Global warming poses an existential threat to humanity according to the document. The evidence of climate change is clear from rising sea levels, global temperatures, shrinking ice sheets and increasing extreme weather events. The main causes are human activities like burning fossil fuels and deforestation that release greenhouse gases like carbon dioxide into the atmosphere, enhancing the natural greenhouse effect. Effects of climate change include further temperature rises, longer frost-free seasons, changing precipitation patterns, stronger hurricanes, and Arctic ice melt. Wildlife like dugongs, okapis and Siberian tigers are also threatened with extinction. Individual actions like conserving energy, choosing renewable power, reducing waste, and greener commuting can help address the crisis.

1. Global Warming
Are we in danger of extinction ?

2. What is the climate change ?
 Climate change is a change in the statistical distribution of weather patterns
when that change lasts for an extended period of time (i.e., decades to millions
of years). Climate change may refer to a change in average weather conditions,
or in the time variation of weather around longer-term average conditions

3. How do we know climate change is real
 The evidence for rapid climate change is compelling:
♦ Sea level rise
Global sea level rose about 8 inches in the last century . The rate in the last
two decades, however, is nearly double that of the last century.4
♦ Global temperature rise
All three major global surface temperature reconstructions show that Earth has
warmed since 1880. Most of the warming occurred in the past 35 years, with 15 of
the 16 warmest years on record occurring since 2001. The year 2015 was the first
time the global average temperatures were 1 degree Celsius or more above the
1880-1899 average. Even though the 2000s witnessed a solar output decline
resulting in an unusually deep solar minimum in 2007-2009, surface temperatures
continue to increase.7

4. ♦ Shrinking ice sheets
 The Greenland and Antarctic ice sheets have decreased in mass. Data from NASA's
Gravity Recovery and Climate Experiment show Greenland lost 150 to 250 cubic
kilometers (36 to 60 cubic miles) of ice per year between 2002 and 2006, while
Antarctica lost about 152 cubic kilometers (36 cubic miles) of ice between 2002 and
2005.
♦ Extreme Events
 The number of record high temperature events in the United States has been
increasing, while the number of record low temperature events has been decreasing,
since 1950. The U.S. has also witnessed increasing numbers of intense rainfall events

5. Why is climate change happening ?
 Most climate scientists agree the main cause of the current global warming
trend is human expansion of the "greenhouse effect" : the process by which
radiation from a planet's atmosphere warms the planet's surface to a
temperature above what it would be without its atmosphere
 Certain gases in the atmosphere block heat from escaping. Long-lived gases
that remain semi-permanently in the atmosphere and do not respond
physically or chemically to changes in temperature are described as "forcing"
climate change. Gases, such as water vapor, which respond physically or
chemically to changes in temperature are seen as "feedbacks.“
 Gases that contribute to the greenhouse effect include :
♦ Water vapor ( 36-70% )
♦ Carbon Dioxide ( 9-26% )
♦ Methane ( 4-9% )
♦ Ozone ( 3-7% )

6.  Climate change can also be caused by human activities, such as the burning of
fossil fuels and the conversion of land for forestry and agriculture. Since the
beginning of the Industrial Revolution, these human influences on the climate
system have increased substantially. In addition to other environmental
impacts, these activities change the land surface and emit various substances to
the atmosphere. These in turn can influence both the amount of incoming
energy and the amount of outgoing energy and can have both warming and
cooling effects on the climate. The dominant product of fossil fuel combustion
is carbon dioxide, a greenhouse gas. The overall effect of human activities since
the Industrial Revolution has been a warming effect, driven primarily by
emissions of carbon dioxide and enhanced by emissions of other greenhouse
gases.
 The build-up of greenhouse gases in the atmosphere has led to an enhancement
of the natural greenhouse effect. It is this human-induced enhancement of the
greenhouse effect that is of concern because ongoing emissions of greenhouse
gases have the potential to warm the planet to levels that have never been
experienced in the history of human civilization. Such climate change could
have far-reaching and/or unpredictable environmental, social, and economic
consequences.

7.  Carbon dioxide is the main cause of human-induced climate change. It has been
emitted in vast quantities from the burning of fossil fuels and it is a very long-lived
gas, which means it continues to affect the climate system during its long residence
time in the atmosphere. However, fossil fuel combustion, industrial processes,
agriculture, and forestry-related activities emit other substances that also act as
climate forcers. Some, such as nitrous oxide, are long-lived greenhouse gases like
carbon dioxide, and so contribute to long-term climate change. Other substances have
shorter atmospheric lifetimes because they are removed fairly quickly from the
atmosphere. Therefore, their effect on the climate system is similarly short-lived.
Together, these short-lived climate forcers are responsible for a significant amount of
current climate forcing from anthropogenic substances. Some short-lived climate
forcers have a climate warming effect (‘positive climate forcers') while others have a
cooling effect (‘negative climate forcers').

8.  Deforestation is the removal of a forest or stand of trees where the land is thereafter
converted to a non-forest use. Examples of deforestation include conversion of
forestland to farms, ranches, or urban use. The most concentrated deforestation
occurs in tropical rainforests. About 30% of Earth's land surface is covered by forests .
 Deforestation occurs for multiple reasons: trees are cut down to be used for building
or sold as fuel, (sometimes in the form of charcoal or timber), while cleared land is
used as pasture for livestock and plantation. The removal of trees without
sufficient reforestation has resulted in damage to habitat, biodiversity loss
and aridity.
 Deforestation is a contributor to global warming, and is often cited as one of the
major causes of the enhanced greenhouse effect. Tropical deforestation is
responsible for approximately 20% of world greenhouse gas emissions.
 In deforested areas, the land heats up faster and reaches a higher temperature,
leading to localized upward motions that enhance the formation of clouds and
ultimately produce more rainfall.
 The water cycle is also affected by deforestation. Trees extract groundwater through
their roots and release it into the atmosphere. When part of a forest is removed, the
trees no longer transpire this water, resulting in a much drier climate. Deforestation
reduces the content of water in the soil and groundwater as well as atmospheric
moisture.

9. What are the effects of climate change ?
♦ Temperatures will continue to rise
 Because human-induced warming is superimposed on a naturally varying climate, the
temperature rise has not been, and will not be, uniform or smooth across the country
or over time.
♦ Frost-free season (and growing season) will lengthen
 The length of the frost-free season (and the corresponding growing season) has been
increasing nationally since the 1980s, with the largest increases occurring in the
western United States, affecting ecosystems and agriculture. Across the United States,
the growing season is projected to continue to lengthen.
♦ Changes in precipitation patterns
 Average U.S. precipitation has increased since 1900, but some areas have had increases
greater than the national average, and some areas have had decreases. More winter
and spring precipitation is projected for the northern United States, and less for the
Southwest, over this century.

10. ♦ Hurricanes will become stronger and more intense
 The intensity, frequency and duration of North Atlantic hurricanes, as well as the
frequency of the strongest (Category 4 and 5) hurricanes, have all increased since
the early 1980s. The relative contributions of human and natural causes to these
increases are still uncertain. Hurricane-associated storm intensity and rainfall rates
are projected to increase as the climate continues to warm.
♦ Arctic likely to become ice-free
 The Arctic Ocean is expected to become essentially ice free in summer before mid-
century.

11.  Climate change affects even the animals . It’s sad to think that these majestic
creatures won’t be around forever, but they might not be.
 Here are some animals that are likely to disappear from this planet entirely while
we’re still living :
♦ Dugong - is one of only four living species of sea cows and are found from the Pacific
Ocean to the eastern coast of Africa
♦ Okapi - Known as the “zebra giraffe,” the Okapi has the legs of a zebra and the long
neck of a giraffe. The animal came to fame during the 1800s, when they were found by
British explorers – though, no one back home believed such a bizarre creature could be
real.
♦ Siberian Tiger - The Siberian tiger is the largest of the six surviving subspecies of
tiger, all of which are threatened. Its historic range spanned all of western and central
Asia. The western populations went extinct over this range over the course of the 20th
century as habitat loss and active persecution (particularly in the Caspian Sea region by
the Soviets), and now the last remaining populations are confined to the Russian Far
East.
♦ Coconut Crab - Coconut crabs are the largest example of arthropods in the world,
weighing up to 9 pounds. As their name suggests, the animals have been known to climb
trees to pick coconuts and then crush them with their powerful claws. Considered a
delicacy by some, these crustaceans are protected in some areas.

12. How can we help the planet
 1. Be energy efficient
 You already switch off lights — what's next? Change light bulbs to compact fluorescents
or LEDs. Unplug computers, TVs and other electronics when not in use. Wash clothes in cold
or warm (not hot) water. Dryers are energy hogs, so hang dry when you can.
 2. Choose renewable power
 Ask your utility to switch your account to clean, renewable power, such as from wind farms.
If it doesn't offer this option yet, ask it to.
 3. Eat wisely
 Buy organic and locally grown foods. Avoid processed items. Grow some of your own food.
And eat low on the food chain — at least one meat-free meal a day — since 18 per cent of
greenhouse gas emissions come from meat and dairy production. Food writer Michael Pollan
sums it up best: "Eat food. Not too much. Mostly plants."
 4. Trim your waste
 Garbage buried in landfills produces methane, a potent greenhouse gas. Keep stuff out of
landfills by composting kitchen scraps and garden trimmings, and recycling paper, plastic,
metal and glass. Let store managers and manufacturers know you want products with
minimal or recyclable packaging.
 9. Green your commute
 Transportation causes about 25 per cent of Canada's greenhouse gas emissions, so walk, cycle
or take transit whenever you can. You'll save money and get into better shape! If you can't go
car-free, try carpooling or car sharing, and use the smallest, most fuel-efficient vehicle
possible.

13. How do you think you can help the
planet ?
 Think about this before it is too late . Humans need to
repair what they destroyed during these centuries . Let’s
live in a better world

16. Thanks for watching
#SCICHALLENGE2017