Oceanography- The Oceans and Climate Change

Feedback Loop

A feedback loop modify the atmospheric processes.

• A positive feedback loop enhances initial change (amplifies change, pushes away from equilibrium).

• A negative feedback loop is to counteract the initial change (counteracts change, stabilizes system).

6 Ways we study past Climate

We use proxy data from sources such as:
1. Sea floor sediments (chemistry of forams, coccolithophores) “patterns”

2. Coral deposits (annual growth rings, coral layers)

3. Glacial ice (gas inclusions)

4. Tree rings (annual growth rings)

5. Pollen (found in sediments) 6. Historical documents

Tools to study past climate

Ice corer, tree ring analysis, sediment corer

Natural Causes of Climate Variation

1. Solar Energy

2. Variations in Earth’s Orbit

3. Volcanic Eruption

4. Plate Tectonics

Solar Energy

The variable energy, luminosity, sunspots, and faculae (bright, irregular patches on Sun surface).

Variations in Orbit

Eccentricity (shape) and obliquity (variations in angle).

Volcanic Eruptions

The volcanic ejecta that can block sunlight (cooling effect) and eruptions also emit CO2 into the atmosphere (warming effect)

Plate Tectonics

Can change ocean circulation patterns, sea level and is an extremely slow process, on order of millions of years to change climate.

When was it hotter than it currently is?

The Earth has experienced much warmer periods, like the Peocene (millions of years ago) or even warmer epochs before that, with higher sea levels.

Rate of Current Global Warming

It is far faster than natural changes and ecosystems can’t adapt quickly.

• The rate of current warming is 5000 times faster than any past natural warming events.

IPCC

Intergovernmental Panel on Climate Change

• Group of scientists who peer review and publish assessments on the climate/

  • Predicted a global temperature change of 2.5- 10.4 degrees F by 2100

Greenhouse Effect

Natural process where atmospheric gases (like \(CO_{2}\), methane, water vapor) trap heat from the sun, keeping Earth warm enough to sustain life

Concerning Greenhouse Gases

Carbon dioxide(CO2), methane(CH4), and chlorofluorocarbons(CFCs)

• Carbon dioxide and methane contribute the most to global warming

Keeling

The Keeling Curve is the longest continual record of CO2 measurements.

• Created by David and Richard Keeling

Why is the Keeling Curve Important

First clear piece of evidence that:

• Atmospheric CO₂ is rising year after year

• Human activities (like burning fossil fuels) are a major cause

PETM

Paleocene Eocene Thermal Maximum. Occurred 56 million years ago.

• Occurred because of a huge release of carbon and methane that occurred at the end of paleocene.

• Studied as an analog for where current climate change may head.

Current global warming predictions

The Intergovernmental Panel on Climate Change (IPCC) works predict global temperature changes of 1.4–5.8°C (2.5– 10.4°F) by 2100

Impacts of rising temps

• Melting glaciers and ice caps

• Shorter winters, earlier and hotter summers

• global temperature rise

• sea surface temperature increases

• Earth would continue to warm even if greenhouse gas concentrations stabilized today. ecosystem changes and extinctions – migrations for mobile animals to remain in preferred climate zones

• increased biological productivity in plants – (they like CO2)

• ice-free Arctic waters with higher oceanic productivity – remember that if productivity is too high in shallow seas, this results in dead zones – but higher productivity, if buried, can remove CO2 from air so the balance between higher productivity, burial of carbon, and dead zone production important

• Ocean levels rising

Ocean Acidification

When carbon dioxide is absorbed into the ocean. CO2 is an acid, so adding it to the ocean reduces ocean pH.

• Corals and shellfish most affected

  • Harder for them to calcify

Ocean Acidification- Climate Change

Increases in climate change correspond with increased ocean acidification