1. The Climate Change Debate

2. What do we know? 3 Facts that ARE NOT in debate However…
There is a greenhouse Effect
Greenhouse gas emissions are increasing due to human activities
There has been a recent pattern of increased average global temperatures
However…
There is not total agreement about the cause of the rise in temperature nor over what we should be doing about it.

3. Its Complicated
The vast majority of scientists in this field accept the correlation between increased GHG emissions and increased temperature, causing climate change and different weather patterns.
But.. Some question the cause and effect…maybe its
Earth’s rotational wobble
Sunspot activity
The increased temperature could be causing the higher levels of GHGs not the other way around
Some simply deny that the trend is even worthy of concern
All agree that it is a complex system that is challenging to model

4. IPCC Intergovernmental Panel on Climate Change says…
Warming of the climate system in unequivocal
Observed changes are unprecedented over decades to millennia
Atmospheric concentrations of GHGs have increased to levels unprecedented in at least the last 800,000 years.
Continued emissions of GHGs will cause further warming
Limiting climate change will require substantial reductions in GHG emissions
Human influence on climate systems is clear
It is extremely likely that human influence was the dominant cause of global warming between and 2010.

5. Feedback
Feedback: The return of part of the output from a system as input, so as to affect succeeding outputs
Two types:
Negative Feedback:
Tends to dampen or reduce any deviation from equilibrium
Promotes stability
Ex: Evaporation in the tropics leads to more snow fall in the polar regions which cools the globe reducing evaporation.
Positive Feedback:
Amplifies or increases change
Leads to exponential deviation away from an equilibrium
Ex: Increased thawing of permafrost leads to increased methane levels which leads to increased global temperatures.

6. What could happen? 5 Possibilities a. May be a direct relationship
b. There may be a buffering action
c. Slow at first and then accelerate
d. May have a threshold (tipping point)
e. Could get stuck at a new equilibrium

7. The Consensus View
There is evidence that greenhouse gas concentration has increased since the industrial revolution
There is also evidence that human activity has caused this
Climate is Changing
Some is probably natural
Some is due to atmospheric forcing (us)
Some parts of the atmosphere respond quickly, and others more slowly
IPCC was set up in 1988 by UNEP
Hundreds of climate scientists from around the world
The first 4 reports were cautionary but used little certainty
By 2014 they were reporting “Unequivocal warming of the climate system with % probability that human influence is the dominant cause”

8. But is it really THAT complicated?