Is it too late to make a difference?
The reaction of many to predictions for the coming century about climate change and its impacts is to feel overwhelmed by the sheer magnitude of the problem. They shrug their shoulders and say, "it seems more or less inevitable now whatever we do." But is that the reality? Can we still make a significant difference to the extent of climate change if we summon the will to act to reduce the emissions that are responsible?
The worst of the impacts predicted by the UN Intergovernmental Panel on Climate Change (IPCC) and others will only take place if we fail to curb our greenhouse gas emissions and break the spiral of fossil fuel-based energy consumption within which we are now caught. If we allow worldwide emissions to continue to double every 30 years, in line with energy usage, as astrophysicist Alberto di Fazio reports is now happening, we will exceed 1,000 parts per million by volume (ppmv) of CO2 in the atmosphere by the end of the century – nearly four times pre-industrial levels, and nearly three times higher than levels are today.
According to the UK’s Hadley Centre, the average temperature increase across the planet would be more than eight degrees centigrade compared with 1990, and double that in the polar regions. Temperatures would be as high as they were 40 million years ago, before Antarctica had a permanent ice sheet.
Clearly, such a future would be catastrophic. Sea-level rise by 2100 due to the thermal expansion of water and from melting glaciers and ice-caps would be nearly one metre higher than today, according to the IPCC’s Third Assessment Report. A lot would be at risk given that the majority of the world’s population lives along the flanks of oceans and some 30 per cent of the world’s best croplands are in coastal plains.
Cyclones, storm surges, hurricanes and a sea with waves generally higher than they were 30 years ago would cause havoc to coastal areas, decimating cities, settlements and agriculture. The potential damage could amount to tens of billions of dollars a year for vulnerable countries such as Egypt, Vietnam, Bangladesh and Poland.
Heat waves and drought would also have a heavy toll. One-third of the world’s population currently live in countries that are water-stressed. ‘This number is projected to increase to around five billion by 2025, depending on the rate of population growth,’ states the IPCC.
Meanwhile, over four million square kilometre of vegetation would die back within 100 years – practically equivalent to the whole of the Brazilian Amazon – leading to a massive venting of carbon into the atmosphere – as much as one billion tonnes of carbon within a century. This would also mean that net uptake from the atmosphere would decrease by a significant amount, hence adding to the total remaining behind, further accentuating global warming.
This could all happen within a century from now – if we do next to nothing to curb our growing emissions.
The extent and severity of the impacts would be lessened somewhat if we were to stabilise concentration levels of CO2 in the atmosphere at 750 ppmv – twice the level they are today. To achieve that, the UK’s Hadley Centre says we would need to reduce global emissions by half from where they are now by 2270.
At that level, the temperature increase would be just over three degrees centigrade and the sea would have risen 40cm in a century’s time. The IPCC points out that that would cause 200 million people a year to suffer from flooding, up from 75 million a year today. Moreover, sea-levels would keep on rising over the next 900 years to 1.5 m. higher than today, as water in the oceans would carry on warming and expanding.
Stablisation at 750 ppmv would also cause as much as three million square kilometres of vegetation to die back over 200 years. We would therefore undoubtedly suffer similar consequences as in an unmitigated emissions scenario, but to a slightly lesser degree.
The impacts would be lessened slightly further if we able to stabilise levels of CO2 in the atmosphere at 550 ppmv – one-and-a-half-times the level they are today – which would require reducing global emissions by about 80 per cent by 2100. That is the level which the UK’s Royal Commission on Environmental Pollution in its report, Energy – the Changing Climate, believes ‘should be regarded as an upper limit that should not be exceeded’.
According to the UK Met Office, stabilisaton at 550ppmv will lead to a committed warming of two degrees centigrade over the next 150 years, leaving us with a temperature that still would not have been exceeded for 38 million years. Sea-level would still rise on average by 40 cm. over the next century and the Gulf Stream circulation (which keeps Northern Europe warmer than it otherwise would be) would become weaker over the next 50 years, but would rebound back to its original strength from then on. The models also indicate that stabilisation at 550ppmv would prevent the Amazon basin drying out to the point of die-back, but would still lead to about one million square kilometres global vegetational die-back over 250 years.
Moreover, the latest climate models which incorporate some of the dynamics between life and climate change, indicate that previous models (such as the IPCC’s) underestimate the temperature increase and the impacts that would follow. The perturbations resulting from stabilizing CO2 levels at even 550 ppmv, therefore, could be far greater than is evident now.
Given such a prospect, the most sensible strategy would seem to be to curb our emissions of greenhouse gases as rapidly and radically as we can, with the aim of keeping atmospheric CO2 concentrations as close to current levels (of 370 ppmv) as possible.
That would require cuts in CO2 emissions of 80-90 per cent within 50 years. It would necessitate a Herculean effort to improve energy efficiencies, reduce use, install alternative technologies for electricity generation and transport and move away from industrialised agriculture, which damages soils and releases carbon. In return, further temperature rise, and hence damage to human communities and wildlife, would be minimised. So too would the risk of triggering feedbacks, which could dramatically increase global warming and cause climate change to spiral out of control, or, in the case of the UK and northern Europe, lead to the collapse of the Gulf Stream and hence bring about a sudden freezing.
But because it would still mean stabilising CO2 concentrations in the atmosphere at about 30 per cent above pre-industrial levels, some climate change would still take place. At today’s levels, we are already experiencing turbulence to the global climate system. Storms in the North Atlantic are getting fiercer, winds stronger, waves bigger. Unprecedented floods – like those that afflicted Orissa during India’s 2001 monsoon and the UK during winter of 2000-2001 – are becoming increasingly common According to the Red Cross, floods, storms, landslides and droughts have doubled from their 200-a-year tally before 1996. The cost of natural disasters in 1999 (85 per cent of which were weather-related) amounted to $70 billion. Recent evidence has shown too that the Gulf Stream is already weaker and less steady than it was. Over the past 30 years, scientists have measured a 20 per cent fall in the cold, dense water flowing across the Faroe Bank Channel.
Also, because of the lag in the climate system, our emissions of the past have yet to make themselves fully felt so even if we suddenly experienced a massive collapse of the global economy and emissions stopped tomorrow, we could expect at least a one degees centigrade rise over the century as the oceans gradually release the beat they have accumulated. Sea levels would also still rise by about one metre over hundreds of years.
But clearly, stabilising concentrations as close to today’s levels as possible would ensure that climatic changes happened over a much longer period of time than would otherwise be the case, providing human and wildlife communities with a much greater opportunity to adapt.
All to play for
Therefore, we do have a choice. The higher the concentration targets we accept, the larger and faster the rises in temperature and sea-level will be, with much greater consequences for life. What will actually happen is up to us. But if we allow the inadequate nature of the political response to the challenge of climate change to remain as it is, and if the paltry emissions reduction targets agreed under the Kyoto Protocol (which would effectively require no cuts below 1990 levels at all) remain unrevised, the chances of keeping levels close to current concentrations seem minimal, given the radical changes that would be required.
Bert Metz, co-chairman of the mitigation group of the IPCIC, believes the best we can hope for is to stabilise carbon dioxide levels in the atmosphere at 450 ppmv. ‘Even 450ppmv is not safe,’ he says, ‘but if we do not take action, it will go higher and higher, up to 1,000ppmv in some estimates. That would be very, very dangerous for the human race.'
The stakes could not be higher. We have no more time to fritter away in talk. In the words of Bert Metz: ‘Five to 10 years’ delay in cutting greenhouse gas emissions could put the job of stabilising the atmosphere beyond reach.’
If that were to happen, the planet would be well on its way to becoming a human-free zone.
Ask the experts: at what level should we stabilise atmospheric CO2
The task of identifying a target level at which we should aim to stabilise atmospheric concentrations of CO2 is of growing urgency to those concerned with climate change. As Michael Zammit Cutajar, Executive Secretary of the United Nations’ Framework Convention on Climate Change (UNFCCC), said before July’s COP6 climate change talks in Bonn: "I believe that the political process on climate change would be greatly assisted by agreement on a target for atmospheric concentrations, at least an intermediate target. This would give a sense of where the whole international community should be heading and a basis for apportioning responsibility for getting there."
Ecologist Report contributor Matilda Lee asked three of the world’s leading climatologists to give their opinions on what level they thought we should aim to stabilise atmospheric concentrations of CO2 and why.
Peter Cox, Climate/Carbon Cycle Modeller, Climate Research Department, Hadley Centre, UK MET Office
"I think we should certainly avoid exceeding 550ppmv (about double pre-industrial levels). This is the point, in our model, at which the land biosphere stops slowing climate change and starts to accelerate it (by becoming a source rather than a sink for C02). The main reasons for this occurring in our model are: (a) a climate change-driven die-back of the Amazon rainforest, (b) release of soil carbon due to accelerated breakdown of soil organic matter at high temperatures. Although both of these processes are uncertain, based on our current knowledge I would advise against gambling with such a potentially strong positive feedback"
Mike Hulme, Executive Director, Tyndall Centre for Climate Change Research, University of East Anglia, UK:
"I do not believe we have any sure basis for establishing what a ‘non-dangerous’ level should be. This is because what ‘dangerous’ is depends on what measures are taken to adapt to climate change. In one assumed future world 550ppmv may be ‘safe’, but ‘dangerous’ in another. The basis for establishing ‘danger’ is contested. One could argue that ‘dangerous’ climate change is change in climate that leads to the death of just one person; or argue that some cost/benefit ratio should be used; or argue that if a sovereign state is extinguished (eg a pacific atoll nation) then that is the definition of ‘dangerous’. I do not believe we can arbitrarily choose 550ppmv or 650ppmv, as done in many scientific pronouncements, and claim that is our target. This can only be done by using the instruments of social and political discourse on an international scale. What we can say is that the higher the concentration Of CO2 reached, the greater the likely risks associated with that concentration will be. But this is a relative argument, not an absolute one."
Robert T Watson, Former Chairman, Intergovernmental Panel on Climate Change: "Unfortunately I will not be able to respond to your request. Establishing the appropriate level to stabilise the atmospheric concentration of CO2 is not a scientific issue alone. The level must be established through a socio-political process, informed by scientific, technical and economic information. The IPCC has consistently taken the position that it will not and must not specify a specific stabilisation target for CO2 (which will vary depending upon the stabilisation level of the other greenhouse gases.) This is because what is considered dangerous by one group of people may not be considered dangerous by a different set of people. My view is that the scientific community must inform policy-makers as to the implications of different stabilisation levels locally, regionally, and sectorally. Also it is important to assess the adaptive capacity, locally, regionally and sectorally.
But the biggest problem is that the stabilisation level is not a well-defined parameter. What society cares about is, for example, changes in food production, water availability, human health, sea-level rise, and the goods and services from ecological systems. These do not respond directly to changes in greenhouse gas concentrations, but to changes in climatic parameters, temperature, precipitation and extreme [weather] events. Unfortunately, there is a factor-of-three uncertainty in the climate sensitivity factor. Therefore, a projected change in temperature can arise from a stabilisation level of 450ppmv (if climate sensitivity is high) or 1,000ppmv (if climate sensitivity is low). So we must evaluate ‘acceptable’ changes in climatic parameters and decide how to apply the precautionary principle given uncertainty in the climate sensitivity factor."
Note: The level Of CO2 in the atmosphere today is approximately 367 ppmv, an increase of almost 30 per cent from pre-industrial levels (approximately 280 ppmv).2 ‘The ultimate objective,’ of the UNFCCC is, ‘to achieve ... stabilisation of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthroppgenic interference with the climate system.’
By Peter Bunyard, science editor of The Ecologist.
© Ecologist Asia, Vol. 10, No. 1