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NewsvineThis year’s Nobel Peace Prize, awarded to former Vice President Al Gore and the United Nations’ Intergovernmental Panel on Climate Change (IPCC), has been 20 years in the making.
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It was 1988 when NASA scientist James Hansen first testified before Congress about the human contribution to climate change and its potentially disastrous consequences. Early on, decision-makers and scientists each responded to research on global warming with a “wait and see” attitude. While many Americans remain skeptical, last week’s award is another sign that it’s time to make up our minds: global warming is real.
At its first meeting in 1990, the IPCC wrote that observed increases in temperature “could be largely due to...natural variability.”
Since then, climate change research has matured, producing a strong body of evidence backed by robust statistics. Successive IPCC congresses have issued ever-grimmer reports about potential environmental consequences.
Compare the language of 1990 to that in this February’s IPCC report: “most of the observed increases in globally averaged temperature is very likely due” to anthropogenic greenhouse gases.
In the language of the Panel, “very likely” is equivalent to 90 percent certainty.
Before its publication, this statement was jointly constructed by IPCC climate scientists from over 100 countries, then independently peer-reviewed by thousands more experts. In effect, the statement itself constitutes a scientific majority opinion.
And yet, Americans remain skeptical.
Our reluctance to accept climate change science has been encouraged by a vocal faction of dissenters, several of whom appeared in the 2007 British film “The Great Global Warming Swindle.”
Figures such as Patrick Michaels (professor emeritus, UVA), Richard Lindzen (Professor of Meteorology, MIT) and Timothy Ball (professor emeritus, University of Winnipeg) have frequently contradicted the majority opinion on climate change — and endured numerous allegations, some confirmed, of receiving funding from petrochemical corporations.
Those who challenge current climate change science claim that major scientific journals refuse to publish any research that opposes IPCC theory. This argument might have at least a kernel of truth: a 2004 study surveyed 928 scientific papers with “global climate change” as keywords. None disagreed with the idea that human actions have contributed to global warming.
Instead of publishing papers, these challengers have communicated largely through op-ed pieces, public addresses and media attention, thereby avoiding scientific peer-review of their own varying theories.
Could the sun’s natural variations in surface temperature — that is, sunspots — have caused climate change? No, the past 20 years of measurements show a correlation, but one that would cause global cooling, not warming.
Satellite measurements — considered more reliable than ground measurement stations that can be influenced by the urban heat island effect — seemed to show cooling, instead of warming. But when engineers corrected for decay in the satellite orbits, measurements confirmed rising temperatures.
Is climate change even our fault? Because global temperatures do not correlate well with historic periods of industrial growth, skeptics have said, the human contribution to climate change must be negligible.
But no model has yet been proposed that matches global temperature rise quite as well as that offered by the scientific majority. Multiple factors, including increases in carbon dioxide, methane and atmospheric aerosols, combined with natural variations in climate, together provide the closest match to empirical climate observations.
For most of the world, alternative explanations have been put to rest. They’ve made up their minds. When will we?