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Jo_Haigh_panel_one.pptx

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Vara Prasad

This document provides an introduction to climate change by defining climate and climate change. It explains that climate is the average weather conditions in an area over many years, while climate change refers to long-term shifts in those conditions. It then outlines the various records and data sources used to determine if and when the climate has changed, such as satellite data since the 1970s, instrumental measurements since 1850, and data from tree rings, corals, ice cores, and ocean sediments. The document discusses how the global average temperature has risen about 1 degree Celsius since the 1800s and identifies both natural and human factors that can force climate change, with a focus on the role of increasing greenhouse gas emissions. It also summarizes the relationship between greenhouse gases

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Introduction to Climate Change Joanna D. Haigh
What is Climate? The average weather conditions in an area. e.g. 30-year averages of temperature, humidity, rainfall, cloudiness, pressure, wind in Birmingham area. Also variability in those conditions. e.g. frequency of exceeding specific extreme values. What is Climate Change? A long-term shift in those conditions.
How do we know if/when climate has changed? Records are carefully compiled from many sources including: • Satellite measurements since 1970s. • Instrumental measurements from across the globe since about 1850. • Indicators in tree rings, corals, stalagmites and stalactites over thousands of years. • Trapped air in polar ice cores over hundreds of thousands of years. • Records in ocean sediments over millions of years.
1 C warmer Average value during 1800s __ __ Global average temperature measurements
The Greenhouse Effect Important for our natural climate, making the surface about 30C warmer than it would be were there no atmosphere.
Factors which force climate to change Natural: • volcanic eruptions • solar radiation Humans: • greenhouse gas emissions • industrial pollution • agriculture and land use Responses which can reduce or enhance the initial warming (or cooling) • changes in humidity, clouds and ice • heat storage by oceans • natural variations & “noise”
Greenhouse gas (GHG) global emissions due to human activity IPCC (2014)
Atmospheric carbon dioxide concentration measured on Hawaii
Atmospheric carbon dioxide concentration over the past 800,000 years Hawaii measurements Ice core measurements
Carbon dioxide (CO2) • CO2 - naturally transferred between plants, soils, atmosphere, oceans & ice balancing at an atmospheric concentration of about 280 ppm. • Now more than 400 ppm - higher than for over 3 million years. • The increase is due to human combustion of fossil fuels. • CO2 remains in the atmosphere for about 200 years so emissions are accumulating.
Greenhouse gases accumulation
C 1.0 - 0.5 - 0.0 - -0.5 - Natural and human impacts on global temperature Black: observations Grey: computer model calculations with and without human drivers
Greenhouse gases and global warming • The global temperature rise is directly related to the accumulated emissions of GHGs. • To stop the temperature rising above any specific threshold means a limit to total GHG emissions. • This amount is called the Carbon Budget. • If the carbon budget is used up then any further emissions must be balanced by removing CO2 from the atmosphere at the same rate as it is put in: “Net Zero Emissions”. • To keep warming below 1.5C above pre-industrial means reducing emissions to net zero by about 2050.

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Jo_Haigh_panel_one.pptx

  • 1. Introduction to Climate Change Joanna D. Haigh
  • 2. What is Climate? The average weather conditions in an area. e.g. 30-year averages of temperature, humidity, rainfall, cloudiness, pressure, wind in Birmingham area. Also variability in those conditions. e.g. frequency of exceeding specific extreme values. What is Climate Change? A long-term shift in those conditions.
  • 3. How do we know if/when climate has changed? Records are carefully compiled from many sources including: • Satellite measurements since 1970s. • Instrumental measurements from across the globe since about 1850. • Indicators in tree rings, corals, stalagmites and stalactites over thousands of years. • Trapped air in polar ice cores over hundreds of thousands of years. • Records in ocean sediments over millions of years.
  • 4. 1 C warmer Average value during 1800s __ __ Global average temperature measurements
  • 5. The Greenhouse Effect Important for our natural climate, making the surface about 30C warmer than it would be were there no atmosphere.
  • 6. Factors which force climate to change Natural: • volcanic eruptions • solar radiation Humans: • greenhouse gas emissions • industrial pollution • agriculture and land use Responses which can reduce or enhance the initial warming (or cooling) • changes in humidity, clouds and ice • heat storage by oceans • natural variations & “noise”
  • 7. Greenhouse gas (GHG) global emissions due to human activity IPCC (2014)
  • 8. Atmospheric carbon dioxide concentration measured on Hawaii
  • 9. Atmospheric carbon dioxide concentration over the past 800,000 years Hawaii measurements Ice core measurements
  • 10. Carbon dioxide (CO2) • CO2 - naturally transferred between plants, soils, atmosphere, oceans & ice balancing at an atmospheric concentration of about 280 ppm. • Now more than 400 ppm - higher than for over 3 million years. • The increase is due to human combustion of fossil fuels. • CO2 remains in the atmosphere for about 200 years so emissions are accumulating.
  • 12. C 1.0 - 0.5 - 0.0 - -0.5 - Natural and human impacts on global temperature Black: observations Grey: computer model calculations with and without human drivers
  • 13. Greenhouse gases and global warming • The global temperature rise is directly related to the accumulated emissions of GHGs. • To stop the temperature rising above any specific threshold means a limit to total GHG emissions. • This amount is called the Carbon Budget. • If the carbon budget is used up then any further emissions must be balanced by removing CO2 from the atmosphere at the same rate as it is put in: “Net Zero Emissions”. • To keep warming below 1.5C above pre-industrial means reducing emissions to net zero by about 2050.

Editor's Notes

  1. Methane Emitted naturally by wetlands, termites, oceans & ice; destroyed in the atmosphere and by soils. Human activities – rice paddies, ruminant animals, waste treatment – have doubled its atmospheric concentration since 1900. Nitrous oxide Emitted naturally by uncultivated soils and oceans; destroyed in the atmosphere Human activities – use of fertilisers, combustion of fossil and biofuels – have increased its atmospheric concentration by 20%. F-gases No natural sources. Developed to replace gases destroying the ozone layer.
  2. global challenge
  3. note range given by shading
  4. global challenge