Ocean Matters

The Causes and Consequences of Global Warming

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It’s got People Talking!
Marine Biologists are talking a lot about global warming these days, although they are not the only ones – kids and adults across the world are talking about it too. Below we take a closer look at the driving factors behind global warming and examine how this phenomenon is affecting life in our sensitive oceans. We also discuss a few global warming solutions.

Basics of the Greenhouse Effect
The Earth is a dynamic planet subject to heat from the sun.  Sunlight in the form of short-wave radiation shines onto the Earth's surface, which in turn reflects the sun’s energy into the atmosphere as long-wave radiation. The long-wave radiation reflected from the Earth's surface is what actually heats our planet. The atmosphere acts like a large greenhouse keeping the heat in and allowing the Earth to stay warm. If the atmosphere did not act like a greenhouse the Earth would be much colder and likely unable to support life as we know it.
The four main gases responsible for the greenhouse effect in the atmosphere are water vapour (H2O), nitrous oxide (N2O), methane (CH4) and carbon dioxide (CO2). Over the past couple of centuries humans have created several other greenhouse gases such as chlorofluorocarbons (CFCs), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6) that also contribute to the greenhouse effect in the atmosphere.  Of these gases, carbon dioxide has had by far the greatest impact on global warming.

Carbon Dioxide Emissions
Carbon dioxide levels in the atmosphere have increased dramatically over the last 150 years, going from 280 parts per million (PPM) to 383 PPM.  In fact, eight of the 10 warmest years since 1860 have occurred within the last decade or so. In order to understand the global warming problem we first have to understand where all of the carbon dioxide is coming from.  Although there is some evidence that humans started to alter the gases in the atmosphere as early as 8,000 years ago through agricultural development, most scientists agree that we really began to change our atmosphere at the start of the Industrial Revolution, around the year 1800. The extensive burning of fossil fuels associated with new technologies brought about by the Industrial Revolution is likely when human activities started to harmfully impact the atmosphere.

Carbon dioxide levels in the atmosphere over the last several hundred years have fluctuated greatly but have never been as high as they are right now. (Image created by Robert Rohde for global warming art and is used with permission.)

World Temperature Increases
Most alarming is how humans have impacted the rate of climatic change over the last 150 years. Since 1850, the amount of carbon dioxide in the atmosphere has increased to levels never before observed in the geological record. Air temperatures around the globe have increased an average of 0.5°C, with ocean temperatures increasing twice as fast. The United Nations estimates that over the next century temperatures will continue to rise between 1.8°C and 4°C. This will have severe impacts on the climate and life forms of this planet.

Consequences of the Greenhouse Effect
Warming on a global scale due to increased greenhouse gases has many impacts. Higher temperatures cause snow packs and ice sheets to melt, leading to rising sea levels. Increased temperatures on land can change vegetation coverage and forest communities. Animal and plant distributions are expected to shift as they attempt to stay within their thermal ranges. Temperate and equatorial species are predicted to move towards the poles, and habitats in the Arctic and Antarctic are expected to shrink. Greenhouse gases will also affect ocean chemistry. As the oceans absorb carbon dioxide, the water will become more acidic, affecting all living things in the marine environment – from small drifting plankton to giant whales.

Solutions
On the international scene, the United Nations has been leading negotiations to reduce greenhouse gas emissions amongst its member states, with the Kyoto Protocol being the most well-known agreement signed thus far.  Although Kyoto has succeeded in reducing greenhouse gas emissions in some countries (for example Germany and the United Kingdom), other nations have seen their emissions rise significantly, with Canada’s results being particularly disappointing.  In 2002, Canada ratified the treaty, requiring it to reduce emissions to 6% below 1990 levels between 2008-2012.  By 2004, however, CO2 emissions in Canada had risen to 27% above 1990 levels!  Although negotiations are continuing, it is all but certain that Canada will not be able to meet its Kyoto obligations, thereby letting down the international community and tarnishing Canada’s reputation.  Despite this, provinces such as British Columbia, Manitoba and Quebec are taking voluntary initiatives to reduce greenhouse gas emissions inline with Kyoto targets.  Given that the Kyoto protocol is supported by a strong majority of Canadians, public pressure may eventually translate into regulatory policies that will put Canada back on track to meet its international commitments.
Apart from international treaties, there are many things we can do as individuals to help reverse the planet’s warming trend.  Te first place to start is by reducing our collective ecological footprints.  The average Canadian is responsible for emitting 5.7 tonnes of greenhouse gases per year!  (This number balloons to 23 tonnes per person if we include the national total of greenhouse gas emissions from all sources, including industry).  Therefore, even modest lifestyle changes could produce measurable emission reductions. Where possible, switching to renewable energy sources would help us reduce our greenhouse gas emissions by easing our dependence on fossil fuels.  Other individual choices we can make include using public transit whenever possible, living in energy efficient homes, being energy smart (like using cold water to wash clothes instead of warm water), and eating local foods that have a smaller ecological footprint.  
By making small lifestyle changes and encouraging our leaders to tackle head on the climate change challenge, we can help reverse the global warming trend.

For more information go to:

United Nations Environmental Programme

Intergovernmental Panel on Climate Change

New Scientist Special Report on Climate Change

David Suzuki Foundation

World Wildlife Fund

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