Climate Change, and the Scientific Process

Let’s review last week: sometimes Venus, Earth and Mars are called the Goldilocks planets

Compare these Three: Venus Earth Mars

Temp at surface 880 F

59 F

-58 F

Pressure at surface ~ 90 atmospheres 1 atmosphere (14.7 lbs/sq in)

0.007 atmospheres

Atmosphere composition

CO2 and sulfuric acid clouds

Nitrogen, oxygen, water vapor clouds,

CO2, nitrogen

Dist. from sun 0.7 A.U. 1 A.U. 1.5 A.U.

One word description?

Let’s look at atmosphere more carefully:

Earth

Nitrogen: 78%!

Oxygen: 21 %!Argon: 0.9%!Water: > 1%!Carbon Dioxide: 0.004% *!

Mars!Carbon Dioxide: 95%

Nitrogen: 3%!

Argon: 2%!

Venus!Carbon Dioxide: 96%!Nitrogen: 3.5%!

!

How did Venus get so hot?

Planetary surface

A planet with an atmosphere

Solar radiation comes in

Planetary radiation goes out, but gets absorbed

The greenhouse gases reradiate. Some of the energy goes towards the surface.

Greenhouse gases

In class, or lab exercise: Greenhouse effect Go to http://phet.colorado.edu/en/simulation/greenhouse

How do greenhouse gases naturally get into the atmosphere?

Water: evaporation

CO2: vaporization of rocks, release from volcanos, vaporization of biotic material (like fossil fuels), respiration

Methane: release from earth, biology (bacteria, cows, rice)

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1. Volcanos brought up gas trapped in rock

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2. Comets hitting the young earth brought water, water vapor and carbon dioxide.

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3. Earth developed an oxygen atmosphere from plant life

What is happening to the atmosphere today?

Report on Global Climate Change –IPCC 2013*

* Intergovernmental Panel on Climate Change: A total of 209 Lead Authors and 50 Review Editors from 39 countries and more than 600 Contributing Authors from 32 countries contributed to the preparation

“Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased .”

Articles published in peer review journals support idea that this is happening, and that it is caused by

humans

Peer review, or refereed: article has been anonymously approved by another expert in the field before publication

Global warming: a look at the data

These temperatures are derived from different methods

CO2 levels in ppm (parts per million)

Class exercise with Mauna Loa (top of volcano in Hawaii) data: Plotting some data on the CO2 concentration in the atmosphere

Each team will plot one year’s worth of CO2 data

Date CO2 (ppm)

July

2005

July

July

July 2006 2007 2008 2009 2010 2011 2012

July

July

July

375

377 376

378

380

386

392 391 390 389 388 387

384 383

395

382

379

381

394

385

393

CO

2 Con

cent

ratio

n (p

pm)

Group # ______

370

375

380

385

390

395

Jan-05 Jan-06 Jan-07 Jan-08 Jan-09 Jan-10 Jan-11 Jan-12

Car

bon

Dio

xide

in p

pm

Time

Keeling Mauna Loa CO2 Data (2005-2011)

Various effects of climate change today

Shrinking ice sheets

Declining arctic ice

Melting glaciers

Sea level rise

Global temperature rise

Warming oceans

Summary of effects:

What can we do to reverse this?

Currently, 30% of both the US House and Senate are on record as denying climate change, or its importance. Solution requires many nations to address the problem: China in particular

What can we do…

• Buy more fuel efficient cars and trucks, do less driving, do more car pooling, use CFL (compact fluorescent) light bulbs, use solar cooker…

• Develop Solar power on homes

• Burn less coal (which creates much of our electricity)

• Develop alternative energy: wind, nuclear

• What are your ideas?

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Take away message:

Lecture tutorial, Greenhouse effect

Earth’s temperature is increasing because carbon dioxide concentration is increasing.

All evidence is that this is caused by human activity.

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Index: Change in earth’s temperature