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The Business of Climate Change: Challenges and Opportunities

Earth warmed by more than 0.6 degrees Celsius (ºC) over the 20th century. Past fluctuations in naturally-occurring atmospheric greenhouse gas concentrations have caused Earth to warm and to cool, in cycles of around 100,000 years, with the timing of these cycles largely determined by a repeating pattern in the Earth’s solar orbit.
However, the most recent warming trend results largely from human activities. Atmospheric CO2 concentration, approximately 280 parts per million by volume (ppmv) before the Industrial Revolution, has increased to about 380ppmv today. Each doubling of greenhouse gas concentration raises Earth’s equilibrium temperature by about 3ºC. But there is considerable systemic inertia: even were emissions to cease today, Earth’s temperature would continue to increase, by more than 1ºC. Greenhouse gas emissions will not cease, however: ‘business as usual’ trends imply
concentration rising above 500ppmv by 2050. In turn, a base case scenario suggests that Earth’s temperature will likely increase by 2-5ºC by 2100. Emerging evidence on positive feedbacks raises the possibility that the temperature rise will be significantly greater.