The hockey stick and the climatologist: An evening with Michael Mann

If you chart global temperature changes in last 1,000 years or so, the resulting graph looks like a hockey stick.

Climatologist Michael Mann published that conclusion in 1998, and he’s still explaining what the data means and how a simple graph became a controversial icon in the debate over whether human-caused climate change is happening.

On April 3, he spoke at Warren Wilson College, offering about 60 attendees a glimpse into his new book, The Hockey Stick and The Climate Wars. “I thought if I could write the book, I could explain why people discredit science,” said Mann. “We have to be more effective in presenting scientific truth.”

Since publishing the Hockey Stick in 1998, he has had his email hacked and picked apart for the purpose of incriminating and discrediting his studies; his family has received death threats, which was apparent at the presentation: A small security team escorted Mann.

In the first part of his presentation, the author discussed his global-warming studies and the creation of the infamous graph, which first appeared in Nature magazine. The Hockey Stick, as he explains in his new book, is “a simple, easy-to-understand graph my colleagues and I constructed to depict changes in Earth’s temperature back to A.D. 1000.” The hockey-stick shape that emerged illustrates little change in global temperature through the 19th century—the shaft of the hockey stick—until the 20th century, where the graph takes a sharp upturn—the blade.

The data used to create the graph came from natural samples and instrumental temperature recordings across the Northern Hemisphere, Mann explained. For the past century, technology has granted us minor variability, and far more accuracy, in temperature recordings. But scientists must also look towards paleo-climatologists to analyze natural samples, or “proxy records,” that can give us an idea of what the climate was like a thousand years ago; proxy records include samples taken from ice cores, tree rings, corals, deep ocean sediments and lake sediments.

In addition to building his studies from this data, Mann also noted his use of climate models in order to recognize patterns that have been occurring on our planet for millions of years. Certain variables, such as the planet’s relative position to the sun, are taken into account and subject to in-depth analysis in a climate model, allowing for a more rounded understanding of Earth’s climate history.

Mann also addressed how to slow the process of global warming: Bring our CO2 emissions down by half of the current output and keep the global temperature below 3 degrees Centigrade. To do this, he advocates setting up more corporate incentives to decrease carbon emissions and getting people to make a more conscious effort to decrease CO2 concentrations relative to transportation, deforestation in the tropics, individual energy use and the industrial and manufacturing sector of the world economy.

What Mann ultimately concluded from his research is a strong correlation between the rise in CO2 emissions in the 20th century and the concurrent rise of global temperatures. In his book he states this determination bluntly: “Humans, through extensive fossil fuel burning and other practices, have upset that natural balance, causing CO2 concentrations to rise steadily. … It will potentially reside there for centuries.”

Among those looking to discredit human-cause climate change is Richard Lindzen, who argues that CO2 concentrations are highly overestimated in climate models. Mann cites a report in which Lindzen states “that a doubling of CO2 concentrations will consequently only raise global average temperatures by roughly 1 degree C.”

However, Mann counters, “The diversity of evidence from the paleo-climate and modern climate record suggests that less than 2 degrees warming for CO2 doubling is highly unlikely.”

During the course of his presentation, Mann provided more arguments to such counter-arguments, and yet, he noted, there’s a stunning lack of action on the part of the government to acknowledge our world-culture’s “addiction to fossil fuels.” The author likened his personal experience to swimming upstream against a current of those who have vested interests in the fossil-fuel industry.

Among scientists, there’s little debate, Mann said. In 2006, the Intergovernmental Panel on Climate Change held a meeting in Madrid, Spain, for the purpose of finalizing its Second Assessment Report concerning human impact on Earth’s climate; it took two days for the panel members to agree on the statement, “the balance of evidence suggests a discernible human influence on the climate.”

The only part of the state that was being debated was the choice of the word “discernible.”

This level of concern on the subject of global warming is what many deem “the politicization of science,” which has deep implications regarding the way 21st century civilians are being made to interpret scientific fact, Mann argued. Hundreds of media outlets associated with major fossil fuel suppliers print stories that discredit human-caused global warming by citing select statistics and facts, taking them out of their original context. In this way, people are often led to believe that climatologists who support the global-warming theory are conspiring to cause unnecessary public panic for the sake of an underlying political agenda, he continued.

Mann labeled attempts to deny climate studies as “the climate wars,” waged between science and politics, wars that don’t abide by what he calls the “good-faith rules” of scientific argument.

But he sees room for hope. Research and technology of solar energy is a fast growing field in the worldwide scientific community, specifically in China, and contributes towards building the bridge that will lead us away from our compulsive consumption of fossil fuels, Mann said. If we can meet this goal of reducing greenhouse gas emissions within the next two decades, he believes, there will be hope for future generations who will inherit the responsibility of stewardship on Earth.

“We’re talking about decisions that are going to effect the lives of our children and our children’s children.”


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