In the long term, higher temperatures entail risks of negative consequences for the environment, and so for human beings as well. Global warming could among other things cause extreme climatic events, more severe droughts, floods, and rising sea levels. Such changes could in turn generate negative consequences in terms of food production, water supplies, and human health.
The negative impacts of climate change will be felt most acutely in developing countries, since their ability to adapt is much more limited, on account of their more limited wealth. Moreover, a larger proportion of their economic activity is concentrated in sectors like agriculture that are more sensitive to climate.
The effects of climate change are not exclusively negative. A higher concentration of CO2 in the atmosphere reduces the water requirements of plants, thereby allowing for faster growth and increased crop yields. Another benefit is reduced heating costs and cold-related health problems, which entail 17 times more deaths than heat-related health problems.(18)
Certain cost-benefit analyses estimate that global warming on the order of 1°C to 2°C would be beneficial to humanity. In the long term, the negative effects of warming greater than this interval, however, would exceed the benefits.(19)
In order to avoid the potential negative long-term effects of climate change, the UNFCCC member states determined that global warming would have to be limited to 2°C.(20)
18. Antonio Gasparrini et al., “Mortality Risk Attributable to High and Low Ambient Temperature: A Multicountry Observational Study,” The Lancet, Vol. 386, No. 9991, 2015, pp. 369-375.
19. Richard S. J. Tol, “The Economic Effects of Climate Change,” Journal of Economic Perspectives, Vol. 23, No. 2, 2009, p. 35; Richard S. J. Tol, Economic Impacts of Climate Change, Economics Department, University of Sussex, Working Paper Series, No. 75-2015, 2015.
20. Paris 2015, op. cit., footnote 3.