Climate Change · Part One
Climate Change · Part Two
Climate Change 2 Syllabus
1.0 - The Ice Ages: An Introduction
2.0 - Discovery of the Ice Ages
3.0 - Ice Age Climate Cycles
4.0 - Climate Through the Last 1000 Years
5.0 - Determining Past Climates
6.0 - Causes of Millennial-Scale Change
7.0 - Climate and CO2 in the Atmosphere
8.0 - Recent Global Warming
9.0 - Climate Change in the Political Realm
10.0 - The Link to the Ozone Problem
11.0 - Future Energy Use
12.0 Outlook for the Future
· 12.1 - The Humpty-Dumpty Problem
· 12.2 - Lurking Monsters
· 12.3 - Strategies for Coping
· 12.4 - Strategies for Tech. Fixes
· 12.5 - Business as Usual
· 12.6 - The Good News
· 12.7 - The Role of Research
Introduction to Astronomy
Life in the Universe
Glossary: Climate Change
Glossary: Life in Universe
Predictions of changes in river runoff patterns in Europe due to climate change. The red and orange regions represent areas where the changes due to global warming
will be significant (From: Hulme et al., 1999).
The Future of Climate Research
We would like to know more about the risks of continued global warming, and of environmental change in general, brought about by human impact. It is useful to ask how warming will factor together with other environmental changes like over-fishing in reefs, overuse of water resources, and fragmentation of ecosystems? Experts from different fields — geophysics, social sciences, ecosystems, agriculture — have to come together to discuss what is known, what is knowable, and what the possible ramifications of change are. Of particular interest are studies in regional impact, because people are interested in how the changes affect their own livelihood and their standard of living. The potential impacts on the various nations have to be worked out, since when negotiating at the U.N., each would want to know whose arguments are scientific and whose are purely serving a particular nation's self-interest.
Economics and the Environment
In order to be useful, predictions of climate conditions have to lead to statements about possible environmental and economic consequences. As a step in this direction, Dr. Mike Hulme and his collaborators from various climate centers in the UK have made an effort to assess the relative impacts of human-induced climate change and natural climate variability, on a regional scale, using both climate simulations and environmental response models. Their paper (Hulme et al., 1999) compared the effects of natural climate variability (on 30-year time-scales) and projected range of human-induced climate change on river runoff and agricultural potential in Europe.
The most significant human-induced impacts, according to Hulme et al., will be experienced throughout Scandinavia, especially in the far north, and also Northern Scotland (and the Faroes and Orkneys). Another zone of expected high impact surrounds the Mediterranean Sea, from eastern Spain to southern Italy, to Greece and southern Turkey, and back along the northern coast of Africa to northern Algeria. The third zone of high projected impact includes the mountain ranges from the Pyrenees to the Alps, from the high Tatra mountains to the Carpathian on to the Dinarids and the Balkan Mountains, and Mount Olympus itself. On the whole, projected changes are favorable to agriculture in the Mediterranean countries, implying an increase in precipitation as the crucial factor.
Projected change in wheat yields for several European countries using a wheat growth simulation program called “EuroWheat”. The left bar (with an X) indicates the changes due to natural variability alone. The middle (black square) and right (black circle) represent the changes due to two climate models with CO2 increases to 435 ppm and 515 ppm respectively. Although these results were statistically significant, whether these changes would be fully realized at large scales is not so clear. (From: Hulme et al., 1999)
Of course, even this kind of advanced geophysical-economic modeling cannot deal with highly irregular potential impacts, such as arise from the spread of insects. Cutting back on winter frosts and increasing wetness has all kinds of consequences for the range extension of agricultural pests and vectors of disease, where chance events play an important role.
The Changing Sun
There is also a role for solar studies. We need to know how the Sun changes its output through time so we can get a hold of the response of the Earth to these changes through time, and also so we can be prepared for changes in the future. Since the observations of Galileo, at the beginning of the 17th century, the sunspot activity (and the corresponding solar output) has varied greatly, and the second half of the 20th century has been entirely unusual in terms of intensity of solar activity, having all four of the maximum amplitude sunspot cycles. As mentioned previously, this increase in solar output is now recognized as an important ingredient in the global warming debate. Naturally, it would be very interesting to know whether the Sun will stay as hot as it has been since its overall background peak in 1950 or whether it is on the way to a cooler state. In 1995, Sir John Maddox (then editor of the science magazine, Nature) speculated that the approximately 100 year cycle in solar activity would assert itself and take the Sun back to a quieter state, thus "saving our bacon" as far as global warming (at least for awhile). Time will only tell if he was right.