Geoengineering Earth's Climate: Resetting the Thermostat
ICELAND RISING The country of Iceland is rising out of the North Atlantic Ocean No this scene is not something from a science fiction movie The land is rising due to climate change Iceland’s rocky terrain is home to many glaciers The warming waters of the Atlantic Ocean and increasing air temperatures are beginning to melt some of the glaciers As the glaciers melt the land below them rises a little a phenomenon known as uplift Imagine a heavy person lying on a mattress pressing it down When the person gets up the mattress bounces up a bit That’s what’s happening to the land below Iceland’s glaciers Geologists say that in some places the uplift rate is 1 2 inches 30 mm per year the melting of either sheet would spell trouble As Greenland warms and sheds its ice so do other parts of the Arctic including Alaska Many climatologists think that the melted ice streaming into the Arctic Ocean and other northern waters is a signal that the canary has stopped singing They say that climate change has reached a dire tipping point Why is this occurring The answer is related to Earth’s atmosphere A DELICATE BALANCE Earth’s atmosphere is composed of 78 percent nitrogen and 21 percent oxygen The remaining 1 percent consists of argon and small amounts of greenhouse gases methane nitrous oxide carbon dioxide water vapor water in gas form and ozone Greenhouse gases in the atmosphere act like a blanket holding in heat and shielding Earth from certain kinds of radiation from the sun When solar energy reaches Earth’s atmosphere about 29 percent of it immediately bounces off clouds and gases and travels back into space The atmosphere absorbs 10 GeoenGineerinGearth’sclimate
another 23 percent while 48 percent of solar energy makes it to Earth’s surface The land and the oceans absorb this energy and heat up The first law of thermodynamics which applies to everything in the universe says that energy can neither be created nor destroyed That means that the amount of energy that goes into a system must equal the amount of energy that the system releases So on Earth at the same time the oceans and land are absorbing energy from the sun they are also releasing energy in the form of infrared rays heat When this heat rises and hits greenhouse gases in the atmosphere the gases trap the heat and send it back toward Earth This exchange of energy from the sun down to Earth’s surface back up to the greenhouse gases and back down to the ground naturally keeps Earth at an average temperature of about 59 F 15 C This is a suitable temperature for life THE GREENHOUSE EFFECT Some radiated heat escapes into space Greenhouse gases in the atmosphere Greenhouse gases trap some radiated heat and send it back to Earth e er h p s o m at sunsunsunsunsunsunsunsunsunsunsunsunsunsunsunsunsunsunsunsun incoming solar energy Some solar energy ref lects off clouds Some solar energy is absorbed by Earth’s surface and is radiated as heat the greenhouse effect is an exchange of energy that keeps earth at a suitable temperature for living things in this exchange greenhouse gases in the atmosphere trap some of the sun’s heat near earth however increasing amounts of greenhouse gases are trapping excessive heat leading to global climate change An Abrupt ChAnge in ClimAte 11
THE SKY ABOVE US Meteorologists divide the atmosphere into five layers The troposphere is the layer closest to Earth All Earth’s wind rainstorms and other weather events take place there The troposphere contains 99 percent of all the water in the atmosphere This water can become an invisible gas water vapor It can become tiny water droplets or ice crystals inside clouds Or it can fall to Earth as precipitation rain and snow The height of the troposphere varies from place to place At the equator the troposphere is 12 miles 19 km high but near the North and South Poles it is only 4 miles 6 4 km high At the top of the troposphere is a thin layer called the tropopause It marks the boundary between the troposphere and the layer above it the stratosphere Jet airplanes sometimes fly in the stratosphere to stay above any stormy weather below At about 9 to 22 miles 15 to 35 km above Earth’s surface the stratosphere contains a band of gas called the ozone layer Ozone is a form of oxygen Whereas an ordinary oxygen molecule has two oxygen atoms an ozone molecule has three oxygen atoms On top of the stratosphere starting about 31 miles 50 km above the surface of Earth is the mesosphere Above that layer beginning about 53 miles 85 km above the planet is the thermosphere Beyond that starting about 429 miles 690 km above Earth is the exosphere It marks the beginning of outer space As you go higher into the atmosphere the concentration of gases gets thinner the gas molecules are more spread out with more empty space between them The air also gets colder as you go higher because there is less gas to trap the sun’s heat
LAYERS OF EARTH’S ATMOSPHERE PACE R S E T U O 6,214 miles 10,000 km 429 miles 690 km 53 miles 85 km 31 miles 50 km 12 miles 19 km 12 miles 19 km OUTER SPA C E E XO SPHERE T H E R M OSPHERE M E S O SPHERE T R A TOSPHERE O Z O N E LAYER t o 2 2 miles 15 to 35 km 9 x a b o v e Earth’s surface R O P OSPHERE RE S ro p p a T T Earth SPA CE 62 6,200 miles 100 10,000 k m ATM OSPHERE up to 62 miles 100 k m Diagram is not drawn to scale the atmosphere is a multilayer blanket of gases around earth because of excess greenhouse gases the layers nearest the ground are heating up leading to climate change and extreme weather An Abrupt ChAnge in ClimAte 13
