Science Short Answers Part 3

Describe two different way in which deforestation can contribute to global warming.

- burning trees releases GHG (Greenhouse gases) - Fewer trees --> Less CO2 removed from the atmosphere

Rank these storage banks of carbon from greatest (most carbon stored) to least: Atmosphere, Surface Ocean, Soil, Deep Ocean, Plant Biomass, Fossil Pool

1) Deep ocean 2) Fossil pool 3) Soil 4) Ocean surface 5) Atmosphere 6) Plant Biomass

Regarding the carbon cycle, described identify two natural sources and two natural sinks of atmospheric carbon.

A sink absorbs more carbon than it gives off, while a source emits more than it absorbs. Two natural sources: - Burning fossil fuels - Phytoplankton respiration Two natural sinks: - Photosynthesis (plants) - Phytoplankton photosynthesis

How do climate models support the assertion that humans are contributing to global warming?

Climate modelers include many different types of data in their models (e.g. variation in solar activity, cloud cover, volcanic eruptions, etc.). Greenhouse gas emissions from human activity are one of the types of data that are included. When modelers remove these human-caused emissions from their models, the models no longer accurately predict the climate change (either by hindcasting or forecasting).

Why is it difficult to perform a valid scientific experiment to answer the question "Is human activity contributes to global warming?"

Climate modelers include many different types of data in their models (e.g. variation in solar activity, cloud cover, volcanic eruptions, etc.). Greenhouse gas emissions from human activity are one of the types of data that are included. When modelers remove these human-caused emissions from their models, the models no longer accurately predict the climate change (either by hindcasting or forecasting).

Describe two different mechanisms for sea level rise resulting from global warming

Sea level rise: ⦁ Melting snow and ice are flowing into the ocean from the land. ⦁ The ocean is expanding due to heating.

Some impacts of global warming are sea level rise and physical discomfort. List three other likely impacts of global warming.

The ocean is becoming more acidic (not good for shelled animals) -CO2 reacts with seawater to form carbonic acid. Less usable fresh water - Lower snow pack - Inconsistent precipitation (droughts and floods) - Encroaching sea water More pests - Small parasites, such as ticks, survive better in warmer temperatures.

Describe how climate scientists test whether or not a new climate model is valid, without waiting for years to see if the model has accurately predicted future climate change.

⦁ "Hindcasting" is used to test new models. Models enter old climate data (e.g. data from the 1970's) into their climate models and then predict how the climate will change in the following decades (e.g. the 80's through today). If the predictions match the actual changes in climate, then the model is validated. ⦁ Forecasting. This is the same as hindcasting, except that the modelers use current data and then wait several years to see if their predictions were correct.

Describe two natural causes of climate change

⦁ Changes in Earth's orbit ⦁ Changes in Solar Output ⦁ Greenhouse gas fluctuations resulting from changes in Earth's orbit and/or the sun's solar output (see feedback loops, below). - Meteor impacts - Volcanism

What is the difference between global warming and climate change?

⦁ Global warming refers to: increasing average temperature of the Earth. ⦁ Climate change refers to: long term changes in temperature, precipitation, wind, ocean currents, and/or other climate characteristics in specific locations. ⦁ Can climate change cause some areas to become cooler? Yes, but most areas will become hotter.

Describe two different positive feedback loops that can contribute to global warming, and briefly illustrate how they work.

⦁ Snow is white and is therefore good at reflecting sunlight back into space. Global warming causes snow to melt. When snow melts, the darker exposed surface of the earth absorbs more sunlight, causing the Earth to heat up. This melts more snow. ⦁ Heating of the Earth melts permafrost. When permafrost melts, it releases CO2 and methane (CH4), which are both greenhouse gases. [This is what scientists think happened in the past, when the original heating was caused primarily by changes in the Earth's orbit.] ( Evaporation of water)

Explain how greenhouse gases contribute to global warming.

⦁ Visible light travels from the Sun to the Earth's surface, mostly passing through our greenhouse gases. ⦁ Visible light is absorbed by the Earth's surface, causing the surface to heat up. ⦁ The warm surface of the Earth gives off infrared waves. Greenhouse gases block many of these infrared waves, keeping them inside our atmosphere and heating up the Earth.

List the top 4 greenhouse gases, in order of impact, and describe at least one important source of each.

⦁ Water Vapor - Evaporation, burning stuff, breathing, global warming ⦁ Carbon Dioxide - 40% from burning fuels to produce electricity; 30% from transportation (cars, trucks, trains, boats, planes); 5-10% from production of cement and concrete; breathing. ⦁ Methane - swamp mud, cow flatus ⦁ Nitrous Oxide - Soil, agriculture, burning stuff