SIO40lecture16

SIO40lecture16 - SIO 40 Life and Climate on Earth Nov. 3rd,...

Info iconThis preview shows pages 1–8. Sign up to view the full content.

View Full Document Right Arrow Icon
SIO 40 – Life and Climate on Earth Nov. 3rd, 2010 Lecture 16 – Climate Change Basics, Part I We have seen that as we change time scales, different parts of the climate system take on different levels of importance. Over very long time scales, the system is regulated by silicate weathering, plate tectonics and changes in atmospheric composition. On time scales of thousands to hundreds of thousands of years (eg. the Pleistocene glaciations), we saw that climate changes were associated with orbital parameters, ice sheets, and atmospheric composition. On interannual to decadal timescales, solar cycles, volcanoes, greenhouse gases and ocean circulation play important roles in climate.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Lecture Outline - Human vs. natural influences on climate - Uncertainty in climate science - The greenhouse effect and major greenhouse gases - Surface and atmospheric temperature observations - The Paleoclimate perspective - Recent “climate scares” - Modern warming is different
Background image of page 2
Relative impacts of humans vs. nature on climate Natural impacts – solar output, volcanic eruptions, Earth’s orbit Human impacts – greenhouse gas emissions, aerosol emissions, ozone depletion, land use changes
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Review: Earth’s annual and global mean energy balance Over the long term, the amount of incoming solar radiation absorbed by the Earth and atmosphere is balanced by the Earth and atmosphere releasing the same amount of outgoing longwave radiation. About half of the incoming solar radiation is absorbed by the Earth’s surface. This energy is transferred to the atmosphere by warming the air in contact with the surface (thermals), by evapotranspiration and by longwave radiation that is absorbed by clouds and greenhouse gases. The atmosphere in turn radiates longwave energy back to Earth as well as out to space.
Background image of page 4
Radiative forcing of climate between 1750 and 2005 Radiative forcing factors change the balance between incoming solar radiation and outgoing infrared (longwave) radiation within the Earth’s atmosphere, thus affecting climate. Positive forcings lead to warming; negative forcings lead to cooling. It is apparent that forcing factors associated with human activity from the period 1750-2005 outweigh natural forcing factors, and are net positive. LOSU = level of scientific understanding
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
The principle of the greenhouse effect is one of the most well-understood parts of the climate system.
Background image of page 6
Feedback loops and the greenhouse effect Increased CO 2 Global warming Increased water vapor Positive loop more evaporation warms atmosphere Increased CO 2 Global warming Increased low clouds Negative loop more evaporation cools atmosphere In thinking about the effect of adding more greenhouse gases to the atmosphere, one must consider not just
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 8
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 19

SIO40lecture16 - SIO 40 Life and Climate on Earth Nov. 3rd,...

This preview shows document pages 1 - 8. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online