I am a paleoclimatologist.
Which means that I am kind of a weird cross between a geologist and a climate scientist.
I have a doctorate in Geology, but the focus on my research is on climate change.
So I didn't choose this career, which is somewhat of a strange career to choose,
just because I couldn't choose between Geology and Climate Science.
I actually started my career in sustainable development.
I spent a lot of time in these small villages in east Africa and southern Africa
and after a while started talking to a lot of farmers, and hearing a lot of stories about how they thought
the rains were changing. And this got me really interested in rainfall in Africa
and what we know about it. So I went back to New York and I started researching this, and
it became very clear that the amount that we know about rainfall and climate change
in the world's tropical regions is abysmal. We know very, very little.
One of the things we've learned is that,
has the climate changed in the past? Yes. Absolutely.
The climate has changed really dramatically in the past. The Earth has gone through
hot-houses, it has gone through ice ages, it has been wet, it has been dry, there's regional
variations. There's all kinds interesting climate changes that have
occurred in the past. A couple of examples that I think will be really interesting
to you all: One is a period of time that we refer to as the Paleocene Eocene Thermal Maximum.
It's a mouthful. The PETM for short. And I use this as an example
partly because it happened about 55, 56 million years ago and that's about when
our beloved Rocky Mountains had just finished their uplift. I also choose it
because it's one of the really well-known examples of what we call a
"hyperthermal" in the Earth's history. And it's a really well-known example of a massive
release of greenhouse gases into the atmosphere that happened very very
quickly.
Another example, we'll come back to that in a second, it is the transition, the most
recent transition out of the last ice age. Now this, for a geologist, is very recent in time.
The peak of the last ice age was about 21,000 years ago.
So 55 million, 21 thousand. Much more recent. And the Last Glacial Maximum was
a period of time when the earth was globally a lot cooler, a lot drier. Sea levels were a lot lower
and that's because a lot of that water was locked up in ice sheets that were
especially in the Northern Hemisphere. So these are two examples, the PETM and the
last ice age, the transition out of the last ice age. Two examples of CO2 being
released into the atmosphere, and temperature warming. Very rapidly, very abruptly, in some cases.
So what's the difference? Why is anything different from that, from what we're seeing today?
And this is a case where -- I am a geologist, I'm also at fault here --
We kind of use some confusing wording when we discuss these climate changes. When we
say rapid, and abrupt, what do you think we mean?
Does anyone have a guess?
Hundreds of years? Anybody else?
Thousands?
A couple million? OK, yeah,
So the release of greenhouse gases
into the atmosphere during the PETM, there's a lot of debates about it, but it
was around 10 thousand, 20 thousand years. That is really rapid, right, for a geologist? It's fast.
It's really fast. But to you and I, where we have an average life expectancy of
I don't know, less than a century, it's not very fast. Pretty slow. When we talk about the
transition out of the last ice age,
same thing. The last ice age, the peak was about 21 thousand years ago, and most
of that CO2 was released into the atmosphere over about 15 thousand years.
So 15 thousand years, 10 thousand years, 20 thousand years. These are rapid
to geologists. It's not so rapid to everybody else. Right? So to kind of demonstrate that
I have what I'm referring here to as a time stick. So everything you see here
in blue is covering 20 thousand years. And that tiny tiny bit of yellow
at the very end is 150 years. 20 thousand years for CO2 to
be released into the atmosphere.
150 is what we've done now. So that so that's the difference in the rate.
So, what have we learned? We know that CO2 is important. We know that it's
very tightly coupled with changes in temperature. We know that CO2 can be
released by all kinds of mechanisms. We also know that today's CO2 is being
released by us, because we can chemically fingerprint that CO2, and I can explain
that later if you're interested. And so we know it's coming from us. So what does that say
for what we do? What don't we know? What are the uncertainties? So to me, I'm a fairly
early career scientist.
And to me, I don't really think that this question of temperature and CO2
is particularly interesting anymore. We know. We've figured this stuff out pretty well.
There are some error bars that we'd like to smack down, and the climate modelers are
working on refining projections, sure. But I started out today by telling you
why I got involved in this field in the first place, right? It's because of water.
Because people who rely on rainfall are really worried, as they should be.
Not just people. Animals, plants. Conservation organizations are really
concerned about water. Temperature is important, but the way that it influences
rainfall is really the next step.