2-1 The Climate System

2-1-1 The "Discovery" of Climate Change

Photo by Todd Klassy

Due to human activity -particularly the large scale consumption of fossil fuel after the industrial revolution- climate change, primarily observed as global warming, has become ever more prominent in the last few decades. What is the background for this phenomenon and how has society dealt with it? Climate change is one of the most widely researched aspects of sustainability and has both created international agreements, such at the Kyoto Protocol coming into effect in February 2005, and significantly influenced national policy and corporate strategy around the world. American historian of science, Spencer R. Weart, provides some background on how global warming has emerged as a key issue in modern society in his book, The Discovery of Global Warming.

Table 1: How Global Warming Was "Discovered"
Source' Adapted from The Discovery of Global Warming, Timeline of Milestones[1]

Year

Milestone
1800-1870 Level of carbon dioxide gas (CO2) in the atmosphere, as later measured in ancient ice, is about 290 ppm (parts per million).
First Industrial Revolution. Coal, railroads, and land clearing speed up greenhouse gas emission, while better agriculture and sanitation speed up population growth.
1896 Arrhenius publishes first calculation of global warming from human emissions of CO2.
1870-1910 Second Industrial Revolution. Fertilizers and other chemicals, electricity, and public health further accelerate growth.
1920-1925 Opening of Texas and Persian Gulf oil fields inaugurates era of cheap energy.
1930s Global warming trend since late 19th century reported.
Milankovitch proposes orbital changes as the cause of ice ages.
1938 Callendar argues that CO2 greenhouse global warming is underway, reviving interest in the question.
1960 Downturn of global temperatures since the early 1940s is reported.Keeling accurately measures CO2 in the Earth’s atmosphere and detects an annual rise. The level is 315 ppm.
1965 Boulder meeting on causes of climate change, in which Lorenz and others point out the chaotic nature of climate system and the possibility of sudden shifts.
1966 Emiliani’s analysis of deep-sea cores shows the timing of ice ages was set by small orbital shifts, suggesting that the climate system is sensitive to small changes.
1967 Manabe and Wetherald make a convincing calculation that doubling CO2 would raise world temperatures a couple of degrees.
1968 Studies suggest a possibility of collapse of Antarctic ice sheets, which would raise sea levels catastrophically.
1970 First Earth Day. Environmental movement attains strong influence, spreads concern about global degradation.
1971 SMIC conference of leading scientists reports a danger of rapid and serious global change caused by humans, calls for an organized research effort.
1972 Ice cores and other evidence show big climate shifts in the past between relatively stable modes in the space of a thousand years or so, especially around 11,000 years ago.
1973 Oil embargo and price rise bring first “energy crisis”.
1977 Scientific opinion tends to converge on global warming, not cooling, as the chief climate risk in next century.
1979 U.S. National Academy of Sciences report finds it highly credible that doubling CO2 will bring 1.5-4.5oC global warming.Election of Reagan brings backlash against environmental movement. Political conservatism is linked to skepticism about global warming.
1982 Greenland ice cores reveal drastic temperature oscillations in the space of a century in the distant past.Strong global warming since mid-1970s is reported, with 1981 the warmest year on record.
1983 Reports from U.S. National Academy of Sciences and Environmental Protection Agency spark conflict, as greenhouse warming becomes prominent in mainstream politics.
1985 Villach conference declares consensus among experts that some global warming seems inevitable, calls on governments to consider international agreements to restrict emissions.Broecker speculates that a reorganization of North Atlantic Ocean circulation can bring swift and radical climate change.
1988 News media coverage of global warming leaps upward following record heat and droughts plus testimony by Hansen.Toronto conference calls for strict, specific limits on greenhouse gas emissions. Intergovernmental Panel on Climate Change (IPCC) is established.
Level of CO2 in the atmosphere reaches 350 ppm.

2-1-2 IPCC: Consensus and Criticism

Photo by Kevin Cameron

In 1988, the United Nations established the International Panel on Climate Change (IPCC) to evaluate climate change and the extent of human contribution to it. Thanks to one of the broadest international collaborative efforts in science and politics, three IPCC reports have been published in 1990, 1996, an 2001. A fourth report is due in 2007.

Important Findings of IPCC Third Assessment Report on Climate Change (2001)

  1. The global average surface temperature has increased over the 20th century by about 0.6oC.
  2. Temperatures have risen during the past four decades in the lowest 8 kilometers of theatmosphere.
  3. Snow cover and ice extent have decreased.
  4. Global average sea level has risen between 0.1 and 0.2 meters during the 20th century and ocean heatcontent has increased since the late 1950s.
  5. Concentrations of atmospheric greenhouse gases and their radiative forcing have continued to increaseas a result of human activities.
  6. Anthropogenic aerosols are short-lived and mostly produce negative radiative forcing (cooling ratherthan warming).
  7. Natural factors have made small contributions to radiative forcing over the past century.
  8. Confidence in the ability of models to project future climate has increased.
  9. There is new and stronger evidence that most of the warming observed over the last 50 years isattributable to human activities.
  10. By 2100, carbon cycle models project atmospheric CO2 concentrations of 540 to 970 ppm, the globalaverage surface temperature is projected to increase by 1.4 to 5.8oC. Global mean sea level is projectedto rise by 0.09 to 0.88 meters.
  11. The effect of anthropogenic climate change will persist for many centuries.

The IPCC is not without its critics. The Marshall Institute, a United States based conservative think tank, has raised some of the most often cited criticisms, a few of which are shown in Table 3 along with the IPCC response.

Criticisms of the IPCC and IPCC Response.
The global warming trend of the end of the 19th century and beginning of the 20th century are simply a natural recovery from a small ice age. It is not caused by human activity. Using the current models, there is no way to show a temperature rise of more than 0.5 degrees each century without increased greenhouse gas, leading to the conclusion that greenhouse gases arethe cause of current warming. Furthermore, the accuracy of the computer models used to create this estimate is high and the results reliable.Also, Nozawa and other scientists at the National Institute for International Studies in Japan have run simulation tests for the 20th century, taking into account almost all known radiative forcing. Current warming cannot be explained without the calculating in green-house gases from human activity.
The data used by the IPCC was mainly gathered from land-surface measurements above developed nations on the European and American continents. The data does not sufficiently take into account the other 70% of the earth's surface. Judgments made on global temperature with such data are not accurate. It is true that there is little data for areas over the ocean, and the IPCC is currently using slightly insufficient data the estimate the current global temperature, while taking into account the impact of urbanization impacts and data inaccuracy. However, since the 1980s, satellite measurements have been used and data insufficiencies have been decreasing.
Solar activity has been identified as a contributor to global warming. While the IPCC suggests a mechanism that amplifies the effect of solar activity on climate change, this position is not supported by sufficient scientific discussion and observations. Sun spots and other changes in solar activity affecting climate change account for less than 1% of changes in the overall solar output and thus make up too small a part of solar radiation to significantly influence temperature change.Computer simulations taking into account changes in solar activity show that such activity may contribute to changes in surface temperature, but current warming cannot be accounted for without the inclusion of greenhouse gas increases.

2-1-3 Society's Reaction to Climate Change

Criticism of IPCC findings focuses mainly on the uncertainty in predicting the outcome of climate change, whereas the fact that global climate change is indeed occurring has gained broad scientific and increasingly political consensus. Effects of global warming and frequent natural calamities observed recently, due to freak weather patterns, have made climate science and predictions an issue of great social and political concern. Politically, Russia's ratification of the Kyoto Protocol allowed it to come into effect on February 16th, 2005 -more than seven years after the Kyoto Conference.

Wikipedia: 2005 G8 Summit

At the 2005 G8 Summit, the heads of science councils from eleven countries (Japan, Brazil, Canada, China, France, Germany, India, Italy, Russia, England, and the United States) released the following joint declaration (PDF) urging broad international action on climate change.[2]

Climate change is real
There will always be uncertainty in understanding a system as complex as the world's climate. However there is now strong evidence that significant global warming is occurring. The evidence comes from direct measurements of rising surface air temperatures and subsurface ocean temperatures and from phenomena such as increases in average global sea levels, retreating glaciers, and changes to many physical and biological systems. It is likely that most of the warming in recent decades can be attributed to human activities

Conclusion
We urge all nations, in line with the UNFCCC principles, to take prompt action to reduce the causes of climate change, adapt to its impacts and ensure that the issue is included in all relevant national and international strategies.

Following this advice of the global scientific community, the chairman of the 2005 Gleneagles G8 Summit included the following response in the climate change portion of his summit declaration:[3]

We were joined for our discussion on climate change and the global economy by the leaders of Brazil, China, India, Mexico, and South Africa and by the heads of the International Energy Agency, International Monetary Fund, United Nations, World Bank, and the World Trade Organization.

We have issued a statement setting out our common purpose in tackling climate change, promoting clean energy and achieving sustainable development.

All of us agreed that climate change is happening now, that human activity is contributing to it, and that it could affect every part of the globe.

We know that, globally, emissions must slow, peak and then decline, moving us towards a low-carbon economy. This will require leadership from the developed world.

Many of the scientists taking part in this Science on Sustainability report identified climate change as a grave risk currently facing humanity. This urgency, and the importance of appropriate risk management, is further evident in the G8 Summit declaration.

However, it is not yet clear through scientific research to what degree current climate changes are natural, and how much of it results from human activity, such as releasing CO2 through the burning of fossil fuels. Likewise, science is unable to predict the exact extent of the dangers and risks involved with increasing concentrations of greenhouse gasses. Despite these uncertainties, accumulated scientific climate change knowledge indicates that the following statements are all but certain:

  1. CO2 is a greenhouse gas (leading to increased atmospheric temperature).
  2. Atmospheric concentrations of CO2 are rising due to the burning of fossil fuels.
  3. As atmospheric concentrations of CO2 rise, global mean temperature can also be expected to rise.
  4. There has been a rapid increase in the global mean temperature since 1980.

Given these scientific observations, we must ask ourselves, “How should we most effectively respond to climate risks?” The precautionary principle is a fundamental guide for decision-making, but at the same time, the socio-economic impacts of any decision must also be taken into account through a risk-benefit analysis. With uncertainties inherent in both approaches, attempting to find a balance between the two seems to be the most realistic option.

Sources

  1. Weart, Spencer R., The Discovery of Global Warming, (Cambridge, MA: Harvard University Press, 2004)
  2. Joint Academy G8 Statement. http://www.academie-sciences.fr/actualites/textes/G8_gb.pdf (accessed November, 2005)
  3. G8 Presidency. http://www.g8.gov.uk/ (accessed November, 2005)