Climate Science: Some Key Facts

Is the climate changing?

  • In a word, yes. For the past 10,000 years Nature provided a stable climate that enabled the evolution of today’s plants and animals, and humanity to develop settlements, agriculture, and industry. 

  • Now, that stable climate is changing, with each successive decade since 1950 being warmer than the last.

  • Scientists have concluded that the average surface air temperature of Earth over the 20th century rose by more than 0.7ºC, with most of that increase occurring in the last 25 years. The rise in global temperature closely parallels the rise in the quantity of atmospheric carbon dioxide (CO2), which is now the highest it’s been in at least 800,000 years.

  • Over the past 30 years, extreme weather events – storms, floods, heat waves, droughts, and wildfires – have become more intense and frequent. The Intergovernmental Panel on Climate Change (IPCC), the world authority on climate change, forecasts this trend will only worsen in the years ahead.  

  • Some of the Earth’s major systems are also changing. For example, the Arctic ice cap, the Greenland and west Antarctic ice sheets, and glaciers everywhere are melting, adding to sea levels already rising from thermal expansion. Permafrost is also melting – potentially allowing the escape to the atmosphere of vast quantities of methane, a greenhouse gas initially twenty times more powerfully warming than CO2

What’s the effect, if any, of human activities?

  • The IPCC, along with many other climate research agencies, says it’s 90% certain that the global temperature increase over the past century is mostly caused by human activities. The national academies of science of every country, including Canada, agree, as do 97% of climate researchers actively publishing in the field. 

How do we know that global warming doesn’t have natural causes?

  • Paleoclimatologists have found that, over the millennia, the Earth has experienced any number of cool and warm periods in response to natural causes, such as changes in the tilt of the Earth or its orbit around the Sun.  When volcanoes erupt – a natural event – they emit particles that reflect sunlight away from the Earth, thereby cooling it.  The global climate changes whenever it’s forced to change.  At present, scientists believe that human-caused greenhouse gases (GHGs) from the burning of fossil fuels and the clearing of land are the dominant factor.  They are causing an imbalance of GHGs in the atmosphere that is warming the planet.

Why is a small rise in temperature such a big deal?

  • As with human body temperature, a degree or so of temperature rise doesn’t sound like much, but it is.  The Earth’s systems, including the water cycle and flora and fauna, as well as human agriculture, are adapted to function best within certain temperature ranges.  Furthermore, while global average surface temperature has risen more than 0.7ºC over the past century, the increase has been much higher in polar regions.  According to the International Energy Agency, unless emissions are substantially reduced, we are headed for a global average temperature increase of about 6ºC above pre-industrial levels by the end of this century, which would trigger feedback loops that amplify the warming – a catastrophe in the making for the biosphere we all depend on.

How is climate change affecting Alberta?

  • According to the Pembina Institute, we should expect increased: flooding and drought, forest and grass fires, health problems from air pollution, vector-borne diseases, and desertification in the southeast.

What targets should we aim for?

  • It is now established that, in order to prevent dangerous climate change, we must prevent global average temperatures from exceeding 2ºC above pre-industrial levels. That equates with a concentration of atmospheric CO2 of about 450 parts per million (ppm), compared to present levels of 391 (and rising by 2 ppm per year). However, over 100 countries (including many threatened by sea-level rise) argue that, given the human and financial cost of the nearly 0.8ºC of warming that has taken place over the past century, the target should be not 2ºC, but 1.5ºC, or less. That equates roughly with a greenhouse gas concentration of 350 ppm in the atmosphere.

  • The International Energy Agency warns that, to avoid that rise of 2ºC, the rise in emissions should peak by 2017 and then decline each year.

  • The European Union is the global leader in climate change policy.  It has set a target, for its 27 member states, of reducing CO2 levels to 20% below 1990 levels by 2020, or 30% below if there is an international agreement.

What were the key points agreed at the 2011 climate conference in Durban?

  • All nations agreed to negotiate a new, legally binding agreement to replace the Kyoto Protocol. Unlike Kyoto, emission targets would apply to all countries, not just to those deemed developed. Work on the new agreement is to start in 2012 and be completed by 2015. The bad news is that the agreement won’t come into effect until 2020. The delay means that when cuts in GHGs do come, they will need to be very steep indeed if we are to stay within the 2ºC limit. 

  • Another key point was the establishment of a $100 billion per year Green Climate Fund – with the World Bank as trustee - to be provided to developing countries to help them adapt to climate change.

What emissions reduction targets do Canada and Alberta have?

  • Canada has followed the US by pledging a 17% reduction in emissions from 2005 (not 1990) levels by 2020. But according to Canada’s Commissioner of the Environment and Sustainable Development, Canada has no coherent plan to achieve that target.  Our emissions are currently heading toward 7.5% above where they were in 2005, not 17% below.  Even if the 17% below target were achieved, it is totally inadequate for Canada to play its part in limiting global warming to 2ºC.

  • Alberta, which accounts for a third of Canada’s emissions, has a target of 14% below 2005 levels for 2050, leaving it 20% above 1990 levels. Alberta’s response to climate change amounts to an intergenerational crime.

What are the basic choices all nations face in dealing with the climate crisis? 

  • One choice is to apply the precautionary principle. That is, to accept the scientists’ expert advice and act immediately to reduce our dependency on fossil fuels and re-engineer our economy towards conservation and renewable energy. The risk is that the scientists’ worst predictions never happen, and the change was premature. But we would be better off anyway.

  • The other is to do nothing now and wait for still better science and technology. The risk is that we discover too late that the effects of climate change are as bad, or worse, than the scientists predicted, and are irreversible. That means widespread human misery, massive loss of life and property, millions of climate refugees as lands become unlivable and, quite likely, serious military conflicts. 


Five highly recommended books
Brown, Lester, 2011. World on the Edge. W.W. Norton.
Henson, Robert, 2011. The Rough Guide to Climate Change. Rough Guides.
Hogan, James, 2009. Climate Cover-up: The Crusade to Deny Global Warming.
McKibben, Bill, 2010. Eaarth: Making a Life on a Tough New Planet. Vintage Canada.
Rifkin, Jeremy, 2011. The Third Industrial Revolution. MacMillan.

Three highly recommended web sites
Bill McKibben’s
The David Suzuki Foundation:
The Pembina Institute:

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Copyright worldwide: © 2007 book text Marian White and Robin White,
and images © 2007 and earlier Robin White
Last updated May 29, 2012