This past week, I was invited to answer a set of questions from a group of high school students [in a Geography Honors class] in Colorado.
I have reproduced them below as others may also be interested in this Q&A. Several years ago, for 2 1/2 years I was the “Weather Guy” on the Kids Only channel at AOL, and enjoyed that activity. This latest Q&A is another opportunity to interact with exceptional young adults!
Question
Is it true that the recent rise in Global Temperature is due to Carbon
Dioxide emmisions?
My Answer
The addition of CO2 to the atmosphere from human activities is a warming influence in terms of reducing the magnitude of heat lost to space over time. However, it is just one of a number of warming influences including from soot (black carbon), ozone, and other aerosol effects.
For those who want to read a summary of these other forcings (including cooling human effects), I recommend the National Academy of Science Report
National Research Council, 2005: Radiative forcing of climate change: Expanding the concept and addressing uncertainties. Committee on Radiative Forcing Effects on Climate Change, Climate Research Committee, Board on Atmospheric Sciences and Climate, Division on Earth and Life Studies, The National Academies Press, Washington, D.C., 208 pp.
Question
If not, what led to this change in temperature?
My Answer
In addition to these human climate forcings, natural climate forcings and feedbacks are also quite important. We need to consider these natural effects as clearly the climate is much more complex than is commonly reported by the media and even the IPCC. For example, the global average temperature anomalies are cooling! See
Question
If the human poulation continues to release carbon dioxide into the atmosphere at this rate, or even at an increased rate, what do you predict the effects on the global temperature will be?
My Answer
Since the CO2 effect is but one of a number of first order climate influences, as discussed above, I have concluded we know much less about the future climate than is claimed by the IPCC and the media. This does not mean we should not be concerned as to how much CO2 we insert into the atmosphere, but the claims that we know its effect on the climate is very much overstated, in my view.
Question
The melting of the polar ice caps and glaciers worldwide has the world significantly alarmed. Can the melting of these formations be contributed to Global Warming?
My Answer
Melting is a response to warming. However, not all glaciers and ice caps are melting. While the Arctic ice, for example, has been decreasing in areal extent; see
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/seaice.anomaly.arctic.png
Antarctic sea ice coverage has not; see
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/seaice.anomaly.antarctic.png
Question
Can these glaciers ever be recovered?
My Answer
Certainly, but it would require colder conditions (particularly in the summer).
Question
In your scientific opinion, does Global Warming exist?
My Answer
Global warming is an oversimplification of the actual behavior of the climate system. See, for example, my weblog post on this topic at
Finally, in terms of climate metrics, I encourage your class to research yourselves from orginal data what is the current status of these metrics. You would be surprised how many of them do not follow the behavior predicted by the multi-decadal global climate model predictions, and being reported in the news.
Thank you for the opportunity to contribute!