1. Climate change

Human-caused (anthropogenic) climate change is a direct result of an over-reliance on cheap energy. The combustion of fossil fuels releases large amounts of greenhouse gases into the earth’s atmosphere, so named because they trap solar radiation and warm the surface of the planet. The main scientific body studying climate change, the Intergovernmental Panel on Climate Change (IPCC), estimated in a 2001 report that around three-quarters of the carbon dioxide that humans have released into the air in the late 20^th century is due to fossil fuel burning.

Some quick climate change facts from the IPCC report:

• Overall, the concentration of carbon dioxide in the earth’s atmosphere has increased by 31% since 1750.
• The global average surface temperature has increased over the 20th century by about 0.6°C.
• This increase in temperature is likely to have been the largest of any century during the past 1,000 years.
• Scientists have been able to show that most of this warming trend is likely a direct result of the increase in atmospheric greenhouse gas concentrations.

This problem is expected to continue into the future. In fact, the IPCC states that emissions caused by fossil fuel burning are “virtually certain to be the dominant influence on the trends in atmospheric CO₂ concentration during the 21st century”. 

However, if greenhouse gas levels continue to rise as predicted, the resulting changes in the earth’s climate could be quite extreme. These changes will also likely include the increase in intensity of tropical storms, dramatic sea level rise, the spread of infectious tropical diseases, changing patterns of temperature and rainfall, increased desertification, habitat destruction and massive disruptions to farms and food supplies.

Increasing tropical storms

 Although tropical storms are caused by many factors, they originate from areas with warm sea surface temperatures. Climate change and global warming can cause a warming of sea surfaces in the sub tropical regions and as a result, many scientists expect that the frequency and intensity of hurricanes and typhoons will increase as global temperatures continue to rise.

In addition, there are indications that climate change will cause the frequency of heavy rainfalls to increase.
 

Sea level rise

Climate change will also have a dramatic effect on the world’s largest bodies of water. As the earth’s oceans warm, thermal expansion, along with the melting of land ice, is causing them to increase in volume. This global impact is already occurring- during the 20^th century, sea levels rose between 0.1 and 0.2 meters on average. Low lying islands and coastal areas are especially vulnerable to this impact of climate change. If the world’s largest ice sheets, Greenland and Antarctica, were to melt completely, world sea level would rise over 70 meters. Recent studies by NASA scientists confirm that climate change is already impacting the retreat and thinning of these ice sheets.  

Increasing incidences of tropical disease

As the northern hemisphere warms and patterns of rainfall change, many diseases indigenous to other parts of the world are expected to spread in a polar direction. These include dengue fever, yellow fever, cholera, and vampire bat rabies.

Changing patterns of temperature and desertification

     As the planet warms, many normal weather patterns will be disrupted. Rainfall, evaporation and seasonal variations will change in ways that are difficult to predict, and both average temperatures and the number of extreme hot days are expected to increase in most parts of the world. Although the impacts of climate change will very considerably among different regions, hot and dry areas are expected to get hotter and drier and in many areas, and desertification may increase. The systems most vulnerable to impacts are glaciers, coral reefs and atolls, mangroves, boreal and tropical forests, polar and alpine ecosystems, prairie wetlands, and remnant native grasslands.

2.      Overshoot

 In the past, the impacts of human activity on earth were primarly absorbed by the earth’s natural systems. However, with a growing global population projected to exceed 10 billion people in the next few decades, this is quickly changing. Today human activites, for the first time ever, directly threaten the survival of our planet and everything else on it.

Why do human activites threaten the survival of the planeth? Our unprecedented growth since the beginning of the industrial era in both population and per capita consumption have placed us on a trajectory toward ‘ecological overshoot’. This term, coined in 1980 by William Catton in his seminal book, clearly illustrates how pressing the need is to Relocalize our communities. 

The availability of cheap energy from fossil fuels has allowed for the economic growth that put us on a trajectory towards overshoot. As a result, transitioning toward a fossil-fuel free future is the best answer to reversing the overshoot trend. We must limit the boundaries of our social organization and economic operations clearly within eco-systemic limits. Currently, if everyone on earth lived with the same level of consumption and fossil fuel use as North Americans we would need over 4 planets to support the world's population. Click here to calculate your individual ecological footprint.