Transcript Climate Change

Climate Change
Agree or Disagree?
• Scientists predict that the entire globe will
get hotter over the coming decades.
• We can see that average global
temperatures are increasing and have been
for about a century. But any one place on
Earth may get colder, not warmer.
Agree or Disagree?
• This year’s scorching drought in much of the U.S.
is unquestionably the result of climate change.
• Weather is what happens over a short time scale
(hours, days, weeks, months).
• Climate is what happens over a long time scale
(years, decades, centuries)
• So we can’t definitely say whether the weather in
one year is due to a changing trend in climate, or is
just a statistical blip.
Agree or Disagree?
• There is only one greenhouse gas, and
that’s carbon dioxide.
• There are a number of gases that absorb
infrared radiation. Carbon dioxide is the
most abundant (besides water vapor).
Methane absorbs even more energy, but is
not as common.
Agree or Disagree?
• The Earth’s atmosphere contains only a
tiny bit of CO2.
• Yes, that’s true. Gases in the atmosphere
(not including water vapor)
• Nitrogen: 78%
• Oxygen: 21%
• Carbon dioxide: 400 ppm (0.0004 %)
Time out for the Greenhouse Effect
• Most of the light from the sun that arrives at
the surface of the Earth is visible light.
• Oxygen, nitrogen and carbon dioxide are
transparent to visible light – it travels
through without being absorbed.
• Carbon dioxide is NOT transparent to
infrared – it absorbs it.
http://climate.nasa.gov/kids/bigQuestions/g
reenhouseEffect/
Sunlight is absorbed at
the surface of the
Earth. Infrared
radiation is radiated
from the ground.
Greenhouse gases
absorb the infrared
Glass is transparent to visible light –
sunlight travels through it and is absorbed
by the things in the greenhouse. Then
they radiate infrared radiation. Glass is
NOT transparent to infrared, so the
radiation is captured.
http://www.columbia.edu/~vjd1/greenho
So if water vapor absorbs infrared
radiation, why are we so worried about
carbon dioxide?
• Yes, water vapor is a greenhouse gas and it
captures much of the heat energy that is in the
atmosphere.
• But water vapor is pretty constant in the
atmosphere. It cycles around, but overall the
amount of water on Earth stays the same.
• The amount of carbon dioxide, though, is
changing because of human activities. So if we
are looking at a change in temperature, we need to
look for a potential cause that is also changing.
Climate v weather
• Weather is what happens over a short time
scale – hours, days, weeks
• Climate is what happens over a long time
scale – decades, centuries, millennia
• What happens in a single year is not an
indicator of what is happening to climate –
we need to look at averages over longer
time periods.
The Data
• Now we’ll look at all the data that each
group analyzed for us.
Temperature Data
• Where does the temperature data come
from?
– Modern data: weather stations - data to late
1800’s
• Increasing urbanization will cause increase in
temperature independent of global temperature
changes
• Correct for problem by comparing stations with
nearest rural stations
Evidence for climate change
• Where does the temperature data come
from?
– Ancient data: oxygen isotopes
• Found in Antarctic ice cores - back to about half
million years
• Found in rock - back millions of years
Time out for Oxygen Isotopes
“Normal”
oxygen.
Over 99% of oxygen
in the atmosphere is
16O
16O:
18O:
Only a tiny
bit of oxygen in
the atmosphere is
the heavier form
of 18O
Because 18O has more
mass than 16O, it is less
likely to evaporate.
When it’s hotter,
more 18O evaporates.
So the ratio of 18O/16O
tells us about the
temperature.
http://www.mhhe.com/biosci/pae/botany/uno/graphics/uno01pob/vrl/images/0041.gif
What do we conclude?
1. Trends through time?
• Getting warmer, more recently it’s
warming faster
1. Geographic patterns?
• N. Hemisphere is warming faster than
southern hemisphere
Surface Temperature Data
• This data is from satellites directly measuring
infrared radiation escaping from the Earth’s
surface.
• Data is mapped as anomalies.
• That means the temperature is compared to the
average from 1951-1980, and the difference
from the average is mapped. Blue means
colder than the comparison period, yellow to
red means warmer
30 years of data
10 years of data
Last year’s data
Judi, play the movie
The Flat curve controversy
• Some climate change skeptics point to a
flattening of the air temperature curve
recently to suggest that the climate has
stopped warming.
• The curve actually is still climbing – 14 of
the past 15 years have been the hottest
measured – but at a more gentle rate.
• It looks like the energy is there – but it’s
going into the deep oceans right now
Air temperature curve
What do we conclude?
1. Patterns in the data?
• Temperature increasing over time, getting
worse more recently
• N. Hemisphere warming faster
1. Which map gives us the best picture of
climate change?
• 30 year map
Greenhouse Gas Levels
• This data is measured (mostly) at the
observatory on the top of Mauna Loa in
Hawaii. The idea is to measure far away
from industrial sources of gases so we can
be confident we are measuring gas levels
over much of the planet, not just next to a
factory.
What do we conclude?
1. Patterns over time?
• CO2 increase over time, rate is getting
faster
• Methane increasing
1. Geographic patterns?
• Lots of methane near north pole
Let’s look at the relationship between
carbon dioxide and temperature
What do we conclude?
• Direct correlation between CO2 and
temperature, and the CO2 is currently rising
faster than the temperature can.
Where does the CO2 come from?
• Let’s look at the contribution of different
countries
• Does increased CO2 correlate with more
wealth?
• Does CO2 always correlate with higher
temperature?
What do we conclude?
1. Patterns over time? Increasing at faster rate
2. What parts of the world produce the most
CO2? US, China, Russia India
3. CO2 v GDP?
4. Wealthiest countries produce more CO2
per person
Glaciers
• This data shows either length of reference
glaciers, or mass balance, which is the
amount of ice gained minus the amount of
ice lost. If mass balance is positive, glaciers
are growing. If it is negative, glaciers are
shrinking.
What do we conclude?
1. Patterns over time? Glaciers are shrinking,
and the rate is increasing
1. Geographic patterns? East Antarctic gain,
everywhere else in world is shrinking
Sea Level
• Sea level is largely measured by satellite
these days using GPS technology.
What do we conclude?
1. Why a seasonal change? Glaciers grow in
winter, keeping water out of the oceans
2. Pattern in time? Sea level rising
1. Geographic patterns? Sea level dropping in
a few places – mostly near poles – and
rising in most places
Climate belts
• USDA plant hardiness zones
• New and disappearing climate zones
• Mammal ranges
Mapped indices of climate change risk for local climate change (A and B), novel 21st-century
climates (C and D), and disappearing 20th-century climates (E and F).
Williams J W et al. PNAS 2007;104:5738-5742
©2007 by National Academy of Sciences
Percentage of mammalian species that are projected to be unable to keep pace with
climate change.
Schloss, Nunez & Lawler, 2012, Dispersal will limit ability of mammals to track climate
change in the Western Hemisphere, Proceedings of the National Academy , 102:22,
www.pnas.org/cgi/doi/10.1073/pnas.1116791109
What do we conclude?
1. How have climate belts already changed?
1. Climate zones in US are shifting north
2. Where are the most endangered climates?
1. Near the equator, S. America, Africa.
Habitat disruptions
• High altitude – moving higher
Pikas live at high altitude in
the western mountains. As
North American warms,
their range is shrinking
upward.
http://naturemappingfoundation.org/natmap
/photos/mammals/pika_5946np.jpg
http://upload.wikimedia.org/wiki
pedia/commons/3/3b/American_P
ika_area.png
Pika
Habitat disruptions
• High altitude – moving higher
• High latitude – getting warmer
• Oceans
– more CO2 in atmosphere makes surface waters
more acid – hard on critters with shells
– Warmer water moves environmental zones and
kills tropical species such as coral
http://images.wri.org/future_bleaching_web_high-res.jpg
http://www.pbs.org/newshour/rundown/2011/02/scientists-forecast-an-altered-ocean.html
Human Impacts
• Food supply – as climate belts move, food
production belts move
• Water supply – greater water insecurity
• Health – parasites and diseases follow
climate belts
• Migration –
– People leaving very stressed climates
– People leaving island nations and coastal cities
http://maplecroft.com/about/news/food-securit
Vorosmarty and others, 2010, Nature 467(7315):555-561
http://vepinet.biologija.unios.hr/goals.html
http://www.ciesin.columbia.edu/documents/clim-migr-report-june09_media.pdf
Maldives: an island nation in the Indian Ocean
Dark Blue: 1 m sea level rise
Light Blue: 2 m sea level rise
http://www.ciesin.columbia.edu/documents/clim-migr-report-june09_media.pdf
Potential Conflicts from Climate-induced Migration
But I heard on the radio…
• Please do not get your science from talk
show hosts, TV commentators or
politicians.
• Get your science from credible news
sources (this does not include editorials,
opinion pieces or blogs), science magazines,
and educational web sites (e.g., NOAA,
USGS, California DWR)
But it’s snowing in Florida
• That’s weather, not climate
• 14 of the 15 hottest years on record globally
were in the last 15 years (1998 is the odd
one)
• 2014 is the hottest year on record, narrowly
beating out 2010 and 2005
• Hotter planet = more weather instability
But Al Gore is a hypocrite – he
has a big house and many cars
• So what? That has nothing to do with the
data.
• Al Gore just made the movie – the data
existed before that.
• This is a classic ad hominem attack – a
logical fallacy. Just because the speaker is a
(insert your favorite insult here) doesn’t
automatically make what he says wrong.
But the scientists made it all up
to keep the grant money flowing
• In all recent surveys of climate scientists,
upwards of 95% agree that climate has
changed due to human influence.
• Media climate skeptics are largely
professional doubters who make a living
appearing on news programs rather than by
doing climate research.
But scientists falsified data – it
was in the Climategate emails
• 2000 emails from 4 scientists were illegally
hacked
• Multiple investigations by boards from
scientists from both the US and UK found
that while the language was intemperate and
showed poor judgment, the data referred to
was consistent with data from many other
researchers
But..but..but
• There is no real controversy among
scientists that climate is changing and that
humans are responsible for at least part of
the change
• The opposition is largely politically and
financially driven, and much more intense
in the US than in other industrial countries,
including China.