Top Ten Origins: Climate Change Written by Dr. Sam White Narrated by Dr. Patrick Potyondy
There is perhaps no greater challenge facing humanity (and all species on the planet) than climate change.
Yet, despite an almost unprecedented scientific consensus on the issue, there remains a vocal
and politically connected minority who deny the existence of any meaningful change.
The data speaks for itself.
Carbon dioxide in the atmosphere, just shy of 400 ppm (parts per million), is at by far
the highest level for 650,000 years.
Global temperature is up 1.4 degrees since 1880, and glaciers are visibly melting.
And the list of climate change indicators goes on.
Here are Origin's top ten facts about climate change.
Number 1: Global climate has changed a lot over Earth’s history.
2.5 billion to 543 million years ago, during the Proterozoic age, global temperatures
plunged at least twice, and ice may have covered the planet.
At other times in the Earth's history, climate was much warmer, with no ice caps or glaciers at all
Many natural forces contributed to these changes over geologic time, including variations in
solar output, the configuration of continents, ocean currents, and volcanic eruptions.
What is different about current climate change is that it is anthropogenic (that is, man-made).
Number 2: Humans evolved during the Pleistocene Epoch, a cold time in Earth history marked by long
ice ages and shorter, warmer interglacial periods.
The rise of agriculture and civilizations began around 11,000 years ago with the start
of the most recent interglacial, which we call the Holocene.
Long cycles in the Earth’s orbit have driven these glacial-interglacial cycles.
These cycles do not, however, explain recent global warming.
Number 3: Global climate has varied during the Holocene.
Temperatures were probably warmest more than 6,000 years ago, and then began to gradually fall.
The coldest period in the last few thousand years was the “Little Ice Age” that started
around 1400 CE.
This natural cooling was much smaller than projections for warming in the 21st century.
Recent historical research implicates the Little Ice Age in famines, rebellions, and
wars particularly in the late 1500s and 1600s.
Number 4: Entering the Anthropocene.
Starting with Britain’s Industrial Revolution around 1800, more countries began to burn
coal and later oil and gas for heating and energy.
By the late 1800s, emissions from burning fossil fuels—and from deforestation, agriculture,
and livestock—began to change global climate, bringing the Little Ice Age to an end.
Industrial technologies also sped up the global extraction of resources and movement of people,
plants, and animals across the planet.
The accelerating human impact on the environment has led some geologists to argue we have
entered the Anthropocene, or “Human Age.”
Number 5: By the mid-1800s, scientists began to discover how burning fossil fuels could change global climate.
In 1859, John Tyndall proved experimentally that carbon dioxide and water vapor trapped
heat by letting in shortwave radiation and reflecting back long-wave.
In 1896, Svante Arrhenius calculated that burning coal could substantially raise average
global temperatures.
In the late 1930s, British engineer Guy Stewart Callendar observed that temperatures were
already rising and pointed to more greenhouse gasses as the cause.
Number 6: From the 1950s to 1990s, new discoveries gradually turned anthropogenic climate change from a
tentative theory into a firm scientific consensus.
Researchers including Roger Revelle and Charles Keeling demonstrated that carbon dioxide levels
in the atmosphere were rising.
Better reconstructions of past climate—including from cores drilled deep into glaciers and
ice sheets—have made it clear that greenhouse gasses drove rapid changes in global climate.
Faster computers and better climate models have improved forecasts and emphasized that
current warming must be anthropogenic, not part of natural cycles as was the case in the past.
Number 7: Even as evidence accumulated and climate scientists grew more alarmed, fossil fuel industries
and allied lobbyists and think tanks worked to obscure and deny the science behind global warming
As investigated by Naomi Oreskes and Erik M. Conway in Merchants of Doubt (2010),
these efforts drew on many of the same tactics—and sometimes the same experts—employed by the
tobacco lobby to deny links between smoking and cancer.
By the 2000s, virtually all climate scientists agreed that human greenhouse gas emissions
were changing the climate, but many Americans remained confused or uncertain.
Number 8: Climate change gradually gained attention as a major international issue.
Since 1988, an Intergovernmental Panel on Climate Change (IPCC) has brought together
global experts to report consensus measurements, estimates, and impacts of climate change.
The 1997 Kyoto Protocol set the first international greenhouse gas targets.
Number 9: The Earth is already warming.
The ten hottest years since instrumental measurements began have all occurred since 1998.
The IPCC projects that without urgent reductions in greenhouse gas emissions, warming will
exceed 2˚C (3.6˚F) by 2100, unleashing potentially catastrophic heat waves, droughts, and sea level rise.
In the last decade the U.S. and Europe have reduced emissions, but increases in China
and India have been faster and more than offset reductions elsewhere on the planet.
Number 10: What climate change means for different people depends on location and circumstances.
Regions threatened by rising sea levels, bigger storms, floods, and droughts could be more at risk.
Poorer nations, for lack of resources, are more likely to struggle to adapt and build
resilient economies and infrastructures.
Historical examples suggest climate change will aggravate political instability, poverty, and conflict.
Already some analysts have pointed to global warming and severe droughts in Syria and around
the world as a contributing factor in the 2011 Arab Spring and Syrian civil war.
The same has been said of the fighting in Sudan and Darfur.
And with sea levels rising, countries like the Maldives (in the Indian Ocean) and Kiribati
(in the Pacific) may simply disappear under water, leaving their populations refugees.
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Narration by Patrick Potyondy, PhD Based on original text by Dr. Sam White Professor of History
The Ohio State University "Top Ten Origins: Climate Change"
Filming by The Ohio State University College of Arts & Sciences Technology Services
With special thanks to Paul Kotheimer Production and editing by Laura Seeger The Goldberg Center, Dept. of History