Changes in Climate and Feedback Loops Climate Change Lesson #3

Learning Goal To better understand the indicators of climate change To better understand and learn the causes of short term and long term changes in our climate

Global Warming The biggest indicator of climate change is global warming The increase in the average temperature of the atmosphere and oceans has been accelerating since the 1960s The amount and rate of warming is felt around the whole planet, where some areas “warm” more than others Why do you think this is?

Impacts of Melting Ice In addition to rising sea levels, melting ice affects the habitat of animals like polar bears Polar bears depend on large areas of ice to hunt their prey When it warms up and the ice melts, polar bears stop hunting and start to starve

Toronto Zoo: Ice Bear The Ice Bear unit uses off-peak electricity, in the middle of the night, to make a big block of ice. The ice then slowly melts through-out the next day and is used to cool the air! If this type of technology is used in cooling systems around the city, our daytime peak demand will be lower, and the need to build more power stations, to cope with peak demand, will be reduced http://www.torontozoo.com/conservation/IceBear.asp

Sea levels & Ocean Acidity Oceans are a part of Earth’s climate system - so changes in the water effects the whole system Climate scientists are especially concerned about sea level and ocean acidity (pH)

Sea levels & Ocean Acidity As parts of the world’s oceans get warmer, changes in pH have dropped due to the excess carbon dioxide in the atmosphere This negatively effects many ecosystems around the world For example, coral reefs that form naturally are now not as stable than they once were

What trends / observations do Ocean Acidity What trends / observations do you notice?

Climate & Health Climate is related to our health, not only with the risk of disease and infections, but also injury due to the extreme HOT or COLD temperatures For example, heat waves, floods, tornadoes, lightning strikes and snowstorms can occur more frequently with such extremes Increasing temperatures also affects the amount of dust in the air, mould, and pollen – which trigger asthma attacks

Changing Winds & Precipitation Changes in heat distribution over Earth’s surface have lead to changing wind patterns The speed, frequency, and direction of winds over the earth’s surface have changed unpredictably for several years Researchers believe that unusual wind patterns have increased further the melting of ice in the artic

Changing Winds & Precipitation The high temperatures increase the rate of evaporation When warm, moist air rises and cools, it adds to the precipitation in the atmosphere In a span of 65 years annual temperatures have increased, and don’t seem to be dropping any time soon

Changes in the Earth’s Climate Short Term & Long Term Effects

Natural Changes in Climate Earth’s climate goes through natural changes Long-term changes over hundreds of thousands or millions of years due to changes in Earth’s orbit Short-term variations caused by natural events such as volcanic eruptions

Natural Changes in Climate Plate Tectonics Is the theory that Earth's outer shell is divided into several plates that glide over the rocky inner layer above the core The plates act like a hard shell compared to Earth's core This strong outer layer is called the lithosphere Thus, researchers believe that continents have moved over the surface of the globe for hundreds of millions of years

Natural Changes in Climate Continental Drift Is the movement of the Earth’s continents closer to one another, as they “drift” across the ocean This theory was first coined by Abraham Ortelius in 1596 Where we see changes in land mass distribution Result: changes air and ocean currents, large effects on climate

Natural Changes in Climate

Long-Term Cycles in Climate For the last 800 000 years or more, Earth’s climate has cycled between freezing ice ages and warmer interglacial periods

Long-Term Cycles in Climate

Long-Term Cycles in Climate Milankovitch theory: Describes the many effects of changes in the Earth's movements that affects its  climate We see that the Earth cycles are triggered by three changes in Earth’s orbit: Eccentricity: shape of orbit varies in 100 000 year cycle Tilt: Earth tilts back and forth over a 41 000 year cycle Precession Cycle (wobble): axis slowly wobbles in a 26 000 year cycle http://www.sciencecourseware.org/eec/globalwarming/tutorials/milankovitch/ http://www.met.reading.ac.uk/~sgs02rpa/MISC/CrollMilanko.swf

Long-Term Cycles in Climate The Eccentricity Cycle  The earth's orbit around the sun is elliptical We see how the shape of the ellipse (eccentricity) varies from less elliptical to more elliptical and back in a 100,000 year cycle Currently, we are in an orbit of low eccentricity (near circular).

Long-Term Cycles in Climate The Precession Cycle The earth is wobbling about it's axis of rotation like a spinning top To make one complete cycle takes about 23,000 years In 11,000 years, the seasons will switch times during year and will be more severe

Long-Term Cycles in Climate The Tilt Cycle / Obliquity The Earth’s axis of rotation is tilted at 23.5° However, this value changes from a minimum of 22.5° to a maximum of 24.5° and takes 41,000 years to complete one cycle Where: at 22.5° the seasonal variation will be _______________than current? at 24.5° the seasonal variation will be _______________than current? SMALLER / LARGER http://apollo.lsc.vsc.edu/classes/met130/notes/chapter16/aerosols.html

Short-Term Cycles in Climate Reflect small variations in climate over 10’s to 100’s of years (much smaller than millions of years ago!) Causes: volcanic eruptions small changes in solar output changes in air and ocean currents

Short-Term Cycles in Climate Volcanoes: dust/gases go high into atmosphere, blocks solar radiation, Earth temporarily cools Solar radiation drops slightly, Earth’s climate cools Solar radiation slightly increases, Earth’s climate warms Ocean current changes may cause abrupt climate changes: not fully understood Some changes in air and ocean currents occur regularly, such as El Niño http://video.nationalgeographic.com/video/el-nino

Short-Term Cycles in Climate

Feedback Loops and Climate Small changes are sometimes made larger by feedback loops Feedback loops can also work the opposite way and make changes smaller

Feedback Loops and Climate Water Vapour Feedback Loop: More water vapour enters atmosphere when climate warms Water vapour = greenhouse gas, its presence causes climate to warm even more If climate cools, less water vapour forms and climate cools further

Feedback Loops and Climate Low Cloud Feedback Loop: Low clouds trap thermal energy near Earth’s surface and reflect more sunlight Result: as Earth warms, more clouds form

Feedback Loops and Climate High Cloud Feedback Loop: High clouds reflect solar radiation back into space Result: cooler temperatures and fewer clouds

Albedo Effect Looks at how well the Earth’s surfaces reflect the sun’s energy Ice has high albedo: reflects back most solar radiation Water has lower albedo: absorbs more solar radiation

Albedo Effect

The albedo effect is a feedback loop between ice on Earth’s surface and Earth’s average temperature.

The albedo effect is a feedback loop between ice on Earth’s surface and Earth’s average temperature.