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The Atlas of Climate Change
Mapping the World's Greatest Challenge
By Kirstin Dow, Thomas E. Downing, Jannet King, Candida Lacey
UNIVERSITY OF CALIFORNIA PRESSCopyright © 2011 Myriad Editions Limited
All rights reserved.
Among the thousands of warning signs of climate change, the array of extreme events that took place in 2010 stand out.
Current climate change is affecting all continents and most oceans. Thousands of case studies of physical changes (such as reduced snow cover and ice melt) and changes in biological systems (such as earlier flowering dates and altered species distributions) have correlated with observed climate changes over the past three decades and more. Scientists have high confidence that these environmental changes are part of the early warning signs of climate change.
Effects on social and economic activities are harder to attribute to climate impacts, although major events attract considerable attention. From prolonged drought in Africa and Australia to the dire flooding in Australia, China, and Pakistan, livelihoods, economies, and politics are at risk.
A single extreme weather event or change in the natural environment does not prove that humans are changing the climate. However, the proven physical science, the history of recent observations, and the consistency in model assessments all support only one explanation: the emission of greenhouse gases by human activity is causing profound changes to the climate system and to the world we live in.
The pace of change appears to be accelerating. Reports of sea levels rising faster than previously expected, of new temperature records, of an increasing toll of weather-related disasters, and anecdotal stories of impacts on livelihoods are accumulating. The year 2010 tied as the warmest year since records began in the 1850s, and threw up an astonishing series of extreme events.
Increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising sea levels led the Intergovernmental Panel on Climate Change (IPCC) to report in 2007 that "warming of the climate system is unequivocal". As evidence continues to mount, that statement is even truer today.CHAPTER 2
Warming in the Antarctic Peninsula and Arctic is driving large-scale melting of ice that will have both local and global consequences.
The presence of a hole in the ozone layer over the southern polar region has altered weather circulation patterns on Antarctica. It has brought more warm, moist, maritime air over the Antarctic Peninsula, contributing to warming and melting there, but has created a cooling effect in other areas. As the ozone hole recovers, that cooling effect is expected to diminish.
In East Antarctica, the changes are much less dramatic than those on the Peninsula, with some melting and thinning on coastal edges and some thickening in the interior. In West Antarctica, however, a coastal section of the ice sheet is now thinning quite rapidly.
Floating Arctic ice has covered the North Pole for millions of years. Its extent fluctuates with the seasons, but eight of the ten lowest extents have occurred in the last decade. The remaining ice is also thinner, with approximately 50 percent of the maximum recorded thickness having been lost by 2008. Already, the North Pole is free of ice in some summers.
In September 2007, the Arctic ice cap shrank to its smallest recorded extent, opening up the possibility of commercial shipping routes operating for the first time along the northern coasts of Canada and Russia. Some projections suggest that sea ice will disappear completely in the summer months by 2080.
While an open Arctic sea would facilitate shorter trade routes, industrial-scale fishing and the exploitation of minerals, it would be at great cost to the environment and to traditional livelihoods. A delay in the formation of the winter ice, an earlier break-up of ice in the spring, and thinner ice year round makes it hard for indigenous people using largely traditional methods to make a living.
The permafrost around the Arctic is generally warming. In some areas, it is making a weakened coastline more prone to erosion, and causing subsidence, leading to the collapse of roads and buildings. It is also creating lakes of trapped melt water, which may increase carbon dioxide and methane emissions.
Each summer, parts of the Greenland ice sheet melt at the edges and on the surface. Although the melt area varies each year, the overall trend since 1979 has been upwards. Surface melt water finds its way through crevasses to the base of the ice, and forms a thin film between ice and bedrock. There are fears that this could increase the speed at which the ice sheet slides towards the sea.CHAPTER 3
Around the world, glaciers are losing mass and are in retreat.
The changes in glaciers over time provide valuable evidence of long-term climate change. The mass and extent of glaciers respond to temperature and snowfall in the very local geography of mountains and polar regions. g Because the tell-tale signs of their expansion and retraction are clearly visible, scientists are able to draw conclusions about climate change from periods well before instrumental records became widespread.
Globally, glaciers have lost an average of more than half a meter (water equivalent) during the past decade or so. This is twice the rate of loss in the previous decade, and over four times the rate of loss in the late 1970s.
The front of most glaciers is receding to higher altitudes, and at such a rate that glaciologists, mountaineers, tourists and local residents are astonished by the changes that have occurred in the past decade. Tree stumps and even, in 1991, human remains that have been preserved in the ice for thousands of years, are now being revealed. Changing landscapes affect local plants and animals that colonize the newly exposed areas.
Glacial melting changes the flow of rivers, adding to water stress for millions of people. Lakes formed from melting glaciers are unstable, prone to abrupt collapse and flooding, threatening property and lives downstream.CHAPTER 4
Around the world, oceans are getting warmer and more acidic, affecting marine life.
Ocean temperatures, from the surface down to a depth of 700 meters, increased 0.1°C between 1961 and 2003. Temperature is fundamental to the basic life processes of organisms. It can influence metabolic rates and population growth of individual species and have broad repercussions on entire ecosystems. Coral reefs are particularly sensitive to temperature increases. Episodes of higher temperatures increase the frequency of coral bleaching and mortality.
Sea levels rose at an average rate of 1.8 ± 0.5 mm a year from 1961 to 2003 due to thermal expansion and melting of land-based ice. The recorded rate for the more recent period, 1 993 to 2010, is much higher (3.3 ± 0.4 mm a year), generating concern among scientists that sea levels will rise faster than previously expected.
A separate issue is the contribution made by higher levels of carbon dioxide in the atmosphere to the acidity of ocean surfaces since the Industrial Revolution. Carbon dioxide in the atmosphere dissolves into the oceans and forms carbonic acid. In some sea areas there has been a 0.1 unit change in pH – corresponding to a 30 percent increase in acidity over levels in the mid-eighteenth century.
Increased acidity is expected to affect the variety of marine organisms with shells of calcium or aragonite, decrease oxygen metabolism of animals, and alter nutrient availability. The expected consequences of this change are already being observed in marine life. Scientists have measured decreases in the weight of the shells of small marine snails (pteropods) as well as decreases in the calcification of corals in the Great Barrier Reef. Impacts on these small organisms, which are the base of the food chain and therefore the foundation of productive habitats, could ripple up to affect fisheries and therefore protein and food security for millions of poor people.
An initial calculation of possible economic losses associated with a 10 to 25 percent decline in mollusk catches in the USA alone estimates losses for the year 2060 at between $324 million and $5.1 billion at current values. Under scenarios of increasing emissions of carbon dioxide, surface ocean pH is projected to decrease further, by 0.4 ± 0.1 pH units, becoming increasingly acidic by 2100 relative to pre-industrial conditions.CHAPTER 5
The frequency of some extreme events is increasing. A shift away from familiar patterns of climate variability is bringing changes in many aspects of climate.
In many parts of the world, the number of occasions on which precipitation is particularly heavy has increased. In China in 2010, heavy rains caused flooding and mudslides in 28 provinces. In Pakistan, unusually heavy rainfall over the watershed to the Indus River caused a large volume of water to move down the river over subsequent weeks, causing extensive flooding.
Since 1950, the number of heat waves has increased, affecting crop yields, human health, and the intensity of droughts. There has also been a widespread increase in the number of warm nights – a seemingly minor change, but one that reduces overnight relief from the day's heat.
It is very difficult to attribute one particular extreme, such as a single heavy rainfall or severe hurricane, to human-induced climate change rather than to the natural range of variability, but the increase in the probability of these events occurring can be linked to changes in the climate. In a sense, we can think of climate change as loading the dice in favor of these extreme events. That loading of the dice is easier to observe in large data sets, such as temperature and precipitation, which include decades of daily information from all over the world. It is much more difficult to detect change in trends of comparatively rare events. For instance, tropical cyclones and hurricanes wreak havoc around the world, yet there is only low confidence at present that their frequency and intensity have increased since the 1970s.
As examples of the impacts of recent extreme weather events, the still-recovering city of New Orleans or the rural population suffering the long-term effects of the Pakistan floods, can provide insight into the types of losses that might be increasingly experienced as the planet warms.
But these impacts cannot all be blamed on climate change. Many other social and economic factors contribute to hazard vulnerability and loss. Poverty, poor warning systems and land-use planning, inadequate shelter, and other issues of economics, education, household resources, and governance contribute to vulnerability to these extremes.
Climate models project that there will be more heat waves in the future. The above analysis of temperatures from 1951 to 2003 provides observational support for models. Here, heat waves, are termed "warm spells", which are defined as the number of days per year with at least six consecutive days of maximum temperatures in the top 10% of all maximum temperatures for that time of year.
Areas in the yellow to red shades indicate a trend to longer warm spells. Black lines enclose areas where statistical analysis indicates that the trend is significant at the 5% level.
Trends were not calculated for areas with fewer than 40 years of data, and data that ended before 1999, so we do not have information for much of Africa, South America, the Middle East, Asia, and Australia.
Climate models also project that, in many parts of the world, rain will tend to fall in more intense bouts. This map represents analysis indicating that in much of the USA, and Europe, as well as parts of Asia, the amount of total annual rainfall contributed by the heaviest 5% of rainy days has tended to increase by 1% or more per decade between 1951 and 2003. Areas in white show lack of adequate data sets for analysis.
There is less area with statistically significant trends in intense rainfall than in longer warm spells.CHAPTER 6
The Greenhouse Effect
The intensification of the greenhouse effect is driving increases in temperature, and many other changes in the Earth's climate.
Without the natural atmospheric greenhouse effect, which captures and holds some of the sun's heat, humans and most other life-forms would not have evolved on Earth. The average temperature would be –18°C, rather than 15°C.
The greenhouse effect operates in the following way. Solar radiation passes through the atmosphere, and heats the surface of the Earth. Some of that energy returns to the atmosphere as long-wave radiation or heat energy. Another portion of that energy is captured by the layer of gases that surrounds the Earth like the glass of a greenhouse, while the rest passes into space. Changes to the composition of this layer of gases are central to climate change.
Over the last 250 years or so, human activity – such as extensive burning of fossil fuels, the release of industrial chemicals, the removal of forests that would otherwise absorb carbon dioxide, and their replacement with intensive livestock ranching – has changed the types and amounts of gases in the atmosphere, and substantially increased the capacity of the atmosphere to absorb heat energy and emit it back to Earth. The major greenhouse gases augmented by human activities are carbon dioxide, tropospheric ozone, nitrous oxide, and methane. Other industrial chemicals, including many halocarbons, also add to the effect.
Some of these gases only stay in the atmosphere for a few hours or days, but others remain for decades, centuries, or millennia. Greenhouse gases emitted today will drive climate change long into the future, and the process cannot be quickly reversed. In addition, warming may cause changes, or "feedbacks", that further accelerate the greenhouse effect. For instance, if the highly reflective snow cover decreases, more solar radiation will warm the Earth's surface. The warmer the Earth, the more heat energy is emitted back to the atmosphere. And if warming leads to extensive thawing of permafrost, there may be a large release of methane, a potent greenhouse gas.CHAPTER 7
The Climate System
The climate system is adjusting to an increase in the heat trapped in the Earth's atmosphere caused by greenhouse gases.
The Earth's climate system functions as a giant "heat distribution engine." Atmospheric and oceanic circulations move heat energy around the world, in an effort to distribute it more equally. This creates the long-term average conditions referred to as "climate", within which we experience the short-term, day-to-day variability of "weather." The addition of more heat energy to the atmosphere and the Earth's surface is expected to alter the climate system's heat distribution patterns, to change many average climate conditions and thus create more variation in the weather.
Most solar radiation and surface heating occurs at the equator, where the sun's rays are nearly perpendicular to the surface all year round. The poles receive much less radiation because of the Earth's orbit and tilt relative to the sun. Atmospheric and oceanic circulations contribute equally in moving energy from the equator towards the poles. The large-scale weather systems that generate the migrating warm and cold fronts, and their associated storms, are part of this process. The climate is also influenced by processes that contribute to multidecadal variability, such as El Niño and others in the Atlantic and Pacific.
The process of heat energy distribution by the global climate system is largely responsible for regional climates, and an increase in temperature differentials between the tropics and the poles could disrupt the climate in many ways. Warmer summers, heat waves, drier winters, less snowfall, and changing frequency and intensity of storms, are all possible results.
Excerpted from The Atlas of Climate Change by Kirstin Dow, Thomas E. Downing, Jannet King, Candida Lacey. Copyright © 2011 Myriad Editions Limited. Excerpted by permission of UNIVERSITY OF CALIFORNIA PRESS.
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Table of ContentsVoices & Visions of Our Future Wangari Maathai Philippe Cousteau About the Authors Introduction Definition of Key Terms PART 1 SIGNS OF CHANGE 1 Warning Signs The array of extreme events in 2010 stand out among thousands of signs of climate change. 2 Polar Changes Warming in the polar regions is driving large-scale melting of ice that will have both local and global consequences. 3 Shrinking Glaciers Glaciers are losing mass and are in retreat. 4 Ocean Changes Oceans are getting warmer and more acidic, affecting marine life. 5 Everyday Extremes The frequency of some extreme events is increasing. PART 2 The Changing Climate 6 The Greenhouse Effect The intensification of the greenhouse effect is driving changes in the Earth’s climate. 7 The Climate System The entire climate system is adjusting to an increase in the heat trapped in the Earth’s atmosphere. 8 Interpreting Past Climates Concentrations of CO2 and CH4 are higher than at any time in the last 650,000 years. 9 Forecasting Future Climates Global temperatures are predicted to continue rising. 10 Climate & Social Crises Climate change results from complex interactions in the natural environment, coupled with social and economic changes. PART 3 DRIVING CLIMATE CHANGE 11 Emissions Past & Present Most greenhouse gases have been, and are, emitted to meet the needs of modern industrial societies. 12 Fossil Fuels The emission of greenhouse gases from the burning of fossil fuels is the major cause of climate change. 13 Methane & Other Gases A range of greenhouse gases contribute to climate change. 14 Transport International trade and travel, and dependence on motor vehicles make transport a major source of greenhouse gas emissions. 15 Agriculture Agriculture is a major source of emissions, and vital for economic welfare in many countries. 16 The Carbon Balance Changes in stored carbon are contributing to climate change. PART 4 EXPECTED CONSEQUENCES 17 Disrupted Ecosystems Many species and ecosystems may not be able to adapt to new climatic conditions and stresses. 18 Water Security Water scarcity has already become a major stress in some regions. Climate change may raise the stress level. 19 Food Security Climate change threatens future agricultural development in some regions, and is benefiting others. 20 Threats to Health The recent increase in the number of victims, and the economic costs of weather-related health effects may be a sign of the future. 21 Rising Sea Levels Thermal expansion of oceans and melting ice will lead to a substantial rise in sea level, threatening many coastal communities. 22 Cities at Risk The combined impact of changes in the climate is falling particularly hard on rapidly growing cities. 23 Cultural Losses Climate change is threatening sites that represent the world’s cultural and historical heritage. PART 5 RESPONDING TO CHANGE 24 Urgent Action to Adapt As climate change becomes more marked, the need for adaptation will be ever greater, and more difficult. 25 Building Capacity to Adapt There is a need to develop effective strategies and actions, and to support efforts being made at all levels. 26 City Responses Cities around the world are taking action to reduce their emissions. 27 Renewable Energy Renewable energy sources could be the key to economically and socially sustainable societies. 28 Low Carbon Futures Economic growth needs to be achieved with lower greenhouse gas emissions, especially in developing countries. 29 Counting Carbon Accurate accounting of carbon and greenhouse gas emissions is essential. PART 6 INTERNATIONAL POLICY & ACTION 30 International Action Most countries have acknowledged the problem of climate change by signing the Convention on Climate Change. 31 Meeting Kyoto Targets Not quite half of Annex I countries are close to meeting their Kyoto commitments. And the agreed targets fall short of what is needed. 32 Looking Beyond Kyoto Negotiations are continuing in the search for a suitable international response in a post-Kyoto world. 33 Trading Carbon Credits Trading carbon credits encourages investment and shares the burden of reducing emissions. 34 Financing the Response Finance for responding to climate change has improved dramatically but is still far from what is required. PART 7 COMMITTING TO SOLUTIONS 35 Personal Action People all over the world are taking measures to reduce the greenhouse gases emitted as a result of the way they live. 36 Public Action The policies, practices, and investments of governments, businesses, and civic organizations will have the greatest impact on our future. PART 8 CLIMATE CHANGE DATA Table Sources & Notes Photo Credits Index
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