Routledge Handbook of Climate Change and Society

Constance Lever-Tracy, Constance Lever-Tracy

• Publisher: Routledge
• Year: 2010
• ISBN:
  9781135998493
• Edition: 1
• Topic: Biological Sciences
• Subtopic: Environmental Conservation & Protection
• Index: Biological Sciences

As the time-scales of natural change accelerate and converge with those of society, Routledge Handbook of Climate Change and Society takes the reader into largely uncharted territory in its exploration of anthropogenic climate change. Current material is used to highlight the global impact of this issue, and the necessity for multidisciplinary and global social science research and teaching to address the problem.

The book is multidisciplinary and worldwide in scope, with contributors spanning specialisms including agro-forestry, economics, environmentalism, ethics, human geography, international relations, law, politics, psychology, sociology and theology. Their global knowledge is reflected in the content of the text, which encompasses chapters on American, European and Chinese policies, case studies of responses to disasters and of the new technological and lifestyle alternatives that are being adopted, and the negotiations leading up to the Copenhagen conference alongside a preface assessing its outcomes. Starting with an initial analysis by a leading climatologist, key issues discussed in the text include recent findings of natural scientists, social causation and vulnerability, media and public recognition or scepticism, and the merits and difficulties of actions seeking to mitigate and adapt.

This accessible volume utilizes a wealth of case studies, explains technical terms and minimises the use of acronyms associated with the subject, making it an essential text for advanced undergraduates, postgraduate students and researchers in the social sciences.

Part 1 Understanding climate change

1 The science of climate change: knowledge, uncertainty and risk¹

Barrie Pittock

DOI: 10.4324/9780203876213-3

Today, global climate change is a fact. The climate has changed visibly, tangibly, measurably. An additional increase in average temperatures is not only possible, but very probable, while human intervention in the natural climate system plays an important, if not decisive role.

Bruno Porro, Chief risk officer, Swiss Reinsurance (2002)

Climate change is a major concern in relation to the minerals sector and sustainable development. It is, potentially, one of the greatest of all threats to the environment, to biodiversity and ultimately to our quality of life.

Facing the Future, Mining Minerals and Sustainable Development Australia (2002)

We, the human species, are confronting a planetary emergency – a threat to the survival of our civilization that is gathering ominous and destructive potential even as we gather here. But there is hopeful news as well: we have the ability to solve this crisis and avoid the worst – though not all – of its consequences, if we act boldly, decisively and quickly.

Al Gore, Nobel Peace Prize Lecture (2007)

Introduction

Climate is critical to the world we know. The landscape, and the plants and animals in it, are all largely determined by climate acting over long intervals of time. Over geological time, climate has helped to shape mountains, build up the soil, determine the nature of the rivers, and make flood plains and deltas. At least until the advent of irrigation and industrialisation, climate determined food supplies and where human beings could live.

Today, humans can live in places that were previously uninhabitable, by the provision of buildings and complex infrastructure tuned to the existing climate, such as urban and rural water supplies, drainage, bridges, roads and other communications. These involve huge investments of time and money. Trade, particularly of food and fibre, has also been strongly influenced by climate. Roads, buildings and towns are designed taking local climate into consideration. Design rules, both formal and informal, zoning and safety standards are developed to cope even with climatic extremes such as floods and droughts. If the climate changes, human society must adapt by changing its designs and rules and retrofitting infrastructure, often at great expense.

In broad terms, ‘climate’ is the typical range of weather, including its variability, experienced in a particular place. It is often expressed statistically, in terms of averages over a season or number of years, of temperature or rainfall and sometimes in terms of other variables such as wind, humidity, and so on. ‘Climate variability’ is variability in the average weather behaviour at a particular location from one year to another, or one decade to another. Changes in the behaviour of the weather over longer time scales, such as from one century to another, are usually referred to as ‘climate change’.

Conventionally, 30-year intervals have been used for calculating averages. However, natural climate varies on time scales from year to year, through decade to decade to longer-term fluctuations over centuries and millennia. Thus climate change is seen as a long-term change or trend superimposed on natural decade-to-decade variability.

Extreme weather events are part of climate. Their impact is reflected in the design of human settlements and activities (such as farming) so as to be able to survive floods, droughts, severe storms and other weather-related stresses or catastrophes. Because climate can vary from decade to decade, reliable averages of the frequency and magnitudes of extreme events require weather observations over longer periods than the conventional 30 years. Engineers design infrastructure to cope with extreme weather events that occur on average only once every 50, 100 or 1000 years. The more serious the consequence of design failure under extreme weather conditions, the longer the time interval considered, for example, for a large dam as opposed to a street drain.

Recent global warming

Climate has changed greatly over geological timescales but has shown an almost unprecedented rapid global warming trend in the last half century.

Since the start of reliable observations in the nineteenth century, scientists from weather services and research laboratories in many countries have examined local, regional and global average surface air and water temperatures, on land, from ships, and more recently from orbiting satellites.

The World Meteorological Organization, which coordinates weather services around the globe, has declared 2005 and 1998 the two warmest years on record, since reliable weather records began around 1850, and just warmer than 2003. The decade of 1998– 2007 was the warmest on record. Twelve of the past 13 years (1995–2007), with the exception of 1996, rank among the 12 warmest years since reliable records began in 1850. Since 1900 the global average surface temperature has risen by 0.74 ± 0.18ºC, and the linear warming trend over the past 50 years, around 0.13 ± 0.3ºC per decade, is nearly twice that for the past 100 years.

Note that when scientists give such estimates they usually include a range of uncertainty, which in the former case above is ± 0.18ºC. Thus the increase could be as low as 0.56ºC or as high as 0.92ºC. In this case the uncertainties allow for possible inaccuracies in individual measurements, and how well the average from the limited number of individual measurement stations represents the average from all locations.

Indirect evidence from tree rings, ice cores, boreholes, and other climate-sensitive indicators suggest that, despite a lesser warm interval around AD 1000 (the so-called ‘Medieval Warm Period’), the warmth of the past half century is unusual in at least the previous 1300 years. The last time the polar regions were significantly warmer than the present for an extended period (some 125,000 years ago), reductions in polar ice volume led to global sea levels 4 to 6 m above the current level. Variations of the Earth’s surface temperature since 1850, along with global average sea level from 1870 and Northern Hemisphere snow cover since the 1920s, are shown in Figure 1.1.

Figure 1.1 Observed changes in global average surface temperature, global average sea level and Northern Hemisphere snow cover, from the start of good measurements

Source: Figure SPM-3 from the IPCC 2007 Working Group I report (used with permission from IPCC).

Based on such observations, the Intergovernmental Panel on Climate Change (IPCC) concluded in 2007 that, despite year-to-year variations due to short-term fluctuations such as the El Niño – La Niña cycle, ‘warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level’.

Three things are notable about these World Meteorological Organization and IPCC conclusions. First, they show that a warming of at least 0.56ºC almost certainly occurred. Second, the most likely value of 0.74ºC, while it may appear to be small, is already a sizeable fraction of the global warming of about 5ºC that took place from the last glaciation around 20,000 years ago to the present inter-glacial period (which commenced some 10,000 years ago). Prehistoric global warming led to a complete transformation of the Earth’s surface, with the disappearance of massive ice sheets, continent-wide changes in vegetation cover, regional extinctions and a sea-level rise of about 120 metres.

The average rate of warming at the end of the last glaciation was about 5ºC in some 10,000 years, or 0.05ºC per century, while the observed rate of warming in the past 50 years is 1.3ºC per century and the estimated rate over the next 100 years could be more than 5ºC per century, which is 100 times as fast as during the last de-glaciation. Such rapid rates of warming would make adaptation by natural and human systems extremely difficult or even impossible.

Some critics have questioned the IPCC’s estimated warming on the following main grounds. First, there are uncertainties due to changes in instruments. These include changes in the housing of thermometers (‘meteorological screens’) which affect the ventilation and radiant heat reaching the thermometers, and changes in ships’ observations from measuring the temperature of water, in buckets dropped over the side of ships, to measurements of the temperature of sea water pumped in to cool the ships’ engines. These changes are well recognised by scientists and have been allowed for. They contribute to the estimate of uncertainty.

Second, there are concerns that estimates are biased by observations from stations where local warming is caused by the growth of cities (the ‘urban heat island’ effect). This effect is due to the heat absorbed or given off by buildings and roads. However, it works both ways. In many large cities, observation sites originally located near city centres (and thus subject to warming as the cities grew) were replaced by sites located at airports outside the cities. This led to a temporary observed cooling until urbanisation reached them. Observations from sites affected by urban heat islands have, in general, been either corrected or excluded. A study of temperature trends on windy nights versus all nights shows similar warming trends, even though wind disperses locally generated heat and greatly reduces any heat island effect (Parker 2004).

Observations from land surface meteorological stations tend to concur with nearby ship observations, with similar trends despite different sources of possible errors. Airborne observations from balloon-borne radio-sondes at near-ground levels also support the land-based observational trends.

Another issue often raised is the apparent difference between the surface observation trends and those from satellites, which began in 1979. The satellite observations require correcting for instrumental changes and satellite orbital variations. Moreover, they record average air temperatures over the lowest several kilometres of the atmosphere rather than surface air temperatures, so they do not measure the same thing as surface observations. Recent corrections to the satellite estimates, to take account of these problems, have removed the discrepancies and confirm that surface and lower atmospheric warming is occurring (Fu et al. 2004). All the above criticisms of the temperature records have been addressed explicitly in successive IPCC reports and can now be dismissed, even though they continue to be raised (IPCC 2007; Royal Society 2007). Legitimate estimates of uncertainty are given in the IPCC assessments.

Supporting evidence for recent global warming comes from many different regions and types of phenomena. For example, there is now ample evidence of recent retreat of alpine and continental glaciers with some exceptions in mid- to high-latitude coastal locations where snowfall has increased (Dyurgerov 2002; Woodwell 2004; World Glacier Monitoring Service 2009). The overall retreat has accelerated in the past couple of decades, as the rate of global warming has increased. Figure 1.2 shows dramatic evidence of this for the T...