Earth’s Changing EnvironmentLecture 13

Global Warming

The Earth is in an Interglacial Period

Last Glacial Maximum was 18,000 years ago and Global temperature was approximately 10 F colder than now

The last ice age ended 11,000 years ago.

Pleistocene: Includes Last Ice AgeHolocene: Since last Ice Age

Average Earth Temperature increased 0.6 oC (1 F) during 20th Century

Temperature Conversions

T (F) = 1.8 T(oC)

Temperature rise of 5 oC is equivalent to a temperature rise of 9 F

T (F) = 1.8 T(C) + 32 F

5 oC is equivalent to 41 F

Current temperature: highest in 1000 years.

Greenhouse Gases

Greenhouse gases are emitted by human activities.

Greenhouse Warming

The surface temperature of the earth is determined by the balance between the energy gain from solar radiation and the energy loss by IR radiation.

Greenhouse Warming:Greenhouse Gases

Greenhouse gases allow sunlight to reach the surface, but absorb IR radiation from the surface. These effects cause the surface of the Earth to get hotter.

Greenhouse Gases

Carbon dioxide – fossil fuel combustion.

Methane – fossil fuel production, decomposition of organic wastes.

Nitrous oxide - agricultural and industrial activities, as well as during combustion of solid waste and fossil fuels.

Impacts

Rising global temperatures are expected to raise sea level,

Change precipitation and other local climate conditions.

Changing regional climate could alter forests, crop yields, and water supplies

Damage ecosystems. Deserts may expand into

existing rangelands.

Sea Level Rise – thermal expansion and melting ice caps and glaciers

Global warming is anthropogenic.

Increasing atmospheric CO2 concentration

Atmospheric increase = Emissions from fossil

fuels 

+ Net emissions from changes in land use 

- Oceanic uptake 

- Terrestrial sinks

Humans emit 24 billion tons per year.

60% stays in atmosphere Increases atmospheric CO2

by 0.4% / year. 25% increase from

280 ppm to 350 ppm

Atmospheric CO2

CO2 550 ppm to 1000 ppm in 2100

Temperature Increase: 1.5 oC – 6 oC by 2100

Extinction of Species

Recent Letter in “Nature”

Extinction risk from climate change

Nature 427, 145 - 148 (08 January 2004); doi:10.1038/nature02121

On the web at www.nature.com

Results of the Study

“ When the average of the three methods and two dispersal scenarios is taken, minimal climate-warming scenarios produce lower projections of species committed to extinction (18%) than mid-range (24%) and maximum-change (35%) scenarios.”

Rapid Temperature Change

Temperature rise over the next 100 years will be so rapid 0.3oC per decade that plants and animals will not be able to migrate north or to higher altitude rapidly enough to survive

Biodiversity

10 million species1.6 million

identified speciesMammals & birds

known Insects & plants

unknown

Biodiversity

Biodiversity increased over the last 600 million years

Occasional mass extinctions

Last major extinction (K-T) 65 million years ago.

Human activities will cause the next mass extinction

Extinctions

Recovery from mass extinctions takes millions of years.

Species are extinct forever.

KT Extinction

All dinosaurs became extinct.

65 million years ago.Caused by meteor

impact.

CO2 effects are long-term

Long term impacts depend on emissions

Adaptation and Mitigation

Mitigation

Reduce CO2 emissions by reducing consumption of fossil fuel.

Protection of rainforests and other CO2 sinks.

Carbon Emission Coefficient(Million Metric Tons of Carbon/QBtu)

Coal 26

Oil 19

Natural Gas 14

Global Carbon Emission

Global Carbon Emission of C in the form of CO2:

6.6 billion metric tons

Convert to CO2:

44/12 x 6.6 billion metric tons

= 24 billion metric tons

Calculate US Carbon Emissions

US Carbon Emission =

26 MMT/QBtu x 22 QBtu

+ 19 MMT/QBtu x 38 Qbtu

+ 14 MMT/QBtu x 23 QBtu

= 1.6 Billion Metric Tons

Calculate US Carbon Emissions

US / Global

= 1.6 BMT / 6.6 BMT

= 24 %

The US emits 24% of Global CO2.

Kyoto Protocol

The US does not support the Kyoto Protocol, an international treaty to reduce global warming.

US Objections to Kyoto

Developing nations not bound, initially.

Reducing fossil fuel use would disrupt US and global economy.

The US has not developed a CO2 Reduction Plan

Bush administration emphasizes energy production and consumption.

                              

Mitigation: Reduce Carbon Emissions

We will address this issue in the next part of the course.

Mitigation: Carbon Sequestration

What are some adaptation steps?

Protect endangered species with larger refuges.Avoid flooding risks.Protect water supplies.Protect grasslands and agricultural lands against overuse.

Global Warming Ice Age?