The document discusses climate change and covers four main topics: 1) Climate science establishes that climate change is real and caused by human greenhouse gas emissions from burning fossil fuels. The level of scientific consensus is extremely high. 2) Climate impacts explains that the effects of climate change are already occurring, with global temperatures rising much faster than historical rates. Impacts include melting Arctic sea ice. 3) Climate solutions acknowledges that solutions exist to address climate change through reducing greenhouse gas emissions, though specifics are not discussed. 4) Climate politics questions why more action is not being taken given the severity of the problem and the existence of solutions. Moving forward will require global cooperation and a shift to more sustainable energy sources.

1. [intro]We know climate change is real.

2. [intro]We know climate change is happening now.

3. [intro]We know that solutions exist.

4. [intro]So why aren’t we doing anything to stop the biggest problem to face humanity?

5. [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.

6. 350 Climate Presentation OverviewIntroClimate science (or, climate change is real)Climate impacts (or, climate change is happening now)Climate solutions (or, we know that solutions exist)Climate politics (or, so why aren’t we doing anything about it?)Conclusions

7. [science] we know climate change is real.

8. [science overview] What is climate change?What is causing it?How sure are we?Are we too late?

9. 1What is climate change?

10. 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

11. 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

12. 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!

13. We know the Earth is warming up quickly (figure 3)

14. Why is the Earth heating up? The Greenhouse EffectThere are many greenhouse gases Carbon dioxide (CO2) – most abundantMethaneNitrous oxideCFCsOzoneThe 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.Figure from “The Wonders of the Weather” by Bob Crowder

15. Some greenhouse gases are good – they allow our planet to be warm enough to support life.

16. Scientists measure how our climate is changing in a few different waysPpm and Ppm-e

17. Degrees CelsiusBut 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

18. 2 What is causing climate change?

19. Greenhouse gases are naturally stored on our planet- in plants and trees- below the ground as fossil fuelsBut since the industrial revolution, human activity has caused these gases to be released at abnormal rates

20. That’s around the time when humans became dependent on coal and oil for transportation and energy.

21. The Carbon cycleBurning fossil fuels releases carbon into the atmosphere that has been stored for millennia (and otherwise would stay stored there)

22. 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.

23. 550ppm? More?Where we’ll be mid-century if we keep this upTODAY: 390ppm +Parts per Million CO2EARLY 1900SCO2 in PPMLAST ICE AGEGLOBAL TEMPERATUREYears agoThroughout our history, global temperature has followed greenhouse gas concentrations

24. To recap: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 atmosphereWhen greenhouse gas concentrations rise, global temperature rises.We are observing that very rise in temperature to match the rise in greenhouse gases.

25. 3 How sure are we of the science?Really, really sure on the general gist, but a little less sure on the specifics

26. 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”

27. SCIENTISTS

28. “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

29. Number of scientific studies dealing with “climate change” published in scientific journals between 1993 and 2003: Number disagreeing with the global consensus that greenhouse gas pollution has caused most of the warming of the last 50 years:And anyone who tries to tell you differently needs to take a closer lookScience, December 3, 2004 Vol. 306, Issue 5702,1686

30. There is uncertainty about just how our climate will change in the futureThat’s because our earth is such a big and complex systemBut in general, scientists’ predictions have tended to be conservative compared to observed impacts so farUNCERTAINTY

31. EXAMPLE: MELTING OF THE ARCTICNew predictionsSatellite observationsMean IPCC predictionMost likely change (melt)IPCC rangeActual observed melting% change in ice coverit has melted nearly80 YEARSahead of when scientists predictedYEAR

32. Much of the uncertainty is due to “feedback loops”, when climate impacts reinforce and amplify each other, which can be hard to modelExample: The Albedo feedback loopEarth gets warmer, causing arctic ocean to warmWhite sea ice melts, exposing dark ocean underneathDark ocean reflects less sunlight, absorbs more energy

33. 4So are we too late?

34. 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.

35. Thankfully, we know where we need to aim:“If humanity wishes to preserve a planet similar to that on which civilization developed and towhich 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

36. 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!

37. Up Next: Find out how climate change is already impacting our planet.IntroClimate science (or, climate change is real)Climate impacts (or, climate change is happening now)Climate solutions (or, we know that solutions exist)Climate politics (or, so why aren’t we doing anything about it?)Conclusions

38. Sources and more informationGrist “Denier Argument FAQ” section350.org “Science of 350” and “FAQ” sections“2 Degrees, One Chance”James Hansen’s “Blue Planet”Scripps CO2 ProgramAudubon society