Week 2: introduction to climate change

Question 1

WEATHER

Answer 1

• Weather is the current state of the atmosphere with respect to temperature (hot or cold), precipitation (wet or dry), wind (calm or stormy) and sky cover (clear or cloudy).
• What we experience on a daily basis
• Individual events

Question 2

WEATHER VS CLIMATE

Answer 2

• Weather is the current state of the atmosphere with respect to temperature (hot or cold), precipitation (wet or dry), wind (calm or stormy) and sky cover (clear or cloudy).
• Climate is the statistical description (average and variability) of the weather at a location over longer periods of time (typically over 30 years)
  
  • Vancouver has a generally mild climate
• Climate is what you expect, weather is what you get
• Bigger picture trends relate to climate

Question 3

CLIMATE CHANGE

Answer 3

-Significant and lasting change in the statistical distribution ( average and/or variability) of weather patterns over periods ranging from decades to millions of years
- Statistical distribution: Describes how often we are to expect days with a specific temperature based on 30 years of observation.

Question 4

IS THE CLIMATE CHANGING?

HAS CLIMATE CHANGE BEEN DETECTED?

Answer 4

• It is unequivocal that human influence has warmed the atmosphere, ocean and land.
• Widespread and rapid changes in the atmosphere, ocean, cryosphere and biosphere have occurred.
• The scale of recent changes across the climate system as a whole and the present state of many aspects of the climate system are unprecedented over many centuries to many thousands of years.
• The global average surface temperature has increased by 1.1C relative to 1850- 1900.
• Each of the last four decades (80s, 90s, 2000, 2010) has been successively warmer at the Earth’s surface than any preceding decade since 1850.
• The 10 warmest years in the instrumental record have now all occurred since 2014.
• The last 10 years rank as the top 10 hottest.
• 2023 ranks as Earth’s warmest year since by far 1880!!

Question 5

ANNUAL PRECIPITAITON

Answer 5

• At warmer temperatures
  
  • Atmosphere can hold more water
  • More and faster evaporation
  • Heavier precipitation
    Existing observations:
• Averaged land precipitation has likely increased since the middle of the 20th century.
• A faster increase in global land precipitation has been observed since 1980.

Question 6

CYROSPHERIC CHANGE

Answer 6

• Over the last decades, global warming has led to widespread shrinking of the cryosphere, with mass loss from ice sheets and glaciers (very high confidence), reductions in snow cover (high confidence) and Arctic sea ice extent and thickness (very high confidence), and increased permafrost temperature (very high confidence).

Question 7

OCEAN AND SEA LEVEL

Answer 7

• Oceans have been absorbing more than 90% of the increase in energy stored in the climate system between 1971 and 2010.
• The upper 75 m of water have warmed by 0.11C
• Global mean sea level is rising (virtually certain) and accelerating.
  2006-2015: 3.6 mm/yr.
  Over the past 100 years, global mean sea level rose about 16-21 cm in response to climate change.

Question 8

CONCLUSION

Answer 8

• Climate is what you expect, weather is what you get.
• Climate change is a significant and lasting change in the statistical distribution of weather patterns over long periods of time.
• Many types of observations indicate that the climate is changing. The change is accelerating, and some areas are changing much more than others