Is Our Climate Changing The years 1998 2003 2005 2010 2013 and 2014 were the hottest on record Temperatures have been recorded in Britain since 1659 The year 2014 saw the highest average summer temperatures since global records were kept Why the climate changes Climate scientists believe that the changes we are seeing now are the result of greenhouse gases building up in the atmosphere Greenhouse gases are a group of gases that collect in a layer at the top of the atmosphere and act like an insulating blanket keeping heat close to earth They are called greenhouse gases because they behave like the glass walls and roof of a greenhouse they trap heat to keep earth warm Carbon dioxide methane and water vapor are all examples of greenhouse gases Hotter and hotter The earth is heated by the sun About one-third of the heat energy from the sun is reflected straight back into space by clouds and dust in the atmosphere about one fifth warms up the atmosphere around earth and about half actually reaches the surface of earth Some of the heat energy that reaches earth is reflected back particularly from the polar ice caps and up into the atmosphere again Some of this reflected heat passes back through the atmosphere and into space but some is trapped by clouds and greenhouse gases The layer of greenhouse gases reduces the amount of reflected heat that can pass from the earth to space Instead the heat is reflected back from the blanket of gases to the surface once more warming earth again Escaping heat Trapped heat Heat from the sun Heat reflected from the surface Although some of the heat from the sun is reflected back into space some is trapped by the layer of greenhouse gases and remains to warm the surface of the earth 8
What is climate change Too much atmosphere and too little The earth’s atmosphere has supported life for millions of years Near neighbors of earth in the solar system show what it’s like to have too little atmosphere or too thick a layer of greenhouse gases They are not planets on which humans could live Venus is earth’s nearest neighbor in space It has a dense atmosphere that is 94 percent carbon dioxide producing an extreme greenhouse effect This atmosphere traps heat near the planet’s surface producing scalding temperatures of around 867 F 464 C The surface of Venus is extremely hot Heat from the sun is trapped by a thick layer of the greenhouse gas carbon dioxide Expert View Although some politicians and business people say that the existence of climate change is still being debated scientists do not disagree about the reality of climate change Consensus as strong as the one that has developed around this topic climate change is rare in science Donald Kennedy editor in chief Science 2001 9
Is Our Climate Changing Mercury is the planet closest to the sun It has virtually no atmosphere and as a result the temperature on the planet’s surface fluctuates wildly The average temperature on the side of Mercury that faces the sun is 800 F 427 C on the side that faces away it is 300 F 184 C Because Mercury spins very slowly on its axis each day on Mercury is longer than the planet’s year of 88 earth days Effects of climate change You might not think that you would notice a difference of only 1 5 F 0 9 C in the temperature and if the only effect were to make the air a little warmer you would probably be right But a rise in temperature even a small one has significant effects on the world around us Weather systems are very sensitive to even the slightest changes A small rise or drop in temperature can be enough to trigger a tropical storm instead of a wind a drought instead of a dry spell or a flood instead of a rainy period Extreme weather events such as heat waves and tropical storms are becoming more frequent These events can have serious direct impacts people often die in heat waves floods and tropical storms but they also have other more indirect effects They change conditions for farming for example sometimes causing crop failures that can lead to famines Even weather that appears less severe can create problems A winter that is milder than normal with fewer frosts and less snow means that more pests can survive to damage crops or cause disease in the following year Drought causes crops to fail In this field of corn between 70 and 90 percent of the crop was lost because there was not enough rain 10
FORUM People hold different views about the human contribution to climate change The human contribution is not significant and observed increases in carbon dioxide and other greenhouse gases make only a negligible contribution to climate warming Professor David H Douglass University of Rochester International Journal of Climatology 2007 Humans are changing the earth and it’s a big effect we’re having Mike MacCracken chief scientist for climate change projects at the Climate Institute in Washington D C What do you think What is climate change Extreme weather can eventually make some areas uninhabitable In some places desertification is already a problem As populations increase people put more demands on the land clearing it to grow crops and taking more water from wells These actions often combined with less than average rainfall result in the land drying out As the land turns into desert the types of plants that can survive also change grassland and crops are replaced by tough scrub that needs little water These plants cannot support people or livestock and make the land unusable by humans How we use the weather In many parts of the world people have built their livelihoods on known and reliable weather patterns Crops and livestock are especially weather dependent as the climate changes people may have to think again about the crops they grow and the foods they eat Areas that depend on tourism may also find that their income is affected as the weather changes Some low lying ski resorts may have less snow and some seaside resorts may become too hot and dry or too prone to storms to attract customers In some ski resorts snowfall has decreased to such an extent that artificial snow is used to cover the runs
