The PETM and Leaf Margin Analysis:

How does the PETM and Leaf Margin Analysis Relate to Climate Change we are facing

today?

Erica Shook

Honors Climate Change Biology- NCSSM Online

20 December 2011

What is the PETM?

PETM stands for Paleocene Eocene Thermal Maximum.

The PETM was a phenomenon in Earth’s history were the temperature jumped to high temperatures for about 10,000 years. This jump reached 6 degrees Celsius in average temperature.

6 degrees Celsius may not seem like much but remember that annual temperature is a average of global temperature so in some places the jump was more than 6 degrees.

When Was the PETM?• Cenozoic Era is known as age

of mammals.

What caused the PETM? There is controversy over what caused the PETM.

Most theories believe there was a release of a green house gas from some kind of sink.

As of now the leading theories include... A release of Methane from Methane stores deep below the

ocean’s surface.

Volcanic eruption that released Carbon Dioxide.

A comet impact that released Carbon Dioxide.

…. And more!

o Some people also argue that just one of these events would not be enough to trigger the PETM and that it would take multiple of these events to cause it.

• In the end as of now we do not know what caused the PETM.

Why is the PETM important?

What did the Earth look like during the PETM?

The Earth was virtually ice-free.

Midwest America looked more like what coastal South Carolina does today.

Palm trees grew in Canada.

Alligators even swam in Artic swamps.

Relative Position of Continents during PETM

Leaf Margin Analysis

Leaf margin Analysis is the process of comparing the amount of smoothed edged leaves to the amount of toothed edged leaves in a sample by a percent.

This percent is then put into a linear function that has been created from data collected of actual samples of temperature compared to the percent of smooth to rough edged leaves.

The output of the linear function is the average annual temperature in Celsius of the time and place from which the leaves are from.

How does this method Work?

The reason this method works is because toothed leaves are able to begin photosynthesis earlier than smooth edged leaves in the spring.

However toothed leaves lead to a high amount of water loss which does not provide adequate water to the tree in a hot climate.

So because of this smooth edged leaves are more likely to be able to grow in warm climates

How does Leaf Margin Analysis help us learn about the PETM?

In the Big Horn Basin in Wyoming fossils have been found from the PETM.

Fossils of Plants and animals were buried by eroded mud of the still growing Rocky Mountains and as this mud hardened the plants and animals fossilized.

Today millions of years later scientists have discovered these fossils.

Scientists can sort these plant fossils by smooth and rough edged leaves and use Leaf Margin Analysis to estimate the temperature of the PETM.

Lab Activity

Hypothesis: Do you believe that your group estimate or the total class estimate will be a more accurate estimate of the annual temperature of Hickory, NC?

Smooth VS. Rough Edged leaves

Finding Percent

We now will find the percent of smooth edged leaves to the total collected.

Smooth Edged Leaves

Total Number of Leaves

So for example if we had 6 out of 10 smooth edged leaves we would plug into the above formula and get…

6/10= .6

However we need a percent answer so we have to multiply our answer by 100….

(6/10) x 100 = 60%

Calculating Temperature

Now we can plug in our percent answer in for x in the linear function…

F(x)= 30.06x+ 1.141

Or

Y=30.06x+1.141

X=Our Percent answer

With our example of 60% we would plug .60 in for X …

Y=30.06(.60)+1.141

And Get…

Y=19.177°C

Where Y equals the estimated temperature in Celsius.

Do our results align with the actual annual temperature?

The actual annual temperature in Hickory, NC in 2011 was 57.6 degrees Fahrenheit or 14.223 degrees Celsius.

Why Might our results not align? Sample Size

Time collected

Leaf Margin Analysis an Imperfect Technique?

The process of Leaf Margin Analysis used by scientists makes the assumption that the percent of smooth to total leaves are relatively the same as million of years ago.

Do we know that Leaf Margin Analysis 100% works… no.

We do have other evidence to support the data concluded from leaf margin analysis from other sources.

How does the PETM relate to Climate Change today?

  PETM Current Warming

Cause ?????Anthropogenic burning of fossil fuels (oil, coal, natural gas, etc)

Carbon emissions Less than 2 billion tons per year

At least 30 billion tons per year

Rate of warming 0.025°C per 100 years 1 to 4°C per 100 years

Environmental impact

Ocean circulation reversed, oceans acidified, permafrost melted, peatlands and forests burned in wildfires

Observed impacts: significant sea ice decline, extreme drought, more wildfires, increase in glacier melt, more catastrophic floods, ocean acidification, sea level rise, shoreline erosion

Potential impacts: degraded air and water quality, permafrost melting, global ocean circulation changes, more violent winter storms and spring tornado seasons, more intense hurricanes

Ecosystem & human impact

Migration of land mammals, extinction of some benthic foraminifera, coral bleaching

Observed impacts: Famine and malnutrition due to drought, coral bleaching, species endangerment

Potential impacts: increased mortality from extreme weather and malnutrition, increase in disease vectors, decrease in agricultural yield, mass wildlife migration and extinction, total societal collapse

How is the PETM different from today’s Climate Change?

Works Cited

Hickory Weather, Forecast, Temperature and Precipitation. n.d. 2011 14 September <http://www.clrsearch.com/Hickory_Demographics/NC/Weather-Forecast-Temperature-Precipitation>.

"Prehistoric Climate Change and Why it Matters." n.d. Smithsonian Education. 15 December 2011 <http://www.smithsonianeducation.org/educators/lesson_plans/climate_change/index.html>.

The Energy Collective. n.d. 15 December 2011 <http://theenergycollective.com/davidlevy/55886/arguing-rocks>.

The Paleocene Eocene Thermal Maximum. n.d. 15 December 2011 <wikipedia.org>.