Science of Climate Change

FREQUENTLY ASKED QUESTIONS ABOUT THE SCIENCE OF CLIMATE CHANGE

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F. Global Impacts of Climate Change

F.1 Isn't there the possibility that we might be much better off with a warmer climate?

Response: For cold countries such as Canada, climate change can indeed provide some significant benefits, like reduced space heating costs and longer, warmer growing seasons. When averaged over the entire country of Canada, these benefits could help offset some or all of the harmful effects caused by climate change provided the rate and magnitude of climate change are modest. However, if climate change is rapid or large, the risks of danger increase significantly, and the overall effect on countries like Canada would be increasingly negative. That is because it is more difficult to adapt to large or rapid change. Moreover, major negative impacts are projected for many of the developing countries of the world, even for modest changes in climate. These off shore impacts can also have indirect yet significant negative consequences for Canadians.

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Explanation: Warmer climates will provide benefits to some sectors of the economy or society, and to some regions of the world.  For example, longer and warmer growing seasons will increase productivity of agricultural crops as well as many natural ecosystems in northern countries if there is adequate moisture. Likewise, warmer winters will reduce their space heating costs and make it easier to navigate through ice-covered waters.  Climate change may also present major opportunities to expand into new areas of environmental technology and services, increase exports, and create jobs. Most of these benefits are due to changes in average temperatures.

However, other consequences of climate change are expected to be very harmful.  These include: the combined effects of sea level rise and ocean storm surges, which can be economically and ecologically devastating and cause major loss of life in some parts of the world, particularly low-lying deltas and small island states; enhanced drought conditions that threaten large populations with starvation in some regions of the world, particularly in many developing countries; increased intensity of summer rainfall and related heavy flooding and erosion, sometimes in the same regions otherwise plagued by drought; and increased frequency of high temperature extremes are related stresses on ecosystems and human populations.

The more rapidly climates change, the more difficult it will be to take advantage of the potential benefits, and the more dangerous the consequences of the extreme events and other harmful changes.  Thus the concern is not about climate change of any particular kind, but about the possibility that rates and magnitudes of change will exceed human and ecological tolerance thresholds. 

Even if the direct effects of climate change were, on average, beneficial to Canadians, disasters elsewhere may also be of major concern to Canadians (e.g. international security, environmental refugees, and aid to affected countries).

Reference: IPCC 2001, WGII, Chapter 19.

F.2 It has been suggested that, within 50 years, warmer climates will cause Halifax's climate to be similar to that of Boston today, Toronto's like that of Kentucky, and Vancouver's like that of San Francisco.  What's so bad about that?

Response:  Ecosystems, culture and socio­economic infrastructures in Canada have been shaped by the local climate of today and the recent past. For example, storm sewer and drainage systems in Canadian cities are based on local rainfall characteristics, and residential and commercial buildings are designed for temperate to cold climates. Changing such infrastructure to suit warmer climates and associated changes in weather may be very costly. If climate change occurs rapidly, the process of adaptation becomes increasingly difficult and potentially unsuccessful, leading to risks of major disasters. The same is true for the natural environment.

Explanation: The past development of the infrastructure of Canadian cities, transportation systems and other social and economic well-being and activities has been significantly influenced by the past conditions of local climates.   For example, most winter sport facilities and activities in most Canadian regions are dependent on the presence of snow and ice.  Storm sewers and drainage systems in Canadian cities are based on, among other things, local rainfall characteristics, and residential and commercial buildings are designed for temperate to cold climates.   Likewise, agriculture, water resource management and flood control infrastructures are based on current growing season and water resource characteristics.   Many of these structures and activities require long lead times in order to prepare for future changes in climate. Hence, the more rapid the change in climate, the greater the potential mismatch of cultural, social and economic infrastructures with altered climate conditions, and the greater the risk of failure to adapt and of negative consequences of climate change.

F.3  Reports indicate that warmer global temperatures will cause some of the largest changes in northern countries such as Canada.  Does this mean we are much more at risk of danger than countries near the equator?

Response: No. Climate models indicate that future changes in temperature will likely be greatest at high latitudes and greatest in winter. Thus, the magnitude of climate change in Canada will probably be greater than in many other countries. However, because our current Canadian climate regularly undergoes large changes from week to week, season to season and year to year, Canadians may be better prepared to deal with climate variability and climate change. Furthermore, warmer temperatures will give us some benefits that will help offset some of the harmful effects. Hence we may be less vulnerable to climate change than many poor tropical countries.

Explanation: Models suggest that changes in temperature in response to a global warming will be greatest at high continental latitudes and in winter.  However, natural climate fluctuations are also greatest in these regions, and in winter.   Hence ecosystems and societies which have developed in these regions, in general, also have a greater tolerance for change and hence may be more adaptable to the large changes predicted for future decades.  Furthermore, since cold temperatures are a limitation to many ecosystems and socio-economic activities in Canada, warmer climates will bring many benefits.  Finally, Canada is a relatively wealthy nation with a social infrastructure that can help Canadians to adapt more readily.  By contrast, societies of many developing countries in low latitudes already have a marginal existence and have less access to such resources. This can make them vulnerable to even very small changes in climate.  Thus, while the large changes for Canada projected by models may result in significant impacts on Canada, many of which will be negative, Canadians may be less vulnerable to the consequences of climate change than residents of many developing countries.

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