‘There are times in the history of humanity when fateful decisions are made. The decision … on whether to enter a comprehensive global agreement for strong action on climate change is one of them. …On a balance of probabilities, the failure of our generation would lead to consequences that would haunt humanity until the end of time.’
Political leaders of 194 countries (as of January 2010) have signed the United Nations Framework Convention on Climate Change (UNFCCC), which states in Article 2 that the Convention's ‘ultimate objective … is to achieve… stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system …’. As we have seen in the preceding chapters, scientists are able to document with a very high degree of certainty that human activities exert measurable influence on several components of the climate system. In addition, most scientists agree that, on the basis of observed changes in the climate system, there is a very high probability (>90% according to the IPCC) that these changes are primarily the result of anthropogenic influences on the climate system. Furthermore, many impacts on human societies and nature have already been recorded (Chapters 5 and 6). These impacts can only be expected to increase in the future.
With Article 2 of the UNFCCC as the point of departure, the next step is to determine what actually constitutes ‘dangerous anthropogenic interference with the climate system’, or ‘dangerous climate change’ as it is often called in shorthand.
‘There is no getting away from the fact that making policy towards climate change unavoidably requires one to take stance on ethical questions…’
The equity dimensions of the climate change challenge discussed in the previous chapter are central to the current debate and, if not solved, will frustrate any attempts to find truly global solutions. The strong focus of the policy dialogue on the present and near future is appropriate and necessary to turn around the trajectory of greenhouse gas emissions and, hopefully, avert what many consider to be dangerous climate change. But just as longer-term studies of the dynamics of the Earth System in the past provide insights into the behaviour of the climate system today, a much longer gaze into the future can provide insights into the implications of the choices and decisions that we are making today.
Our ancestors have clearly shown an ability to think about their long-term futures, and to organise their institutions, economies and resource base to deliver desired outcomes hundreds of years into the future. If they had not had this capability, we would today be unable to marvel at the Great Wall of China, the exquisite ruins of the Mayan civilisation in meso-America, the great cathedrals of medieval Europe or the hauntingly beautiful old Buddhist city of Bagan in northern Myanmar (Figure 10.1). Our ancestors also differed from contemporary society in their capability to integrate utilitarian and spiritual views of the rest of nature.
‘It's also why the world must come together to confront climate change. There is little scientific dispute that if we do nothing, we will face more drought, more famine, more mass displacement – all of which will fuel more conflict for decades. For this reason, it is not merely scientists and environmental activists who call for swift and forceful action – it's military leaders in my own country and others who understand our common security hangs in the balance.’
Politicians have observed regularly in recent years that climate change first emerged as an ‘environmental’ issue, which later became reconceptualised as an ‘economic’ issue, and is now perceived as a ‘security’ issue. What exactly this means is not always clear – notably whether it means that climate change can cause violent conflicts or that climate change as such is the biggest threat humankind faces (Section 13.6; Wæver, 2009a). Nevertheless, this transformation in the perception of climate change carries with it the unmistakable message that the importance of climate change has moved up some kind of ladder of politicisation. Climate change is not a technical issue, but a political one – and it belongs to the category of ‘high politics’ (Hoffmann, 1966) in that it affects the survival of the state (as opposed to ‘low politics’, which deal with more mundane or practical issues).
‘This is an externality like no other… there is a big probability of a devastating outcome’
Striking developments in the climate system in recent years have reinforced the view that anthropogenic global warming is unlikely to cause a smooth transition into the future. The record minimum area coverage of Arctic sea-ice in September 2007 drew widespread attention, as has the accelerating loss of water from the Greenland and West Antarctic ice sheets (Chapter 3). These large-scale components of the Earth System are among those that have been identified as potential ‘tipping elements’ – climate sub-systems that could exhibit a ‘tipping point’ where a small change in forcing (in particular, global temperature change) causes a qualitative change in their future state (Lenton et al., 2008). The resulting transition may be either abrupt or irreversible, or in the worst cases, both. The most ‘policy-relevant’ tipping elements have been defined as those that (i) have a tipping point that could be crossed this century, (ii) would undergo, as a consequence, a qualitative change within this millennium, thereby (iii) affecting (if not damaging) a large number of people. For a full definition of a tipping element and its tipping point, see Box 7.1 (and Lenton et al., 2008). In IPCC terms such changes are referred to as ‘large-scale discontinuities’ (Smith et al., 2009). Should they occur, they would surely qualify as dangerous climate changes (Schellnhuber et al., 2006) (although not all are equally dangerous, as we will explore further).
‘The world that is bequeathed to us is, in our hands and in our time, being unmade … the future complexity of life – our potential gift to the future – is being eradicated’
Biodiversity represents the fabric of life itself. It is comprised not only of numbers of species, but also includes the variety of all life forms and their genes as well as the communities and ecosystems of which they are a part. The consequences of climate change for biodiversity are potentially profound.
Many acknowledge the importance of biodiversity in its own right, without any consideration of utilitarian value. However, biodiversity also provides the underpinning of the ecosystem services on which human societies are ultimately dependent. Without well-functioning ecosystems we humans, as a biological species, could not exist.
Even before anthropogenic climate change became a significant issue, biodiversity has been in decline in many parts of the world. The reasons are almost entirely linked to human numbers, economic activity and resource use; the proximate causes include landscape modification and conversion, direct predation (i.e. hunting and fishing), introduction of alien species, extraction of water resources, and application of excess nutrients. Climate change now represents an additional stressor, usually interacting with the already existing stressors in complex ways. The acceleration of biodiversity decline with climate change, and the consequent further degradation and loss of ecosystem services, provides important information to inform the discussion of what constitutes dangerous climate change.
Climate change is having, and will have, strongly differential effects on people within and between countries and regions, on this generation and future generations, and on human societies and the natural world…
‘We are only a tool in the cycle of things … (we) go out into the world and help keep the balance of nature. It's a big cycle of living with the land, and eventually going back to it …’
The Earth's element cycles – nitrogen, carbon, phosphorus, sulphur, silicon and others – are central to the functioning of the climate system, and to life itself. In the context of climate change, the carbon cycle has assumed centre stage, primarily through the rapid rise in human-induced emissions of the important greenhouse gases carbon dioxide (CO2) and methane (CH4). The political debate on responses to the climate change challenge has focused primarily on one aspect of the carbon cycle – reducing the emissions of CO2 to the atmosphere. However, the carbon cycle is very complex and human activities affect other parts of the cycle – for example, the ability of natural processes on the land and in the ocean (carbon ‘sinks’) to take up a significant fraction of the CO2 emitted to the atmosphere. The human imprint also operates indirectly on the carbon cycle via climate change itself, as several important feedback processes are predicted to be activated as the planet warms. For example, pools of carbon in the natural world, such as the CH4 stored in frozen soils in the northern high latitudes, that have hitherto been stable could become an important new source of a powerful greenhouse gas as the planet warms.
‘The only engine big enough to impact Mother Nature is Father Greed: the Market. Only a market, shaped by regulations and incentives to stimulate massive innovation in clean, emission-free power sources can make a dent in global warming.’
The joint climate and development imperatives described in the previous chapters demand a strong, immediate and sustained response. As outlined in Chapter 8, the global community has approximately four decades to implement a reduction in greenhouse gas emissions in the order of 90%.
The transition to a low-carbon/low-emissions economy will likely take many forms and be played out on local, national and regional levels as well as on the global stage (Chapter 13). While little has so far been done to initiate this transition, a diverse suite of existing and near-term technologies exist that can be components of regionally tailored low-carbon energy mixes, and which can underpin an aggressive expansion of energy efficiency worldwide. The challenge is, in effect, one of inventing and implementing a new energy economy in around four decades; i.e. in a fraction of the time it took to build the entire current industrial energy infrastructure.
A new ‘triple bottom line’ is therefore needed: one that is low-carbon, high-growth and job-creating. To further increase this challenge, this must be achieved in not only a few small segments of the global population, but also widely across industrialised and developing nations – from household and village scales, to national and regional economies.
‘Business-as-usual is dead’
Climate change is now understood as a central issue for economic prosperity and development. The Stern Review (Stern et al., 2006) can be seen as the turning point after which climate change has been considered an important economic issue, in addition to being an environmental one. In-depth reviews of the economics of climate change have been conducted for various countries and regions, for example for Australia (Garnaut, 2008) and South-East Asia (Asian Development Bank, 2009), and the development community now sees climate change as one of its main challenges (Chapter 15; World Bank, 2009).
Climate change could affect the fundamentals of economic systems. Meanwhile, curbing greenhouse gas emissions by the extent required to limit the risk of dangerous climate change (e.g. the 2 °C guardrail; Chapter 8) will require comprehensive changes in technologies, energy systems, industrial production practices and locations, and consumption patterns.
Countries will strive to effect such change with the minimum of economic cost; that is, keeping any sacrifices in economic prosperity as small as possible. While it can be argued that excessive consumption is one of the root causes of high greenhouse gas emissions, it is equally clear that few, if any, societies will readily make big cuts to their levels of material well-being. To achieve emissions cuts effectively and efficiently will require sound economic policies, integrated across different sectors of the economy and harmonised with other objectives of economic policy.
‘The people who are bearing the brunt of the effects of climate change are those who can least afford to do so and who have done least to cause the problem. Adaptation is both a practical need and a moral imperative.’
Climate change is a reality. Previous chapters in this volume have presented an up-to-date summary of the science of climate change, a description of some of the impacts that are already occurring, and an analysis of the risks that lie ahead as the climate continues to change. It is clear that even the most vigorous approaches to mitigation will not prevent a further escalation of the risks of climate change. Further impacts are unavoidable.
Adaptation to climate change is thus now considered essential in order to reduce the impacts of climate change that are already happening and to increase the resilience to future impacts, some of which cannot be reversed (Parry et al.,1998). Some countries have already started adaptation programs (Kabat et al., 2005; Swart et al., 2009). The IPCC started to address adaptation more comprehensively in a single chapter of its Third Assessment Report (McCarthy et al., 2001), while in its Fourth Assessment Report, adaptation attracted significant attention throughout the whole document (Parry et al., 2007). The shift from a focus primarily on mitigation towards embracing adaptation too can also be observed in the scientific literature (Figure 14.1), where adaptation and mitigation now get equal attention.
‘Never doubt that a small group of thoughtful, committed citizens can change the world; indeed, it's the only thing that ever has.’
An effective response to the risks of climate change can build on the ideas and actions of many different individuals – both as citizens and consumers, and as leaders of business and other organisations. Individual citizens can play an important role in the response to climate change, especially when they make decisions to reduce their greenhouse gas emissions or adapt to climate change encouraged by institutional structures and access to credible, understandable and relevant information. There is considerable evidence that individual behavioural change can contribute to reductions in emissions, especially from households and transportation and when supported by government policies, incentives and private sector activities.
Individuals are also engaged with climate change as decision-makers, members of non-governmental organisations (NGOs) and voters in ways that influence the actions of governments and corporations. Public support is critical in the success of national and regional government actions, and public perceptions can impede the acceptance of mitigation technologies. Behavioural and attitudinal changes are also important in terms of political and corporate leadership where, for example, business leaders and city mayors have made significant commitments to emission reductions that go far beyond national political obligations or simple cost–benefit analysis. In terms of adaptation, millions of farmers and herders have adjusted their practices to past climate shifts and are already making decisions in response to the onset of warming and other shifts associated with climate change.
‘You melt, we drown’
Sea-level rise has emerged as one of the most intensely studied and discussed aspects of climate change in recent years. The period of relative stability of sea level over the past 6000–7000 years (Harvey and Goodwin, 2004) has now ended, and sea level is undoubtedly rising in the post-industrial period (IPCC, 2007a). Given the massive heat capacity of the ocean, the Earth is already committed to many more centuries of sea-level rise due to thermal expansion alone. The dynamics of the large polar ice sheets and the rapid retreat of glaciers and ice caps will significantly add to the magnitude of sea-level rise. The critical questions are: how much and how fast? The implications for long-lived coastal infrastructure, coastal ecosystems, and low-lying urban areas and settlements are significant. This chapter explores our current understanding of sea-level rise, including observations of sea-level rise in the more recent past as well as insights from deeper in Earth's history, projections of sea-level rise out to the end of this century, the dynamics of the large polar ice sheets in Greenland and Antarctica, and the consequences of sea-level rise for contemporary society.
Observations of sea-level rise
Observations of sea level from 1870 to 2001 (Figure 3.1) show an increase of about 20 cm over the period (Church and White,2006). An extension of the record with more recent data shows that the rate of sea-level rise has increased within the past two decades, from 1.6 mm yr−1 in the 1961–2003 period to 3.1 mm yr−1 in the 1993–2003 period (Church and White, 2006; Domingues et al., 2008).
For many key parameters, the climate system is moving beyond the patterns of natural variability within which civilisations have developed and thrived…
Defining ‘dangerous climate change’ is an issue for societies to discuss and determine but the climate change research community is providing much more information to support this process…
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