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Climate Change2022-Aug-15  9:25:41 PM


1.The earth’s climate is regulated largely by the biogeochemical process know as the carbon cycle. The global carbon cycle circulates hundreds of billions of tons of carbon annually among various terrestrial, oceanic and atmospheric sources. Carbon in the atmosphere in the form of CO2, is the most abundant of several trace gases that are responsible for the “greenhouse effect.”

2. The greenhouse effect is a natural process responsible for keeping the earth warmer than it otherwise would be if all the heat generated by solar energy hitting the earth''s surface were reradiated back into space. It is the layer of CO2 and other Greenhouse Gases (GHGs) in the upper atmosphere which trap the reradiating heat and make the earth approximately 32C warmer than it otherwise would be.

3.The warming of the earth by the greenhouse effect was a critical factor in the evolution of life on the planet. The greenhouse effect is responsible for the earth being a water rather than an ice planet. All living things depend on specific climatic environments to thrive. Many species cannot survive outside a rather narrow set of climate conditions which are significantly influenced by the greenhouse effect.

4.The atmospheric concentration of C02has changed considerably over the long history of the planet , but has been fairly stable over the last 400,000 years, remaining below 300ppm over this period. Ever since the rise of human civilizations some 5000-6000 years ago, and up to about 1800, atmospheric C02 levels fluctuated within an even narrower range of 250-290ppm.

5. Since the beginning of the industrial period, when atmospheric CO2 concentrations were approximately 275 ppm, atmospheric CO2 concentrations rose to 375 ppm by 2000, an increase of over 30%.

6. Human use of fossil fuels since the beginning of the industrial revolution(largely coal,oil and natural gas) is the primary cause of this increase in atmospheric CO2 concentrations. Land clearing was the most important factor prior to about 1900, and remains the second largest driver of CO2 increases after fossil fuels.

7. Scientists overwhelmingly agree that these well established changes in GHG production by humans will affect global climate. It is less clear precisely what changes in climate will occur due to projected increases in GHG levels over the current century. The majority of scientists project several major effects: a global temperature increase of from 1 to 5 degrees C, increased precipitation, and less stable weather patterns.

8. Continued human-induced emission of GHGs at the current rate will lead to a level of atmospheric CO2 concentration which is at least 2 to 3 times the preindustrial level by 2100. Even higher emission rates are projected over future decades. Such increases will result in dramatic climate changes that would adversely affect all human societies on the planet, in addition to numerous plant and animal species.

9. Some of the impacts associated with different levels of climate change include: reduction of many crop yields, drying of tropical soils, loss of coastline infrastructure due to a rising sea level, increased spread of insect borne diseases as their ranges vary, significant biodiversity loss due to changing habitat and climate conditions, new and more frequent disease outbreaks in domestic and farm animals, more frequent and severe storms, more forest fires, loss of coral reefs, and more flooding, among other impacts.

10. How serious these climate induced changes are will depend on how much GHGs we continue to emit. Scientists agree that the more GHGs emitted the more serious and costly the damages will be.

11. Unchecked, increased concentrations of GHGs in the atmosphere could alter the global carbon cycle irrevocably. If this complex yet robust global biogeochemical cycle is altered in this way, the impact on human civilization would be catastrophic, as new global weather patterns would be established, which are likely to be far less suitable to life as we know it.


Exceeding Maximum Sustainable Scale Maximum sustainable scale is the highest level of material throughput in the global economy which allows all essential ecosystem functions to be maintained. The increased material throughput of GHGs already appears to have disrupted the ecosystem’s capacity to maintain global climate stability; maximum sustainable scale appears to have been exceeded. This is the case for at least some ecosystem functions; as GHG concentrations continue to increase with more fossil fuel use, we can expext that more and more vital ecosystem functions will be disrupted.

Climate stability is one of the most robust and importance ecosystem services of the carbon cycle and related greenhouse effect. Human-induced emissions of GHGs appear to have exceeded the maximum sustainable scale for climate stability because they have exceeded the atmospheric concentrations of GHGs which were present throughout the rise of human civilizations. In do so, they have affected the atmosphere’s capacity to absorb further amounts of GHGs without altering global climate patterns.

Many of the negative consequences anticipated from change in climate stability are undoubtedly occurring now (increased global temperatures, changes in regional climate variability, sea level increases, increases in the frequency and severity of storms, and the destruction of biodiversity, etc). We also know that current levels of GHG concentrations exceed those which have endured for the last 420,000 years, that GHG concentrations are continuing to rise, and that they are rising at an unprecedented rate. [ quote from Schneider “…agreements [among climate scientists] are consistent enough to argue that such cause and effect associations are quite plausible – I consider it 80 to 90% likely that there is a causal relationship between the twentieth century warming trend and greenhouse-gas forcings.”] P83

The conclusion that maximum sustainable scale has been exceeded by current levels of GHG emissions cannot yet be stated with absolute scientific certainty. By definition, climate changes are long term events and a longer time series is required to firmly establish this conclusion. However, climate theory, and a wide array of documented climate impacts are consistent with this conclusion. To wait for absolute scientific certainty in this matter before taking action might well be too late to either reduce GHG concentrations below maximum sustainable scale, or too costly to mitigate the consequences.

A further difficulty in unequivocally stating that maximum sustainable scale has been exceeded by current GHG concentrations is that the ecosystem functions which are likely most affected are so poorly understood. However, given the central role of climate stability in maintaining life support systems for so many species, and the multiple changes around the planet which are consistent with disruption of climate stability, it is reasonable and prudent to consider the likelihood that ecosystem disruption is already occurring, and will intensify as GHG concentrations increase (see Areas of Concern).

If maximum sustainable scale of GHG emissions is exceeded, it is only a matter of time before maximum scale for climate stability is also exceeded. This occurrence would be catastrophic for modern civilization.

Maximum Scale Maximum scale is a level of material throughput in the global economy beyond that of maximum sustainable scale, where the processes responsible for maintaining an essential ecosystem function would be irrevocably disrupted. The current level of CO2 concentrations does not appear to pose an imminent threat to the ongoing functioning of these mechanisms which account for climate stability. However, it is likely that maximum scale will be exceeded if current practices continue. [Schneider p 114-115 “the bulk of such experts [in the scientific community] consider…there is also a 10 to 20 percent chance that there will be widespread catastrophic outcomes from the human activities creating global change.”

We do not know what levels of GHG concentrations would trigger such a catastrophic shift in climate equilibrium, and without such knowledge we risk inadvertently exceeding this point of no return. There are several disturbing facts with respect to the potential for the present course to exceed this catastrophic threshold:

  • First of all, the current attempt to reach an international agreement about how to manage the challenge of global GHG emissions, the Kyoto Protocol, scheduled to be ratified in 2005, will not result in climate stability.
  • Efforts to negotiate an international agreement regarding global GHG emissions currently exclude the nation responsible for some 25% of global emissions, the United States
  • Policies and practices which encourage or support the use of fossil fuels (eg subsidized prices for fossil fuels) remain priorities for many governments
  • Populations in industrialized and rapidly industrializing countries are poorly informed of the potential consequences of their current or aspiring fossil fuel based economies and lifestyles
  • Policies and practices to encourage alternative sources of energy and/or to conserve energy are under funded and under resourced
  • Powerful vested interests are at play to maintain the status quo
  • There are a number of positive biophysical feedback loops involved in climate change, which could create a runaway situation leading to maximum scale (see above Positive Feedback Loops).
Optimal Scale Optimal scale is that level of material throughput which provides an adequate safety margin in terms of not exceeding maximum sustainable scale. Given that over the course of human civilization the range of CO2 was between 250 and 290 ppm, this range can reasonably regarded as safe with respect to climate stability.

These facts outlined above raise the serious possibility of human induced GHG emissions triggering a catastrophic shifting of the global climate equilibrium by exceeding maximum scale.

A variety of possible climate scenarios have been explored and discussed by scientists, politicians and citizens from around the world. Scientists of the IPCC ( ref?) have calculated that emission reductions of 70-80% from 1990 levels would be required to return atmospheric levels of CO2 to those of the preindustrial era. Political compromises led to a rejection of this option as too damaging to global economic growth. The target agreed to in the Kyoto Protocol is an emission reduction of only 5.2% compared to 1990 CO2 levels. What impact, if any, this will have on atmospheric concentrations is unknown. Furthermore, this target is not a global target, but a target only for the Annex A countries who have ratified the Protocol (largely the developed countries). Annex B countries (large developing economies like those of Brazil, China, and India) have agreed to join the Protocol at a later date, but are currently not obligated to reduce their emissions.

IPCC scientists have identified what they call a “low risk” scenario with a target of 450 ppm. They point out that such a level of CO2 concentration, even if achieved, would still involve considerable changes in global climate and have serious consequences for many areas and regions of the earth. It should be noted that this “low risk” target is almost twice the preindustrial level, and 50% above the levels prevalent during the rise of modern civilizations. This level may exceed maximum sustainable scale which is difficult to define with high accuracy; a more precautionary approach would seem prudent.

Continuing Risks Thinking about climate change in terms of scale offers a perspective different from that reflected in the many official documents about the issue generated over the past two decades. The potential for exceeding maximum scale, which would involve the irrevocable disruption of the global climate systems, is a challenge unprecedented in the history of civilization. The issue of climate stability is far from solved, and several significant risks remain.

  • The current attempt to reach an international agreement about how to manage the challenge of global GHG emissions is inadequate
  • Even if the first stage of the Kyoto Protocol is sucessfully implemented, it will almost certainly not result in a sustainable level of GHG emissions.
  • Maximum sustainable scale may already be exceeded for some critical ecosystem functions.
  • A fourth risk has to do with how other scale challenges may impact climate stability.
Current International Agreement Inadequate The initial phase of the Kyoto Protocol is weak in several respects. Its goal of reducing CO2 emissions to 1990 levels by 2012 by 5% is unlikely to have much impact on climate stability, even if implementation is successful. Emissions have been rising steadily since this goal was set, and reaching it will be more difficulty because of this increase. In addition, the world''s largest CO2 emitter, the United States, continues to refuse to ratify the Protocol. Several developing countries like Brazil, China and India are not included in the current Protocol, although their total emissions continues to rise. In effect, there is still no global agreement about how to manage the challenges of GHG emissions. Without such an agreement and the involvement of large GHG emitting nations, it is highly unlikely the problem will be solved. But whatever flaws the Kyoto Protocol may have, it at least provides an international forum for addressing the challenge, and for taking the first important steps.

Will Sustainable Scale Be Achieved? Even if the current target of the Kyoto Protocol are reached by 2012, it will not allow sustainable scale to be achieved. The initial target of a 5.2% reduction relative to 1990 emissions is not designed to solve the problem, but only to begin the process on a global basis. No official targets have yet been set beyond these introductory ones. Even, the “low risk” scenario of 450 ppm identified by the IPCC as “feasible” may not be sustainable.

The preindustrial range of 250 to 290 ppm is the only CO2 concentration which is know to be safe with any degree of certainty. Any official target that exceeds this 420,000 year old level, runs the risk of disrupting critical ecosystem functions, as well as the risk of triggering irrevocable positive feedback mechanisms. The release of high concentrations of methane in permaforst due to global warming, is one such positive feedback loop, as methane is an even more potent greenhouse gas than CO2. Such an event could well push GHG levels beyond maximum scale.

In addition to setting appropriate goals for an international agreement on climate stability, the issues of implementation, monitoring and enforcement are still to be worked out. Experience with the simpler Montreal Protocol to protect the atmospheric ozone layer involved politically motivated reversals, blackmarket smuggling and production of banned substances, and national demands for exemptions to satisfy domestic constituents. Reducing fossil fuel use to a sustainable level requires massive societal change on an unprecedented scale. It is unclear whether global international institutions are up to this unique challenge.

Is Maximum Sustainable Scale Already Exceeded? The fact that current GHG concentrations exceed the 250-290 ppm range that endured for at least 420,000 years prior to the industrial revolution, suggest that at least some of the many and varied ecosystem functions supported by these levels will have been disrupted. Unfortunately, we simply do not have the answer to this critical question. Large scale scientific projects are now underway to provide a better understanding of these complex interrelationships among patterns of climate stability and ecosystem functions.

The conundrum we face is that by the time these relations are well understood, the process of human-induced climate change may already be irrevocable. Typically, civilizations begin to alter and adapt the driving forces that propel them only when there is a catastrophe. In the case of climate change, the inherent time lag between when the irrevocable process has been triggered, and the certain knowledge that catastrophe has occurred, means there would be no opportunity to adapt. Application of the precautionary principle, ensuring that GHG levels do not exceed the historical range of 250-290 ppm, would appear to be the safest approach. This is in sharp contrast to the current approach of risking irrevocable and catastrophic climate change for the sake of continued economic growth.

The international debate about GHG emissions has touched on this question of optimal scale, without using this terminology. A major weakness of the Kyoto Protocol is that it has not attempted explicitly to set a target for GHG emissions that would be safely within a sustainable range – a key component of the concept of optimal scale. Consequently, the current direction of a negotiated solution continues to entail serious risks.

How May Other Scale Concerns Impact Climate Stability? At least two other scale issues are likely to impact climate stability: atmospheric ozone depletion, and energy. Successfully solving the ozone depletion problem may actually contribute to global warming, as ozone depletion servers to cool the atmosphere. Paradoxically, reducing global warming could contribute to restoration of atmospheric ozone, as cooling of the upper atmosphere would slow the depletion of ozone. Continued adherence to the Montreal Protocol is essential to restoring atmospheric ozone levels.

In addition to being affected by other scale issues, climate stability is also vital to many other scale concerns, including impacts on biodiversity loss, coral reefs, fisheries, and various nutrient cycles (see Areas of Concern).

A Scale Perspective. A scale perspective raises the following kinds of issues:

  • What is a sustainable level of GHG emissions in terms of the ongoing capacity of the carbon cycle and Greenhouse Effect to continue providing a stable global climate?
  • What is an optimal level of GHG emissions?
  • What is the process for participation of an informed global public’s priorities in determining optimal scale?
Sustainable vs Politically Acceptable GHG Emission Levels? The focus of the Kyoto discussions has been on obtaining an acceptable international political agreement, rather than addressing the issue of sustainability directly. Sustainability, in terms of maintaining natural capital and especially the critical natural income which it provides for human well-being (see Ecosystem Functions), is viewed in this process as just one of many criteria to be satisfied. Sustainability is rarely regarded in international agreements as an overriding imperative that must be met. As one among many criteria, it is viewed as adjustable and negotiable, something that can be compromised in the difficult and delicate exchanges of international tradeoffs.

The energy issue will have a much greater impact on climate stability. If only a quarter of the known fossil fuel reserves are combusted, concentrations of GHG will exceed the level identified by the IPCC as a “low risk” scenario (450 ppm). At current and projected rates of fossil fuel consumption, this will occur within the next two decades. Yet conversion to alternative fuels remains on a voluntary basis, national governments continue to heavily subsidize fossil fuels, and dedicated plans to make the transition to renewable energy sources are non-existent. Global oil production is expected to peak within the next ten years or so, and natural gas will follow shortly. Coal is the most abundant fossil fuel and will last the longest. But it is also the dirtiest, most CO2 intensive, and most harmful to human and ecosystem health.

This approach is in stark contrast with the concept of maximum sustainable scale as a biophysical process governed by laws of science. By sidestepping this issue of sustainability, international negotiators have sidestepped the issue of what are the most values for humanity''s well-being.

The Kyoto Protocol does not address the issue of what constitutes a sustainable level of GHG emissions from the perspective of interfering with the capacity of ecosystems to provide the life support services that were available prior to the industrial revolution. Rather than focusing on increasing our understanding of what these services are and their importance, the emphasis has been on how to minimize interference with current economic practices. The emphasis has been political and economic rather than scientific in relation to sustainability.

The complexity of the scale climate challenge is considerably greater than for atmospheric ozone depletion – both in terms of the science involved, and political considerations.

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