Climate Change - Human causes

Human Causes

The Intergovernmental Panel on Climate Change (IPCC) in its Fourth Assessment Report (AR4) on climate change in 2007, confirms that human activity is the primary driver of the observed changes in climate. Humans influence the global climate through emitting key greenhouse gases - carbon dioxide (CO2),methane and nitrous oxide. These gases are responsible for the greenhouse effect which traps heat in the atmosphere and causes global warming.

More specifically, approximately 7 billion tonnes of CO2 is emitted globally each year through fossil fuel use mostly through burning coal, oil and gas for energy. An additional 1.6 billion tonnes are emitted by land use change mainly by deforestation. The IPPC affirms that in the absence of effective international effort, GHG emissions will continue to grow rapidly over the coming decades. On current projections, this would result in a warming of between 1.7°C and 4.0°C by 2100, this depends on the amount of emissions.

Consequences of Climate Change

Change of Climatic Patterns

• Increased precipitation and change in Earth’s hydrology.
• Droughts and wildfires will occur more often.
• Heat waves will be more frequent and more intense.

Melting Ice Caps and Sea Level Rise

• The flow of ice from glaciers in Greenland has more than doubled over the past decade.
• There has been a 40% drop in the amount of arctic ice since the 1970s. If this spreads and the northern ice fields melt, a rise in sea levels of up to seven meters would occur. This would not simply devastate countries like Bangladesh and island nations, but also major western cities such as London, Rome and New York.
  

Biodiversity

• The impact of climate change on some wildlife will already be catastrophic even with little further change in the climate.
• Up to a third of land-based species could face extinction by the middle of the century (RSPB).

Health

• 150,000 people die every year as a result of climate change (World Health Organization)

Food and Water Supplies

• Disruption to agriculture and food supplies.
• Water availability could decline-over 3 billion people in the Indian subcontinent and the Middle East may face water shortages (Oxfam)
• 30 million people may be hungry by 2050 because of climate change (Hadley Centre, UK)

Economy

• Financial costs from hurricane damage and flooding.
• The negative effects of these changes will be felt everywhere but will fall disproportionately heavily in developing countries that ironically are the least responsible for harmful emissions