2010 Diary week 47
Climate Change
Book Review
Below you will find Part 6 of the review of Climate Change: Turning up the Heat by A. Barrie Pittock. These are some snippets: “The IPCC report in 2001 summarised the impacts of climate change under 5 categories or ‘reasons for concern’, as follows: Risks to unique and threatened systems; Risks from extreme climate events; Distribution of impacts; Aggregate impacts; Risks from future large-scale discontinuities.” “In the period 1995-2002, the average cost of windstorm damage in the US from hurricanes, tornados and severe thunderstorms was about US$5 billion annually.” “In many regions what was a 1-in-100 year flood in the 20th century may well become a 1-in-25 year flood by late in the 21st century.” “In 2004 the UK Government released a report on future flooding in England and Wales. It addressed the question: how might the risks of flooding and coastal erosion change in the UK over the next 100 years? Over 200 billion pounds worth of assets are at risk, along with disruptions to transport and power. The report emphasised the long lead times involved to influence future risk since large engineering works have long gestation times and long lifetimes and it could take decades for changes in planning policies to take effect.” ““The authors state that ‘While global food production appears stable, regional differences in crop production are likely to grow stronger through time, leading to significant polarization of effects, with substantial increases in prices and risk of hunger among the poorer nations, especially under scenarios of greater inequality (A1F1 and A2).’ Cereal price increases by 2080 under most scenarios were between 8 and 20%. Clearly, as the developed countries have a far smaller population than the developing countries, the majority of people will be worse off.”
CLIMATE CHANGE
TURNING UP THE HEAT
A. BARRIE PITTOCK
EARTHSCA/CSIRO PUBLISHING 2005
PART VI
Chapter 6: Impacts: Why Be Concerned?
• The key question for policy-makers (including you the reader) is whether projected climate changes due to greenhouse gas emissions are likely to lead to unacceptable impacts on human and natural systems.
• The United Nations Framework Convention on Climate Change seeks to avoid ‘dangerous interference to the climate system’, so we should ask whether what is projected would be dangerous. If so, we must try to avoid it by adopting appropriate policies.
• In 1988 scientists at a major conference in Toronto reached the rather startling conclusion (quoted below) that human-induced climate change is a major threat to international security.
Humanity is conducting an unintended, uncontrolled, globally pervasive experiment whose ultimate consequences could be second only to a global nuclear war. The Earth’s atmosphere is being changed at an unprecedented rate by pollutants resulting from human activities, inefficient and wasteful fossil fuels use and the effects of rapid population growth in many regions. These changes represent a major threat to international security and are already having harmful consequences over many parts of the globe.
• The Intergovernmental Panel on Climate Change (IPCC) conclusions in its 2001 report largely confirm the 1988 statement by providing much more detail and a better basis.
• Climate change impacts are complex in that they can be both direct and indirect. Direct impacts, adaptation and indirect effects are largely conditioned by the nature of the relevant human society, including its institutions, how well informed people are, and how readily they can adapt.
• Another important factor, which has not been adequately studied, is the rate of change of climate, not just the magnitude of change. Rapid change requires rapid adaptation, and a subsequent need to change capital investments, which will tend to be more expensive and not always possible.
• Studies have found that climate change and sea-level rise of the magnitude and rates suggested would greatly affect many natural systems like forests, rivers and wildlife, as well as human activities and society.
Climate change impacts – reasons for concern
• The IPCC report in 2001 summarised the impacts under 5 categories or ‘reasons for concern’, as follows:
Risks to unique and threatened systems: Natural systems are vulnerable to climate change, especially where migration is not possible or too slow, and increasing numbers will be irreversibly damaged as global warming increases.
Risks from extreme climate events: Changes in the frequency and severity of extreme events are expected, and will likely be a major cause of damages to ecosystems, crops, and society.
Distribution of impacts: Adverse impacts are likely to be greater and to occur earlier in low-latitude developing countries than in mid-and high-latitude developed countries. As warming increases with time even more developed countries will experience adverse effects, but the poorer countries will remain more seriously affected. Thus inequality between countries will be made worse.
Aggregate impacts: The majority of people are expected to be worse off even at small warmings.
Risks from future large-scale discontinuities: While not well understood, there is a strong possibility that large-scale and possibly irreversible changes in Earth systems will result in large impacts at regional and global scales.
Thresholds and abrupt changes
• Threshold events signal a distinct change in conditions. An example is set by the damage to buildings caused by wind gusts. Australian insurance figures indicate damage rises dramatically for peak wind gusts in excess of 50 knots, or 25 metres per second.
• Wind damage is one of the major economic impacts of climatic extremes, which may change in frequency or intensity with global warming.
• In the period 1995-2002, the average cost of windstorm damage in the US from hurricanes, tornados and severe thunderstorms was about US$5 billion annually.
• Abrupt changes also occur in ecological systems; sudden changes in system behaviour often arise from an element of the system reaching a limit or threshold at which instability sets in, and the system moves into a new stable state.
• When a system is close to such a threshold, even quite small random events or trends can force the system into a different state. It may take the form of a switch from a negative to a positive feedback.
• Abrupt changes, and exceeding thresholds, can occur in many climate impact situations, ranging from water stress in an individual plant, through topping of flood levee banks, to economic crises or forced migration due to rapid sea-level rise.
Risks from extreme climate events
• Physical, biological and indeed human systems in general have evolved, or are designed, to cope with a certain range of variations in the weather, based on past variability. However, when weather variables fall outside those limits, the affected system under-performs or fails.
• Sequences of extreme events, such as repeated floods or droughts, can compound damage and lead to irreversible change.
• A large part of the observed increase in deaths and financial losses from extreme events in recent decades is due to population growth and demographic shifts into hazardous locations. This means that many societies are becoming more vulnerable to extreme events – in other words, societies often display counter-adaptive behaviour.
• Small changes in average climate have a disproportionately large effect on the frequency of extreme events. Global warming increases the moisture holding capacity of the atmosphere, and thus preferentially increases the likelihood of high intensity rainfall.
• In many regions what was a 1-in-100 year flood in the 20th century may well become a 1-in-25 year flood by late in the 21st century.
• Because the force of flowing water increases rapidly with velocity and depth, damages increase very rapidly and has a ‘snowballing’ effect.
• Many systems may survive a single extreme flood or drought, but not repeated floods or droughts in quick succession.
• Even in rich countries, two or more successive extreme events may force losses on a farming enterprise.
• Crop yields are often dependent on temperatures and soil moisture at critical times in the growth cycle, with extremely high temperatures reducing fertility and thus grain yield.
Box 5: Future flooding in England and Wales
In 2004 the UK Government released a report on future flooding in England and Wales. It addressed the question: how might the risks of flooding and coastal erosion change in the UK over the next 100 years? Over 200 billion pounds worth of assets are at risk, along with disruptions to transport and power. The report emphasised the long lead times involved to influence future risk since large engineering works have long gestation times and long lifetimes and it could take decades for changes in planning policies to take effect.
Four different socio-economic scenarios were used, termed: World Markets (global interdependence and high emissions); Global Sustainability (global interdependence with low emissions); National Enterprise (national autonomy and medium to high emissions) and: Local Stewardship (national/local autonomy with medium to low emissions).
Some key findings are:
If flood-management and expenditures were unchanged, annual losses would increase under all scenarios by 2080, by less than 1 billion pounds under the Local Stewardship scenario to around 27 billion pounds under the World Markets scenario.
Besides flooding from rivers and coasts, towns and cities would be subject to localized flooding caused by sewer and drainage overwhelmed by local downpours. Damages could be huge but are not yet quantified.
The number of people at risk would more than double by 2080.
Drivers of future flood risk include climate change, urbanization, environmental regulations, rural land management, increasing national wealth and social impacts. Climate change has a high impact in all scenarios, with sea-level rise increasing the risk of coastal flooding 4 to 10 times, and precipitation changes increasing risk 2 to 4 times.
An integrated portfolio of responses could reduce the risk of river and coastal flooding from the worst scenario of 20 billion pounds annual damage down to around 2 billion pounds (still double the present damages).
Distribution of impacts
• The impact of global warming will not be distributed evenly among people, countries and regions.
• Countries such as the Philippines, Guyana and Nigeria, which are at low latitudes with high average surface temperatures are more likely to be early losers, along with low-lying countries such as Bangladesh and Kiribati, which are subject to flooding by sea-level rise.
• Mid- and high-latitude countries such as the United States and Russia may gain in the early stages of global warming from longer growing seasons, and the opportunity to grow more heat-tolerant plants and crops. This advantage may be negated by water supply problems in mid-latitudes, the spread of tropical pests and diseases, heat stress in summer, and other problems.
• The second reason commonly advanced for an uneven distribution of impacts is the greater capacity of richer and more technologically advanced countries to adapt to climate change.
• Extreme climatic events such as floods, droughts and storm surges cause far more deaths in poor countries than in rich ones. In rich countries the population is more likely to be warned, can be evacuated, fed and clothed, and has access to better health services.
• Damages in monetary terms from climatic disasters tend to be much higher, and to be increasing more rapidly, in rich countries than in poor ones.
• Global warming will increase the inequity between the rich and the poorer developing ones, with the poorer nations of Africa and the small island states especially vulnerable.
Box 6: Impacts on food production
The impacts of climate change on food production, prices and numbers at risk of hunger depend on a number of factors. These include regional climate change, biological effects of increasing atmospheric carbon dioxide, changes in floods, droughts and other extreme events, existing agricultural systems, adaptive capacity, changes in population, economic growth and technological innovation. In a major international study, Martin Parry of the Jackson Environmental Institute, University of East Anglia and colleagues made preliminary estimates using the SRES family of scenarios of greenhouse gas emissions and socio-economic change.
The study used a linked system of climate scenarios, agricultural models, and national, regional and global models. Adaptation was at the farm level, such as changes in planting dates, fertilizer applications and irrigation, and at the regional level via new cultivars and irrigation systems. Economic adjustments included changes in national and regional investment in agriculture, crop switching, and price responses.
Results for four illustrative SRES scenarios (A1F1, A2, B1 and B2) showed small percentage gains (3 to 8%) in average crop yields in developed countries by 2080, but decreases in developing countries of –1 to –7%.
This increased the inequity, measured by changes in yield, by between 7 and 10%. The authors state that ‘While global production appears stable, regional differences in crop production are likely to grow stronger through time, leading to significant polarization of effects, with substantial increases in prices and risk of hunger among the poorer nations, especially under scenarios of greater inequality (A1F1 and A2).’ Cereal price increases by 2080 under most scenarios were between 8 and 20%. Clearly, as the developed countries have a far smaller population than the developing countries, the majority of people will be worse off.
Results are highly dependent on the benefits from increased CO2 concentrations as measured in experiments, which are uncertain in the real world, and on effects of pests and disease, which have not been estimated.
It should be noted that these results are for climate change scenarios simulated with only one climate model, that from the Hadley Centre in the UK. Other climate models would give different results. These results are broadly consistent with the conclusions of the IPCC (2001).