December 9, 2015

Seven Questions About Climate Change

Climate change is at the top of the agenda of policymakers as they gather inParis for the United Nations Climate Change Conference, COP21. Climate change is a threat to the very survival of humanity. Notwithstanding the severity of the threat, actions to halt climate change have been scant and uneven across countries. This Q&A article provides brief answers to seven questions about climate change, its consequences, and the coordination for developing mitigation strategies.[1]

Question 1: What is climate change?

Climate change refers to changes in the patterns of the overall climate of the earth. It can refer to changes in the Earth’s average temperature and precipitation patterns. Among them, the gradual increase in the average temperature of the Earth’s atmosphere and its oceans is often referred to as global warming (see Figure 1), and the potential causes and consequences from global warming have been the main focus of many discussions.

Some causes of climate change are natural. These include changes in the Earth’s orbit and in the amount of energy coming from the sun. Volcanic eruptions are also natural causes of climate change. There is however a consensus among scientists that recent global warming cannot be explained by nature alone.

Human activity is another source of climate change. Most scientists argue that global warming since the mid nineteenth century is mostly due to the combustion of fossil fuels (coal, oil, and natural gas) that constitute today’s major sources of energy for the global economy. The burning of these fossil fuels releases greenhouse gases, such as carbon dioxide, into the air.[2]

Question 2: Is there evidence of global warming?

The average temperature of the Earth has risen by a little more than one degree Fahrenheit over the past 100 years or so. It may not seem like much, but small changes in the Earth’s average temperature can lead to big consequences. The Intergovernmental Panel on Climate Change’s (IPCC) Fifth Assessment Report concludes, that “the human influence on the climate system is clear and is evident from the increasing greenhouse gas concentrations in the atmosphere, positive radiative forcing, observed warming, and understanding of the climate system.

There is a strong scientific consensus that the global climate is changing and that human activity contributes significantly to this trend. According to Cook and others (2013), 97 percent or more of climate scientists agree that this is due to human activity—notably, emissions of carbon dioxide.

Considering that carbon emissions are chiefly caused by the burning of fossil fuels following the industrial revolution, human activity is seen as playing a key role in global warming. Scientists find that around 1950, carbon dioxide levels in the atmosphere reached its highest point in 650,000 years and has been increasing with dramatic speed since then (see Figure 2). The carbon lifecycle and deforestation have made it harder to resorb carbon dioxide. Oceans absorb carbon dioxide and this in turn leads to acidification. Changes in the ocean’s ecology then destroys coral reef habitats.

Question 3: What are the economic and social consequences of global warming?

Global warming can cause climatic catastrophes. Global warming leads to rising sea levels, melting of glaciers, and ice sheets; and these changes, in turn, affect precipitation patterns. The severity and frequency of hurricanes and storms also increase as a result. These catastrophes include irreversible events. For example, permafrost melting allows previously frozen organic matter to release potentially large amounts of methane.

The social consequences of global warming can be dramatic. While air pollution associated with use of coal and oil has consequences on the immediate health and wellbeing of individuals, the resulting global warming can affect human and animal livelihoods by endangering and even destroying their habitat.[3] Global warming can thus trigger famines, mass movement of populations, and endanger animal species directly; and it can also alter the balance of ecosystems indirectly.

Global warming disproportionately affects vulnerable groups and certain territories. For example, islands and coastal areas are the most threatened loci because of rising sea-levels. Individuals living in rural areas in poor countries are also disproportionately affected by climate change because they are more reliant on natural resources and the environment for their subsistence (see e.g., World Bank, 2011).

Climate change and global warming reduces economic growth and slows economic activity in different ways.[4] For example, global warming can affect agriculture in two ways. First, it can destroy agricultural harvests. Second, it can also affect agricultural productivity permanently. Beyond agriculture, global warming can damage infrastructure, raise health costs and insurance premia, and cause financial stress. The disorder caused by socioeconomic tensions, including mass migration and conflicts, resulting from global warming can also deter foreign investment, and, hence, reduce growth.

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