Climate Change: The Evidence and Our Options
Lonnie G. Thompson
Ohio State University
Abstract
Glaciers serve as early indicators of climate change. Over the last 35 years, our research team has recovered ice-core records of climatic and environmental variations from the polar regions and from low-latitude high-elevation ice fields from 16 countries. The ongoing widespread melting of high-elevation glaciers and ice caps, particularly in low to middle latitudes, provides some of the strongest evidence to date that a large-scale, pervasive, and, in some cases, rapid change in Earth’s climate system is underway. This paper highlights observations of 20th and 21st century glacier shrinkage in the Andes, the Himalayas, and on Mount Kilimanjaro. Ice cores retrieved from shrinking glaciers around the world confirm their continuous existence for periods ranging from hundreds of years to multiple millennia, suggesting that climatological conditions that dominate those regions today are different from those under which these ice fields originally accumulated and have been sustained. The current warming is therefore unusual when viewed from the millennial perspective provided by multiple lines of proxy evidence and the 160-year record of direct temperature measurements. Despite all this evidence, plus the well-documented continual increase in atmospheric greenhouse gas concentrations, societies have taken little action to address this global-scale problem. Hence, the rate of global carbon dioxide emissions continues to accelerate. As a result of our inaction, we have three options: mitigation, adaptation, and suffering.
INTRODUCTION
Climatologists, like other scientists, tend to be a stolid group. We are not given to theatrical rantings about falling skies. Most of us are far more comfortable in our laboratories or gathering data in the field than we are giving interviews to journalists or speaking before Congressional committees.
Why then are climatologists speaking out about the dangers of global warming? The answer is that
virtually all of us are now convinced that global warming poses a clear and present danger to civilization (‘‘Climate Change,’’ 2010).
That bold statement may seem like hyperbole, but there is now a very clear pattern in the scientific evidence documenting that the earth is warming, that warming is due largely to human activity, that warming is causing important changes in climate, and that rapid and potentially catastrophic changes in the near future are very possible. This pattern emerges not, as is so often suggested, simply from computer simulations, but from the weight and balance of the empirical evidence as well.
THE EVIDENCE
Figure 1 shows northern hemisphere temperature profiles for the last 1,000 years from a variety of high resolution climate recorders such as glacier lengths (Oerlemans, 2005), tree rings (Briffa, Jones, Schwerngruber, [sorry, please go to link below to see the figure which is more horrifying that Al Gore on top of a fork lift, way more]
Link to full paper: http://researchnews.osu.edu/archive/TBA--LTonly.pdf
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