Background Research Paper on the Predicted Climate Change Impacts of Greatest Relevance to Oxfam

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The world’s climate is changing at an unprecedented rate, largely as a consequence of human activity. This paper summarises the predicted impacts of these changes that are of greatest relevance to Oxfam. It focuses on the medium to long-term (25-50 years) dynamics in five key areas: water, food security, health, extreme events and political stability. It explains how the geopolitics of the historic responsibilities and future impacts of climate change are distinctly unequal - those countries with the greatest ‘ecological debt’ currently stand to suffer least from the consequences of their past activities. Without political action to mitigate and adapt, climate change threatens to widen global inequalities and undermine recent gains in social and economic development.
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  Background research paper on the predicted climate change impacts of greatest relevance to Oxfam Written for Oxfam GB by Dr J Lorimer, PhD, Oxford University Centre for the Environment. Abstract The world’s climate is changing at an unprecedented rate, largely as a consequence of human activity. This paper summarises the predicted impacts of these changes that are of greatest relevance to Oxfam. It focuses on the medium to long-term (25-50 years) dynamics in five key areas: water, food security, health, extreme events and political stability. It explains how the geopolitics of the historic responsibilities and future impacts of climate change are distinctly unequal - those countries with the greatest ‘ecological debt’ currently stand to suffer least from the consequences of their past activities. Without political action to mitigate and adapt, climate change threatens to widen global inequalities and undermine recent gains in social and economic development. Introduction There is now a global consensus that the world’s climate is changing and that this is a consequence of human activity. Scientists agree that these changes are largely a result of the emission of greenhouse gases (GHGs) at rates that exceed the earth’s absorption capacity. While our climate has always been dynamic the character and rates of these changes are historically unprecedented. Furthermore, there is such inertia in our climate system that it would still take several hundred years for our climate to respond to a stabilisation of GHG emissions. 1  Where there is less certainty however is in the prediction of future climate change and the implications of these changes for economic and social development. There are three causes of this uncertainty: i) The nature of the climate response to increasing GHGs. The physical climate is a non-linear system and the interactions and possible feedbacks between its different variables are still not completely understood. For instance, there is a  possibility that the climate will change abruptly once key ‘tipping points’ have  been reached; ii) The resolution of the climate models, which still struggle to account for regional and local variables and to make predictions at this scale; iii) The social response to climate change. The nature and severity of the future consequences of climate change will greatly depend on our actions over the next generation. These actions include efforts to mitigate for change – to produce fewer GHGs – and to adapt to the predicted consequences of a changing climate. Climate modelling Despite this uncertainty, climate modellers for the Intergovernmental Panel on Climate Change (IPCC) 2  have established a range of possible future climate change outcomes, whose diversity is narrowing as our understanding of the physical science improves. On the social side long-term prediction is inevitably more difficult and these models are therefore based around a range of speculative scenarios . These chart different trajectories for future global development over the next century, their 1  associated changes in GHG emissions and the likely impacts of these trends. These models thus provide broad-brush analyses of the future social and economic implications of climate change. Predicted impacts  This document summarises the most widely accepted existing predictions of climate change that are emerging from these models, according to a ‘business-as-usual’ scenario of global economic change. At present none of the existing scenarios include the effects on GHG emissions of explicit efforts to mitigate for and adapt to climate change. This paper gives an overview of the geopolitics of the impacts of climate change. It then summarises the five impacts of greatest importance to Oxfam’s work in the developing world, all of which are interwoven. It covers impacts on water resources, food, health, natural disasters and political stability. This is a large-scale global/regional analysis, which shows general trends and highlights potentially vulnerable area. On the ground there will be a great deal of local variation in the nature and severity of the impacts summarised here, depending as much on local climatology as on levels of social and economic resilience and adaptive capacity. The geopolitics of climate change The global costs, benefits and responsibilities for climate change are unequally shared. The tragic irony of climate change is that those with the least historical responsibility stand to suffer most from its predicted consequences. Many of the citizens of developing countries in equatorial regions, who have historically emitted less GHG per capita, will be hardest hit. This is due to both the severity of the predicted environmental changes in these countries and the lower levels of resilience and adaptive capacity in their economies. In contrast, there is some evidence that climate change might initially create economic opportunities for previously inhospitable more Northern regions. As a consequence, without intervention climate change is likely to exacerbate existing global inequalities. This disparity is also likely to be played out at a local scale within developing countries, where wealthy, urban elites are much better placed to adapt to a changing climate than either their slum-dwelling neighbours or poor farmers living in remote rural areas. 1. Water resources The availability and quality of water resources are likely to be severely affected by climate change. There is predicted to be an increased risk of both drought and floods, with severe consequences for human health and agriculture. The impacts will result from changes in four factors: i) The distribution, seasonality and intensity of precipitation; ii) Increased rates of glacier melt and retreat; iii) Sea level rise; 2  iv) Alterations in average and extreme surface temperatures.  Precipitation Generally speaking climate change is predicted to lead to more precipitation and thus a wetter world. The key question is where this water goes. On a global scale one consistent prediction for the next century is for increases in the mean annual stream flow in high and mid latitude regions and for declines in tropical and sub-tropical areas – the precipitation moves north. 3  However, the most important changes are likely to occur at a regional scale and on a  seasonal  basis. In Africa ’s large river basins total available water has already decreased by 40-60%. 4  If current trends continue, climate models predict that by 2050 sub-Saharan Africa will be much drier, with 10% less rainfall in the interior and with water loss exacerbated by higher evaporation rates. This change will be subject to great r egional variation with less rainfall expected in Southern Africa but more in East Africa. 5  In South-East Asia , climate change is predicted to affect the Indian monsoon , which could have severe impacts on millions of people living in India, Pakistan and Bangladesh. Although all models predict changes in precipitation patterns there is little certainty about their character. However, a 10% fluctuation in average rainfall in either direction is known to cause either severe drought or flooding. 6   Extreme events  – the increased energy in the climate system is likely to make periods of intense rainfall more frequent. This, in turn will increase the frequency and magnitude of flooding in many regions. 7  Furthermore, the concentration of  precipitation into extreme events will decrease the incidence of low stream flows in many regions. 8  More intense downpours will also affect the capture of water by the soil as infiltration rates decline and more water runs off. Both of these trends may affect the general availability of water . Furthermore, more intense rainfall events can cause increased soil erosion, which may lead to the silting up of reservoirs. 9  In contrast, recent evidence suggests that climate change is increasing the frequency and magnitude of drought in the Sahel and sub-Saharan Africa. Rainfall in the Sahel has declined substantially in the last fifty years and this trend is expected to continue. 10   Glacier melt Valley glaciers and small ice caps store fresh water over long time scales. Many rivers are supported by seasonal glacier melt, which maintains flows through the dry season. However, most valley glaciers and small ice caps have been in general retreat for the last 150 years. Increased temperatures and declines in snowfall are expected to accelerate glacier retreat leading to the disappearance of many small glaciers. 11  Glacier retreat has implications for downstream river flows. As the glacier melts flows initially increase as water is released from long-term storage. However, as the glacier gets smaller and disappears the volume of meltwater is substantially reduced. The disappearance of glaciers may have serious hydrological consequences in higher latitude countries, which are dependent on meltwater for stream flow during dry seasons. 3  This trend will particularly affect those areas directly sourced from glacier meltwater. In Peru, for example, glacier coverage has fallen by 25% in the last 30 years, while in China virtually all glaciers have shown substantially melting. This has potentially severe consequences for almost a quarter of the country’s population that depends on meltwater for their water supply in dry seasons. 12  Sea level rise The global average sea level has risen by 10-20 cm over the past 100 years. 13  Models  predict that the melting of the ice caps and the thermal expansion of the oceans will lead to a further 50 cm rise in global sea level by 2100. 14  This will lead to an increase in flooding in low-lying coastal areas and increased rates of coastal erosion. Sea-level rise will also cause the intrusion of saline waters into the fresh water coastal aquifers of many small island states and low-lying coastal areas. This process degrades fresh water supplies. Temperature changes Water quality is generally degraded by higher water temperature as this encourages the growth of organic matter. Lower flows in equatorial and sub-tropical regions will enhance this degradation. Higher temperatures will also lead to increased evaporation and thus a need for irrigation to grow existing crops. This irrigation may compound water shortages in some areas. Overview Overall, it is estimated that these changes will increase the number of people suffering water resource stress by 0.5 billion by 2020. There are significant geographic variations in this trend. Under most scenarios, climate change increases stresses in many countries in southern and western Africa and the Middle East, whereas it ameliorates stresses in parts of Asia. 15  These changes in water quality and availability could have a number of knock-on effects on food supply, health, transport and regional and local economies. The severity of these affects will depend on the existing management strategies for water resources and the potential for future adaptive management. 2. Agriculture and food security Global agriculture already faces many challenges over the coming decades as degrading soils and scarce water resources threaten food security amongst growing  populations. These challenges could be worsened by large-scale climate change  beyond the critical threshold of 2 o C. A warming below this level could have minimal or positive effects on overall food production, warming above this level could reduce global supplies and lead to higher prices and famines. On a  global scale  climate change will lead to a shift in agricultural zones towards the  poles. In terms of global productivity, increased temperatures and CO 2  levels within certain bounds will lead to increased yields by speeding up photosynthesis – a process known as CO 2  fertilisation . This is likely to happen in high latitude regions, generally in the developed world. However, these gains might be undone by the increased risk of heat stress and drought, which lower crop yields. This is likely to occur in tropical regions. As such 4
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