The Role of Humans in
Climate, Costs and Changes
Inaccuracy in Proxy Data
Prediction and Assumption Error
Costs to humans
Change over time, it’s natural
Abrupt climate events have occurred in the Earth’s climate
•Dansgaard-Oeschger events- rapid warming episodes followed by gradual
cooling events. Closely related to Heinrich events in which the
thermohaline circulation is shut down.
•The little ice age cooling from mid 14th to mid 19th centuries (1300s to
1800’s). Ended the medieval climate optimum (warming). The Little Ice
Age is the peroid from which we are exiting presently.
The younger dryas
Shutdown of the
circulation within 50
year period greatly
Lasted for about
1,000 years and
reversed in about 20
There are uncertainties in gathering data.
Predictions and Assumptions
“IAMs [Integrated Assessment Models] are based on a
multitude of assumptions about the atmosphere and
oceans, land cover and land use, economic growth, fossil
fuel emissions, population growth, technological change,
etc. However, making assumptions about what will happen
in the future is a very difficult task. To begin with there is a
natural human bias that the future will resemble the past. It
is also very difficult to project events such as the energy
crisis of the 1970s or the evolution of computer technology
in the 1980s. The task for model developers is daunting--
they not only must project how climate will change in the
future, but they also must anticipate how society will
evolve regardless of whether the climate changes”
(CIESIN “Integrated Assessment Modeling”).
Example of Uncertainty in Earth’s
The Iris hypothesis proposed by Richard Lindzen states
that the atmospheric water content possesses a “checks
and balances” type system. “Much like the iris in a
human eye contracts to allow less light to pass through
the pupil in a brightly lit environment, Lindzen suggests
that the area covered by high cirrus clouds contracts to
allow more heat to escape into outer space from a very
warm environment” (NASA Earth Observatory).
The debate of this theory lies in the percentage as well
as the albedo and outgoing longwave/ net flux of the
clouds. These assumptions create differing results for
Are Humans or Oil Responsible??
How can we know??
The future of the Earth’s climate is very
uncertain. The ability to predict climate
in future periods is based on
assumptions and data sets riddled with
And what is the cost??
Oil Companies are being targeted as the
scapegoat of Carbon Dioxide emissions
without substantially solid information.
Reductions in oil and increased taxes on
oil, etc. will impact every area of a
countries economy. Shipping, farming, air
A challenge to think about your morning
Chris Scotese, University of Texas, Arlington
Columbia University Center for International Earth
Science Information Network
NASA Earth Observatory
Scientific American Frontiers
Lomborg, Bjorn. “The Skeptical Environmentalist”
World Climate Report