HOW TO PREVENT FROM GLOBAL WARMING
Global warming and climate change are terms for the observed
century-scale rise in the average temperature of the Earth's climate
system and its related
effects. Multiple lines of
scientific evidence show that the climate system is warming. Although the increase of near-surface
atmospheric temperature is the measure of global warming often reported in the
popular press, most of the additional energy stored in the climate system since
1970 has gone into ocean warming. The remainder has melted ice and warmed the
continents and atmosphere. Many of the observed changes since the
1950s are unprecedented over tens to thousands of years.
Scientific understanding of global
warming is increasing.
The Intergovernmental Panel on Climate
Change (IPCC) reported in 2014 that scientists were more than 95%
certain that global warming is mostly being caused by human (anthropogenic) activities,
mainly increasing concentrations of greenhouse
gases such as carbon
dioxide (CO2). Human-made carbon
dioxide continues to increase above levels not seen in hundreds of
thousands of years: currently, about half of the carbon dioxide released from
the burning of fossil fuels is not absorbed by vegetation and the oceans and
remains in the atmosphere. Climate model projections
summarized in the report indicated that during the 21st century the global
surface temperature is likely to rise a further 0.3 to 1.7 °C (0.5 to
3.1 °F) for their lowest emissions scenario using stringent mitigation and 2.6 to
4.8 °C (4.7 to 8.6 °F) for their highest. These findings have been
recognized by the national science academies of the major industrialized nations and are not disputed by any scientific
body of national or international standing.
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Future climate
change and associated impacts will differ from region to region around the globe. Anticipated effects include
warming global temperature, rising sea levels, changing precipitation, and expansion of deserts in the subtropics. Warming is expected to be greater over
land than over the oceans and greatest in
the Arctic, with the continuing retreat of glaciers, permafrost and sea ice.
Other likely changes include more frequent extreme
weather events
including heat waves, droughts,
heavy rainfall with floods and heavy snowfall; ocean acidification; and species extinctions due to shifting temperature regimes.
Effects significant to humans include the threat to food security from decreasing crop yields and the abandonment
of populated areas due
to rising sea
levels. Because the
climate system has a large "inertia" and CO2 will stay in the atmosphere for a long
time, many of these effects will not only exist for decades or centuries, but
will persist for tens of thousands of years. Possible societal responses to
global warming include mitigation by emissions reduction, adaptation to its effects, building systems resilient to
its effects, and possible future climate engineering. Most countries are parties
to the United
Nations Framework Convention on Climate Change (UNFCCC), whose ultimate objective is to prevent dangerous anthropogenic
climate change. The
UNFCCC have adopted a range of policies designed to reduce greenhouse gas
emissions and to assist in
adaptation to global warming. Parties to the UNFCCC had agreed that deep cuts
in emissions are required and as first target the future global warming should
be limited to below 2.0 °C (3.6 °F) relative to the pre-industrial
level, while the Paris
Agreement of 2015
stated that the parties will also "pursue efforts to" limit the
temperature increase to 1.5 °F (0.8 °C). Public reactions to global
warming and general fears of its effects are also steadily on the rise, with a
global 2015 Pew Research Center report showing a median of 54% who consider it "a very
serious problem". There are, however, significant regional differences.
Notably, Americans and Chinese,
whose economies are responsible for the greatest annual CO2 emissions,
are among the least concerned.
Global Warming- Facts, Causes & Effects
Global
warming is the term used to describe a gradual increase in the average
temperature of the Earth's atmosphere and its oceans, a change that is believed
to be permanently changing the Earth’s climate. There is great debate among
many people, and sometimes in the news, on whether global warming is real (some
call it a hoax). But climate scientists looking at the data and facts agree the
planet is warming. While many view the effects of global warming to be more
substantial and more rapidly occurring than others do, the scientific consensus
on climatic changes related to global warming is that the average temperature
of the Earth has risen between 0.4 and 0.8 °C over the past 100 years. The
increased volumes of carbon dioxide and other greenhouse gases released by the
burning of fossil fuels, land clearing, agriculture, and other human
activities, are believed to be the primary sources of the global warming that
has occurred over the past 50 years. Scientists from the Intergovernmental
Panel on Climate carrying out global warming research have recently predicted
that average global temperatures could increase between 1.4 and 5.8 °C by the
year 2100. Changes resulting from global warming may include rising sea levels
due to the melting of the polar ice caps, as well as an increase in occurrence
and severity of storms and other severe weather events.
The
Consequences of a Warming World
Over the last century, global average temperature has increased by more
than 1°F (0.7°C). The 2001-2010 decade is the warmest since 1880—the earliest
year for which comprehensive global temperature records were available. In
fact, nine of the warmest years on record have occurred in just the last 10
years. This warming has been accompanied by a decrease in very cold days and
nights and an increase in extremely hot days and warm nights. The continental
United States, for example, has seen record daily highs twice as often as
record daily lows from 2000 to 2009. While the record shows that some parts of
the world are warming faster than others, the long-term global upward trend is
unambiguous.
Of course, land and ocean temperature is only one way to measure the effects
of climate change. A warming world also has the potential to change rainfall
and snow patterns, increase droughts and severe storms, reduce lake ice cover,
melt glaciers, increase sea levels, and change plant and animal behavior.
Global
Warming Is Urgent and Can Be Addressed
CO2 survives in the atmosphere for a long time—up to many centuries—so
its heat-trapping effects are compounded over time. Of the many heat-trapping
gases, CO2 puts us at the greatest risk of irreversible changes if it continues
to accumulate unabated in the atmosphere—as it is likely to do if the global
economy remains dependent on fossil fuels for its energy needs. To put this in
perspective, the carbon we put in the atmosphere today will literally determine
not only our climate future but that of future generations as well.
Substantial scientific evidence indicates that an increase in the global
average temperature of more than 3.6 degrees Fahrenheit (°F) (or 2 degrees
Celsius [°C]) above pre-industrial levels poses severe risks to natural systems
and to human health and well-being. The good news is that, because we as humans
caused global warming, we can also do something about it. To avoid this level
of warming, large emitters such as the United States need to greatly reduce
heat-trapping gas emissions by mid century. Delay in taking such action means
the prospect of much steeper cuts later if there is any hope of staying below
the 3.6°F (2°C) temperature goal. Delayed action is also likely to make it more
difficult and costly to not only make these reductions, but also address the
climate consequences that occur in the meantime.
Regional
Actions Add Up to Global Solutions
We encourage you to visit the solutions
section of this
web feature to find out how you can take action to slow the pace of climate
change and help minimize the harmful consequences described in the hot spots!
Any action to reduce or eliminate the release of heat-trapping gases to
the atmosphere helps slow the rate of warming and, likely, the pace and
severity of change at any given hot spot. Local sources of carbon emissions
vary from region to region, suggesting that solutions are often decided at the
community level. The Climate Hot Map points to regional examples of
climate-friendly energy, transportation, or adaptation choices. Some regions,
however, must rely upon global solutions such as international agreements to
reduce the carbon overload in the atmosphere that threatens them. Small
islands, for example, are a paltry source of carbon emissions and yet are
disproportionately affected by the consequences of global carbon overload as
accelerated sea level rise threatens the very existence of low-lying islands.
Individual, regional, and national actions can all add up to global
solutions, slowing and eventually halting the upward climb of CO2 concentrations
in the atmosphere.
What is Global Warming?
Global
Warming is the increase of Earth's average surface temperature due to effect of
greenhouse gases, such as carbon dioxide emissions from burning fossil fuels or
from deforestation, which trap heat that would otherwise escape from Earth.
This is a type of greenhouse effect.
Is global warming, caused by human activity, even remotely
plausible?
Earth's
climate is mostly influenced by the first 6 miles or so of the atmosphere which
contains most of the matter making up the atmosphere. This is really a very
thin layer if you think about it. In the book The End of Nature, author Bill Mc Kibbin tells of walking three miles to from
his cabin in the Adirondack's to buy food. Afterwards, he realized that on this
short journey he had traveled a distance equal to that of the layer of the
atmosphere where almost all the action of our climate is contained. In fact, if
you were to view Earth from space, the principle part of the atmosphere would
only be about as thick as the skin on an onion! Realizing this makes it more
plausible to suppose that human beings can change the climate. A look at the
amount of greenhouse gases we are spewing into the atmosphere (see below),
makes it even more plausible.
What are the Greenhouse Gases?
The
most significant greenhouse gas is actually water vapor, not something produced
directly by humankind in significant amounts. However, even slight increases in
atmospheric levels of carbon dioxide (CO2) can cause a
substantial increase in temperature.
Why
is this?
There are two reasons: First, although the concentrations of these gases are not nearly as large as that of oxygen and nitrogen (the main constituents of the atmosphere), neither oxygen or nitrogen are greenhouse gases. This is because neither has more than two atoms per molecule (i.e. their molecular forms are O2 and N2, respectively), and so they lack the internal vibrational modes that molecules with more than two atoms have. Both water and CO2, for example, have these "internal vibrational modes", and these vibrational modes can absorb and reradiate infrared radiation, which causes the greenhouse effect.
Secondly, CO2 tends to remain in the
atmosphere for a very long time (time scales in the hundreds of years). Water
vapor, on the other hand, can easily condense or evaporate, depending on local
conditions. Water vapor levels therefore tend to adjust quickly to the prevailing
conditions, such that the energy flows from the Sun and re-radiation from the
Earth achieve a balance. CO2 tends
to remain fairly constant and therefore behave as a controlling factor, rather than a reacting factor. More CO2 means that the balance occurs at
higher temperatures and water vapor levels.
How much have we increased the Atmosphere's CO2 Concentration?
Human
beings have increased the CO2 concentration
in the atmosphere by about thirty percent, which is an extremely significant
increase, even on inter-glacial timescales. It is believed that human
beings are responsible for this because the increase is almost perfectly
correlated with increases in fossil fuel combustion, and also due other
evidence, such as changes in the ratios of different carbon isotopes in
atmospheric CO2 that
are consistent with "anthropogenic" (human caused) emissions. The
simple fact is, that under "business
as usual" conditions, we'll soon reach carbon dioxide concentrations that
haven't been seen on Earth in the last 50 million years.
Combustion
of Fossil Fuels, for electricity generation, transportation, and heating, and
also the manufacture of cement, all result in the total worldwide emission of
about 22 billion tons of carbon dioxide to the atmosphere each year. About a
third of this comes from electricity generation, and another third from
transportation, and a third from all other sources.
This
enormous input of CO2 is
causing the atmospheric levels of CO2 to rise dramatically. The following
graph shows the CO2 levels
over the past 160 thousand years (the upper curve, with units indicated
on the right hand side of the graph). The current level, and
projected increase over the next hundred years if we do not curb emissions, are
also shown (the part of the curve which goes way up high, to the right of the
current level, is the projected CO2 rise). The projected increase in CO2 is very startling and disturbing.
Changes in the Earth's average surface temperature are also shown (the lower
curve, with units on the left). Note that it parallels the CO2 level curve very well.
