Overview
on Global Warming
Understanding Why Action is Urgent
From
a talk given by Christine Missik at a
Healthy Planet Initiatives Meeting
If
you pretend that the whole planet earth is an onion, only the outermost
parchment skin would represent the earth’s atmosphere. On average, only about
the bottom two and a third miles of the atmosphere is breathable. If we were to
take the earth’s atmosphere and condense it into a liquid, it would be only
1/500th the size of our oceans. So we can understand why it is so easy for our
atmosphere to be polluted. Our most major environmental crises have been due to
air pollution. Fortunately we have put the brakes on acid rain by mandating the
use of scrubbers in smoke stacks. And fortunately we have put the brakes on the
expanding hole in the ozone layer by banning chlorofluorocarbons. Now we have
perhaps the most dangerous crisis of all - the climate change crisis due to
greenhouse gas pollution.
There is some good news recently, though, with the Supreme Court decision that
carbon dioxide is a pollutant and therefore can be regulated by the
Environmental Protection Agency.
Greenhouse Gases
1.) Carbon dioxide
Carbon dioxide (CO2) stays in the atmosphere for one hundred years or more, so
we are experiencing effects of carbon dioxide emitted into the atmosphere as far
back as the early 1900s. And what we emit now, we will be living with for a long
time to come. Carbon dioxide makes up a small percentage of our atmosphere but
its effects are enormous. It is causing tipping point changes that alter the
climate and also increase
the concentration of other greenhouse gases.
If Carbon dioxide were 1% of the atmosphere, the earth’s surface would be at a
boiling point.
Before the 1800s carbon dioxide was 280 parts per million in the
atmosphere. Now it is at 380 parts per million. Scientists generally
agree that unless we cap carbon dioxide in the atmosphere at 450-550
parts per million it will be impossible to stabilize the earth’s climate, and
runaway catastrophic changes will occur.
In order to prevent carbon dioxide from exceeding this dangerous
threshold, scientists generally agree that we must decrease our carbon
emissions by 70-80% by the year 2050 or approximately 2% per year.
Considering that our carbon emissions have been greatly increasing over the
years, and that the population of the world is expected to grow from six
billion to nine billion people by the year 2050, you can see that this is a
difficult challenge.
Carbon Dioxide emissions come from the burning of fossil fuels. The
very worst is the burning of coal in power plants, but carbon dioxide emissions also
come from the burning of oil and gasoline. The two major areas of
intervention are decarbonizing the power grid and decreasing emissions
from transportation. Both are essential, but decarbonizing the power
grid is hands down the highest priority. The
generation of electricity causes more emissions than come from the
transportation sector. Not only that, if we switch to green (sustainable) energy such as solar, wind,
or tidal energy for powering the electric grid, then we will be able to
have electric plug-in cars which have no carbon emissions. Of course,
lessening the use of electricity through conservation and efficiency is also very effective.
2.) Water vapor
Water vapor is an extremely potent greenhouse gas. Water vapor retains
two thirds of all the heat trapped by greenhouse gases on earth. The
amount of water vapor in the atmosphere depends on the temperature.
3.) Methane
Methane is 60% more potent than carbon dioxide, but fortunately it
lasts far fewer years. It is estimated that methane will cause 15-17%
of the global warming. We are seeing more in the news lately about
methane, because raising of beef cattle causes methane emissions. As I will
describe, warming of the earth is greatly increasing methane in the atmosphere.
4.) Nitrous oxide
Nitrous oxide is 270 times more efficient at trapping heat than carbon
dioxide. Fortunately there is much less of it. Nitrous oxide is also
released by burning fossil fuels, and from burning biomass. There is
20% more now than in pre-industrial times.
Dangerous Feedback
Loops
1.) Albedo
Albedo is the scientific term for the fact that light from the sun
hitting white surfaces is reflected back to space. One third of all the
energy reaching the earth is reflected back to space by white surfaces. Fresh
snow and ice reflect 80-90% of light, while water reflects only 5-10% of light.
Water and earth tend to absorb heat from the sun rather than reflect it.
So the problem is that increased carbon dioxide causes some warming, which is
causing melting of polar snow and ice. This means less Albedo -- less snow
and ice to reflect the sun’s energy -- and more water to absorb heat.
The additional heat causes more melting which causes less albedo, more melting,
more heat
absorption....
2.) Increase in water vapor
Increased carbon dioxide causes warming. This extra amount of
warming means that the air holds more water vapor. Water vapor, as
mentioned earlier, is a powerful greenhouse gas which will then trap
more heat, causing more water vapor, more heat, more water vapor....
3.) Increase in methane
Warming caused by increased carbon dioxide emissions sets in
motion two dangerous feedback loops involving methane.
There is a large amount of methane stored in the vast areas of permafrost. An
increase in temperature caused by increased carbon dioxide has already started
causing the thawing of permafrost, which causes the release of methane. Since methane
is a very potent greenhouse gas, this leads to further warming,
further thawing of the permafrost, further release of methane, further
warming....
Ice crystals with trapped molecules of methane (called clathrates) are
present in massive amounts buried in the seabed under pressure of cold
overlaying water. There is perhaps twice as much energy buried in this
way in clathrates than in all the other fossil fuels combined. If the
temperature of the artic oceans were to increase, the crystal matrix
could melt and colossal amounts of methane could be released. Paleontologists suspect that 245 million years ago, the unleashing of
methane under the sea off the Norwegian coast may have been responsible for the
biggest extinction of all time.
4.) Increase in Carbon Dioxide
Cool water holds more carbon dioxide than warm water. Warming of the
oceans causes increased release of carbon dioxide into the atmosphere, which
causes more warming, more release of carbon dioxide....
Other Possible Calamities
1.) Ones you have heard about
You have probably heard about the problems of droughts in inner continental
areas, flooding in other areas,
hurricanes and rising sea level due to global warming.
Decreased precipitation results in increased forest fires and burning of peat
bogs, both which increase greenhouse gases.
2.) Possible calamities you may not have heard of:
Shutting down of the Gulf Stream. Scientists worry
that fresh
water from melting ice caps could dilute the saltiness of the ocean
water up north, preventing the water from sinking, which would shut
down the gulf stream. (The Gulf Stream has shut down on several occasions in our earth’s history.) This would have terrible
consequences for the climate in both the northern and southern
hemispheres. Additionally, if the Gulf Stream were to shut down,
currents would not carry oxygen to deeper levels in the ocean causing
massive dying off of ocean life.
Collapse of the Amazon rain forest. Increased
carbon dioxide in
the atmosphere and global warming can cause drying of the rainforest
with resulting dying of the plants and trees. A dead rain forest cannot
absorb carbon dioxide from the air, and the rotting of vegetation results in more release of carbon into the air.
Dying of coral reefs. When ocean
water temperature exceeds a
certain threshold, bleaching occurs in coral reefs, which, if the
conditions persist, results in dying of the reef. Considering that one
quarter of all ocean inhabitants spend at least part of their life
cycle in coral reefs, dying of coral reefs would massively impact
ocean life. Unfortunately, we are already seeing extensive problems
with coral reef bleaching and death. A significant amount of the Great
Barrier Reef, for example, has already suffered from damage. Scientists
estimate, for example, that a further rise in global temperature of one degree
will cause 82% of the Great Barrier Reef to bleach and die. Since it takes
several decades for ocean temperature to catch up with the atmospheric
temperature, the damage may already have been set in motion.
Arguments Denying
Global Warming is a Problem
Some people (fewer and fewer) state that the planet goes through
natural climate change cycles, so we shouldn’t worry.
Actually in the past, many million years ago, there have been dramatic
climate changes precipitated by releases or absorption of greenhouse
gases, or large changes in Albedo. These climate changes resulted in
massive extinctions with as much as 95% of all species vanishing. For
example, 65 million years ago every living thing weighing more than 77
pounds vanished along with a vast number of smaller species.
There are milder natural climate change cycles, which are well
understood by scientists, called Milankovich cycles. These are caused by the
elliptical orbit of the earth around the sun, and the tilt and
wobble of the earth on its axis. These factors would at this time be
causing a cooling, not a warming which we are now seeing. The climate
changes occurring now are unnatural - caused by human activity.
The Royal Society, which is the academy of sciences in the United
Kingdom, lists common arguments denying global warming and rebuttal explanations (www.royalsoc.ac.uk
, click on “climate change
controversies”).
Some people feel that the United States should not act until developing
countries agree to the same controls on their carbon emissions as developed
countries. However, we should remember that most of the carbon has been
emitted by the developed world.
Developing countries can
reasonably say that they should not be
held to the same costs of stopping a problem, which we, not they, have
caused. By developed countries taking the lead in a new sustainable
economy with new sustainable technologies, the prices of these
technologies will fall. Developing countries should then be able to leap
frog over dirty coal technologies (much like Africa is bypassing the
land telephone lines in many areas and going directly to cell phones).
In Summary
We must act urgently, in this decade, because increases in carbon
dioxide cause changes in temperature, which in turn further increase
greenhouse gases to the extent that we could have a warming which spirals entirely
out of our control. If we take steps now, reducing carbon dioxide
emissions is manageable with current technology, but the more we delay, the more
draconian the measures needed to prevent a run away calamitous climate change.
Resource
A good resource for understanding the history of climate change on
earth, the current problem, and solutions is The Weather Makers by Tim
Flannery, or the shorter version, We Are the Weather Makers. The
shorter version is new and not available yet in the USA but can be
ordered through www.theweathermakers.com
. Most of the information in this essay is from Tim Flannery who is an
internationally acclaimed
scientist and professor at the University of Adelaide (Australia).