* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download OVERVIEW OF CLIMATE SCIENCE
German Climate Action Plan 2050 wikipedia , lookup
Soon and Baliunas controversy wikipedia , lookup
Climatic Research Unit email controversy wikipedia , lookup
ExxonMobil climate change controversy wikipedia , lookup
Michael E. Mann wikipedia , lookup
Global warming controversy wikipedia , lookup
Politics of global warming wikipedia , lookup
Global warming hiatus wikipedia , lookup
Heaven and Earth (book) wikipedia , lookup
Fred Singer wikipedia , lookup
Climate change denial wikipedia , lookup
Economics of global warming wikipedia , lookup
Climatic Research Unit documents wikipedia , lookup
Climate resilience wikipedia , lookup
Climate change adaptation wikipedia , lookup
Effects of global warming on human health wikipedia , lookup
Global warming wikipedia , lookup
Climate change in Saskatchewan wikipedia , lookup
Climate governance wikipedia , lookup
Citizens' Climate Lobby wikipedia , lookup
Climate change and agriculture wikipedia , lookup
Climate engineering wikipedia , lookup
Climate change in Tuvalu wikipedia , lookup
General circulation model wikipedia , lookup
Physical impacts of climate change wikipedia , lookup
Effects of global warming wikipedia , lookup
Media coverage of global warming wikipedia , lookup
Instrumental temperature record wikipedia , lookup
Scientific opinion on climate change wikipedia , lookup
Public opinion on global warming wikipedia , lookup
Climate change in the United States wikipedia , lookup
Climate change and poverty wikipedia , lookup
Global Energy and Water Cycle Experiment wikipedia , lookup
Effects of global warming on humans wikipedia , lookup
Years of Living Dangerously wikipedia , lookup
Attribution of recent climate change wikipedia , lookup
Surveys of scientists' views on climate change wikipedia , lookup
Climate change feedback wikipedia , lookup
Climate change, industry and society wikipedia , lookup
Climate sensitivity wikipedia , lookup
OVERVIEW OF CLIMATE SCIENCE What is the difference between climate and weather? Climate A composite of a region’s average conditions Climate • Applies to long-term changes • Measured in terms of: – Temperature – Precipitation – Snow and ice cover – Winds • Can refer to – The entire planet – Specific regions (continents or oceans) Weather Weather • Shorter fluctuations lasting – Hours – Days – Weeks • Can refer to very short changes Climates on Earth are Favorable to Life • Surface Temperature – Averages 15oC (59oF) – Much of the Surface Ranges from 0o C to 30oC Temperature Scales • Kelvin Scale – Divided into units of Kelvin instead of degrees – Absolute scale • Converting values between the Fahrenheit and Celsius Scales Tc = 5 (Tf – 32) 9 Tf = 9 (Tc + 32) 5 Geologic Time 1 km = 1 million years LA to NY: 4,500 million yrs Precambrian: LA to Pittsburgh, PA Paleozoic – entirely in PA Mesozoic – 179 km drive to NJ, 65 from NYC End of ice age – 10 m from destination 2,000 AD years is 2 meters Human life span<10 cm Another Geologic Time Analogy . . . If all Earth history had been recorded from its origin to the present as a motion picture • Each frame would flash on the screen for 1/32 of a second which would equal 100 years • To show all Earth history would take 16 days. • The last 2,000 years would take ¾ of a second • The present to the last ice age would be less than 7 seconds. • The last 65 million years would take almost six hours • The Paleozoic Era would last two days • We will focus on the last several million years of Earth’s history (about 10% of its total age) • This can only be represented by: – A series of magnifications – Using a log scale that increases by factors of 10 Time Scales of Climate Change Longest Shortest Tectonic Change: The Longest Time Scale • Shows a slow warming – Between 300 Myr and 100 Myr • Last 100 million years – Gradual Cooling – Led to ice ages during the last 3 million years • Note shorter oscillations Time Scales of Climate Change • As the time scales become shorter – Progressively smaller time scales are magnified out from the larger changes at longer time scales. Degree of Resolution • Amount of detail retrieved from records • Older records have less resolution – Long term averages over millions of years • Younger records have progressively greater resolution – Shorter term averages – Occur within intervals of: • Thousands • Hundreds • Even tens of years Development of Climate Science National Center for Atmospheric Research Boulder, CO • Modern climatology is an interdisciplinary endeavor throughout the world – Universities – National Laboratories – Research Centers Diversity of Studies • • • • • • Meteorology Oceanography Chemistry Glaciology Ecology Geology – Includes geophysics, geochemistry, paleontology • Climate Modelers • Historians Studying Climate Change – The Scientific Method • Hypothesis – An informal idea that has not been widely tested by the scientific community – Most are discarded. • Theory – When a hypothesis is capable of explaining a wide array of observations. – Additional observations support the theory • New techniques for data analysis • Devise models Theories can be discarded Ongoing work may disprove the predictions of a current theory An Historical Example . . . The Geocentric Model of the Solar System • Devised by Ptolemy (Claudius Ptolemaeus) in the second century AD • Accepted until 1543 The Heliocentric Model replaced the Geocentric Model Pluto is no longer considered a planet! Pluto’s Been Demoted! • On August 24, 2006 the International Astronomical Union redefined the definition of a planet as: – “a celestial body that is in orbit around the sun – has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a nearly round shape, – and has cleared the neighborhood around its orbit.” Pluto is now considered a “Dwarf Planet” • Pluto lost its status as a planet because it’s highly eccentric orbit crosses over the orbit of Neptune. – As such it hasn’t “cleared the neighborhood around its orbit. • A dwarf planet like Pluto is – Any other round object that • Has not “cleared the neighborhood around its orbit • Is not a satellite A Law or Unifying Theory • If a theory has survived the test of time – Years or decades • It’s the closest approximation to “the truth” as possible. • It’s impossible to prove a theory as being true. • We can only prove it’s untrue. Revolutions in Climate Change • A scientific revolution that endeavors to understand climate change has accelerated. • The mystery of climate change yields it’s secrets slowly. • This revolution has achieved the status so that it has begun to take its place alongside two great earlier revolution in knowledge of Earth history. Evolution Evolution of the Jaw in Fish Who is the Descendent of this Mammal? Plate Tectonics The unifying theory of geology Tectonic Plate Boundaries Earth’s Four Spheres • • Earth is divided into four independent parts Each loosely occupies a shell around Earth - This why they’re called spheres Earth Systems Interact • Earth Systems Interact Video from the American Geological Institute (AGI) • http://www.youtube.com/watch?v=BnpF0ndXk8&list=PLTBBygdCOWWd-7-WOjPvPBSawmlvMoSDH Earth’s Climate System • Small number of external factors • Force or drive changes in the climate system Earth’s Climate System • Internal components respond to external factors • They change and interact in many ways Earth’s Climate System • End Result of interactions – A number of observed variations in climate – Can be measured – Analogous to a machine’s output after input (factors) Studies of Earth’s Climate Cover a Wide Range of Processes Climate Forcing Three fundamental kinds of climate forcing 1. Tectonic Processes • Part of Plate Tectonic Theory • Alter the geography of Earth’s surface – Changes in distribution of land and sea – Changes in surface topography • Formation of mountain ranges • Erosion of the land surface – Slow processes • Occur on a scale of millions of years 2. Variations in Earth’s Orbit • Alter the amount of solar radiation received on Earth – By season – As a function of latitude • Occur over tens to hundred of thousands of years. 3. Changes in the Sun’s Intensity • Affects the amount of solar radiation arriving on Earth • Long-term increase since Earth’s origin • Shorter-term variations may be partially the cause for changes on shorter time scales of – Decades – Centuries – Millenia A Fourth Factor to be Considered • Anthropogenic Forcing – In a strict sense, not part of the natural system – The effect of humans on climate – Unintended byproduct of agricultural, industrial, and other human activities – Results from additions of materials to the atmosphere Climate System Responses • • • • • Changes in global and regional temperatures Extent of ice Amounts of rainfall and snowfall Wind strength and direction Ocean circulation – At Depth – At the surface • Vegetation – Types – Amount Response Time An Example . . . • The rate at which water in the beaker warms – Water rises 50% towards equilibrium during the first response time • As warming trend continues – Warming continues in 50% increments as the water temperature approaches equilibrium Response Time An Example . . . • Each step takes one response time. – Moves the system half of the remaining way towards equilibrium. • The total amount of response time remaining after each step is: – ½, ¼, 1/8, 1/16 – This is an exponential change • Rate slows as response approaches equilibrium Variation in the Response Times of Climate System Components Time Scales of Forcing Vs. Response • Forcing is Slow in Comparison to Response • Forcing is Fast in Comparison to Response • Forcing and Response Time Scales are Similar Slow Forcing in Comparison to Response Earlier Time Later • Response keeps pace with gradual forcing (i.e., Equivalent to slowly increasing the bunsen burner flame.) • Typical of tectonic scales of climate change – Climate changes in response to movement of landmasses • 1 degree of latitude per million years (100 km/million years) • Slow changes in solar heating • Average temperature over the continent keeps pace with average changes in solar radiation because of the short response time of land and water Fast Forcing in Comparison to Response Earlier Time Later • Response time of the climate system is much slower than the time scale of the change in forcing – Little or no response – Analogous to turning the Bunsen burner on and off so quickly that temperature doesn’t respond Fast Forcing in Comparison to Response The Eruption of Mt. Pinatubo - 1991 • Earth’s average temperature decreased by 0.5o C in less than a year • Most of the fine dust remained aloft for only a few years • No long-term climate change Similar Forcing and Response Time Scales • Bunsen Burner Analogy – Abruptly turned on • Left on for awhile • Turned off – Turned on again • And so on . . . Earlier Time Later – Varying degrees of response • Examples C and D – Same equilibrium values – Length of time heat is applied varies • C – Flame turned on and off less frequently • D – Flame turned on and off more frequently • In the natural world climate forcing rarely acts in an “on-orof” way. Similar Forcing and Response Time Scales • Climate forcing (Bunsen Burner) – Behaves as a “moving target” Earlier Time Larger response as water has time to reach values nearer equilibrium • Climate system response (temperature) never Later catches up – lags behind • Continuously changing series of equilibrium values – Created by the moving target of climate forcing • Rate of response is always fastest when the system is farthest from equilibrium Smaller response as water has less time to reach values nearer equilibrium Cycles of Forcing and Response • Response to a “moving target” forcing is usually cyclic • Fundamentally the same as the physical response of the beaker of water. • Actual examples; – Daily and seasonal changes in heating • Time “lag” between maximum and minimum insolation and maximum and minimum temperature Cycles of Forcing and Response • Larger climate change – Slower cycles of change – The climate system has ample time to respond • The same amplitude of forcing produces – Smaller climate changes if the climate system has less time to respond. Cycles of Forcing and Response • Results from changes in Earth’s orbit – Over tens of thousands of years – The climate response time characteristic of large ice sheets that advance and retreat • Characteristic of Seasonal time lags between – Highest solar intensity and hottest temperatures – Lowest solar intensity and lowest temperatures Response Times Can Vary with an Abrupt Change in Climate Forcing For example: Greenhouse Warming causes increased temperatures Ocean surface Ice sheets • Climate responses can range from slow to fast within different components of the climate system. • Depends on their inherent response times. Variations in Cycles of Response • Some fast-response parts of the climate system track right along with the climate forcing. • Other slow-response parts lag behind the forcing. Variations in Cycles of Response • Fast response – Seasonal changes in tropical monsoons • Slow response – Ice sheets Variations in Cycles of Response Single point of time A huge ice sheet in Canada and northern U.S. • Low position of asterisk on the cold slowresponse curve – Ice sheet is at its maximum size – Heating from the Sun has begun a slow, long-term increase • Has not yet begun to melt any of the ice This Has Happened in the Past Pleistocene Ice Age: 20,000 years ago to 11,000 years ago Two Possible Responses of Air Temperatures Over Land South of the Ice Sheet Single point of time A huge ice sheet in Canada and northern U.S. • Would air warm with slow increase of solar radiation? – Climate response would track right along with the initial forcing curve • Would air temperature still be affected by the ice sheet? – If so, the response might follow a slower, delayed response pattern of the ice. – The ice would also be exerting and influence of its own Both Explanations are Sound and Plausible • The response of air temperatures could be influenced by both the Sun and the ice. • Then, the air temperature response would fall between the fast and slow responses. – Faster than the response of the ice – Lagging behind the forcing of the Sun Climate Feedbacks Processes that Alter Climate Changes Already Underway Positive Feedback • Produces additional climate beyond that caused by the original factor • Amplifies change underway • Not to be interpreted as a “good” change. • Example: – Decrease in solar energy could result in glaciers at high latitudes • Increase in ice and snow cover could further result in lower temperatures. Positive Feedback Example Negative Feedback • Climate change is muted. • Not to be considered a “bad” change. • After initial climate change is triggered, some components of the climate system reduce it. • Example – Effect of clouds on warming effects of increasing CO2 in the atmosphere. Negative Feedback Example Quantifying Feedback • Feedback Factor – The strength of a feedback on temperature Temperature Change with Feedback f = Temperature Change without Feedback • If no feedback exists: f = 1 • Positive Feedback: f >1 • Negative Feedback: f < 1