Climate Science

Global warming refers to the increase in the average temperature of Earth’s surface, air and water bodies. The overwhelming scientific consensus is that the current global temperature increase is caused by human activity.

The Greenhouse Effect

The greenhouse effect refers to the naturally occurring process that allows Earth to absorb and release heat energy from the sun. This energy cycle is the key to maintaining Earth’s temperature at a level that sustains life.

However, due to imbalance composition of molecules in the atmosphere, the greenhouse effect has intensified. There are numerous molecules in the atmosphere suchas: oxygen, carbon, nitrogen, methane etc. that influence the global temperature.

TRCA climate change climate science global warming greenhouse effect


Currently the levels of some of these molecules has been increassing at a rapid rate. Carbon dioxide, a greenhouse gas that is emitted into the atmosphere through burning coal to generate energy and oil to fuel our cars, is one of the greatest threat to global warming. Measurement of CO2 composition in prior to the industrial revolution was 289 parts per million; today the atmosphere contains over 400 parts per million. This is the highest concentration in recorded history.

Why Is Climate Change Happening?

Climate change is happening because we’re putting too much burden in the Earth’s natural cycle. The amount of pollution emitted is too much for the natural system to neutralize.

TRCA climate change climate science


Global warming is difficult to address because it is engaged in a self-reinforcing cycle that further exacerbate the problem as the cycle continues. The cycle works like this:

  • CO2 concentration in the atmosphere increases from human activities.
  • Greenhouse effect intensifies.
  • Water vapour content in the atmosphere increase due to evaporation.
  • Higher concentration of CO2 and water vapour amplifies the greenhouse effect.
  • Higher temperature is experienced.

This cycle of global warming will continue unless the greenhouse gas concentrations in the atmosphere are reduced.

Climate Change and Watershed Management

Toronto and Region Conservation’s jurisdiction is influenced by the sheer magnitude of its urban centres. Urban centres rely on municipal infrastructure such as sewage and water treatment facilities, roads, bridges and dams, electricity and communications. The forecasted increase in extreme events, such as storms, flooding and drought, will create additional risk to both these facilities and their operational function, placing municipal infrastructure at risk.

Further exacerbating the effects of climate change are urban centres and urban sprawl, which contribute to energy absorption and surface runoff. This is a result, in large part, of the abundance of paved surfaces. Along with warmer water temperatures, increased surface runoff will impact the physical, chemical and ecological health of the streams, rivers and lakes in TRCA’s jurisdiction.

TRCA climate change climate science watershed mangement

At this time, as a result of the current state of the science of climate modelling, the levels of uncertainty with both Global and Regional climate models, it is difficult to clearly define how climate change will be manifested on the scale of TRCA’s jurisdiction. While most global climate change models predict increases in temperature and variability in precipitation in the southern Ontario region, predictions vary widely between models in terms of both total change and the seasonal distribution of those changes.

Further, because of the scale of the global models, the smallest prediction units are in the range of 100,000 square kilometres, it is not possible to effectively predict climate change effects on a local scale. To better understand how local climate patterns will be influenced by climate change, TRCA and its partners have begun to explore techniques to more accurately predict local climate change.