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Climate Change and Human Activities:

Some basic observations from ice core samples, etc:

The concentration of carbon dioxide is higher than it has been in the past 420,000 years

The 20th century was the hottest century in the past 1000 years

Since 1861, the average global temperature has risen 1.1 (+/- 0.4) degrees Fahrenheit

The 1990s was the warmest decade and 1998 the warmest year since 1861.

Glaciers are melting at an accelerated rate. Especially alarming is the recent (March 2006) publications in Science Magazine about the glaciers in Greenland.

Some conclusions that might be reached are that human activities will

1. enhance Earth's natural greenhouse effect.

2. raise the average global temperature of the atmosphere near Earth's surface.

There is little doubt that global warming is occurring and that human activities are contributing to the problem. The real argument is how much is natural and how much is from human activities and what we might do about it.

We also could argue how catastrophic the warming might be. That, just how bad will it be?

What do you think?
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Some Possible Outcomes or Correlations:

Heat Waves

Extreme Weather

Changes in Water Supply, Loss of Snowpack, etc

Forest Fires

Species Extinctions

Expansion of Tropical Diseases

Melting Glaciers

Rising Sea Levels and Storm Surges

More intense storms (e.g., hurricanes)

We already are seeing signs or evidence for many of these phenomena.

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For More EPA Info, Click here

Information from the EPA, March 2006:

Like many fields of scientific study, there are uncertainties associated with the science of global warming. This does not imply that all things are equally uncertain. Some aspects of the science are based on well-known physical laws and documented trends, while other aspects range from 'near certainty' to 'big unknowns.'

What's Known for Certain?

Scientists know for certain that human activities are changing the
composition of Earth's atmosphere. Increasing levels of greenhouse
gases, like carbon dioxide (CO2 ), in the atmosphere since
pre-industrial times have been well documented. There is no doubt
this atmospheric buildup of carbon dioxide and other greenhouse
gases is largely the result of human activities.

It's well accepted by scientists that greenhouse gases trap heat in
the Earth's atmosphere and tend to warm the planet. By increasing
the levels of greenhouse gases in the atmosphere, human activities
are strengthening Earth's natural greenhouse effect. The key
greenhouse gases emitted by human activities remain in the
atmosphere for periods ranging from decades to centuries.

A warming trend of about 1°F has been recorded since the late 19th
century. Warming has occurred in both the northern and southern
hemispheres, and over the oceans. Confirmation of 20th-century
global warming is further substantiated by melting glaciers, decreased
snow cover in the northern hemisphere and even warming below
ground.

What's Likely but not Certain?

Figuring out to what extent the human-induced accumulation of
greenhouse gases since pre-industrial times is responsible for the
global warming trend is not easy. This is because other factors, both
natural and human, affect our planet's temperature. Scientific
understanding of these other factors most notably natural climatic
variations, changes in the sun's energy, and the cooling effects of
pollutant aerosols remains incomplete.

Nevertheless, the Intergovernmental Panel on Climate Change
(IPCC) stated there was a "discernible" human influence on climate;
and that the observed warming trend is "unlikely to be entirely natural
in origin." In the most recent Third Assessment Report (2001), IPCC
wrote "There is new and stronger evidence that most of the warming
observed over the last 50 years is attributable to human activities."

In short, scientists think rising levels of greenhouse gases in the
atmosphere are contributing to global warming, as would be
expected; but to what extent is difficult to determine at the present
time.

As atmospheric levels of greenhouse gases continue to rise,
scientists estimate average global temperatures will continue to rise
as a result. By how much and how fast remain uncertain. IPCC
projects further global warming of 2.2-10°F (1.4-5.8°C) by the year
2100. This range results from uncertainties in greenhouse gas
emissions, the possible cooling effects of atmospheric particles such
as sulfates, and the climate's response to changes in the
atmosphere.

The IPCC states that even the low end of this warming projection
"would probably be greater than any seen in the last 10,000 years,
but the actual annual to decadal changes would include
considerable natural variability."

What are the Big Unknowns?

Scientists have identified that our health, agriculture, water
resources, forests, wildlife and coastal areas are vulnerable to the
changes that global warming may bring. But projecting what the
exact impacts will be over the 21st century remains very difficult. This
is especially true when one asks how a local region will be affected.

Scientists are more confident about their projections for large-scale
areas (e.g., global temperature and precipitation change, average
sea level rise) and less confident about the ones for small-scale
areas (e.g., local temperature and precipitation changes, altered
weather patterns, soil moisture changes). This is largely because the
computer models used to forecast global climate change are still
ill-equipped to simulate how things may change at smaller scales.
[See the U.S. Climate section for more detail on climate models.]

Some of the largest uncertainties are associated with events that
pose the greatest risk to human societies. IPCC cautions, "Complex
systems, such as the climate system, can respond in non-linear ways
and produce surprises." There is the possibility that a warmer world
could lead to more frequent and intense storms, including hurricanes.
Preliminary evidence suggests that, once hurricanes do form, they will
be stronger if the oceans are warmer due to global warming.
However, the jury is still out whether or not hurricanes and other
storms will become more frequent.

More and more attention is being aimed at the possible link between
El Niño events the periodic warming of the equatorial Pacific Ocean
and global warming. Scientists are concerned that the
accumulation of greenhouse gases could inject enough heat into
Pacific waters such that El Niño events become more frequent and
fierce. Here too, research has not advanced far enough to provide
conclusive statements about how global warming will affect El Niño.

Living with Uncertainty

Like many pioneer fields of research, the current state of global
warming science can't always provide definitive answers to our
questions. There is certainty that human activities are rapidly adding
greenhouse gases to the atmosphere, and that these gases tend to
warm our planet. This is the basis for concern about global warming.

The fundamental scientific uncertainties are these: How much more
warming will occur? How fast will this warming occur? And what are
the potential adverse and beneficial effects? These uncertainties will
be with us for some time, perhaps decades.

Global warming poses real risks. The exact nature of these risks
remains uncertain. Ultimately, this is why we have to use our best
judgement guided by the current state of science to determine
what the most appropriate response to global warming should be.