Climate Change: Fitting the pieces together The topic of climate change is like a puzzle with many different pieces—oceans, the atmosphere, ecosystems, polar ice, natural and human influences. Scientists have been working on this puzzle for more than a century, and while there are still gaps in our knowledge, most experts feel we have the puzzle is complete enough to show that human activities are having an adverse effect on our planet. This talks looks at many of those puzzle pieces, the evidence behind them, and the conclusions we can draw from them. 1

Average weather conditions of the Earth or a particular area Climate Average weather conditions of the Earth or a particular area Main focus: temperature & precipitation Minimum period: 3 decades

Greenhouse Gases Gases that absorb and radiate heat Major greenhouse gases Methane Nitrous oxide Carbon dioxide Water

Increasing greenhouse gases trap more heat “Greenhouse effect” Increasing greenhouse gases trap more heat [Image 1] Earth’s surface absorbs heat from the sun and then re-radiates it back into the atmosphere and to space. [click, Image 2] Much of this heat is absorbed by greenhouse gases, which then send the heat back to the surface, to other greenhouse gas molecules, or out to space. Though only 1% of atmospheric gases are greenhouse gases, they are extremely powerful heat trappers. By burning fossil fuels faster and faster, humans are effectively piling on more blankets, heating the planet so much and so quickly that it’s hard for Mother Nature and human societies to adapt. 4

Measuring Greenhouse Gases Charles Keeling Studied atmospheric CO2 Mountains in Hawaii Far away from forest and cities

Carbon Dioxide Levels

Global Warming A gradual increase in the average global temperature that is due to higher concentrations of greenhouse gases

Causes of Climate Change Variation in the sun’s energy Natural 11 year cycle (small) Changes occurring in the sun itself can affect the intensity of the sunlight that reaches Earth’s surface. The intensity of the sunlight can cause either warming (during periods of stronger solar intensity) or cooling (during periods of weaker solar intensity). The sun follows a natural 11-year cycle of small ups and downs in intensity, but the effect on Earth’s climate is small.[1]

Causes of Climate Change Variation in the sun’s energy Changes in the Greenhouse affect Decrease/Increase in Greenhouse gases

Greenhouse Gas Emissions Water (H2O) Evaporation Transpiration Steam from energy generation

Greenhouse Gas Emissions Carbon Dioxide (CO2) Volcanic Activity Decomposition Respiration Ocean exchange Industrial revolution Burning fossil fuels (87%) Deforestation Agriculture

Greenhouse Gas Emissions Methane (CH4) – 64 % anthropogenic Wetland (anaerobic bacteria) Burning or fracking for natural gas Landfills Permafrost melt Agriculture (Beef) % - 2006 study in nature

Greenhouse Gas Emissions Nitrous Oxide (N2O) Soil microbes Ocean microbes Fertilizers Manure & chemical Burning of fossil fuels Human sewage from septic tanks (bacteria)

Greenhouse Gas Emissions Ground Level Ozone (troposphere) Good in stratosphere – blocks UV Produced from photochemical reactions with pollutants in the atmosphere

Greenhouse Gas Emissions CFCs (Chlorofluorocarbons) No natural source (created in 1928) Refrigerants Aerosols Cleaning solvents **destroy stratospheric ozone **phased out in 1989 – Montreal Protocol

Effects on Earth Temperature Risen 1° in 100 years Predict 1-2° more by 2050

Precipitation Droughts Flooding

Vulnerable ecosystems Temperature changes Migrations

Ocean Acidification Oceans is a major carbon reservoir 30% of anthropogenic C Oceans are warmer Holds less CO2 Ocean Acidity Water + Carbon Dioxide = Carbonic Acid 30% increase in last 200 years

Rise in sea level Glacier melt Threatens small islands & coastal areas Video in glacier pic

Loss of species Video in polar bear pic

What do climate scientists really think? 24