No challenge, the president said, "poses a greater threat to future generations than climate change."
The day after the president's speech, the Senate voted 98-1 to "express the sense ... that climate change is real and not a hoax." But the Senate also rejected wording that human activity significantly contributes to climate change.
Sen. Brian Schatz, D-Hawaii, who sponsored the amendment, noted on Twitter that he pulled in "five Republican yes votes and all Democrats. That is a start. Looking forward to finding more common ground."
The president's remarks and the Senate action come on the heels of an announcement from NASA and the National Oceanic and Atmospheric Administration that 2014 was Earth’s warmest year since 1880. The news made headlines and went viral. But as Obama suggested during his speech, some people still deny that human activity is responsible for climate change.
During the past decade, studies have focused on the percentage of climate researchers who believe human activity is responsible for global warming and the percentage of published research papers reaching the same conclusion. In at least two cases, researchers announced that 97 percent of either climate scientists or their research papers supported the notion that human activity was responsible for climate change.
Each time, skeptics challenged the math or the premise of the research. It is now more common to hear broadcasters or politicians generalize: Numerous scientists believe human activity is responsible for climate change, or an overwhelming number of scientists believe human activity is responsible climate change.
Either way, it is clear that an ever-widening chorus of climate researchers believe humans are responsible for climate change. Here is a summary of two pieces of research:
The Science
The basics: The term that often comes up in research is anthropogenic climate change or anthropogenic global warming. Webster’s Dictionary defines anthropogenic as “of, relating to, or influenced by the impact of man on nature.”
A 2010 study: “Expert credibility in climate change,” was published April 9, 2010, in the Proceedings of the National Academy of Sciences of the United States of America. Led by William R. L. Anderegg, then a doctoral candidate in Stanford University's biology department, the work concludes that 97 to 98 percent of climate researchers actively publishing in the field “support the tenets of ACC (anthropogenic climate change) outlined by the Intergovernmental Panel on Climate Change.”
So what is the Intergovernmental Panel on Climate Change and what are these tenets? According to its website, the panel was established in 1988 by the United Nations Environment Programme and the World Meteorological Organization. The organization's mission is to provide a clear scientific view regarding climate change and its potential environmental and socioeconomic impact.
In the 2010 study, Anderegg and his fellow researchers write: “Preliminary reviews of scientific literature and surveys of climate scientists indicate striking agreement with the primary conclusions of the Intergovernmental Panel on Climate Change: anthropogenic greenhouse gases have been responsible for ‘most’ of the ‘unequivocal’ warming of the Earth's average global temperature over the second half of the 20th century.”
Notably, the Intergovernmental Panel’s most recent report (2014) says this: “Anthropogenic greenhouse gas emissions have increased since the pre-industrial era, driven largely by economic and population growth, and are now higher than ever. This has led to atmospheric concentrations of carbon dioxide, methane and nitrous oxide that are unprecedented in at least the last 800,000 years. Their effects, together with those of other anthropogenic drivers, have been detected throughout the climate system and are extremely likely to have been the dominant cause of the observed warming since the mid-20th century.”
About the research: To reach their conclusions, researchers analyzed the work of 1,372 climate scientists.
They took a close look – at both the scientists convinced by the evidence and those unconvinced by the evidence regarding man-made climate change. They decided that a researcher "must have authored a minimum of 20 climate publications to be considered a climate researcher, thus reducing the database to 908 researchers.” While not a comprehensive list, they added, “We have likely compiled the strongest and most credentialed researchers” either convinced or unconvinced.
Results: Those researchers unconvinced of the evidence of man’s contribution to climate change comprise only 2 percent of the top 50 climate researchers as ranked by expertise (number of climate publications), 3 percent of researchers of the top 100, and 2.5 percent of the top 200. In other words, 97 to 98 percent of the top climate researchers are convinced that anthropogenic greenhouse gas is contributing to climate change.
Another study: “Quantifying the consensus on anthropogenic global warming in the scientific literature” was published May 15, 2013, in Environmental Research Letters. It can be found online.The research was led by John Cook of the Global Change Institute at the University of Queensland, Australia. Academics from Australia, the U.S., England and Canada participated in research, examining 11,944 climate abstracts (summaries of research articles) on the topics “global climate change” or “global warming” from 1991 to 2011. They report that in about 66 percent of the research, scientists expressed no position on whether global warming is caused or influenced by human activities.
Why would 66 percent of the research take no position? This is anticipated in consensus situations where scientists focus on questions that are still disputed or unanswered rather than on matters about which everyone agrees, according to the research: “The fundamental science of AGW (anthropogenic global warming) is no longer controversial among the publishing science community and the remaining debate in the field has moved to other topics.”
The conclusion: “Among abstracts expressing a position on AGW, 97.1 percent endorsed the consensus position that humans are causing global warming.”
Criticism: David Friedman, an economist, has taken issue with Cook's findings, questioning the paper's methodology and conclusions.
Popular Opinion
Gallup: When it comes to climate change, Americans can be lumped into three categories, according to an April 2014 Gallup.com report. The largest share –39 percent of adults – are “concerned believers.” They attribute global warming to human activities and are concerned. The next group, “the mixed middle,” takes in about 36 percent of adults, who hold various views. For example, some believe humans are causing the global warming but aren’t worried, according to Gallup. Finally, 25 percent of adults are not worried about global warming.
Pew Research Center: On Jan. 29, Pew published a report on the views of scientists and the general public regarding climate change and other issues. See that report here. In a report published Jan. 15, "How Americans view the top energy and environmental issues," the center found that 71 percent said the country “should do whatever it takes to protect the environment.” But fewer want to pay the bill: 56 percent said “stricter environmental laws and regulations are worth the cost,” and 39 percent said tougher environmental regulations "cost too many jobs and hurt the economy."
Related:
NASA: Arctic snow has thinned significantly