Without such an effect, the earth's surface temperature would be more than 30°C cooler (McBoyle, 1990).

Over the past century, concentrations of natural greenhouse gases, especially CO2, in addition to human-made gases such as chlorofluorocarbons (CFCs) and aerosols - emitted for example from refrigeration or chemical sprays - have all increased as a result of human activities. In doing so, each has contributed to greenhouse warming (IPCC, 1990; Nilsson and Pitt, 1991). Through the burning of fossil fuels, deforestation, agriculture, and industrial processes, the concentrations of these gases are presently escalating (McKay and Hengeveld, 1990). Given the nature of the greenhouse process and increasing levels of greenhouse gases within the atmosphere around the earth, some changes in future climatic regimes are to be expected.

The best tool presently available for understanding the change associated with an increase in greenhouse gases - in particular an increase of CO2 - is a general circulation model (GCM). These highly complex, three dimensional computerized models attempt to simulate current climates under a 1xCO2 scenario (250 ppm) and are then used to project what climatic changes may occur with a doubling of CO2 (500 ppm). Among the models which could be used to estimate climate change and related effects in the Long Point area are: Canadian Climate Centre (CCC); Goddard Institute for Space Studies (GISS); Geophysical Fluid Dynamics Laboratory (GFDL); and Oregon State University (OSU) (Marie Sanderson, pers. comm.).

While GCMs neither predict future climates nor establish the cause and effect relationships among greenhouse gases and warmer temperatures, the scenarios or general pictures that they paint are useful in lessening the uncertainty associated with the issue of global climatic change. They provide at least a first approximation of possible change as a basis for further monitoring and planning.

The output from the Canadian Climate Centre (CCC) GCM was used in this study to determine the potential changes in climate for the Inner Bay area. The CCC GCM has higher spatial resolution or accuracy than other GCMs, such as GISS and GFDL which were tried in an earlier version of this research.

Figure 2 shows world temperatures from 1880 to 1980. Under the CCC GCM 2xCO2 scenario, substantial changes in both temperature and precipitation regimes are likely to occur for the Inner Bay by the middle of the next century. Winter and spring temperatures are expected to warm by as much as 10.5°C, while summer and fall temperatures are likely to only increase slightly, possibly as little as 2.1°C.

Figure 2. World Temperatures, 1880-1980 (from Sanderson, 1988)

Decrease in Great Lakes Water Levels

Changes in temperature and precipitation regimes derived from the CCC GCM would affect the water levels of the Inner Bay. High summer temperatures and increased evaporation rates coupled with significant decreases in summer precipitation, could be expected to reduce runoff from the land, and thus lower water levels. Lake Erie's water levels are expected to drop an average of 1.35 m (Sanderson, 1988) (Table 1).

Table 1. Changes in Mean Monthly Lake Erie Water Levels Using CCC GCM Output (From Staples, 1993)

Month	Present Conditions (m)	2 x CO2 Conditions	Amount of Change
January	172.85	171.49	-1.36
February	172.85	171.55	-1.30
March	172.94	171.64	-1.30
April	173.09	171.73	-1.36
May	173.15	171.80	-1.35
June	173.17	171.82	-1.35
July	173.15	171.82	-1.33
August	173.08	171.76	-1.32
September	172.99	171.65	-1.34
October	172.90	171.53	-1.37
November	172.83	171.44	-1.39
December	172.83	171.43	-1.40

Such lake and climatic changes are generally expected to take place by about 2050.

With such a marked decrease in water levels, the nature of the Inner Bay may be altered (Figures 3 and 4). Remaining "open or standing" water would be concentrated at the northern and northwestern portions of the Bay, with land exposed in the shallower southwestern and northeastern portions. However, a channel likely would still connect the Inner Bay to Long Point Bay and hence, provide continued access to Lake Erie.

Figure 3 Water Depths in Long Point Inner Bay (adapted from Wilcox and Knapton, 1994)

Figure 4. Changes in Shoreline Position and Water Depths iof the Inner Bay (adapted from Staples, 1993)

The decreased water levels associated with warmer and drier conditions will likely have significant effects on the wetland environment of a large portion of the present Long Point area. Naturally confined marshes can be expected to revert to marsh meadow, succeeding to dryland conditions as the water table falls (Wall, 1988). Interference from the sand along the Long Point and Turkey Point spits could prevent the marsh from moving lakeward and vegetation likely would shift from species and communities favouring a water-loving to those favouring a dryer environment. In doing so, vegetation could be altered considerably as species intolerant of drying are replaced by hardier species from buried seeds and other sources. The diversity of the wetland ecosystem could decline as the flora of the terrestrial environment gradually dominate Long Point (Wall, 1988).

Changes in Plants and Animals

With the onset of any climatic change, the existing biological character of the Long Point Bay area may be altered. Many of the marshes of the Inner Bay could drastically decrease in area or even vanish as water levels fall. As the wetland vegetation migrates out into the Inner Bay, so could its associated wildlife such as waterfowl, amphibians and fish. It is unknown what effects such changes would have on the diversity and health of the current plants and animals of the Bay, but this diversity could decrease.

Economic Effects

A reduction in water levels would have significant impacts on the current tourism and recreational activities of Long Point and on the economy of the region. If, as seems likely with a drop in lake level, the marshlands decrease in extent, this would result in some loss of waterfowl hunting and sport fishing opportunities within the region. Most of the present marina facilities would not function under lower water levels, especially along the southwestern and northeastern shoreline of the Inner Bay. Trailer and camp facilities along parts of the Inner Bay could fall into disuse as the lakeshore receded and was displaced by grass, shrubs and/or forest vegetation. However, such facilities could re-establish nearby and other economic factors being equal, the expected warmer, drier, longer summer - in conjunction with newly exposed beaches - could continue to attract thousands of visitors to the Provincial Parks, Conservation Areas, private beaches and cottages of the Inner Bay each year.

Glossary

Basis of Comparison (BOC)	a data set consisting of the average monthly mean Lake Erie water levels from 1900-1989 and are used to represent the existing water levels for comparison with other data sets such as GCM output
Chlorofluorocarbons (CFCs)	organic molecules consisting of chlorine and fluorine bonded to carbon. Used as spray can propellants and coolants. Previously thought to be inert, but now known to destroy the ozone layer
General Circulation Models (GCMs)	highly complex computer models used to estimate future large-scale climatic conditions given an increase in CO2 levels in the atmosphere to 500 ppm
Greenhouse Effect	mechanism that explains atmospheric heating caused by increasing CO2 and other trace gases
Macrophytes	large aquatic plants (e.g. crowfoot or water lily), as opposed to phytoplankton or other small algae.
Vegetation Succession	the progressive natural development of vegetation towards a climax, during which one community is gradually replaced by others

Work Cited

Canadian Climate Centre, No Date. Unpublished Document.

International Panel on Climate Change (IPCC). 1990. Policy maker's Summary of Scientific Assessment of Climate Change Report of Working Group 1.

Kellogg, W.W., 1990. "Comparison of Climate Models: What They Tell Us About a Warmer World" In (Wall, G. and Sanderson, M. eds). Climate Change: Implications for Water and Ecological Resources Waterloo: Department of Geography, University of Waterloo, Waterloo, Ontario: 90-102.

McBoyle, G. 1990. "Climate Change: The Demand for Human Ingenuity" In (Wall, G. and Sanderson, M. eds). Climate Change: Implications for Water and Ecological Resources Waterloo: Department of Geography, University of Waterloo, Waterloo, Ontario: 1-25.

McKay, G.A., and Hengeveld, H., 1990. "The Changing Atmosphere" In (Mungall, C. and McLaren, D. eds). Planet Under Stress Oxford University Press, Toronto, Ontario.

Niisson, S., and Pitt, D. 1991. Mountain World in Danger: Climate Change in the Forests and Mountains of Europe Earthscan Publications Limited. London, England.

Pauls, K., and Knapton, R. 1993. Submerged Macrophytes of Long Point's Inner Bay: Their Distribution and Value for Waterfowl Long Point Environmental Folio Publication Series. (Nelson, J.G. and Lawrence, P.L. eds). Technical Paper 1. Waterloo: Heritage Resources Centre, University of Waterloo, Ontario.

Phillips, D.W. 1989. "Climate Change in the Great Lakes Region" In Impacts of Climatic Change on the Great Lakes Basin Proceedings of a Canada-US Symposium. Toronto, Ontario: 54-68.

Sanderson, M. 1988. "Effects of Climate Change on the Great Lakes" Transactions of the Royal Society of Canada Series 4(3): 33-46.

Staple, T. 1993. Climate Change and Long Point Bay: A Preliminary Analysis with Some Implications Long Point Environmental Folio Series. (Nelson, J.G. and Lawrence, P.L. eds). Working Paper 2. Heritage Resources Centre, University of Waterloo, Waterloo, Ontario.

Wall, G. 1988. Implications of Climatic Change for Tourism and Recreation in Ontario, CCD, 88-05. Ministry of Supply and Services, Ottawa, Ontario.