2010 Diary week 42
Climate Change
Book Review
These are some snippets from Foreword by Dr Pachauri, Chairman, Intergovernmental Panel on Climate Change from the review of Climate Change: Turning up the Heat by A. Barrie Pittock. “An extremely eloquent statement is conveyed in the title of Chapter 4, which states ‘Uncertainty is inevitable, but risk is certain.’ This really is the key message in this book.” “In Chapter 8 a comprehensive and detailed assessment is provided on several mitigation actions. The volume ends by making a logical transition into political issues that have national as well as international dimensions.” “For sheer breadth and comprehensiveness of coverage, Barrie Pittock’s book fills a unique void in the literature in this field.” “In my view, which is shared by a growing body of concerned citizens worldwide, climate change is a challenge faced by the global community that will require unprecedented resolve and increasing ingenuity to tackle in the years ahead.” “Efforts would need to be based on knowledge and informed assessment of the future. Barrie Pittock’s book provides information and analysis that will greatly assist and guide decision makers on what needs to be done.”
CLIMATE CHANGE
TURNING UP THE HEAT
A. BARRIE PITTOCK
EARTHSCA/CSIRO PUBLISHING 2005
PART I
Foreword by Dr Pachauri, Chairman, Intergovernmental Panel on Climate Change
• In this book Barrie Pittock has provided a comprehensive analysis of the various aspects of climate change. A study of paleoclimate is an important component of present day climate change research, and the book goes through a lucid and useful assessment of the evidence available today.
• Also presented in considerable detail are projections of climate change in the future. An extremely eloquent statement is conveyed in the title of Chapter 4, which states ‘Uncertainty is inevitable, but risk is certain.’ This really is the key message in this book.
• In Chapter 8 a comprehensive and detailed assessment is provided on several mitigation actions. The volume ends by making a logical transition into political issues that have national as well as international dimensions.
• For sheer breadth and comprehensiveness of coverage, Barrie Pittock’s book fills a unique void in the literature in this field.
• In my view, which is shared by a growing body of concerned citizens worldwide, climate change is a challenge faced by the global community that will require unprecedented resolve and increasing ingenuity to tackle in the years ahead.
• Efforts would need to be based on knowledge and informed assessment of the future. Barrie Pittock’s book provides information and analysis that will greatly assist and guide decision makers on what needs to be done.
Introduction
• In 1988 I became the founder of the Climate Impact Group in CSIRO Atmospheric Research in Melbourne, Australia, whose object was to provide advice on what might happen, its impacts on society, and on the consequences of policy choices so that decision-makers could make informed decisions.
• Two developments stood out: the release of the fictional disaster film The Day After Tomorrow in May 2004; and a paper in Nature on 27 January 2005 refining estimates of the range of uncertainty in what is known as the ‘climate sensitivity’.
• It seems important to set the record straight for all those who were scared, or at least challenged, by the film, and to put the situation in a more hopeful perspective. There is still hope of avoiding the worst consequences if we act now.
• Climate sensitivity is the amount of global surface warming which would occur if the carbon dioxide concentration in the atmosphere were to double, as is likely during this century. All three major reports of the IPCC, including the latest in 2001, used 1.5 to 4.6ºC. The new results in 2004 suggest that the range is more likely to be 2.4 to 5.4ºC, while the paper by a UK team puts the range at 2 to 11ºC.
• We are now forced to consider whether in order to avoid dangerous climate change we must keep greenhouse gas concentrations below 400 to 500 ppm carbon dioxide equivalent.
• We are already at about 380 ppm and rising at a rate of 1 or 2 ppm each year. These new results heighten the urgency of reducing emissions well below present levels in the next decade.
• So maybe it is too late after all, especially if we take the advice of politicians who deny the need for immediate action and continue with business as usual.
• I prefer to follow a risk management strategy so that we can improve living standards in both industrial and developing countries, while minimizing the risks of climate change. But our individual actions would be more effective if we could persuade governments to recognize the urgency and act now to really push for a reduction in greenhouse gas emissions this decade.
• Climate change, abrupt or not, is a real risk. With luck and skill we can transform the challenge of climate change into a positive.
• My intention in this book is to answer frequently asked questions about climate change, sorting fact from fiction. It should help readers to choose a sensible course between the head-in-the-sand and the doom-and-gloom options.
Chapter 1: Climate Change Matters
• Climate is critical to the world as we know it. Today, with modern technology, humans can live in places where it was impossible before.
• Extreme weather events are part of climate. Engineers design buildings, bridges, dams, drains, etc. to cope with extreme weather events that occur on average only once in every 50, 100 or 1000 years.
Turning up the heat
• Climate has shown an almost unprecedented rapid global warming trend in the last few decades. 2004 was the fourth warmest year since records began in 1861, just warmer than 2003. The warmest year remains 1998, while each of the last 10 years (1995-2004), with the exception of 1996, is one of the warmest 10 years on record.
• Prehistoric global warming led to a complete transformation of the Earth’s surface, with the disappearance of ice sheets, and massive changes in vegetation cover, regional extinctions and a sea-level rise of about 120 meters.
• There has been a decrease of about 10% in snow cover since the 1960s, and a 10 to 15% decrease in spring and summer sea-ice since the 1950s in the northern hemisphere. Warming has also been rapid near the Antarctic peninsular, although not around mainland Antarctica.
• Arctic sea ice has thinned substantially over the last 20-40 years. In 2002, the Greenland ice sheet experienced the most extensive melt since satellite observations began in 1980. There has been a northward movement of the Arctic tree line since the late 1950s.
Box 1: Observed changes in the Arctic
Highlights of presentations at the final conference on the Arctic Climate System Study, St. Petersberg, November 2003, included:
• The Arctic experienced very strong warming during the last 30 years in concert with global trends.
• Some evidence suggests that a recent freshening of the sub-Arctic seas might be a local expression of a change in the global water cycle.
• Satellite microwave data reveal that Arctic sea ice extent has decreased by 2.5% per decade since 1972, with September (the seasonal minimum) showing the largest decrease.
• Arctic sea ice has thinned substantially over the last 20-40 years in most deep-water areas, especially in summer.
• In 2002, the Greenland ice sheet experienced the most extensive melt since satellite observations began in 1980.
• River runoff into the Arctic Ocean has increased significantly during recent decades and the river ice season has shortened.
• There has been a northward movement of the Arctic tree line since the late 1950s, particularly in north-west Canada and eastern and coastal Siberia.
Why is the present rapid warming happening?
• Scientists believe that rapid warming in the last several decades is due mostly to human-induced changes to the atmosphere, on top of some natural variations.
• Natural greenhouse gases include carbon dioxide, methane and water vapour. These help to keep the Earth some 33ºC warmer than if there were no greenhouse gases in the atmosphere.
• Human activities have increased the concentrations of several greenhouse gases in the atmosphere, leading to the ‘enhanced greenhouse effect.’
• Given that climate has changed during the 20th century, the key question is how much of this is due to human-induced increased greenhouse gas emissions, and how much to other more natural causes.
• There is the possibility that human influence on the climate was significant before the industrial revolution, due to the cutting down of forests and irrigated farming.
• It has been calculated that this has led to the Earth being 0.8ºC warmer than if humans had not been active, but the effect was cancelled out due to cooling due to orbital variations.
• The best agreement between model simulations of climate and observations over the last 140 years has been found when all human-induced and natural forcing factors are combined.
• It is likely that the 20th century warming has contributed to the observed sea-level rise of 10 to 20 cm through sea water expansion as it gets warmer, and widespread melting of land-based ice.
• Climate models suggest a slowdown of the ocean-circulation driven by differences in temperature and salinity in response to warming, increased rainfall and runoff at high latitudes, and reduced sea-ice formation.
The importance of delayed climate responses
• Emissions of carbon dioxide from the burning of fossil fuels and deforestation will have to be reduced eventually by 70 or 80% relative to present emissions to stop concentrations increasing in the atmosphere. This will take many decades to achieve without disrupting human society.
• The more we delay in reducing greenhouse gas emissions, the larger the inevitable magnitude of climate change will be, and the more drastic will be the reductions in emissions needed later to avoid dangerous levels of climate change.
• Because of the slow mixing and overturning of the oceans, surface temperatures will continue to rise slowly for centuries, even after concentrations of carbon dioxide have stabilized.
• This will lead to continuing thermal expansion and rising sea levels long after we have gone.
Observed impacts
• While the 0.6ºC increase in global average surface temperature in the 20th century may seem small, evidence suggests that a variety of physical and biological systems have already been affected.
• Changes in the distribution of wild animals and plants have shifted polewards at 6.1 km per decade and spring occurs earlier on average 2.3 days per decade.
• A forerunner of the future is the series of extreme high temperatures in Europe during the summer of 2003 when maximum temperatures were 5ºC above the long-term averages and drought conditions, low river flows and wild fires were widespread.
Box 2: Delayed climate system responses matter
Slow or delayed responses are widespread (but not universal) characteristics of the interacting climate, ecological, and socio-economic systems. This means that some impacts of human-induced climate change may be slow to become apparent, and some could be irreversible if climate change is not limited in both rate and magnitude before crossing thresholds at which critical changes may occur. The positions of such thresholds are poorly known. Several important policy-relevant considerations follow from these delayed response effects.
• Stabilization of the climate and climate-impacted systems will only be achieved long after human-induced emissions of greenhouse gases have been reduced.
• Stabilization at any level of greenhouse gas concentrations requires ultimate reduction of global net emissions to a small fraction of the current emissions, and it will likely take centuries to reduce carbon dioxide concentrations much below the highest levels reached.
• Social and economic time scales for change are not fixed. They can be changed by policies, and by choices made by individuals, or by reaching critical thresholds where change may become rapid and traumatic (for example, emergency programs, policy revolutions, technological breakthroughs, famine or war.)
• Higher rates of warming and multiple stresses increase the likelihood of crossing critical thresholds of change in climatic, ecological, and socio-economic systems (see Chapter 6).
• Delays and uncertainty in the climate, ecological, and socio-economic systems mean that safety margins should be considered in setting strategies, targets and timetables for avoiding dangerous levels of climate change.
• Inevitable delays in slowing down climate change makes some adaptation essential, and affect the optimal mix of adaptation and mitigation strategies.
• Slow responses in the climate system, and the possibility of reaching thresholds in the interacting climate, ecological and socio-economic systems, make anticipatory adaptation and mitigation actions desirable.
Trends in human vulnerability
• Poorer countries are likely to be more adversely affected by climate change than richer ones in terms of deaths while monetary damages are greater in richer countries.
• The ratio of increase in disasters between the decade 1960-69 and 1990-99 is: Number of weather-related disasters 4.5; Number of non-weather-related disasters 1.5; Economic losses 7.9; Insured losses 13.6.
Projections of future climate change
• The IPCC estimates that by the year 2100, atmospheric carbon dioxide concentrations would range from 490 to 1260 – 75% to 350% higher than the pre-industrial estimate of 280 ppm in 1750.
• By 2100 average global surface temperatures are likely to be between 1.4 and 5.8ºC warmer than the baseline year of 1990.
• The estimated sea-level rise will be in the range of 9 to 88 cm, mostly due to thermal expansion.
• Projected temperatures would be much warmer than the Medieval Warm period, 800 to 1000 AD.
• Evidence from past climate changes of similar magnitude point to major impacts, which, if humans had been present, would have been disastrous.
Facing the challenge
• Scientific research led scientists to alert governments to the issue of climate change and the setting up of the IPCC to provide policy-relevant scientific advice.
Conclusion
• Climate change is happening. It will take centuries to reduce greenhouse gas concentrations and probably more than a century to even stop it increasing. The impacts of climate change will become more serious, with an increasing risk of drastic changes to the climate system. Our capacity to adapt is limited and costly.
• In the following chapters we will look at the complexities of climate change and its potential impacts; examine potential policy responses, and the varying interests of different countries.
• Despite some costs, there are realistic solutions, which can be reached with some effort and cooperation. Our task is to see that this happens, and that it starts now.