Climate science part 3 - climate models and predicted climate change
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Many lines of evidence, from ice cores to marine deposits, indicate that Earth’s temperature, sea level, and distribution of plant and animal species have varied substantially throughout history. Ice cores from Antarctica suggest that over the past 400,000 years global temperature has varied as much as 10 degrees Celsius through ice ages and periods warmer than today. Before human influence, natural factors (such as the pattern of earth’s orbit and changes in ocean currents) are believed to be responsible for climate changes. For more, visit: http://www.extension.org/69150
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Climate science part 3 - climate models and predicted climate change
- 1. Climate Science: Part 3. Climate Models and Predicted Climate Change Pam Knox, Agricultural Climatologist, University of Georgia
- 2. Topics you will learn about • Review: Causes of changes in climate • Carbon dioxide and other gases • Methods for predicting climate • Predicted changes in climate
- 3. Climate and Energy Balance
- 4. Climate of the Last 100 Years
- 5. Changes in Atmospheric Composition
- 6. Changes in Atmospheric Composition
- 7. Review of Climate Trends What kinds of trends are there? • Linear • Exponential • Changing variability • Change in slope • Step function
- 8. Atmospheric Window The “atmospheric window” refers to the wavelengths at which light can enter the Earth’s atmosphere as solar radiation (rainbow at left) or leave it as terrestrial radiation (red bar). As the amount of carbon dioxide, methane, water vapor and other greenhouse gases increases, the part of the window that lets light energy back to space gets pinched and energy stays in the climate system, which causes the climate to get warmer.
- 9. How to Predict Climate You can predict climate by predicting trends, but that depends on things continuing the same way they have in the past. Not always a good assumption! Instead, climatologists use climate models to simulate the future climate based on physics and predictions of future CO2 and other emissions.
- 10. Climate Models
- 14. Problems with Models • Coarse resolution leaves out mountains, Great Lakes, alters local conditions like coastlines • Simplification processes make rainfall less believable since most of it happens in sub-gridscale processes like thunderstorms • They are not very good at predicting current climate, making them less believable • No El Niño, hurricanes
- 15. Weather vs. Climate Models Weather models are designed to predict detailed hourly weather information for up to 7 days across a continent. Emphasis: short term, individual storm evolution Climate models are designed to predict multi-year climate conditions across the entire globe. Emphasis: long-term, seasonal to multi-year average climate conditions
- 16. Models can separate out C02 effects Models can be used to separate out the effects of individual factors to see what effect each factor has on the temperature trend.
- 17. Scenario Modeling Modelers use scenarios of various projections of changing CO2, changing energy efficiency, etc. to produce a series of graphs giving a range of expected outcomes. Observations don’t always agree with predictions. So which is right?
- 18. Sea Ice For sea ice, the observed decline in sea ice cover in the Arctic is faster than any of the models predicted.
- 19. Predictions of Future Temperature • Temperatures will increase, day and night • Amount of warming is not certain (5-10 F in next 100 years) • Longer growing season • Increased evaporation http://www.globalchange.gov/nca3-downloads-materials (new site with similar material has replaced original site)
- 20. Predictions for Future Precipitation • Predictions of future rainfall are not well modeled • Trends indicate increased rainfall intensity (more thunderstorms) with longer dry spells in between • Precipitation changes by season cannot be predicted • Effects on El Niño and hurricane frequency not known
- 23. Things that are Harder to Predict
- 24. Summary of Part 3 In this section we have covered: • Changes in atmospheric composition • Climate models • Trends in climate
- 25. For a full list of references cited in this presentation, please visit: www.animalagclimatechange.org This project was supported by Agricultural and Food Research Initiative Competitive Grant No. 2011-67003-30206 from the USDA National Institute of Food and Agriculture.
Hinweis der Redaktion
- Weather and climate have had significant impacts on animal agriculture over the last 2,000 years. This module provides an introduction to the changes that have occurred and the challenges they present -- to producing a consistent and quality product for consumers. OR YOU COULD END THE SENTENCE – to maintaining a reliable food supply OR to maintaining a reliable business income.
- Thank you for your attention and please visit the project websites listed here for more information.