GEO 702 Lecture Notes - Lecture 4: Permafrost, Ozone Depletion, Shortwave Radio
• What is Climate Change?
• Climate change is not all about global warming, it is a change of climate -
• Climate change is a significant and lasting change in the statistical distribution of weather
patterns over periods ranging from decades to millions of years.
– Changes in the following generate climate change:
• Chage i Sola adiatio ad su’s output - so if suns radiation is higher or lower/smaller
then there's a change in the climate on Earth
• Change in Plate tectonics and drifting continents -
• Eath’s oit Chages - Earth is turning so since it moves around the sun/orbits the sun,
sometimes there's a change due to the position of the Earth in relation to the Sun
• Volcanic eruptions - they spring out and cover the earth and make Earth's surface colder
• Biotic processes - in terms of biology and ecosystems, rainforests these are all changes
that are possible and may impact earths climate
• Greenhouse gases -
• Human activities - has an impact and plays the biggest role in climate change ex cars,
factories - emissions from burning fossil fuels for all these activities into the atmosphere
play a role
• These are the possible reasons for climate change
• We expect the weather to change a lot from day to day, month to month, year to year,
season to season but we expect the climate to remain relatively constant without
hagig ut if thee is a hage that is, if this ostat does’t eai ostat the
we have climate change
• If the liate does’t eai ostat, e all it climate change.
• Climate change may occur over long and short timescales from a variety of factors. It used
to be longer, billions of years but nowadays it takes less time
• Scientists have a good understanding of what has changed earth's climate in the past:
• Scientists have a good understanding of what has changed in terms of earth's climate due
to solar radiations. They have tested and measured solar radiations and have found that
solar radiation has a big impact on climate change and is the main climate driver. During
the night it's cold but the highest temp is in the afternoon due to the radiation of Earth -
The Earth has different types of radiations. What radiates from Earth? What do Earth's
radiations consist?
• The Sun's radiation consists of UV rays, infrared ray, x-ray, short and long rays - there are
lots of rays that expose the Earth
• The one that makes the Earth the warmest if infrared (IR) because it has long rays - there
are lots of rays that come into the earth and due to these rays or radiations from the sun
which is called solar radiation, the climate changes. So when the earth orbits and is close
to the sun the climate is hotter while in the winter time its further
• Incoming solar radiation is the main climate driver.
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• Solar energy output increased about 0.1% from 1750 to 1950, increasing
temperatures by 0.1°C (0.2°F) in the first part of the 20th century.
• Almost everything changed post industrial revolution - but regardless they have
measured that the temp increase was just by 0.1 however since 1979, almost 40
years, when measurements were taken from space using satellite (so technology was
improved_ they found that there are no long-term changes in terms of solar energy
due to solar radiation although the Earth was still getting warmer than it was 40
years ago. So the solar reason was eliminated, it's not due to the sun
• But since 1979, when measurements were starting taken from space, the data show
no long-term change in total solar energy, although Earth has been warming.
• Repetitive cycles in Earth’s orbit that occur over tens of thousands of years can influence
the angle and timing of sunlight. When the earth is just rotating around the sun, it occurs
over years and the angle and timing of the sun is different so there arent very big change
sin terms of temperatures due to this
• In the distant past, drifting continents make a big difference in climate over millions of
years by changing ice caps at the poles and by altering ocean currents, which transport
heat and cold throughout the ocean depths. Continents were united but now they are
separated and we may have more, 6 or 7, continents in the future due to the rising sea
levels. The water will cover more parts of the world and create more continents. This
didn't play a big role in the climate change situation either in terms of the transportation
of heat and cold and also ocean current movements and also alterations in the movement
of ocean currents - these were under study
• One reason dinosaurs are thought to have become extinct was due to volcanic eruptions -
they may have been buried under the ash so again it plays a big role in making the earths
temperature cooler so this may be one reason for climate change
• Huge volcanic eruptions can cool Earth by injecting ash and tiny particles into the
stratosphere.
• Changes in the concentration of greenhouse gases (GHGs), which occur both naturally and
as a esult of hua atiities, also ifluee Eath’s liate.
• On the other hand the concentration of GHGs is now showing to play a big role - it used to
be hotter on earth due to wild fires and eruptions etc but nowadays we see that human
activities that create more GHGs plays a bigger role and earth is in danger due to this
Lets say these are the diff types of rays coming in to the earth, some pf these rays will
reflect back due to ex clouds, germs in the space, asteroids, plants etc and so when the
rays (we'll look at UV and IR for now) reach the earth, some parts are reflected back and
some parts get converted into IR which are the long waves so what reaches and is
absorbed on earth by the earths surface and is making the earth warm - this happens
naturally so the ice caps where the white surfaces are, if there are dark areas like water
oceans, they absorb more because dark color absorbs more - in LA California they are
planning on changing the color of the streets to white in order to reflect the heat back to
the sky and make the temp cooler -this occurs naturally but what happens when we
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