Global Warming

Magdalena AnguelovaMagdalena AnguelovaPh.D. Student Advisor: Ph.D. Student Advisor: Prof. Ferris WebsterProf. Ferris Webster

What is the Global

Warming?

What is the Global

Warming?5 min.5 min.

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A 100-year Old Question

In 1896 the Swedish chemist Svante Arrhenius asked:

“Is the mean temperature of the ground in any way influenced by the presence of heat-absorbing gases in the atmosphere?”Philosophical Magazine

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In 1896 the Swedish chemist Svante Arrhenius asked:

The global warming question

was opened.

The global warming question

was opened.

A 100-year Old Question

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Well, more than 100 years later we still have not answered this question.

Moreover, it is a hotly debated issue.

A 100-year Old Question

Uncertainty

10 years have passed since this presentation was made. Today (2011), we have constrained some of this uncertainty.

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What is Global Warming?

Global warming is a greenhouse effect in excess of the natural greenhouse effect.

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Greenhouse gases

An increasing amount of greenhouse gases in the atmosphere causes the excessive warming.

The change in greenhouse gas concentrations can be:» Natural;» Man-induced.

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Human Impact

Humans have always changed their surroundings to some degree.

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However, in the last century our activities have altered the global environment as never before.

Human Impact

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Nitrous oxide (NNitrous oxide (N22O)O)

Our daily life adds to the naturally occurring greenhouse gases:

Methane (CHMethane (CH44))

Carbon dioxide Carbon dioxide (CO(CO22))

Gas Emissions

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Nitrous oxide (NNitrous oxide (N22O)O)Methane (CHMethane (CH44))

Carbon dioxide Carbon dioxide (CO(CO22))

Gas Emissions

The changes since the industrial revolution are:

30%30%

100%100%15%15%

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Adding More

Even worse -- we add unnatural long-lived (100’s of years) greenhouse gases:

– this is “bad” ozone,

– different from the one in the UV-protective ozone layer high in the stratosphere.

» ChloroFluoroCarbons (CFCs),» and Surface Ozone (O3)

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The Statistics

U.S. CO2 emissions, 1995. Greenhouse

gas concentrations are projected to double pre-industrial levels by the middle of the next century.

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The Effect

An increased amount of greenhouse gases, however, may disrupt the planet’s heat budget.

The global heat budget is balanced in the long run:

Incoming sunlight=

Earth’s Reflected + Earth’s Emitted

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Troubled Heat Budget

If the amount of CO2 doubles, the outgoing radiation from Earth would decrease. To restore the balance, an increase in the mean surface temperature of the Earth is required. By 2100 Earth would be 2 - 6oF warmer, hence...

Climate Changes

Temperature

Precipitation

Sea Level Rise

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The Role of the Ocean

A chain of processes removes atmospheric CO2 and stores it in the ocean depths:

» Atmosphere-ocean gas exchange;

» Phytoplankton photosynthesis;

» Ocean circulation;» Biological pump.

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The Removed CO2

The ocean is the greatest reservoir for CO2.

The net carbon uptake by the ocean is about 34% of the carbon put into the atmosphere.

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Keeling Curve

Atmospheric CO2 concentration, Mauna Loa, HI.

It became an icon of the global warming problem .

No doubt, the amount of greenhouse gases increases.

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Why the Uncertainty Then?Our uncertainty stems from these

questions:Our uncertainty stems from these

questions:

Is the warming solely man-Is the warming solely man-induced?induced? Or is this a natural variation Or is this a natural variation in climate?in climate?

What is the climate change What is the climate change rate?rate?» Slow -- centuries to millennia? Slow -- centuries to millennia? » Fast -- decades?Fast -- decades?

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Natural Climate Variability

The Earth’s climate has always been changing.

No doubt, the climate will continue to change.

Greenhouse gas concentrations have changed accordingly.

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If natural climate change is slow:

Slow Climate Change

» We can find ways to deal with the man-induced warming;

» Ecosystems have an opportunity to adjust.

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» The man-induced warming may initiate even more rapid warming;

Fast Climate Change

If natural climate change is fast:

» Ecosystems will be drastically affected.

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Study, Study, Study...

...know past climate changes well.

...predict future climate changes accurately.

...understand present climate better.

Thus, we need to Thus, we need to

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Actions

Everything Everything helps:helps:

Observations:

Computers:

» Ice and sediment cores;» Ship measurements;» Satellite monitoring.

» Ocean-atmosphere models;» Chemical-physical-

biological models;» Socio-economic models.

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We have a lot of work to do!

We have a lot of work to do!

Global Warming Concern

The EndThe End