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A Climate Change Backgrounder

What is the problem?

There is considerable evidence that the climate is changing, that it is being caused by human activities, and its effects will worsen if no action is taken. Virtually all of the world's top scientific experts in the subject area agree with these conclusions, drawn from the most recent report1 by the Intergovernmental Panel on Climate Change (IPCC). The IPCC concludes that 11 of the last 12 years (1995-2006) rank among the warmest since 1850. It has also concluded that atmospheric carbon dioxide equivalent (CO2-equivalent) concentrations increased from a relatively stable 280 parts per million (ppm) to 380 ppm over the past 150 years, as shown in Chart 1, and that current concentrations are the highest on record for 650,000 years according to analysis of ice cores.

1  Intergovernmental Panel and Climate Change, Fourth Assessment Report: Climate Change 2007: Synthesis Report, November 17, 2007. See

These increases are primarily due to fossil fuel combustion and land use changes, releasing increased amounts of carbon dioxide, methane, and nitrous oxide into the atmosphere. These gases act to trap more solar heat within the earth’s atmosphere than was the case in pre-industrial times, much like a greenhouse, hence the term “greenhouse gases.” The likely key global effects of these atmospheric changes as described by the IPCC, if no action is taken, include:

  • estimated global warming of 1.8 to 4.0 degrees Celsius by 2100 (average annual best estimate) is projected, with the higher value reflecting the impact of higher emissions;
  • rising sea levels, decreased snowpacks, and glacial melting;
  • increased heat waves and drought occurrences; and
  • increased tropical storm intensities and frequency of extreme precipitation events, leading to increased flood risks.

Chart 1 shows the close correlation between CO2-equivalent concentrations and average world temperature since the 1850s.

Chart 1.

What is the Intergovernmental Panel on Climate Change?

The IPCC was established by the World Meteorological Organization (WMO) and United Nations Environment Programme (UNEP) in 1988 to evaluate climate change science, impacts and options for adaptation and mitigation. The IPCC is open to all member countries of WMO and UNEP. The IPCC has coordinated four major assessments of climate change, published in 1990, 1995, 2001 and 2007.

The drafting and review process for the most recent assessment involved 450 lead authors working with 800 contributors and 2,500 expert reviewers from 130 countries. Hundreds of scientists all over the world contribute to the work of the IPCC as authors, contributors and reviewers. Over 25 of those collaborating on the fourth assessment report (2007) are Canadians from leading universities, government, and other organizations, and 11 of these work in British Columbia.

Why should we be concerned?

Changes in climate affect everything from food production, the abundance of water resources, the frequency of catastrophic weather events, forest health, and recreational activities. For North America, the IPCC concludes that there will be:

  • lower snowpacks in the western mountainous areas, with more winter flooding and competition for already over-allocated water resources;
  • challenges for crops that are already susceptible to warm weather events or depend on highly-utilized water a resources; and
  • more extreme heat waves, causing increased health problems in cities.

On a world-wide basis, the IPCC also concludes that there are increased risks of:

  • extinction for approximately 20 to 30 per cent of plant and animal species; and
  • decreases in global food production if local average annual warming exceeds the 1 to 3 degrees Celsius range.

Global average temperature increases greater than 2 degrees Celsius (relative to pre-industrial temperatures) are generally viewed by scientists as leading to impacts in many regions that may be beyond society’s capacity to adapt.2 The 2007 IPCC report concludes that based on the current understanding of the sensitivity of the global climate system to greenhouse gas emissions, avoiding a global increase greater than 2.0–2.4 degrees Celsius above pre-industrial levels requires that emissions by 2050 be reduced by 50–85 per cent relative to 2000 levels. This implies stabilization of atmospheric concentrations of greenhouse gases at 445–490 ppm CO2-equivalent.

However, it is not only scientists and governments that are concerned. A recent report by Lloyd’s, the world's leading insurer, states that “The frequency and magnitude of catastrophes — especially weather related catastrophes — has increased significantly in recent years. Climate change is expected to exacerbate this further, and by 2050 mega-catastrophes like Hurricane Katrina, which used to occur every 100 years, are predicted to happen every 25 years. Businesses need to prepare for the prospect of growing natural hazard risks now.”3

2  Based on IPCC Working Group 2 “Impacts, Adaptation, and Vulnerability” Report (2007) and reports submitted to the Exeter “Avoiding Dangerous Climate Change” conference (2005).
3  See

How is all this relevant to British Columbia?

The Pacific Climate Impacts Consortium (PCIC) at the University of Victoria concludes that BC’s climate has also changed over the last 50–100 years, with the data showing temperatures up by an average 0.6 to 1.7 degrees, depending on the region. Winters have warmed faster than summers.

While this increase seems small, it has been enough to contribute to large losses in snowpack (-25 per cent to -50 per cent in lower elevations) during the past 50 years. In addition this warming is causing spring snowmelt events to occur 10 to 30 days earlier. While there are regional variations, total province-wide annual precipitation has increased roughly 20 per cent across the province over the last 100 years.

Warmer winters are also a contributing factor to the Mountain Pine Beetle epidemic that is devastating much of the BC interior’s pine forests. There are also growing concerns about summer water shortages in the agriculturally-significant Okanagan region and the risks to electricity generation in the Columbia- Kootenays due to the decline in snowmelt runoff and the impending loss of glaciers.

Chart 2.

What are the main sources of emissions and what is the trend if we do nothing?

In BC, 65.9 million tonnes of CO2-equivalent were released in 2005. Under a “business as usual” scenario, emissions are anticipated to continue to rise as they have in the past. However, government is legally committed to reducing 2020 emissions to 33 per cent below the 2007 level, as indicated in Chart 2.

In order to design effective strategies to reduce emissions, it is important to know which types of human activities generate greenhouse gases. Because fossil fuels play such an important role in providing energy for most industries and for our daily activities, emissions originate from a variety of sectors as shown in Chart 3.

Chart 3.

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