Joseph J. Hobbs – Fundamentals… 25 Global Climate Change 39 Uppopulo 40 CHAPTER 2 Pryscal Processes and World Regons a gas that has the important effect of preventing much of the sun’s harmful ultraviolet radiation from reaching the Earth’s surface. In the car as-Earth metaphor, continued production of these greenhouse gases has the effect of rolling up the car windows on a sunny day, with the result of increased tempera- tures and physical overheating of the occupants. have all happened since 1998. In descending order, they are 2014 2010, 2005, 1998, 2013, 2003, 2002, 2006, 2009, and 2007 And what is the forecast? The IPCC uses a number of differ ent emission scenarios” that consider such variables as rates of population and economic and industrial growth, as well as efforts that might be made to curb greenhouse gas emissions. IPCC scientists predict that if emissions continue unabated, global mean temperatures between the years 2080 and 2100 will be 6.7°F to 8.6°F 2.6°C to 4.8°C) higher than today. Nos long ago we spoke of climate change mainly in futuristic ter but the IPCC is telling us that climatic changes and their conse quences are happening all around us now: “In recent decades, changes in climate have caused impacts on natural and human systems on all continents and across the oceans.” Following are the most prominent changes that are anticipated or under way in this warming world (see Figure 2.14). The Effects of Global Warming The trend toward a warmer world is remarkable. Although for mal records of meteorological observations began only about a century ago, past limites left evidence in the form of marine fos- sils.corals, glacialice, fossilized pollen, and annual growth rings in trees. These indirect sources, along with formal records dating back to 1861, indicate that the twentieth century was the warm- est of the past six centuries. The ten warmest years on record . 58 – Figure 2.12 Industrialization, the buming of tropical forests and other factors have produced a steady increase in carbon dioreide emissions. Most sentists believe that these increased emissions explain the corresponding ready increase in the global mean temperature ARCTIC 2.5 Global Climate Change In the atmosphere the layer of oxygen, nitrogen, and other gases extending from the Earth’s surface to about 60 miles (100 km) above changes are occurring that are having pro found effects on natural and human systems. Many of these changes are attributable to human activities, and the final section of this chapter is a prelaxle to the following chapter on haman processes affecting the planet. Climate change is the greatest challenge of our time,” said Thomas Stocker, co-chair of the United Nations Intergovernmental Panel on Climate Change “It threatens our planet, our only home. Now we will exam in closely the threats posed by climate change and the promising agendas for combating them. Because so much of the world is being affected by climate change, this detailed overview will help you as you proxeed through the regional chapters. You will have the foundation to think critically about mitigation and adapta- tion choices facing individual countries and will be able to see what future environments may look like around the world that last, but not least, National Geography Standard 18 is “To apply 5 geography to interpret the present and plan for the future.” Until about 2000, there was considerable uncertainty in the science of climate change. Most scientists had insisted that human activities were responsible for a documented warming of the Earth’s surface (by 1.4F, or about 0.8°C, since the latenine teenth century), but a significant minority argued either that warming was not curring or, if it was, that a natural climatic cycle was responsible. Now there is far less scientific uncertainty about the human role in climate change by 2014, only an esti- mated 3 percent of scientists were climate change skepties. *** The remaining 97 percent of the roughly 2500 atmospheric scientists from more than 130 countries who make up the United Nations-sponsored Intergovernmental Panel on Climate Change (IPCC) have concluded that global warming is us. equivocal, and that human activities are causing the tempera- ture changes. According to the IPCCN Comate Change 2014: Impacts, Adaptation, and Vulnerability report, there was a 95 to 100 percent chance that human production of greenhouse gases (GHG) such as carbon dioxide (CO) has been respon: sible for most of the warming of recent decades (Figure 2.12). Only some of the heat radiated from the earth scopes to space 法: 4: dii- = = EUROPE Heat radiated www from the earth de NORTH AMERICA * do 04 ASIA Most hast absorbed by greenhouse guses and radiated back to the earth Buildup of greenhouse STRATOSPHERE As AFRICA Sola energy TROPOSPHERE SMALL ISLANDS Absorbed as het by the earth CENTRAL & SOUTH AMERICA * . Bath dhe NE AUSTRALASIA * 三三 . Figure 2.13 The greenhouse effect. Some of the solar energy radiated as heat inferenciation from the scene while greenhouse gasestrap the rest. Naturally occurring greenhouse gases make the Earth habitable, but carbon dioxide and greenhouse gases nitted by human activities accentuate the greenhouse effect, making the planet unnaturally warmer ANTARCTIC 59 Olieved to imate change for scere change The Greenhouse Effect In 1827, a French mathematician named Jean-Baptiste Joseph Fourier (who had distinguished himself as a member of Napoleon Bonaparte’s scientific survey of Egypt), established the concept of the greenhouse effect. This term is a metaphor of Earth’s atmosphere acting like the transparent glass cover of a greenhouse – Figure 2.13: you can also think of the atmo- sphere as being like a car’s windshield). Visible sunlight passes through the glass to strike the planet’s surface. Oceans and land, like the floor of the treenhouse or the car’s upholstery, re flect the incoming solar energy back as heat invisible infrared radiation). Acting like the greenhouse glass or car windshield, the Earth’s atmosphere traps some of that hear. The greenhouse effect is not a bad thing. In fact, if not for naturally occurring greenhouse gases such as carbon dioxick oscar 44 Se and water vapor, the Earth would be too cold for most forms of life. What is worrisome is what happens when human ac tivities add newer and greater quantities of greenhouse gases into the atmosphere, trapping wanatural amounts of heat; these are the so-called anthropogenic” (made by human) causes of climate change. Carbon dioxide released into the atmosphere from the burning of coal, oil, and natural gas is the greatest source of concern, but methane from rice pad. dies and the guts of ruminating animals like cattle, and from thawing permafrost), nitrous oxide from the breakdown of nitrogen fertilizers), and chlorofluorocarbons (CFCs), used as coolants and refrigerants are also greenhouse gases resulting from human activities. CFCs also destroy stratospheric zone, tெ rite Maor sometimes stars – Watch Figure 2.14 Global patterns of impacts in recent decades attributed to climate change. Impacts are shown at a range of geographic scales Symbols indicate categories of attributed impacts the reative contribution of climate change major or mind to the observed impact, and confidence in attribution Source: The Untergovernale Cime Change and the many beteg AmagesdWS SPM FI wees omedyo may hellige priser Joseph J. Hobbs – Fundamentals… 42 CHAPTER 2 Physkal Processes and World Regions 58 A warmer climate overall, but not warmer everywhere As geographers, we want to know where the anticipated changes will occur and what they will be. Computer models suggest that there will not be a uniform temperature increase across the globe. Increases will instead vary spatially and sca- sonally. Some places will actually become cooler. Warming will be greatest in the polar and tropical regions, Geographically, the impacts of climate change are expected to be greatest at the higher latitudes, especially in the polar realms. Permafrost, the frozen ground typical of the polarre gions, has been melting at an alarming rate. Among other things, this has been forcing Arctic peoples to relocate from So traditional settlements as their buildings sink into mack. Im pacts on marine environments are also profound in these high latitudes. The IPCC estimates that the average coverage of Arctic sea ice has shrunk about 3 percent per decade since 1978, with summertime ice decreasing 7 percent per decade. Aboard a Russian icebreaker, I saw open water at the North Pole in August 1996. The vessels Russian “Ice Master” said that in 30 years of working on icebreakers in the Arctic, he had never seen anything like this: vast expanses of the Arctic Ocean completely ice-free or merely dotted with sea ice and icebergs. Ever since that summer, there have been reports of unprecedented change in Arctic waters. The trend is a self perpetuating the darker ocean waters that replace the white ice cover absorb ever more solar radiation. Think of cars here again: How hot would the surface of a dark blue car feel to your touch on a summer day compared with the surface of a white car? That warning melts even more ice creat ing more dark surface water and more warming (Figure 2.15). This is known as polar amplification and is an example of a positive feedback loop, which represents change in a natural . Figure 2.16 Malé pronounced mah-lay’. capital city of the Valdives Some sources describe this as the world’s most densely populated city. For more on the Maldives,sce page 329 THINK CRITICALLY: How is Male vulnerable to some of the climate change problems described by the IPCC (pages 40-4317 How would you describe its geographical situation
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