Climate Change Facts

Our planet's climate is anything but simple. Many factors influence it, from the massive events on the Sun to volcanic eruptions on Earth, to the ocean's currents, to the growth of microscopic creatures in those oceans, and there are subtle interactions between many of these factors.

Yet despite all the complexities, a firm and ever growing body of overwhelming scientific evidence points to a clear picture: that global warming is occurring.

That this warming is largely being caused by significant increased amounts of "greenhouse gases" in our atmosphere caused from human activity. And that we are causing this increase by the burning of fossil fuels (like coal, oil, and natural gas) and through the conversion of natural habitats.

The facts:

1. Global Temperatures are rising

   Greenhouse gases such as carbon dioxide, methane and water vapour behave like a blanket around the Earth, and keep our planet much warmer than it would otherwise be. These gases allow the Sun’s rays to reach Earth’s surface but prevent that heat from escaping back into space. Any increases in the levels of greenhouse gases in the atmosphere mean that more heat is trapped and global temperatures increase.

   Carbon Dioxide (CO2) is by far the greatest contributor to greenhouse gases, although Methane (CH4) is the most aggressive – more than 20 times more aggressive than CO2. There is present concern that the current warming trends will further exacerbate atmospheric greenhouse gas concentrations through the increased release of methane from melting permafrost and from the reduced ability of the world’s oceans to absorb excess CO2.

   Over the last 650,000 years the natural range for CO2 concentrations in the atmosphere has been between 180 to 300 parts per million (ppm) – this data being found through Antarctic ice core surveys, where air trapped as the ice froze hundreds of thousands of years ago. The graph below, highlighting temperature and CO2 concentrations (in parts per million, ppm) during the last 400,000 years to 1950, shows the clear link between the two:

   
   Source: WMO

2. Greenhouse gas concentrations and conversion of natural habitats are the main causes of temperature increases

   Temperatures provide the clearest evidence that the climate is changing. Globally the average temperature has risen by more than 0.7 °C over the last 100 years and by approximately 2.0 °C in the Arctic since the 1950s. Eleven of the last twelve years rank amongst the twelve warmest years on record for global temperatures since 1850. (source: Met Office and IPCC, 2007)

   

   In addition to increased atmospheric concentrations of greenhouse gases, human activity has resulted in a high proportion of natural habitats (forest, grasslands, etc.) being converted to ‘human landscapes’.  This has caused indirect warming by reducing the earth’s capacity to store carbon, thereby helping to increase CO2 levels in the atmosphere and by creating more ‘heat intensive’ landscapes. (Source: IPCC)

3. CO2 concentrations are now the highest they have ever been.

   The atmospheric concentrations of CO2 today (2009) is 387ppm. That is nearly 30% more than the highest natural levels over the past 650,000 years (180 to 300 ppm) as determined from ice core surveys.

   Worse, over the last 10 years, we have seen the fastest annual growth rate in the carbon dioxide concentration, since the start of direct atmospheric measurements (1960). It has risen 17ppm since 1985 alone (when the total was 370ppm). This is an unprecedented growth which is ringing alarm bells in the scientific community Worldwide (Ssource: Energy Information Administration, USA)

   Carbon Dioxide Emissions and Carbon Dioxide
   Concentrations (1751-2008)

   

4. Other Evidence:
   • Sea temperatures have risen by on average 0.5 degrees C (0.9 degree F) over the last 40 years (Scripps Institution of Oceanography, California, USA)
   • 20,000 square kilometers of fresh water ice melted in the Arctic between 1965 and 1995 (Woods HoleOceanographic Institution, Connecticut, USA)
   • Worldwide measurements from tidal gauges indicate that global mean sea level has risen between 10 and 25 cm (18 cm average) during the last 100 years (Warwick et al, 2005).
   • Since 1975, the increase of the 5-year mean temperature is about 0.5°C - a rate that is faster than for any previous period of equal length (NASA 1999)
   • Glaciers are retreating in many mountain areas of the world - since 1850 the glaciers of the European Alps have lost about 30 to 40% of their surface area and about half of their volume (Haeberli and Beniston, 1998)
   • The greatest surface melt extent on the Greenland ice sheet occurred in 2007 (Tedesco M, 2007 and Mernild et al, 2009)
     
     
5. The effects are being felt in the Polar Regions more than anywhere else in the World.

   No-where is climate change being noticed more than in the Polar Regions. In the Arctic average surface air temperature north of 60°N has increased by 0.09°C decade, 2-3 times faster than the global average (IPCC, 2004)

   The Arctic is undergoing a system-wide response to climatic change and the effect of a warmer and wetter climate on these fragile and unique eco-systems have implications for the rest of our planet. The maintenance of healthy Arctic ecosystems is a global imperative as the Arctic plays a critical role in the Earth’s physical, chemical and biological balance.