Global Warming Video Lecture - Biology Class 12 - NEET

for 2.5 million years the Earth's
climate has fluctuated cycling from ice
ages to warmer periods but in the last
century the planets temperature has
risen unusually fast about 1.2 to 1.4
degrees Fahrenheit scientists believe
it's human activity that's driving the
temperatures up a process known as
global warming
ever since the industrial revolution
began factories power plants and
eventually cars have burned fossil fuels
such as oil and pull releasing huge
amounts of carbon dioxide and other
gases into the atmosphere these
greenhouse gases trap heat near the
earth through a naturally occurring
process called the greenhouse effect the
greenhouse effect begins with the Sun
and the energy it radiates to the earth
the earth and the atmosphere absorbs
some of this energy while the rest is
radiated back into space
naturally-occurring gases in the
atmosphere trap some of this energy and
reflected back warming the earth
scientists now believe that the
greenhouse effect is being intensified
by the extra greenhouse gases that
humans have released evidence for global
warming includes a recent string of very
warm years scientists report that 1998
was the warmest year in measured history
with 2005 coming in second meanwhile
readings taken from ice cores show that
the greenhouse gases carbon dioxide and
methane have hit their highest levels in
the past 420 thousand years
Arctic sea ice is also shrinking
according to NASA studies the extent of
Arctic sea ice has declined about 10
percent in the last 30 years as long as
industrialized nations consume energy
and developing countries increase their
fossil fuel consumption the
concentration of greenhouse gases in the
atmosphere will continue to rise
researchers predict that temperatures
will increase about two to 10 degrees
Fahrenheit by the end of the century
what's less certain is what rising
temperatures mean for the planet some
climate models predict subtle changes
others forecast rising sea levels which
could flood coastal areas around the
world weather patterns could change
making hurricanes more frequent severe
droughts could become more common in
warm areas and species unable to adapt
to the changing conditions would face
extinction although much remains to be
learned about global warming
many organizations advocate cutting
greenhouse gas emissions to reduce the
impact of global warming
consumers can help by saving energy
around the house switching to compact
fluorescent light bulbs and driving
fewer miles in the car each week these
simple changes may help keep the earth
cooler in the future
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