About & Overview: The Climate Science
According to peer-reviewed studies on climate change, it is “very likely” that human activity is warming the planet at a dangerous rate. While the media run articles on the issue, sometimes attention is also given to those who deny the scientific evidence, and the comment sections of online media outlets are riddled with opinions claiming that climate change is not happening.
A minority of people claiming to be climate experts question climate science. When reviewing information presented by so-called experts on climate change, ask yourself:
- Has their work related to climate change been peer-reviewed?
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Where are they receiving their funding? Is it a university or government agency? Or is it an industry, such as oil, that will lose profits during the transition to a low-carbon economy? Is it a think tank or PR firm that is being funded by an industry afraid of losing profits?
For more on climate change in the media visit Beyond the Ivory Tower: The Scientific Consensus on Climate Change by Naomi Oreskes in Science Magazine.
More information on the organized campaign to heighten doubts about climate science, and ensure the widest audience for the handful of contrarian scientists, is available online at ExxonSecrets, DeSmogBlog and in their recent book Climate Cover-Up. Most Cited Authors on Climate Change, compiled by Jim Prall, lists large numbers of climate scientists and names who have signed petitions arguing for or against policies to cut greenhouse gases, ranking them by their publication record in the peer-reviewed literature.
For more on the Climate Science:
The Intergovernmental Panel on Climate Change (IPCC) is the international science body that reviews and assesses the most recent scientific, technical and socio-economic information on climate change. More than 2,500 scientists from 130 countries contribute to the IPCC on a voluntary basis. According to the IPCC, which won the Nobel Peace Prize in 2007, greenhouse gas emissions from human activity are responsible for most of the increase in global average temperature with greater than 90 percent certainty (IPCC 2007a).
Scientific methodology is a rigorous process. Objectivity is at its very core and credibility lies in citing work published only in peer-reviewed journals. The entire scientific method is based on conducting research which can be replicated by peers in order to check accuracy and objectivity.
Review is an essential part of the IPCC process, to ensure an objective and complete assessment of current information. Differing viewpoints existing within the scientific community are reflected in the IPCC reports.
Probability of occurrence:
Virtually certain - more than 99%
Extremely likely - more than 95%
Very likely - more than 90%
Likely - more than 60%
More likely than not - more than 50%
Unlikely - less than 33%
Very unlikely - less than 10%
Extremely unlikely - less than 5%
Greenhouse gases, such as water vapour, carbon dioxide, methane and ozone, make up a tiny fraction of the earth’s atmosphere. They block some of the sun’s energy from escaping into space. Without them, the average global temperature would be minus 18°C. Natural greenhouse gases are generated by water vapour, decaying bio matter, fires and volcanic activity. Human Beings produce greenhouse gases from burning carbon that has been locked in the earth for millions of years (fossil fuels), and generating methane from landfills and agribusiness.
Preindustrial levels of carbon dioxide were 280 parts per million (ppm). These levels are currently at 387 ppm.
According to the IPCC, 450 ppm of carbon dioxide will lead to dangerous global warming. The IPCC warns that unless greenhouse gas emissions are reduced by 20 to 40 percent of 1990 levels by 2020 and 80 to 90 percent by 2050, the planet will reach a tipping point where positive feedback loops will lead to runaway global warming. For example, melting arctic ice will unlock methane that has been stored in polar cap for hundreds of thousands of years, which will lead to greater warming. If a tipping point is reached, the IPCC estimates that the global temperature will increase by 5.8°C by the end of this century.
The planet’s climate has changed throughout its history. The IPCC estimates that the average global surface temperature is likely to increase by between 1.4°C and 5.8°C by 2100, depending on how fast world governments are willing to act. Geologically speaking, a 5.8°C increase by 2100 is very fast and catastrophic. Some species cannot tolerate sudden changes in climate. Their demise impacts those species that rely on them for their survival, right up the food chain. As a result, climate change will seriously compromise the planet’s biosphere. Other current and projected consequences of swift climate change include:
- Greater acidity in oceans due to their absorption of carbon dioxide, destroying critical ecosystems and species such as coral reefs and hard shell sea life. This could lead to the collapse of entire marine ecosystems.
- Disappearing glaciers, which millions rely on for drinking water.
- Melting continental ice sheets from Greenland and Antarctica, leading to massive flooding along coastal areas, displacing millions of people.
- Increases in infestations due to warmer temperatures such as the mountain pine beetle, which has destroyed more than 300,000 hectares of lodgepole pine forests in the British Columbian interior since 2007.
- Increases in viruses.
- Increases in drought and famine, particularly in areas near the equator.
- More extreme weather events.
- Wetter weather in some regions, such as Canada.
The Intergovernmental Panel of Climate Change is the leading body for the assessment of climate change, established in 1988 by the United Nations Environment Programme (UNEP) and the World Meteorological Organization (WMO) to provide the world with a clear scientific view on the current state of climate change and its potential environmental and socio-economic consequences.
Since its inception the IPCC has issued four assessment reports.
The First Assessment Report (FAR, 1990) supported the establishment of the United Nations Framework Convention on Climate Change (UNFCCC) at the United Nations Conference on Environment and Development (UNCED, commonly known as “The Earth Summit”) held in Rio de Janeiro, Brazil, in 1992. The UNFCCC treaty serves as the foundation of international political efforts to combat global warming.
The Second Assessment Report (SAR, 1996), along with additional special materials on the implications of various potential emission limitations and regional consequences, provided key input to the negotiations that led to the adoption of the Kyoto Protocol to the UNFCCC in 1997. The Kyoto Protocol is an international agreement that establishes binding targets for reducing the heat-trapping emissions of developed countries.
The Third Assessment Report (TAR, 2001) concluded that temperature increases over the twenty-first century could be significantly larger than previously thought, and that the evidence for human influence on climate change is stronger than ever.
The Second Assessment Report (SAR, 1996), along with additional special materials on the implications of various potential emission limitations and regional consequences, provided key input to the negotiations that led to the adoption of the Kyoto Protocol to the UNFCCC in 1997. The Kyoto Protocol is an international agreement that establishes binding targets for reducing the heat-trapping emissions of developed countries.
The Third Assessment Report (TAR, 2001) concluded that temperature increases over the twenty-first century could be significantly larger than previously thought, and that the evidence for human influence on climate change is stronger than ever.
The Fourth Assessment Report (AR4, 2007) concluded that human activity is responsible for most increases in global temperature. Since the IPCC considers only published, peer-reviewed science in its assessments, the AR4 did not examine any research published after July 2006. In the years since then, a significant body of new peer-reviewed science has been published, much of which is relevant to policy decisions that will be made before the next IPCC assessment, due in 2014. A brief overview of some key new findings is provided in the IPCC report:
For more of an overview of the IPCC, visit
The IPCC: Who Are They and Why Do Their Climate Reports Matter?, by the Union of Concerned Scientists
Intergovernmental Panel of Climate Change - Frequently Asked Questions
Pew Centre - Global Warming Basics
The Encyclopedia of Earth - Climate Change (collection)
The Royal Society - Facts and fictions about climate change
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