The threat of rapid climate change due to greenhouse gas build-up in the atmosphere is the result of the sources of greenhouse gas to the atmosphere exceeding the sinks. The transformation of CO2 in the atmosphere is very slow. In the previous chapter we considered how to change the radiative balance by adjusting the energy flux provided by the sun. We should now turn to examining the issues in using the ocean as a sink of carbon. Already the total mobile carbon in the oceanic waters is of the order of 40000GtC, much greater than the 2200GtC on the land. The carbon in the ocean is stored mostly as bicarbonate, and the total dissolved inorganic carbon has a concentration of order 2000μmol kg−1.

Carbon is cycled by the marine planktonic ecosystem. Houghton et al. (1996), in the second assessment report of the Intergovernmental Panel on Climate Change, concluded that if there were changes in the oceanic plankton, there is a large potential for the biological pump to influence CO2 concentrations in the atmosphere.

Carbon is also cycling in and out of the ocean as a result of the vertical circulation in the large ocean basins bringing water to the surface with a different partial pressure to that of the atmosphere above.

Changing carbon dioxide intensity

In the previous chapter we saw how business as usual scenarios lead to a rapid increase in the concentration of carbon dioxide in the atmosphere. We saw how GDP per person and population combines with CO2 intensity to give the total emissions to the atmosphere. The population momentum that comes from past high fertility and the falling mortality makes it difficult for policies to have a short-term impact on population. However, there are some examples such as China, which has changed the rate of increase of its population through regulations known as the one-child policy. Population is a field not usually in the domain where engineers practice. Reducing population growth might be a cost-effective way of managing greenhouse gas, as well as addressing a number of other challenges facing the world, but we will not pursue it further. Readers are referred to Birdsall (1994) for a discussion of population momentum.

The first term, involving the GDP per person, is not one we would advocate reducing to control greenhouse gas emissions. Some assert that the people living in the developed nations consume too much and so have too high a GDP. They are profligate consumers! No-one sensible advocates that the poorest reduce the GDP per person. Would a much fairer distribution of wealth help all to have an acceptable level of GDP with no-one living in poverty? Could the global GDP then be lower than at present and so reduce the emissions of greenhouse gases?

In the previous chapter we considered approaches to providing energy with near-zero emissions of carbon dioxide. While this may be technically possible, there are impediments to the adoption of these concepts. Some are political, some are economic and some are resistance to change. The alternative approach is to accept the rise in carbon dioxide concentration in the atmosphere due to continuing emissions of carbon dioxide, and to modify some other components of the climate system to maintain a desirable climate. This is known as geoengineering – engineering on a global scale. It implies exerting control over nature, a concept that comes more naturally to engineers than to others with different cultures.

Five hundred years ago, humans had made only a small dint on the global ecosystem. The land biomass was presumably in steady state, so that on the average it neither stored carbon, nor released it to the atmosphere. Then came land clearing for agriculture, with the consequent release of carbon dioxide. As the CO2 level started to rise with the Industrial Revolution, carbon flowed from the atmosphere to the sea because of Henry's Law. The ocean sink is currently estimated at 1–2GtCyr−1. One way to make this estimate is to measure the carbon dioxide partial pressure difference between the atmosphere and the ocean surface layer and use this in a flux calculation. This topic is discussed in Chapter 5.

Introduction

The previous chapters looked at how to manage climate change by a number of different approaches. We considered controlling greenhouse gas concentration in the atmosphere or adjusting the solar radiation reflected from the earth back into space. Instead of trying to manage the anthropogenic climate change, the human race could simply adapt to the changes. This option does not seem to have received the attention that it deserves. This is especially true since adaptation is the likely outcome of a lack of resolve to avoid climate change. Lack of resolve comes about from a number of causes. There is uncertainty about the impacts of climate change. There are ‘ethical’ questions that have been raised about mitigation options. There are people who have decided that reduced consumption is the ‘politically correct’ behaviour, and harangue others to change their way of living. They oppose schemes to store carbon dioxide and the continued use of fossil fuels. Voluntary reduction of consumption is unlikely to be adopted. There are anti-capitalists who do not want solutions that provide avenues for increased profit. All these diverse opinions inhibit the investment in technology for mitigation.

Climate change can be divided into three categories. First is the slow rate of change that has historically occurred. Changes are small over a human lifetime and are not recognised by the bulk of the people. The human race has adapted to these changes with little problem.

Introduction

The period examined in this chapter extends back one million years, a time span that was chosen as encompassing the mid and late Quaternary and being slightly longer than the oldest Antarctic ice obtained at the time of writing: this was drilled at Dome C and extends back to ~800 kyr BP (years before AD 1950) (Parrenin et al., 2007). It also comprises the modern half of the Pleistocene (‘most recent’) epoch, a term originally coined by English geologist Charles Lyell in 1839. Throughout this period there has been the cyclic growth and decay of major Northern Hemisphere ice sheets through the exchange of mass between these ice sheets and the oceans.

On the notation used

Examining climate on this long-term timescale, using oxygen-isotope (δ18O) stratigraphy analysis of marine sediment cores and ice cores, has led to the development of a particular notation that allows direct comparison between records with differing sedimentation/accumulation rates. Emiliani (1955) introduced marine isotope stages (MIS) based on δ18O records derived from deep sea sediment cores. These MIS are time periods with boundaries at the mid-point between isotopic temperature maxima and minima of successive stages (Fig. 4.1). Beginning with MIS 1, which characterises the Holocene, odd and even stages represent interglacial and glacial periods further back in time, respectively: the exception is MIS 3, which was incorrectly identified as an interglacial when first defined and actually forms part of the last glacial with MIS 2 and MIS 4.

Introduction

Carbon has been stored in the trees, vegetation and soil of the earth and as fossil carbon in the forms of coal gas and oil for millions of years. The Industrial Revolution of the eighteenth century, combined with expanding land use for agriculture to feed the rapidly rising population, has transferred significant amounts of this carbon to the atmosphere. The rising affluence of an increasing global population is predicted to lead to the release of more greenhouse gas to the atmosphere in the future. With industrialisation's present dependence on fossil fuels for economic energy, there is unlikely to be restraint in the use of fossil carbon. The generation of greenhouse gas is expected to rise, particularly in rapidly developing countries such as China and India. Concentrations of these greenhouse gases in the atmosphere will increase unless there is deliberate expenditure on enhancing carbon sinks. With this change in concentration of greenhouse gas will come a change in the climate. The central theme of this book is how to have more economic growth using low-cost energy and at the same time sustain the earth's environmental quality. Engineers need to think in the time frame of 50 years because the consequences of their decisions on capital investments will be with us for many decades. To provide a better future, engineers need to constantly embrace innovation and plan for the environmental change that results from their actions. The management of the earth's environment can no longer be left to nature.

The past

When Svante Arrhenius published his paper in 1896 suggesting that by adding carbon dioxide to the atmosphere the temperature of the earth would be increased, he generated little interest. He used the idea proposed by Joseph Fourier that the earth was warmed by the trapping of heat by the atmosphere, much as in a greenhouse. Arvid Hogbom, a Swede, had pointed out that the amount of carbon dioxide released by humans burning coal was of the same order as the carbon added to the atmosphere from volcanoes and the like.

In scientific circles, the concept of trapping of heat by the addition of carbon dioxide in the atmosphere was not taken seriously until the absorption spectrum was able to be measured with fine enough resolution to show that the carbon dioxide lines did not lie right on top of the water absorption lines.

When Revelle and Suess (1957) calculated, on the prevailing knowledge, that most of the CO2 released by artificial fuel combustion was absorbed in the ocean, it seemed that there would be no problem. However this was not the case. A molecule of CO2 left the ocean nearly as often as one entered it, and it was the net flux of carbon dioxide that was important. This problem of stating that there is a large flux of carbon across the sea surface is still bedevilling us, and concepts of net flux needed to be clarified by Ametistova and Jones (2001).

Introduction

Analyses of the conventional surface meteorological observations indicate that the near-surface air temperature of the Earth as a whole has increased by about 0.6 °C over the last century (IPCC, 2007). However, the patterns of surface change across the Earth in the instrumental era are complex and sensitive to the period examined. Many studies highlight that some of the largest environmental changes have taken place at high latitudes.

In this chapter we are concerned with high latitude atmospheric, oceanic and cryospheric changes over the period for which there are a reasonable number of in-situ instrumental records. This is obviously shorter than for the more populated mid latitude regions and covers only about the last 100 to 150 years in the Arctic, and about 50 years in the Antarctic. The first long meteorological records started in Europe during the seventeenth century at locations such as Paris and London, but measurements from the Arctic generally began during the nineteenth century. However, as will be discussed later, there are several Arctic or near-Arctic temperature records that extend back to 1840–1860, such as those from Murmansk, Russia and Reykjavik, Iceland, and around a dozen starting from the second half of the nineteenth century. The greatest increase in the number of Arctic meteorological records came over 1930–40, and later in this chapter we discuss the temperature records from 59 stations in the high latitude areas of the Northern Hemisphere that provide reasonable longitudinal coverage over the areas around the Arctic Ocean.

Introduction

Many of the high latitude climatic changes discussed in earlier chapters occurred because of natural climate variability, associated with fluctuations in the orbit of the Earth around the Sun, changes in the amount of solar radiation emitted by the Sun, volcanic eruptions that injected large amounts of dust into the atmosphere, changes in the ocean circulation and exchanges of heat between the ocean and atmosphere. However, from about the middle of the eighteenth century, at the start of the Industrial Revolution, humankind began to influence the climate system through the emission of increasing amounts of greenhouse gases. At first the impact was very small, but in the last decade of the nineteenth century Svante Arrhenius (Arrhenius, 1896) suggested that the increasing blanket of greenhouse gases above the Earth could raise temperatures in the troposphere. However, it was only in the second half of the twentieth century that there was widespread interest in climate change as decade on decade the mean temperature of the Earth started to increase and record high temperatures were registered with increasing frequency.

The occurrence in recent decades of high profile severe weather events, such as droughts, severe hurricanes and heat waves, resulted in major debates on the role of humans in these events. In the early years of the twenty-first century it was hard to open a newspaper or switch on a television without encountering discussions on the reasons for recent climate change, with environmentalists and global warming ‘sceptics’ presenting opposing views.

It is common when comparing alternative engineering strategies that have a lifetime of several years to calculate the present net value. This approach is also known as discounted cash-flow analysis. This approach recognises that income due sometime in the future is not as valuable as income now. The discount rate expresses this as a percentage change per year.

Most projects involve the investment of risk funds (equity), the borrowing of money secured by future income or capital (loan funds), secured by the assets created in the project. Money is expended constructing the plant and then expenses are incurred in operating the plant. Revenue is generated by selling the product produced by the plant.

The concept of present net value recognises that income due sometime in the future is not as valuable as income now. This occurs because income received now can be invested to earn additional income in the future. Thus income is devalued by the discount rate. If the discount rate is X% pa then US$100 in one year is worth 100(1 − X/100) today. Income of $1, n years in the future, has a present value of (1 − X/100)n.

A similar approach can be applied to expense. An expenditure of $1, n years in the future, has a present cost of (1 − X/100)n.

Capital has a cost in terms of the borrowing interest rate. Say this is Y% per year. Then 100 US dollars borrowed for n years costs 100(Y/100)n.

Abstract

Plant communities in montane regions are useful for studying the potential effects of climate change. Many mountain species have affinities with colder climates and may not survive local temperature rises. Although Irish mountains are not of high altitude and are influenced by the tempering effect of the Atlantic Ocean, they support some species of arctic–montane affinity. In Ireland, the climate termed hyperoceanic, with its constant moisture and mild temperatures, prevails on western mountains. There it benefits the growth of bryophyte communities, which are more abundant due to higher cloud cover and precipitation as well as lower evapotranspiration. As these bryophyte communities occur up to c. 1000 m, alongside the arctic–montane higher plant species, they can be complementary as climate change indicators, as they respond differently to such change. There is little systematic information on the distribution of these scarce montane plant communities. Their distribution on the mountains of the west of Ireland is being mapped, and data are being gathered on the local climate of selected mountains. This will supply useful case-study material for climate change modelling, specifically providing information on regions that have little precise climatic information and on plant communities that are likely to be very vulnerable to aspects of climate change.

Abstract

The impact of climate change, in particular increasing spring temperatures, on life-cycle events of plants and animals has gained scientific attention in recent years. Leafing of trees, appearance and abundance of insects, and migration of birds, across a range of species and countries, have been cited as phenotrends that are advancing in response to warmer spring temperatures. The ability of organisms to acclimate to variations in environmental conditions is known as phenotypic plasticity. Plasticity allows organisms to time developmental stages to coincide with optimum availability of environmental resources. There may, however, come a time when the limit of this plasticity is reached and the species needs to adapt genetically to survive. Here we discuss evidence of the impact of climate warming on plant, insect and bird phenology through examination of: (1) phenotypic plasticity in (a) bud burst in trees, (b) appearance of insects and (c) migration of birds; and (2) genetic adaptation in (a) gene expression during bud burst in trees, (b) the timing of occurrence of phenological events in insects and (c) arrival and breeding times of migratory birds. Finally, we summarise the potential consequences of future climatic changes for plant, insect and bird phenology.

Introduction

The recent resurgence of interest in phenology (the timing of recurring life-cycle events in plants and animals) has stemmed from research on the impact of climate change, in particular, global warming.

Abstract

The Intergovernmental Panel on Climate Change (IPCC) has acknowledged that climate change represents a tangible threat to species richness, based largely on the evidence from climate envelope modelling and the shifts in ranges of current species. However, because of uncertainty in the accuracy of extinction forecasts from climate envelope modelling, it would be useful to have an alternative source of information. The evidence from the fossil record is less widely discussed, but supports the view that a warmer global climate will increase extinction rates even without other associated human impacts such as habitat loss. Fine-scale studies show heterogeneity in results, but global-scale analyses demonstrate that extinction rates are generally elevated during greenhouse phases and that biodiversity is depressed. These trends are consistent with studies of extinction events that have implicated global warming as a consistent cause, triggered by carbon dioxide (CO2) release from large igneous province eruptions. They suggest that abiotic factors such as climate are a major influence on biodiversity through time, but relatively predictably so (unlike the paradigm of the Court Jester). They indicate that there are perils of a warm climate distinct from those of climate change alone; that global biodiversity loss through climate change will only be reversed on geologic timescales; and that any reduction in global warming will bring some benefit to global biodiversity.

Introduction

What will be the consequences of anthropogenic climate change during the current and next centuries? This question dominates much of the current research in the biological and earth sciences.

Abstract

The influence of vascular land-plant evolution on long-term fluctuations in atmospheric carbon dioxide (CO2) concentration has been much discussed. However, the direct evolutionary consequences of changes in past atmospheric CO2 concentration have not been widely explored despite experimental evidence showing that elevated CO2 can intensify interplant competition, alter plant reproductive biology, and thus potentially influence plant speciation. In this chapter, we put forward the hypothesis that changes in atmospheric CO2 may have directly enhanced vascular plant speciation rates in the course of land-plant evolution, particularly in the late Palaeozoic when numerous pteridophyte and gymnosperm lineages were radiating rapidly (between approximately 400 and 240 million years ago – mya). Our hypothesis is based on the observation of significant correlations between land-plant speciation rates and long-term records on fluctuations in atmospheric CO2 levels over the past 410 million years. The relationship is complex, however, with a strong positive correlation between gymnosperm and pteridophyte speciation rates and CO2 concentration above 1000 ppmv, but a weak negative correlation between angiosperm speciation rates and atmospheric CO2 levels. These results suggest that fundamental plant evolutionary responses to atmospheric CO2 may be dependent on evolutionary grade. Model estimates of palaeo-atmospheric CO2 values are subject to considerable uncertainties, as are large-scale literature compilations of fossil plant speciation rates through geological time. Future collections of plant speciation data and palaeo-CO2 estimates are therefore required to test this hypothesis further.