Transcript Climate Change - Nanjing

Climate Change
• BEFORE WE BEGIN………..
• This is a controversial subject.
There is lots of good and not so good information
that promotes differing points of view on the
subject.
We will be looking at some of these in detail.
• Climate change.
• Why should we care?
The climate has been changing since the
beginning of Earth.
Why is it a problem all of a sudden?
• Earth’s temperature over the last 600 million
years:
• Look!!! It’s cold now!!! Of course we are going to
get warmer.
• IT’S ALL NATURAL CYCLES !!!
• Climate change over the last 425000 years.
• Look!!! It gets warm then cold then warm then
cold then warm.
• AHHH! We’re heading for another ice age!
• Good thing there’s global warming!
• Yes, the climate does change naturally.
Plate tectonics
Volcanoes
Meteorite impacts
Sun cycles
Changes in Earth’s tilt and orbit……
• Yes, the climate does change naturally.
Plate tectonics
Volcanoes
Meteorite impacts
Sun cycles
Changes in Earth’s tilt and orbit……
HOWEVER………..
What you need to understand in order
to engage in intelligent discussion about
climate change:
• Earth’s temperature in the Holocene (last 10000
years)
• We have been very lucky to have a long stretch
of time that has very little climatic change!
• Consistent temperatures make it easier for
ecosystems to develop.
• The ecosystems we have on Earth today are
strong because they have been able to adapt to
their environment for the last 10000 years.
• This consistent temperature is very good for
ecosystems, and it’s good for the people who
rely on those ecosystems.
• If left alone, the consistent Holocene climate
should last for several thousand years into the
future.
•
(Berger, A. & Loutre, M. F. Science 297, 1287–1288 )
•
http://www.sciencemag.org/content/297/5585/1287.full
• So…..
Having a consistent climate is a good thing (for
us)
We have a forecast of a consistent climate for the
next few thousand years
• Why is this happening?
• At any point you are welcome to introduce any
new information from respected peer-reviewed
journals.
The introduction of this unit will be:
Before we begin....
This was meant as a film to
introduce the idea of climate
change.
It is meant for the general public.
Also note:
There is a lot of criticism about the
information shown in this film, some of
which valid.
We will be looking at critical
perspectives after watching the film.

http://www.56.com/u69/v_NDU0Mzk2NTA.html
http://video.sina.com.cn/v/b/261972721068641897.html
Terminology to know:
IPCC:
Intergovernmental Panel on Climate Change

The Intergovernmental Panel on Climate
Change (IPCC) is the leading international body
for the assessment of climate change. It was
established by the United Nations Environment
Programme (UNEP) and the World
Meteorological Organization (WMO) to provide
the world with a clear scientific view on the
current state of knowledge in climate change
and its potential environmental and socioeconomic impacts. The UN General Assembly
endorsed the action by WMO and UNEP in
jointly establishing the IPCC.
Reputable specialist who
study climate change.
Endorsed by the UN (United
Nations)
Controversy after the film.
The film was shown in the United Kingdom.
A student's parents didn't like the film being
shown in school so they challenged the content
of the film in court.
The court found 9 things that they did not think
were correct.


http://en.wikipedia.org/wiki/Dimmock_v_Secreta
ry_of_State_for_Education_and_Skills#The_nin
e_inaccuracies
http://www.carbonpositive.net/viewarticle.aspx?
articleID=1306
Sea levels probably won't rise by 7
metres anytime soon
according to the IPCC
 we are probably heading towards
about a 59cm rise by 2100


2012 update: the projection now is for
about a 1m – 1.4 m rise by 2100.
( http://www.pnas.org/content/early/2009/12/04/0907765106.full.pdf)

A 1 meter rise in ocean levels would create a
very difficult situation for low lying cities.
http://www.grida.no/graphicslib/detail/populationarea-and-economy-affected-by-a-1-m-sea-levelrise-global-and-regional-estimates-based-ontodays-situation_d4fe
Pacific islands are being evacuated.
Maldives is buying land so they can move.
Mount Kilimanjaro may be melting for other
reasons
nobody knows for sure how the polar bears
drowned
lake Chad was a combination of irrigation for
farming and climate change.
• http://www.skepticalscience.com/al-goreinconvenient-truth-errors.htm

Does this mean everything
in the film is false?
The Main Claims made by the film:
The planet is getting warmer
The planet is getting warmer
True,
 This is easily verifiable.

The best explanation for why the planet
is warming is the increase in
greenhouse gases, (mostly CO2) in
the atmosphere.
The best explanation for why the planet
is warming is the increase in
greenhouse gasses, (mostly CO2) in
the atmosphere.

True, this is consistent with the
overwhelming scientific consensus
Global warming will increase the
chance of extreme weather (stronger
hurricanes, more rain and floods in
wetter places, more drought in dryer
areas)
Global warming will increase the
chance of extreme weather (stronger
hurricanes, more rain and floods in
wetter places, more drought in dryer
areas, longer forest fire seasons)


True,
This is verifiable
In the end The court ruled:

“Al Gore's presentation of
the causes and likely
effects of climate change
in the film was broadly
accurate."
The Greenhouse effect

This is probably what you have learned before:

This is more realistic:

1. Simple: Greenhouse gases act as an
insulating “blanket,” making it harder for energy
to escape and resulting in the warming of the
surface until its higher temperature can still
force enough energy through to maintain
energy balance.

More sophisticated: Greenhouse
gases absorb outgoing infrared
and heat up. They re-radiate their
energy both upward to space and
downward to the surface. The
surface is warmed by this back
radiation and, therefore, radiates
more infrared to maintain energy
balance.

Most sophisticated: The upper atmosphere, being
cooler than Earth’s surface, can’t emit as much
radiation as the surface. Radiation from the
atmosphere alone, then, can’t keep the planet in
energy balance. Therefore, the surface temperature
must be higher than the atmosphere temperature to
provide enough additional radiation that can escape
through the nearly but not completely opaque
greenhouse gases. Thus, the greenhouse effect
depends crucially on the temperature difference
between surface and upper atmosphere. Increasing
greenhouse warming actually entails cooling the upper
atmosphere.
Note that there has always naturally
been some CO2 in the atmosphere.
Before fossil fuels were burnt it was
about 280ppm.
PPM:
Parts per million.
If there were no greenhouse gases
the world would be much colder.
Probably be about 30 degrees
colder.
So...
greenhouse gases keep the
world at a comfortable
temperature for us.
However.....
In recent years we have been using
a lot of fossil fuel. Carbon that has
been trapped underground for
hundreds of millions of years
(mostly from the Carboniferous
Period) is now being released into
our biosphere.
http://co2now.org/
We are now at about 396 ppm.
This is far more than has been in the atmosphere
in all of human history.
The problem is that there is more
greenhouse gas in the
atmosphere now than ever before
in human history.
This will very predictably cause a
change in global temperature.