For well over a decade, the world has debated climate policy and now the United States Congress is poised to take up legislation to cap carbon dioxide (CO2) emissions, the Supreme Court has ruled that EPA had the authority to regulate CO2, and many states are moving to establish their own restrictions on emissions. Underlying all of these actions are perceptions about the certainty of scientific information about climate change and the human effect on the climate. There remain many questions over what science does and does not tell us about human influence on the climate and the potential impacts of global warming.
We believe that sound public policy must be based on a sound factual foundation. This report of the George C. Marshall Institute offers perspective on some of the fundamental questions concerning the science of climate change. It provides clear and succinct summaries of what we know and do not know about our climate system and the human influence on it.
As the public considers the risks, consequences, and costs of responding to climate change, we hope this report will be a valuable basic reference and help policy makers to better match actions with the state of knowledge. Only by doing that can policy makers limit unintended consequences and not jeopardize the economic well being of this and future generations.
This is the third edition of Climate Issues and Questions Like the others, it addresses fundamental questions about climate change by summarizing the best available scientific information. The information provided is not intended to rebut claims about human impacts on climate or the potential for adverse impacts later this century. It is intended to separate fact from speculation and to demonstrate that while concerns are legitimate, there is not a robust scientific basis for drawing definitive and objective conclusions about the extent of human influence on climate, past, present, or future. The presentation moves from what is well established, to what is not certain, to what is unknown, and what may be unknowable.
Climate Issues and Questions considers 30 important questions, including:
- How is the scientific consensus on climate change established and what does it mean?
- Is the Arctic is warming faster than the rest of the Earth?
- Are satellite and surface temperature trends different?
- What influence does the Sun have on global climate?
- What is the basis for forecasts of large temperature increases and adverse climate impacts between 1990 and 2100?
- What do we know about the extent of human influence on climate? To what extent has the temperature increase since 1975 been the result of human activities?