• Global mean sea-level has risen ∼25 cm since 1900 CE and seems to be accelerating with the current observed rate 3.5 mm/yr
• Predictions of future sea level rise are difficult, due to uncertainties in melting rates & ocean heat storage. Most models suggest 0.3-1.2 m rise by the end of this century, but larger values cannot be ruled out
• An estimated 1–2 billion people living in low-lying coastal areas would be directly impacted by such a rise
  

Anthropogenic sources of greenhouse gases
• CO2 (carbon dioxide) - burning of fossil fuels & forests
• CH4 (methane) - from decomposition of vegetation in absence of O2
• N2O (nitrous oxide) - from chemical fertilizers & automotive combustion
• O3 (ozone) - from automotive/industrial gases (smog)
• CFC (chlorofluorocarbons) - from coolants & solvents (now banned)

• As a result, CO2 concentrations are ∼50% higher than before the industrial revolution, and the highest they have been for perhaps ∼20 million years
• This has driven a parallel increase global average temperature of ~0.7 C.

Models predict that Earth will warm between 2-6 C in the next century, at least 20x faster than natural rates
o Rising temperatures are not distributed evenly across the globe, with polar regions absorbing far more of the excess heat than low latitude areas. This has resulted in rapid melting of the Greenland and Antarctic ice sheets and of mountain glaciers and ice caps worldwide.
o ~90% of excess heat from anthropogenic global warming is absorbed by the oceans
o As water warms it increases in volume: thermal expansion (more important than ice sheets melting)
o The melting of continental ice and the thermal expansion of seawater are causing sea-level rise

When global warming has occurred naturally in the geological past, it has done so at rates of at most ~1000 years/C. The current rate of warming is ~10 times faster, & accelerating

Northern Canada
o The Northwestern Passage opened for commercial maritime traffic; NW passage through Arctic may open up to Maritimes traffic
o Potential for more Arctic Ocean drilling operations
o Melting permafrost weakens & undermines infrastructure
o Wildlife adapted to cold climates shift northward by 150 km for every degree of warming

Atlantic Canada
o Rising sea levels & greater storm activity will generate more powerful storm surges
o Increased flooding, coastal erosion & property damage
o Little chance for cod & salmon recovery possibility for new invaders species to take over

Ontario & Quebec
o Reduced water levels in the Great Lakes & St. Lawrence River affects shipping & hydroelectric power generation
o Reduced risk from snowmelt & ice jam flooding, but higher risk of flash flooding
o Longer & more severe heat waves
o Potential for worse air pollution in the form of smog, airborne dust & ground-level ozone

British Columbia
o Pacific waters too warm for sockeye salmon
o Increased likelihood of more wildfires & a longer fire season
o Increased winter precipitation raises the risk for spring snowmelt flooding
o Higher winter precipitation also increases the risk for landslide & avalanches in mountainous regions

• Rising temperatures and sea-levels are already driving a number of upward trends in weather-related hazards
• The uneven nature of climate change is likely to lead to a higher frequency of extreme weather events, increasing the severity of droughts and flood
  

• Rising ocean heat content provides more energy for tropical storms & cyclones, and is likely responsible for the recent rise in the number, size and intensity of North Atlantic hurricanes
  o 1991 - Since 1970, there has been an average of 6 Atlantic hurricanes per year
  o 2017 - During last year's season, 10 hurricanes formed. It has widely been called the worst year on record
  • Harvey, Maria, Irma ruined the lives of thousands. They cost a combined $265 billion
  

• Number & intensity of tropical storms are increasing
  o Big recent hurricanes, if temperature continue to rise, it will increase 20% by rising global temperature of 2-3 C
  

• Sea level rise will also increase coastal vulnerability to storm surge
  o 1-2 billion people are nearly at risk as those place that have risk of storm surge
  

• Wildfires are increasing in number, size, and duration of fire season, due to higher temperatures
• In western North America, also by an increase in forest fuels driven by beetle species (live in warmer temperatures)

Mountain Pine Beetle problem - winter in NA is not cold enough (winter) to kill the beetles

-Melting ice sheets & deglaciation shown evidence of earthquakes

The Parvie fault scarp in Sweden, which formed in a single M~8 earthquake ~10,000 years ago due to isostatic rebound
o Mantle underneath (crust) flexing trigger earthquake