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Climate Change. What is it and what are scientists doing to gather information about it?. What is the difference between weather and climate? . What is it? How the atmosphere is CURRENTLY behaving. How it affects humans TODAY .
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Climate Change What is it and what are scientists doing to gather information about it?
What is it? • How the atmosphere is CURRENTLY behaving. • How it affects humans TODAY. • Can change from minute to minute, day to day, and season to season. • Components • Temperature • Humidity • Precipitation • Brightness • Visibility • Wind • Atmospheric pressure • Different kinds of weather • Sunny or Rainy • Clouds and wind • Hail, snow, or sleet • Floods, blizzards, thunderstorms • Cold front or heat front • Heat wave Weather
What is it? • LONG TERM pattern of weather. • Average weather for an area. • Can be local or global. • Why is it important to study? • Keeping a record of the weather. • Deviations from the average could be an indication of climate change in an area. Climate
What contributes to the climate of an area? • Proximity to oceans and lakes: • Bodies of water absorb heat when it is hot and release heat when it is cold, contributing to the climate of an area. • Heat exchanges between the ocean and atmosphere cause wind. • Winds drive ocean currents. • Oceans absorb CO2, slowing global warming. • Evaporation: Hot water from the tropics evaporates and is carried by trade winds to the north and south. • Storms often develop over warm oceans before hitting land. The ocean, land, and air are all connected. Changes can have dramatic effects in interconnected systems (e.g., El Nino).
External Forces of Climate Change • Long term climate cycles (measured in thousands of years) are driven by astronomical forces. • Milankovitch cycles: The Earth’s orbit, axial tilt, and other movements go through long cycles of change which affect climate on Earth. • Stretching of orbit • Elliptical obits cause interglacial periods • Circular orbits cause glacial periods • Occurs every 92,000 years • Tilt of axis • Affects polar sunlight • Changes by about 2 degrees every 41,000 years • Has great affects on climate • Wobble of axis • Like a top spinning the axis of the Earth wobbles • Causes changes in the intensities of seasons • Occurs every 21,000 years
CLIMATE IS WHAT YOU EXPECT WEATHER IS WHAT YOU GET
The Greenhouse Effect • Why do gardeners use greenhouses? • Solar radiation is trapped inside the glass or plastic material. • Gases such as water, carbon dioxide, methane, and nitrous oxide absorb and emit the radiation.
Paleoclimatology • How do scientists know what the climate was like thousands of year ago? • Sediments • Ice Cores • Tree Rings
Sediment Cores • Similar to ice cores • Taken from oceans or lakes • Sedimentation rate • Charcoal • Pollen • Diatoms, foraminifera
Foraminifera -Also know as forams -Most are benthic: live on the bottom of the sea or lake -Some live in water column -Range in size from 1 mm to 200 mm -Important part of food chain -Produce hard shells made of calcium carbonate
Foraminifera and Diatoms The chemical makeup of their environment depends on the temperature of the water. Oxygen has 3 isotopes. In warmer water, atoms with lighter isotopes evaporate faster than atoms with heavy isotopes. Isotope: Natural variation in the number of neutrons in the nucleus of an atom. • There are thousands of different species. • Each lives in a particular environment. • The chemical makeup of their shells depends on the chemical makeup of their environment.
Tree Rings Many trees form annual growth rings. The width, density, and isotopic composition of tree rings is influenced by the environment. Some trees are thousands of years old. To extend chronologies from living trees, scientists use fossilized wood or wood from old buildings. Overlapping patterns found in tree rings allows us to date tree rings back as far as 11,000 years ago.
Extending chronologies from living trees http://www.ncdc.noaa.gov/paleo/slides/slideset/18/18_355_slide.html
Ice Cores Collected from ice sheets in Greenland and Antarctica. Can date as far back as 750,000 years ago.
Information That Can Be Obtained From Ice Cores • Annual snowfall • Substances found in snow • Dust, ash, gas, radioactive substances • Proxy for • Temperature • Precipitation • Composition of atmosphere • Volcanic eruptions
How Can Scientists Use Ice Cores To Determine Past Climate Conditions? They use isotopic ratios of water in cores to determine temperature and precipitation. Dust particles can determine atmospheric circulations, volcanic eruptions, and wind speed. Volcanic eruptions help scientists age ice cores accurately. Atmospheric composition is determined by air bubbles compressed in the ice.
Paleoclimatic data Vostok Ice Core
How has Florida’s Climate Changed? Today, Florida has a subtropical climate Approximately 130,000 years ago giant ground sloths roamed the coasts of Florida They are a tropical species, meaning the climate was warmer and wetter at this time. • Mastodon fossils found off of the coast of Florida indicate a colder climate and lower sea levels. • Fossils found in Florida date back to about 13,000 years ago, during the last ice age.
Climate Change vs. Global Warming Climate Change Global Warming The climate on Earth and other planets is constantly changing over large time scales. Abrupt climate change is rare but possible. Going from a warm period to an ice age is considered climate change. Climate change occurs with or without the presence of humans, or life in general. Caused by increases of greenhouse gas concentrations in the atmosphere. Occurs naturally due to astrological phenomena. Can occur by disrupting the natural carbon dioxide cycle. The intensity of effects is different in different parts of the world.
Local Changes • Changes where you live many not reflect global changes. • For example, the average yearly temperature of an area can stay the same, while the seasons may become more intense. • Warmer summers and colder winters
