CLIMATE CONSENSUS: STRONGER EVERYDAY

Scientists did not simply "jump" to the conclusion that climate change is real and significant, but this result came from years of careful research and review by respected scientific bodies, including the American National Academy of Science. Here is how discussion of climate change developed over the years.

 

1990: Climate change could be happening

In 1990, the Intergovernmental Panel on Climate Change (IPCC) produced its First Assessment Report, which evaluated all research on the subject of climate change and led to the conclusion that it "could be"[1] happening.

1995: The balance of evidence suggests a human influence on the climate

In 1995, the IPCC submitted its Second Assessment Report in light of new evidence and concluded that: "The balance of evidence, from changes in global mean surface air temperature and from changes in geographical, seasonal and vertical patterns of atmospheric temperature, suggests a discernible human influence on global climate."[2]

2001: New and stronger evidence for increasing surface temperatures

In 2001, the IPCC's Third Assessment Report (TAR) stated that "new and stronger evidence" implies that "there has been a generally increasing trend in global surface temperature over the 20th century."[3]

2005: The scientific understanding is sufficiently clear to justify action

Four years later, 11 National Academies of Science, which included the U.S., agreed in 2005 that "The scientific understanding of climate change is now sufficiently clear to justify nations taking prompt action."[4]

2006: The risks are more serious than previously thought

Then in 2006, the U.K.'s Department of Environment, Food, and Rural Affairs compared recent evidence with the results of the TAR and concluded that "there is greater clarity and reduced uncertainty about the impacts of climate change across a wide range of systems, sectors and societies. In many cases the risks are more serious than previously thought."[5]

 

Bottom line: Over two decades, the scientific opinion on climate change has become a solid consensus, which gets stronger everyday.

 

---

[1] IPCC First Assessment Report, 1990. http://www.ipcc.ch/pub/reports.htm

[2] IPCC Second Assessment Report, 1995. http://www.ipcc.ch/pub/reports.htm

[3] IPCC Third Assessment Report, 2001. http://www.ipcc.ch/pub/reports.htm

[4] Joint Statement of National Academies, 2005. http://nationalacademies.org/onpi/06072005.pdf

[5] The UK's Department of Environment, Food, and Rural Affairs. "Avoiding Dangerous Climate Change," Conference Report, 2006. http://www.defra.gov.uk/environment/climatechange/internat/pdf/avoid-dangercc-execsumm.pdf