Book Review

Below you will find Part 9 of the review of Climate Change: Turning up the Heat by A. Barrie Pittock. These are some snippets: “Mitigation acts to reduce the upper bounds of projected warming, and thus to avoid the most extreme and damaging possibilities. Mitigation action taken now will have its most significant effects decades into the future, but it is necessary to limit climate change to that which can be adapted to.” “If we take as our working definition of ‘dangerous climate change’ a change that exceeds the limits of acceptable adaptation strategies, and thus incurs unacceptable costs and damages, a dangerous situation will arise if mitigation is too small or too slow to avoid global warming exceeding that for which adaptation strategies can work.” “The percentage reduction needed in greenhouse gas emissions to avoid dangerous changes to the Earth’s climate is large, around 60-80% by 2100, but uncertain.” “The longer emission reductions are delayed the faster they will need to be reduced later to reach the same stabilised atmospheric concentration of greenhouse gases.” “Global emissions of greenhouse gases have to be reduced to well below the present levels (currently about 8 Gt of carbon per year) by 2300. To achieve the lower and safer stabilisation levels, global emissions need to peak before 2050 and then reduce to a fraction of the present emissions by 2150. An equilibrium concentration of 450 ppm requires a reduction to below present emissions by 2050.”

 

CLIMATE CHANGE

TURNING UP THE HEAT

BARRIE PITTOCK

EARTHSCA/CSIRO PUBLISHING         2005

PART IX

 

Chapter 8: Mitigation: Limiting Climate Change

Why mitigation is necessary

• The projected climate changes in the 21^st century are so large that, even at the low end of the range of possibilities, impacts will require costly adaptations, and in some case our capacity to adapt will not be enough to avoid serious damage to individuals and society.
• It will therefore be necessary to reduce climate change by reducing net greenhouse gas emissions to the atmosphere. This is called ‘mitigation’.
• Adaptation is effective where climate change is small enough for adaptation strategies to significantly reduce damages and take advantage of any opportunities posed by global warming, without unacceptable monetary or other costs.
• Adaptation can produce immediate gains over inaction, particularly because it can improve societal responses to climatic extremes occurring now. It is also necessary to cope with global warming that is already inevitable due to past emissions, and which will become inevitable due to future emissions until they are reduced to levels leading to stabilisation of climate.
• Mitigation, in contrast to adaptation, needs time to take effect due to the lags in the climate system and the time necessary to reduce emissions sufficiently to stabilise climate.
• Mitigation acts to reduce the upper bounds of projected warming, and thus to avoid the most extreme and damaging possibilities. Mitigation action taken now will have its most significant effects decades into the future, but it is necessary to limit climate change to that which can be adapted to.
• If we take as our working definition of ‘dangerous climate change’ a change that exceeds the limits of acceptable adaptation strategies, and thus incurs unacceptable costs and damages, a dangerous situation will arise if mitigation is too small or too slow to avoid global warming exceeding that for which adaptation strategies can work.

 

How much mitigation is needed?

• The percentage reduction needed in greenhouse gas emissions to avoid dangerous changes to the Earth’s climate is large, around 60-80% by 2100, but uncertain.
• Stabilising the Earth’s climate requires total emissions at some time in the future to be less than or equal to the total removal of greenhouse gases from the combined atmosphere – shallow oceans – land – soil – biota – system. Removal can occur by natural processes or it can be artificially accelerated.
• To stabilise greenhouse gas concentrations in the atmosphere the alternatives are either to reduce emissions by limiting the consumption of fossil fuels by such measures as energy efficiency or substitution of renewable energy, or to remove and sequester the carbon dioxide from the use of fossil fuels in additional biomass and soil storage (increased ‘carbon sinks’), in geological formations or into the deep ocean.
• The last might be accomplished in one of two ways, either directly by pumping carbon dioxide into the deep ocean, or via increased biological activity stimulated artificially in the shallow ocean.
• The precise reduction in emissions needed depends on what is the upper limit to concentrations of greenhouse gases that will avoid dangerous climate change, taking account of possible abrupt and irreversible changes in the climate system as well as gradual climate change.
• It also depends on how rapidly we need to achieve stabilisation to avoid excessive sea-level rise over centuries to come, and to avoid rates of warming that might lead to abrupt changes.
• The longer emission reductions are delayed the faster they will need to be reduced later to reach the same stabilised atmospheric concentration of greenhouse gases.
• There are two major uncertainties in deciding what concentration of greenhouse gases is a suitable target to aim for. The first is uncertainty regarding how sensitive the global climate is to various increases in greenhouse gases.
• According to the IPCC in 2001, this uncertainty is large – a doubling of atmospheric carbon dioxide could cause an eventual increase in global average temperature ranging anywhere from 1.5 to 4.5°C.
• An estimate in 2004 by UK scientists James Murphy and others puts the 95% confidence range as 2.4 to 5.4°C.
• A follow-up study by David Stainforth at Oxford University and others found a range from 1.9 to 11.5°C, with a 4.2% chance of being greater than 8°C.
• Thus there now appears to be only a small chance of a climate sensitivity as low as 1.5°C, and a considerable chance that it may well be above 4.5°C.
• This makes it far more likely that temperatures will reach dangerous levels, and will require lower limits of stabilised greenhouse gas concentrations to avoid such risks.
• The second major uncertainty in deciding on a target concentration of greenhouse gases is in determining what is a ‘dangerous’ level of global warming. What may be ‘dangerous’ in one locality or to one entity (industry, group, activity or species) may not be dangerous somewhere else or to another entity.
• Since different groups or countries will experience different impacts of climate change, defining a dangerous level of climate change becomes a value-laden moral and political process, not a scientific one.
• There seems to be wide agreement, at least among the non-governmental environmental organisations, and some governments, especially those in the European Union, that global average warmings of around 2 or 3°C may be considered ‘dangerous’ in the terms of the UNFCCC.
• Stabilising equivalent carbon dioxide concentrations at 1000 ppm leads to estimated warmings of 2.0 to 3.5°C by 2100 and, by the time climate has stabilised, to warmings of 3.5 to 8.7°C. So 1000 parts per million (ppm) is a concentration that is very likely to cause dangerous impacts.
• Stabilising at a concentration of 450 ppm leads to a warming of only some 1.5 to 2.3°C by 2100, which barely overlaps with what is considered dangerous. However, by the time of a stabilised climate several centuries later, warming will have reached 1.5 to 3.9°C.
• This suggests that aiming to initially stabilise equivalent carbon dioxide concentration at 450 ppm leads to only a mall risk of dangerous impacts by 2100, but leaving the concentration at 450 ppm for centuries thereafter would lead to dangerous consequences for future generations.
• Fortunately, it might be possible in the centuries after 2100 to further reduce the greenhouse gas concentrations by artificial sequestration of carbon dioxide so as to avoid at least some of the later dangerous consequences.
• Global emissions of greenhouse gases have to be reduced to well below the present levels (currently about 8 Gt of carbon per year) by 2300. To achieve the lower and safer stabilisation levels, global emissions need to peak before 2050 and then reduce to a fraction of the present emissions by 2150. An equilibrium concentration of 450 ppm requires a reduction to below present emissions by 2050.
• To stabilise at 450 ppm allows only a small increase from 1990 levels to a peak of about 7 to 13 Gt of carbon per year in about 2010-20, followed by a steep decrease to less than 4 Gt by 2100, and an eventual decline to less than 2 or 3 Gt per year.
• Climate-carbon cycle interactions, which amplify the rate of increase in carbon dioxide in the atmosphere, may further reduce the peak emissions allowable. Thus critical concentrations of carbon dioxide in the atmosphere may be reached earlier, and more rapid reductions of emissions will be needed to counter this effect.
• The uncertainty regarding the target for greenhouse gas concentrations and related emission reduction targets must lead to the setting of pro tem targets which should be subject to periodic reassessment as uncertainties are reduced due to better science, observed changes and progress on mitigation. The success of legislative and market mechanisms in achieving emissions reductions must also be assessed.
• The important question is not what the exact target should be, but how such a large emission reduction might best be accomplished in the decades ahead. Such a demanding technological target is not unprecedented.
• Previous tall technological targets that were achieved through strong national commitments include the US/UK Manhattan Project to produce nuclear weapons during World War II and the US race for a landing on the moon in the 1960s.
• However, reaching the present greenhouse emissions reduction target requires much more societal participation. It is a matter of motivation, incentives and technological innovation.
• Setting a long-term target, even if subject to periodic revision, provides a degree of certainty in planning and expectations that facilitates action and commitment. It establishes a mindset necessary for success.

 

Where we are now

• Mitigation, or emissions reductions, must start from where we are now. For this, some facts are necessary.
• In the year 2000 (the latest I could find with reliable numbers for all countries), global greenhouse gas emissions, measured as the equivalent amount of carbon dioxide, were 59% from fossil fuel carbon dioxide, 18% from carbon dioxide from land-use change (deforestation minus regrowth forests), 14% from methane, 8% from nitrous oxide, and 1% from several other highly active greenhouse gases.
• Methane comes from biomass decomposition, coal mining, natural gas and oil system leakages, livestock, wastewater treatment, cultivation of rice, burning of savannah and some from burning of fossil fuels.
• Nitrous oxide comes from agricultural soils (especially where too much nitrogen fertiliser has been applied), industrial processes, automobiles and other fossil fuel burning, human sewage and animal manure.
• Other highly active greenhouse gases are mostly substitutes for ozone-depleting substances, and various industrial processes including semi-conductor manufacture, production of aluminium and magnesium and electrical equipment.
• Table 9 summarises some useful information for the year 2000 on total emissions of greenhouse gases (GHG) for each of the 25 major emitting countries, the emissions per person, and carbon intensity (carbon emissions per unit economic output), as well as percentage changes in carbon intensity and GDP for the decade 1990-2000.
• These statistics demonstrate a wide variety of national situations, and help to explain various perceived national interests and negotiation stances on mitigation policies.
• A relatively small number of countries contribute most of the greenhouse gas emissions. These countries have either large populations or high gross domestic product (GDP), or both. These are the two main drivers of high emissions, although carbon intensity is also important.
• Carbon intensity varies greatly between countries, depending on economic structure, the mix of fuels used, and energy efficiency.
• There is a downward trend in carbon intensity in many developed and developing countries. However, in most of the 25 major emitting countries GDP is rising more rapidly.
• The statistics for changes are for the decade 1990-2000, during which there was an economic decline in the former Soviet Union countries, with the closure of many carbon-intensive industries. This economic decline is unlikely to continue.
• China shows a large fall in carbon intensity that may not continue, and the accuracy of the figures has been questioned.
• The relatively low carbon intensity in France is due largely to its high percentage of nuclear power generation.
• Note the large range in per capita emissions, from 0.5 tons per person in India to in excess of 6 tons per person in Australia and the United States.
• Statistics on cumulative emissions from 1850 to 2000 show that the developed countries dominate, with 29% of emissions originating from the US and 27.2% in total from the EU member countries. Russia is next with 8.3%, while China contributed 7.3% and India 2.0%
• Brazil, Indonesia and Pakistan each contributed less than 1%. This helps to account for the developing countries’ argument that the primary responsibility for early emissions reductions lies with the developed countries.

 

Table 9: Emissions data for major greenhouse emitting countries

Emissions data are shown for the 25 top greenhouse gas emitting countries. Data includes carbon dioxide from fossil fuels and cement, and five non-CO2 greenhouse gases (collectively, GHG), but not emissions from land-use (LU) change. Statistics are also given for the 25 present member countries of the European Union as a single unit, as well as the major member countries separately. Data are based on that aggregated by the World Resources Institute and published by the Pew Center on Global Climate Change in December 2004. CO2 intensity is in units of CO2 emissions per unit Gross Domestic Product (GDP), expressed in units of Purchasing Power Parity (PPP) for comparability. The abbreviation tCe is tonnes carbon equivalent, and is the carbon equivalent of the six GHGs emissions as if they were all CO2.

	Total GHG emissions 2000 (except LU change)		GHG emissions per person In 2000		Carbon intensity TCe/$m GDP (PPP)	Carbon intensity change 1990-2000 %	GDP-PPP change 1990-2000 %
Country	% of world	rank	tCe	rank
Argentina	0.9	24	2.1	17	86	-16	56
Australia	1.4	17	6.8	1	193	-11	42
Brazil	2.5	8	1.3	21	73	18	30
Canada	2.1	9	6.3	3	172	-8	32
China	14.8	2	1.1	22	201	-47	162
EU 25	14.0	3	2.8	11	107	-21	22
France	1.5	15	2.3	16	72	-20	20
Germany	2.9	7	3.2	6	111	-28	18
India	5.5	5	0.5	25	99	-4	70
Indonesia	1.5	16	0.7	23	127	30	51
Iran	1.3	18	1.9	18	223	6	50
Italy	1.6	11	2.5	15	87	-8	17
Japan	4.0	6	2.9	10	104	-2	15
Mexico	1.5	14	1.4	20	125	-11	41
Pakistan	0.8	25	0.6	24	112	11	47
Poland	1.1	21	2.7	12	230	-41	43
Russia	5.7	4	3.6	5	427	3	-34
Saudi Arabia	1.0	23	4.3	4	260	41	25
South Africa	1.2	19	2.6	13	200	-2	19
South Korea	1.6	12	3.1	8	185	2	82
Spain	1.1	20	2.6	14	104	4	30
Turkey	1.1	22	1.5	19	149	5	42
Ukraine	1.6	13	2.9	9	483	28	-57
United Kingdom	2.0	10	3.1	7	110	-23	26
United States	20.6	1	6.6	2	162	-14	38
World			1.5		147	-13	30