Devastating for the world's poor: climate change threatens the development gains already achieved.

• Author: Dervis, Kemal

Climate change has emerged as one of the biggest environmental challenges facing the world. Twenty years ago at the United Nations, Gro Harlem Brundtland, Norway's former Prime Minister and former Director-General of the World Health Organization, first drew global attention to the threats posed by climate change to the earth and its inhabitants.

Speaking at the 15th session of the UN Commission on Sustainable Development in May 2007, Ms. Brundtland--one of three Special Envoys on Climate Change appointed by the UN Secretary-General in April--made clear that there can no longer be any doubt about human-induced climate change and its likely impact on the planet.

Today there is broad international scientific consensus that greenhouse gas (GHG) emissions from human activity, particularly fossil fuel use and deforestation, have increased the concentration of these gases in the atmosphere. As a result, according to the Intergovernmental Panel on Climate Change (IPCC), the earth's mean surface temperature has warmed by 0.75° Celsius over the past century, and 11 of the last 12 years (1995-2006) have been among the 12 warmest years since 1850. Based on projected GHG trends, temperatures could rise by another 2°C to 5°C, or perhaps even more, by 2100. Increases of this magnitude are expected to have widespread negative impacts on human welfare and natural ecosystems, including wide-ranging economic, ecological and social effects.

Climate change is likely to increase the prevalence of vector-borne diseases, such as malaria and dengue fever, and may increase the intensity of severe weather events. It is likely to lead to an increase in water levels and serious flooding, and at the same time cause water scarcity in arid regions. Climate change is expected to irreversibly damage some natural resources and ecosystems. Overall, climate change is projected to deliver a devastating combination of adverse impacts for the world's poor, both because of geography and low income, making adaptation to climate change much more difficult. While developing countries have contributed the least to the problem, they are expected to bear the brunt of the impact of climate change, which threatens to jeopardize many of the developmental gains that have already been achieved.

While there is overwhelming scientific evidence that climate change is happening and that GHG emissions caused by human activity is a significant and probably dominant cause, there is still a great...