Studying Clues to Past Climate Climate Change Lesson #4

Learning Goal To find out more information about how scientists are able to learn more about our changing climate and signs of global warming To better understand the ways we can monitor and model climate change

How Do We Know Today’s Changes Aren’t Natural? Scientists are more than 90 % certain current changes in climate are due to human emissions of greenhouse gases. How do scientists know that today’s changes are human-caused, and not natural?

How Do We Know Today’s Changes Aren’t Natural? They develop complex computer models to test the effects of different factors on the climate system. They compare current changes to changes in the past. Let’s take a look at these changes!

9.6 How Do We Know Today’s Changes Aren’t Natural? (1) They develop complex computer models to test the effects of different factors on the climate system. (2) They compare current changes to changes in the past.

Studying Clues to Past Climates There is over 200 years of documented temperature and climate Informal records before that kept in journals, oral histories etc. Paleoclimatology: is the study of climate change taken on the scale of the entire history of the Earth http://www.savitapall.com/WeatherDynamics/Notes/11-Clues%20to%20Past%20Climates.pdf

Studying Clues to Past Climates Natural materials such as rock and ice preserve clues to discovering the climate of the past Investigations are one by using proxy records which are stores of natural information that we can measure today that tell us what the climate was like in the distant past.

Studying Clues to Past Climates Proxy records are indirect records of climate They are not quantitative measurements of temperature or precipitation Scientists compare proxy records with quantitative records to determine proxy observations present

Studying Clues to Past Climates Proxy records can include: Fossils Tree rings Ice cores Coral reefs Rock Ocean sediments

a) Ice Cores Ice cores drilled in Antarctica and Greenland contain trapped air bubbles. Studying these air bubbles gives information about concentrations of greenhouse gases and air temperature at the time the bubbles formed. Ice cores provide records going back 800 000 years.

a) Ice Cores Scientists have learned the following information from ice cores: Concentrations of greenhouse gases have changed dramatically over Earth’s history Temperature and greenhouse gas concentrations increase and decrease at the same time Earth has gone through many changes in climate, from ice ages to interglacial periods, and back to ice ages.

a) Ice Cores Also tested for different types of oxygen: different types of atoms exist, some with are heavier than others The ratio between the lighter and heavier atoms can obtain information about the air temperature Also give information about precipitation and volcanic eruptions through preserving layers of dust During warm periods, levels of greenhouse gases were higher; when it was cooler, levers were lower

a) Ice Cores Video (2) http://scied.ucar.edu/ice-cores-studying-past-climate-movie https://www.youtube.com/watch?v=fjGxYDLEXP0 (6)

b) Tree Rings Trees create one growth ring per year Thickest in years with good growing conditions (warm & wet environment) Thinnest in bad growing conditions (cold & dry environment)

c) Coral Reefs Coral reefs also add layers of growth each season Scientists drill cylinders of coral and study layers Help determine the temperature of the surface ocean when each layer of coral grew http://www.savitapall.com/WeatherDynamics/Notes/11-Clues%20to%20Past%20Climates.pdf

d) Rock Layers of rock contain clues, such as plant pollen or fossils, to the climate at the time and place where the rock formed.

e) Ocean Sediment Scientists drill sediment cores from the ocean floor. The layers in sediment cores contain fossils and other clues that provide evidence of different climates over time.  

f) Caves In caves, rock formations grow as the minerals dissolved in dripping water solidify into rock. Scientists can measure and date rock layers in caves to obtain information on how much precipitation occurred at different times in the past

Modeling & Monitoring Climate Change

Introduction Are oceans getting warmer? Are sea levels actually rising? I tell you yes … but how do we know for sure? Well, scientists collect accurate information over long periods of time based on observations and measurements This is what we call monitoring

Monitoring Is the only way to identify climate trends, like increases in average global temperatures There are many different ways and instruments that can be used to collect this data

Improving Technology & Data While many different tools and techniques are used to measure atmospheric temperature, humidity, precipitation for over 200 years now We are looking for ways to jump forward with the invention of various technologies that can measure atmospheric changes above the earth!

Radar and the Weather Meteorologists and climate scientists use radar data to forecast the weather and other climate factors around the world Radar systems take measurements by emitting short pulses of microwaves These microwaves travel by being reflected off of water and ice in the atmosphere

Climate Data from Satellites Today hundreds of satellites orbit Earth to measure different components of climate There are two main ones used: Geostationary Satellites Orbit the earth at the same speed as the earth rotates lets them stay at the same point on Earth (positioned at Markham – still records there 24/7) This allows the satellite to constantly monitor changes over one specific area of the planet

Climate Data from Satellites Polar Orbiting Satellites These satellites move over the North and South poles as Earth turns over them One complete orbit takes just over 2 hours and only 6 hours for the whole planet https://www.youtube.com/watch?v=E4k3kEA3pmo

Earth Orbiting Systems In 1997 Canada, USA, and Japan combined resources to launch the first of a series of satellites to monitor the Earth’s changing satellite Today there are more than 50 specialized satellites that work to perform 1 of 4 basic functions https://www.youtube.com/watch?v=m2WrY1GdQ74

Earth Orbiting Systems The Quick Scatterometer (QuickSCAT) Measures the speed and direction of winds near the surface of oceans For example, this satellite can be used to see how winds and water interact to produce El Nińo Also used to monitor changes in rainforest vegetation and changes in ice coverage in the north and south pole

Earth Orbiting Systems Terra Works by carrying 5 remote sensors to monitor heat emissions Reflections from earth Cloud coverage Amount of Pollution in the troposphere

Earth Orbiting Systems Aura Carries 4 instruments to monitor atmospheric chemistry and concentrations of greenhouse gases Measures: Ozone Water vapour CFC’s Methane Carbon monoxide Nitrogen compounds Used to monitor the ozone hole in the Antarctic

Earth Orbiting Systems Aqua Carries 6 instruments designed to study: Precipitation Evaporation Cycling of water Uses the Atmospheric Infrared Sounder (AIRS) to accurately measure the amounts of water vapour and greenhouse gases in the atmosphere

Modeling Climate Change Gathering accurate data is only the first step in understanding climate change But it is also important to interpret this information correctly using tools such as maps, math formulas, or computer programs Often scientists use observations of past climate data and compare this to what they are seeing to better identify climate features currently

Modeling Climate Change For example, when comparing current weather systems over Texas to previous ones, meteorologist are able to predict weather and expected damages

Modeling Climate Change Climate Models are computer programs designed to analyze climate data and project how climate may change in the future Able to do this through software that describes, stimulates, and predicts the interactions of the atmosphere, oceans, land surfaces, and ice of Earth to simulate past, present and future climate conditions

Modeling Climate Change Climate models used today connect data about the atmosphere and oceans together into General Circulation Models GCMs is a complex computer program that uses math equations to describe the physical processes of the atmosphere and to manipulate the variables that affect how the natural climate system works

Uncertainty in Climate Models Sometimes computer systems don’t add up data the same way, and can lead to discrepancies in results Thus, improvements in data processing and models has lead to the advancements of “virtual climates” These virtual climates help reduce discrepancies, but does not remove them completely

Uncertainty in Climate Models Three other sources of uncertainty in climate models include : Sophistication of the model Quality / Quantity of data available Complexity of variables

Uncertainty in Climate Models Thus, the predictions of climate models are not 100 % accurate because of inaccuracies in the data and difficulties in the calculations In the end, the major climate models agree on approximately how much some factors like greenhouse gases contribute to climate change – which are still on the rise