Unit 3 Notes Part 5: Climate Change

What are natural causes that could result in global climate change? Plate tectonics – when the continents move they may receive different amounts of sunlight Earth’s orbit and tilt – more elliptical orbits cause large variations in seasons Volcanic activity – ash from eruptions can reflect solar energy and decrease global temperatures Mount Pinatubo June 1991

How are past climate changes studied? Paleoclimatologists find clues in natural records. These records offer natural clues to past climate that are: – buried in sediments at the bottom of the oceans – locked in coral reefs – frozen in glaciers and ice caps – preserved in the rings of trees – fossils

Sea-Floor Sediments measure: -concentrations of oxygen isotopes in shells -Charcoal trapped in sediments can indicate past fire events. -Remains of microorganisms such as diatoms, foraminifera, microbiota, and pollen within sediment can indicate changes in past climate, since each species has a limited range of habitable conditions. -When these organisms and pollen sink to the bottom of a lake or ocean, they can become buried within the sediment. Thus, climate change can be inferred by species composition within the sediment. How are past climate changes studied?

Ice cores can be analyzed for trapped gas (CO2), stable isotope ratios, and pollen trapped within the layers to infer past climate. How are past climate changes studied?

Fossils measure changes in pollen type, leaf shapes, and animal adaptations How are past climate changes studied?

Tree Rings can be counted to determine age. The thickness of each ring can be used to infer fluctuations in temperature and precipitation, since optimal conditions for the particular species will result in more growth, and thus thicker rings for a given year. Scars and burn marks can indicate past natural events such as fire. How are past climate changes studied?

As carbon dioxide levels have risen so have global temperatures What is the relationship between the emissions of carbon dioxide, and the average global temperature over the past 150 years?

Trends in surface temperatures & CO 2 over the past 1,400 years

Given data on the annual trends of CO2 concentration increase, what could the global temperature be by 2100? Global temperatures are predicted to rise 2-4  C

What are the consequences of warmer oceans and changing climatic zones? If oceans become warmer it will lead to an increase in evaporation. This could cause more cloud formation and precipitation in areas that normally have drier conditions. Sea levels would rise around the world causing flooding. Ocean currents could be changed causing climates around the world to be altered Ice reflects sunlight, so with less of it Earth would heat up