We know climate change is real.

[intro]

We know climate change is happening now.

[intro]

We know that solutions exist.

[intro]

So why aren’t we doing anything to stop the biggest problem to face humanity?

[intro]

It’ll take a movement of concerned people like us to ensure our leaders act in the face of the biggest challenge to ever confront humanity.

[intro]

1. Intro

2. Climate science (or, climate change is real)

3. Climate impacts (or, climate change is happening now)

4. Climate solutions (or, we know that solutions exist)

5. Climate politics (or, so why aren’t we doing anything about it?)

6. Conclusions

350 Climate Presentation Overview

[science]

we know climate change is real.

[science overview]

1. What is climate change?

2. What is causing it?

3. How sure are we?

4. Are we too late?

1

What is climate change?

What is climate change?

Climate is the average weather conditions of a place or area (or the whole globe) over a period of years

‘Climate change’ is a long term change in the average weather

• Our climate has always been variable.• Glacial periods and warmer periods have occurred

throughout Earth’s history.• This variability is natural and is caused by many things

• HOWEVER…• Global temperature change (between glacial and

interglacial periods) occurs normally at a rate of 0.05 – 0.005°C every 100yrs.

• In the last 50yrs the global average temperature has increased by 0.5 degrees!

• This is between 20 and 200 times the normal rate, and it’s accelerating!

We know the Earth is warming up quickly

• (figure 3)

Why is the Earth heating up? The Greenhouse Effect

Figure from “The Wonders of the Weather” by Bob Crowder

The gases in the atmosphere that trap heat in the earth’s surface are called greenhouse gases and they occur naturally in our atmosphere, in small amounts.

There are many greenhouse gases

Carbon dioxide (CO2) – most abundantMethaneNitrous oxideCFCsOzone

Some greenhouse gases are good – they allow our planet to be warm enough to

support life.

Scientists measure how our climate is changing in a few

different ways

• Ppm and Ppm-e

• Degrees Celsius

But historically, greenhouse gases have stayed in a particular range. Since industrialization, the concentration of CO2 in the atmosphere has risen from about 280ppm (parts per million) to over 392ppm due to human activities.

The present CO2 concentration has not been exceeded during the past 420,000yrs and likely not in the past 20 million yrs

(humans only appeared on earth 2 million yrs ago!)

The earth’s fragile atmosphere, as seen from a shuttle

2 What is causing climate

change?

•Greenhouse gases are naturally stored on our

planet- in plants and trees- below the ground

as fossil fuels

But since the industrial

revolution, human activity

has caused these gases to be released at

abnormal rates

That’s around the time when

humans became dependent on coal and oil for transportation

and energy.

The Carbon cycle• Burning fossil

fuels releases carbon into the atmosphere that has been stored for millennia (and otherwise would stay stored there)

There is no debate that burning fossil fuels releases greenhouse gases into our atmosphere – or that we have burned a lot of fossil fuels since the industrial revolution.

CO2 in PPM

GLOBAL TEMPERATURE

Years ago

Part

s p

er

Million

C

O2

TODAY: 390ppm +

550ppm? More?

EARLY 1900S

LAST ICE AGE

Where we’ll be mid-century if we keep this up

Throughout our history, global temperature has followed greenhouse gas concentrations

• Humans are causing climate change.• By burning more and more fossil fuels for our energy

needs, it is very clear that:• Humans have raised and continue to raise the

concentration of greenhouse gases in our atmosphere

• When greenhouse gas concentrations rise, global temperature rises.

• We are observing that very rise in temperature to match the rise in greenhouse gases.

To recap:

3 How sure are we of the science?

Really, really sure on the general gist, but a little less sure on the specifics

The largest research project in history: In 1988, the IPCC was

created to “provide the decision-makers and others interested in climate change with an objective source of information

about climate change”

SCIENTISTS

• “Some scientific conclusions or theories have been so thoroughly examined and tested, and supported by so many independent observations and results, that their likelihood of subsequently being found to be wrong is vanishingly small. Such conclusions and theories are then regarded as settled facts. This is the case for the conclusions that the Earth system is warming and that much of this warming is very likely due to human activities.”– The US National Academy of Sciences, 2010

And anyone who tries to tell you differently needs to take a closer look

Number disagreeing with the global consensus that greenhouse gas pollution has caused most of the warming of the last 50 years:

Science, December 3, 2004 Vol. 306, Issue 5702,1686

Number of scientific studies dealing with “climate change” published in scientific journals between 1993 and 2003:

• There is uncertainty about just how our climate will change in the future

• That’s because our earth is such a big and complex system

• But in general, scientists’ predictions have tended to be conservative compared to observed impacts so far

UNCERTAINTY

EXAMPLE: MELTING OF THE ARCTIC

New predictions

Satellite observationsMean IPCC predictionMost likely change

(melt)IPCC range

Actual observed melting

it has melted nearly 80 YEARS ahead of when

scientists predicted

YEAR

% c

han

ge in

ice

cover

Much of the uncertainty is due to “feedback loops”, when climate

impacts reinforce and amplify each other, which can be hard to model

• Example: The Albedo feedback loop

Earth gets warmer, causing arctic ocean to warm

White sea ice melts, exposing dark ocean underneath

Dark ocean reflects less sunlight, absorbs more energy

4

So are we too late?

Once emitted, greenhouse

gases stay in the atmosphere and

trap heat for decades.

That’s why its essential to cut emissions now. It will be difficult to stabilize our climate, but it’s not impossible.

“If humanity wishes to preserve a planet similar to that on which civilization developed and to which life on Earth is adapted, paleoclimate evidence and ongoing climate change suggest that CO2 will need to be reduced from its current 387ppm to at most 350ppm.”

- NASA climatologist Dr. James E. Hansen,

2008

Thankfully, we know where we need to aim:

The 350ppm target means that at our current level – 392ppm, we are already in the danger zone.

The Earth and the species that live on it have never gone through a change in climate such as the one we are now facing.

But it’s not too late – if we act now!

1. Intro

2. Climate science (or, climate change is real)

3. Climate impacts (or, climate change is happening now)

4. Climate solutions (or, we know that solutions exist)

5. Climate politics (or, so why aren’t we doing anything about it?)

6. Conclusions

Up Next: Find out how climate change is already impacting our planet.

Sources and more information

• Grist “Denier Argument FAQ” section• 350.org “Science of 350” and “FAQ” sections• “2 Degrees, One Chance”• James Hansen’s “Blue Planet”• Scripps CO2 Program• Audubon society