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Explaining the Evidence Activity 2: Clearing the Air.

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Presentation on theme: "Explaining the Evidence Activity 2: Clearing the Air."— Presentation transcript:

1 Explaining the Evidence Activity 2: Clearing the Air

2 Climate change is due to human activities. or… Climate change is due to human and natural causes. Nearly all climate scientists agree on causes of climate change. or… Most scientists do not agree on causes of climate change. How Many of You Have Heard That…

3 People have beliefs about many things. – Ideas that we think are true – Based on a number of sources such as past experiences, faith, or what someone said – Can change as people learn and have new experiences Assumptions are underlying ideas behind beliefs. – Connect evidence to conclusions – May or may not be based on fact – Important to distinguish assumptions from beliefs Beliefs and Assumptions

4 Assumption: Carbon dioxide occurs naturally in small amounts, but is very efficient at absorbing heat energy. Therefore, it is logical to believe… Belief: Any amount of carbon dioxide added to the atmosphere by humans can cause climate change. Sample Beliefs and Assumptions about Climate Change Assumption: Carbon dioxide is one of many atmospheric gases, and it makes up a small percent of the total gases in our atmosphere. Therefore, it is logical to believe… Belief: The small amount of carbon dioxide added to the atmosphere by humans cannot cause climate change.

5 Science is a way of knowing about the natural and material world. – Hypothesis – Data – Evidence – Conclusions Science


7 Weather describes the atmospheric conditions at a specific place at a specific point in time. Climate is determined by long term trends in weather. Weather vs. Climate

8 Will not be the same everywhere – Some places will be wetter, others will be drier – Polar regions will see greater increases in temperature than tropical regions Includes changes in – Earth’s average temperature – Patterns and amounts of precipitation – Ice and snow cover – Sea level – Extreme weather events Evidence of Climate Change

9 1. Temperature (1880-2010)

10 1. Temperature (1000-2000) Variations of the Earth’s surface temperature for the past 1,000 years

11 Observed Precipitation Changes: 1901-2007 2. Precipitation

12 3. Sea Ice

13 4. Sea Level

14 5. Catastrophes, Including Extreme Weather Events


16 Historical Climate Change Solar radiation Ocean composition Greenhouse effect Albedo effect Continental land arrangement Volcanic eruptions Recent Climate Change Solar radiation Ocean composition Greenhouse effect Albedo effect Continental land arrangement Volcanic eruptions Fossil fuel combustion Land-use change from human activities Climate is Affected by Several Factors


18 Solar Radiation

19 Radiative Forcing

20 In the Southeast U.S., land use changes from bare soil in cotton and other row crops to forests (currently 70 percent of the region) may have contributed to the negative trend in temperature over the past 100 years. Land-Use Change

21 Greenhouse Gas Pre-1750 Tropospheric Concentration Recent Tropospheric Concentration Change in Tropospheric Concentration Carbon dioxide (CO 2 ) 280 ppm393 ppm40% Methane (CH 4 ) 700 ppb1874 ppb168% Nitrous oxide (N 2 O) 270 ppb324 ppb20% Chlorofluorocarbons (CFCs) 021-529 ppb (different for each CFC) NA Ozone (O 3 ) 25 ppb34 ppb36% We Have Also Altered the Atmosphere ppm = parts per million ppb = parts per billion

22 Atmospheric Greenhouse Gases a

23 CO 2 has changed the most. CO 2 stays in the atmosphere a long time. The US emits more CO 2 than other greenhouse gases. We can do something about it. Focus on CO 2 800,000 Year Record of CO 2 Concentration

24 Carbon is Everywhere

25 Natural forces alone do not explain the changes in temperature. Global and Continental Temperature Change

26 97% of climate scientists combine this and other evidence to draw these conclusions: – Earth’s climate is currently changing due to global warming. – Changes are not the same at all locations on Earth. – Future changes may be more rapid than historical changes. – Human activities are responsible for most of the climate change being observed. What Does All This Mean?

27 Agreement Among Climate Scientists


29 What Will Happen in the Future?

30 Current Modeled Forest Future Model – Low Emissions Future Model – High Emissions Forest Habitat Changing Legend White/Red/Jack Pine Spruce/Fire Longleaf/Slash Pine Loblolly/Shortleaf Pine Oak/Pine Oak/Hickory Oak/Gum/Cypress Elm/Ash/Cottonwood Maple/Beech/Birch Aspen/Birch No Data

31 A Movable Carbon Map

32 Southeast’s climate is largely influenced by El Niño and La Niña Sea level rise – Coastal erosion Warmer temperatures – More invasive exotic organisms – Greater risk of wildfire Increased yield in some crops if water is plentiful Less rain in the growing season in some places – Harm to crops, or changes in planting times What Could Happen in the Southeast?


34 A very complex system Regional variation Changes are hard to see No firm predictions; models have limitations Not just about the science - Political, Economic It’s a Challenge

35 The U.S. Public Has Many Beliefs about Climate Change

36 People see and remember information that matches what they know – So it is hard to change someone’s mind People have partial information and leap to conclusions – And then when presented with complete information, it doesn’t match People listen to influential leaders – Rather than figuring it out for themselves But Why disagreement?

37 Lots of options; no single solution – Adaptation – Mitigation Policies and actions implemented by – Governments: international, national, state, local – Industry and business – Individuals – all of us! Solutions to Climate Change

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