some of that heat,
though, is absorbed by the oceans.

74
00:04:00,240 --> 00:04:04,953
so the surface of the oceans absorb heat,
and then they mix, taking the heat down

75
00:04:04,953 --> 00:04:06,287
into the depths of the ocean.

76
00:04:06,287 --> 00:04:08,122
And then the surface can absorb more.

77
00:04:08,122 --> 00:04:10,625
But some of that heat
remains in the atmosphere.

78
00:04:10,625 --> 00:04:12,126
And that's what we're experiencing.

79
00:04:12,126 --> 00:04:15,129
As increases in temperature
is this heat that's remaining.

80
00:04:15,338 --> 00:04:19,467
And it's affecting people and ecosystems
and causing impacts all around the world.

81
00:04:20,635 --> 00:04:23,638
Perfect.

82
00:04:26,099 --> 00:04:27,141
this.

83
00:04:27,141 --> 00:04:29,602
El Nino is a natural cycle that affects

84
00:04:29,602 --> 00:04:32,605
temperatures
and and weather around the world.

85
00:04:32,855 --> 00:04:37,068
El Nino years
tend to be warmer on average than others.

86
00:04:37,235 --> 00:04:40,238
La Nina years
tend to be cooler on average.

87
00:04:40,280 --> 00:04:44,450
But with climate change, what we're seeing
is an overall trend in warming.

88
00:04:44,450 --> 00:04:49,580
So our La Nina years are also getting
warmer, as well as our El Nino years.

89
00:04:49,747 --> 00:04:52,959
And so we see an overall trend in warming,
but we're still seeing

90
00:04:52,959 --> 00:04:56,212
individual years that are warmer
or cooler than the previous year

91
00:04:56,296 --> 00:04:58,298
because of El Nino and La Nina.

92
00:04:59,799 --> 00:05:00,591
Yeah.

93
00:05:00,591 --> 00:05:03,928
So 2022 was a long any year on average.

94
00:05:03,928 --> 00:05:06,264
La Nina years are cooler than other years.

95
00:05:06,264 --> 00:05:09,559
But 2022 was the hottest
la Nina year on record.

96
00:05:09,976 --> 00:05:12,395
2023 was an El Nino year.

97
00:05:12,395 --> 00:05:16,024
We moved into El Nino, 
and as a result, 2023.

98
00:05:16,024 --> 00:05:20,403
The combination of climate change,
El Nino and other factors mean that 2023

99
00:05:20,570 --> 00:05:23,573
was the hottest year on record.

100
00:05:29,620 --> 00:05:33,124
So scientists have been studying
our planet for more than a century,

101
00:05:33,249 --> 00:05:35,376
and we have different ways
of looking at Earth

102
00:05:35,376 --> 00:05:37,837
and measuring it and understanding
what's happening.

103
00:05:37,837 --> 00:05:40,923
So we have observations,
and so we can look at temperature records

104
00:05:40,923 --> 00:05:45,178
dating back to the late 1800s
and see that temperatures are rising.

105
00:05:45,345 --> 00:05:48,973
We have observations of carbon dioxide,
a greenhouse gas

106
00:05:48,973 --> 00:05:50,058
that's driving that warming.

107
00:05:50,058 --> 00:05:53,061
And we can look at how carbon
dioxide has risen.

108
00:05:53,186 --> 00:05:56,647
We have laboratory experiments
dating back to the 1850s

109
00:05:56,647 --> 00:06:00,777
that tell us that carbon
dioxide traps heat and warms temperatures.

110
00:06:01,069 --> 00:06:02,528
We have models.

111
00:06:02,528 --> 00:06:04,113
These are computer programs

112
00:06:04,113 --> 00:06:07,325
that capture our understanding of physics
and how the Earth works.

113
00:06:07,617 --> 00:06:11,412
And from those models, we can see that
the only way to replicate recent

114
00:06:11,412 --> 00:06:15,249
warming is to include carbon
dioxide and greenhouse gases.

115
00:06:15,541 --> 00:06:18,753
And last, we can look at what we what
scientists call fingerprints.

116
00:06:18,753 --> 00:06:21,964
So these are how exactly, climate change

117
00:06:21,964 --> 00:06:24,967
is affecting
or or how temperatures are changing.

118
00:06:24,967 --> 00:06:27,303
And that gives us information
about the drivers.

119
00:06:27,303 --> 00:06:30,640
So we can look at temperature
in different parts of the atmosphere.

120
00:06:30,932 --> 00:06:31,808
And what you see

121
00:06:31,808 --> 00:06:36,062
is that the upper atmosphere is cooling
and the lower atmosphere is warming.

122
00:06:36,062 --> 00:06:37,063
And that's consistent

123
00:06:37,063 --> 00:06:40,566
with with, greenhouse gas effect,
where heat is being trapped.

124
00:06:40,817 --> 00:06:44,362
If we had more incoming sunlight,
you would expect all of the atmosphere

125
00:06:44,362 --> 00:06:46,948
to warm with greenhouse gases.
You don't have,

126
00:06:46,948 --> 00:06:50,368
that you have trap the heat at the lower
part of the atmosphere.

127
00:06:50,410 --> 00:06:52,662
So less is reflected back into space.

128
00:06:52,662 --> 00:06:53,704
And that's what we're seeing.

129
00:06:53,704 --> 00:06:56,374
So we can combine
all of these different types

130
00:06:56,374 --> 00:07:00,795
of information, observations,
laboratory experiments, models,

131
00:07:00,795 --> 00:07:04,298
and together that tells us both
what is happening and also why.

132
00:07:12,014 --> 00:07:14,517
So what we do at NASA is we're actually
measuring

133
00:07:14,517 --> 00:07:16,769
individual temperatures
all around the world.

134
00:07:16,769 --> 00:07:18,980
And we have different ways
of doing this. One.

135
00:07:18,980 --> 00:07:20,690
We use the surface temperature record.

136
00:07:20,690 --> 00:07:22,692
That's the one we often talk about.

137
00:07:22,692 --> 00:07:26,279
when we're talking about hottest year,
hottest month

138
00:07:26,279 --> 00:07:27,905
and what that surface temperature record,

139
00:07:27,905 --> 00:07:30,074
it's a bunch of stations
all around the world

140
00:07:30,074 --> 00:07:32,368
that are measuring temperature
at the surface of the Earth.

141
00:07:32,368 --> 00:07:36,122
You might have one,
you could have a temperature,

142
00:07:36,122 --> 00:07:39,625
in your backyard or at an airport
or in other parts of the world.

143
00:07:39,834 --> 00:07:43,713
and we measure that at the surface,
and then we can calculate the global

144
00:07:43,713 --> 00:07:45,339
average temperature from that.

145
00:07:45,339 --> 00:07:48,468
We at NASA
also measure temperature from space.

146
00:07:48,468 --> 00:07:51,095
So we have satellites
that can measure temperature.

147
00:07:51,095 --> 00:07:54,932
And what we see from
those is we actually see the same trends

148
00:07:54,932 --> 00:07:56,809
that we see
with the surface temperature records.

149
00:07:56,809 --> 00:07:59,395
So we can confirm those surface
temperature measurements

150
00:07:59,395 --> 00:08:01,898
by looking at satellite
measurements of temperature.

151
00:08:01,898 --> 00:08:04,108
But what we're measuring
is local temperature.

152
00:08:04,108 --> 00:08:05,735
And then calculating an average.

153
00:08:11,324 --> 00:08:14,619
did we do this human activities
in principle

154
00:08:14,619 --> 00:08:17,997
through the release of greenhouse
gases are warming our planet.

155
00:08:17,997 --> 00:08:22,710
So we can look at changes over time
and we can see an increase in greenhouse

156
00:08:22,710 --> 00:08:26,422
gas emissions
that are trapping heat, in the atmosphere

157
00:08:26,422 --> 00:08:29,383
and warming our planet.

158
00:08:34,013 --> 00:08:35,306
Is there hope?

159
00:08:35,306 --> 00:08:37,600
Well, we know what's
driving the warming on our planet.

160
00:08:37,600 --> 00:08:40,603
We know it's driven
by increases in greenhouse gases.

161
00:08:40,686 --> 00:08:43,272
We also know, how to limit warming.

162
00:08:43,272 --> 00:08:46,234
So we know that by reducing greenhouse
gases and reaching,

163
00:08:47,235 --> 00:08:49,195
we can reduce the rate of warming.

164
00:08:49,195 --> 00:08:53,449
And there are options available today
that can help us reduce greenhouse gases.

165
00:08:53,783 --> 00:08:56,077
There's also people all around the world

166
00:08:56,077 --> 00:08:59,914
that are working to better understand
our planet, and to develop technologies

167
00:08:59,914 --> 00:09:00,623
and understanding

168
00:09:00,623 --> 00:09:03,626
that can help us address the changes
that are happening where I live.

169
00:09:03,751 --> 00:09:06,337
And there's people like you
that are learning about this now

170
00:09:06,337 --> 00:09:07,630
and can help us in the future.

171
00:09:09,006 --> 00:09:12,009
That's

172
00:09:14,262 --> 00:09:14,971
record?

173
00:09:14,971 --> 00:09:16,138
Not necessarily.

174
00:09:16,138 --> 00:09:16,472
So we're

175
00:09:16,472 --> 00:09:20,309
seeing an overall trend in warming,
but we might still see individual years

176
00:09:20,309 --> 00:09:22,645
that are hotter
or cooler than the previous,

177
00:09:22,645 --> 00:09:26,274
and individual months that are hotter
or cooler than the previous month.

178
00:09:26,274 --> 00:09:29,735
So we are seeing an overall
trend in warming, but that doesn't

179
00:09:29,735 --> 00:09:32,697
necessarily mean
every single month will be the hottest.

180
00:09:38,786 --> 00:09:39,829
planets?

181
00:09:39,829 --> 00:09:43,291
The sun is the source of heat
for our planet and other planets.

182
00:09:43,291 --> 00:09:45,167
And so we have incoming sunlight.

183
00:09:45,167 --> 00:09:48,004
Some of that is reflected back into space.

184
00:09:48,004 --> 00:09:49,964
Some of it is trapped as heat.

185
00:09:49,964 --> 00:09:53,259
and increase in greenhouse gases
in our atmosphere mean we're

186
00:09:53,259 --> 00:09:56,762
trapping more heat on Earth, and it's
warming the surface of our planet.

187
00:09:57,096 --> 00:09:57,722
These are things

188
00:09:57,722 --> 00:09:58,347
we can measure,

189
00:09:58,347 --> 00:10:01,684
so we can look over time and see
the change in the incoming sunlight.

190
00:10:01,892 --> 00:10:06,314
We can see the change in the amount of
heat going back into space and understand

191
00:10:06,314 --> 00:10:09,609
what's what's happening
and what's driving it, and so on Earth.

192
00:10:09,609 --> 00:10:11,527
What we've seen
is this increase in greenhouse

193
00:10:11,527 --> 00:10:15,656
gases, is trapping
more heat and warming our planet.

194
00:10:16,032 --> 00:10:18,909
We can also look at other planets
and see what's happening there.

195
00:10:18,909 --> 00:10:19,660
So Venus

196
00:10:19,660 --> 00:10:23,664
is slightly closer to the sun than Earth,
so it's getting more sunlight coming in.

197
00:10:23,664 --> 00:10:27,418
But it also has a much, much higher
concentration of carbon dioxide

198
00:10:27,418 --> 00:10:28,377
in its atmosphere.

199
00:10:28,377 --> 00:10:33,215
So it's trapping a lot more heat, and it's
hundreds of degrees warmer than Earth.

200
00:10:33,215 --> 00:10:36,594
at the surface, because of both
the closer to the sunlight,

201
00:10:36,594 --> 00:10:39,597
but most importantly
because it has a higher concentration

202
00:10:39,639 --> 00:10:41,682
of greenhouse
gases that are trapping heat.