chapter 26 climate change when the trees leave scientists grapple with a shifting climate

CHAPTER 26 CLIMATE CHANGE

WHEN THE TREES LEAVEScientists grapple with a shifting climate

Main Concept


Evidence for climate change is overwhelming, and human activity is

the main driver.

Changes throughout our natural environment, from species diversity to

declining human health on a worldwide scale are in our own hands.

Information and literacy will help us make sound policy

decisions.

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Learning Outcomes


At the end of this chapter you will know:• The difference between climate and

weather.• The evidence for climate change and

anthropogenic drivers is overwhelming.• Acknowledging human factors and

making changes is imperative.

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Climate change is causing ice in the lakes of northern forests to melt earlier in the

year, winters are coming later, some species of trees are dying off, and other

species are popping up in unexpected places.

Forests are at risk of becoming scrublands or savanna, prairies in Africa and the

Americas are becoming deserts, coral reefs are becoming bleached, and change is

happening everywhere at unprecedented speed.

Case: Ham Lake in North Woods of Minnesota

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Climate change is causing ice in the lakes of northern forests to melt earlier in the

year, winters are coming later, some species of trees are dying off, and other

species are popping up in unexpected places.

Forests are at risk of becoming scrublands or savanna, prairies in Africa and the

Americas are becoming deserts, coral reefs are becoming bleached, and change is

happening everywhere at unprecedented speed.

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Case: Ham Lake in North Woods of Minnesota

Climate is not the same thing as weather26Temperature on a given day is part of what we refer to as weather. The predictions and range of conditions we expect is based on climate.

Weather is short-term and geographically limited, while climate is the larger, long-term picture.

No single weather event can be attributed to global warming.

However, the rapidly shifting range of temperatures that are being recorded around the world are indications of climate change associated with global warming.

Dr. Lee Frelich of the University of Minnesota surveying the damage following the 75,000 acre fire at Ham Lake.

http://www.forestry.umn.edu/People/Frelich/index.html

Climate is not the same thing as weather26Range shifts have happened before.

As the North American ice cap retreated 12,000 years ago, tree species range shifted northward at a rate of 50 km per century.

About 6000 years ago, another tree range migration occurred—this time south and west.

Instead of having thousand of years to adapt as with past climate changes, tree species today might have only a few decades in which to adapt or die.

Dr. Lee Frelich of the University of Minnesota surveying the damage following the 75,000 acre fire at Ham Lake.

http://www.forestry.umn.edu/People/Frelich/index.html

Evidence of global climate change abounds26TERMS TO KNOW:Climate changeWeatherClimate

Consider this:

Birch trees, long established in the Minnesota north woods are dying as growing seasons get longer and soil temperatures rise.

Red maple, common in Louisiana, is becoming well established in Minnesota.

Spring, marked by budding, is two weeks or more ahead of historic averages for the last two decades.

The National Oceanic and Atmospheric Administration (NOAA) has recorded global average land temperatures almost 2oF higher than the twentieth-century average and sea surface temperatures as much as 5oF higher in some parts of the world.

Evidence of global climate change abounds26TERMS TO KNOW:Climate changeWeatherClimate

Icebergs 200-feet tall,

formerly part of the

Greenland Ice Sheet, now

float into the North Atlantic

Ocean.

Small changes have big impact.

Evidence of global climate change abounds26Just a few degrees warmer and we see big effects—especially in the Arctic.

Temperature change is not evenly distributed. Researchers evaluated weather patterns of Ellismere Island in the Arctic and found thatspring and summer temperatures were 20−29oF higher than in previous years.

This difference is equivalent to locations 1000−1400 miles farther south.

Rising sea levels have already displaced hundreds of thousands of people.

Evidence of global climate change abounds26

Evidence of global climate change abounds26Warmer temperatures can be expected to lead to weather extremes.

Evidence of global climate change abounds26

A variety of factors affect climate26TERMS TO KNOW:Greenhouse gasesGreenhouse effectRadiative forcerAlbedoPositive feedback loops

Greenhouse gases include carbon dioxide, methane, and nitrous oxide. These gases maintain the Earth’s temperature—a good thing! Unfortunately, since the middle of the twentieth century, evidence of an enhanced greenhouse effect from the use of fossil fuels started to mount.

Greenhouse gases each have different abilities to trap heat, expressed as CO2 equivalents.

A variety of factors affect climate26TERMS TO KNOWGreenhouse gasesGreenhouse effectRadiative forcerAlbedoPositive feedback loops

Greenhouse gases include carbon dioxide, methane, and nitrous oxide. These gases maintain the Earth’s temperature—a good thing! Unfortunately, since the middle of the twentieth century, evidence of an enhanced greenhouse effect from the use of fossil fuels started to mount.

Greenhouse gases each have different abilities to trap heat, expressed as CO2 equivalents.

A variety of factors affect climate26TERMS TO KNOW:Greenhouse gasesGreenhouse effectRadiative forcerAlbedoPositive feedback loops

The greenhouse gases are one type of radiative factor—something that alters the balance of incoming solar radiation with heat that escapes out into space.

Another influence is the ability of a surface to reflect away solar radiation. This factor, albedo, comes into play as glacier ice is lost along with its role in reflecting light.

A variety of factors affect climate26

Monitoring CO2 released from thawing permafrost in Alaska – long-term increases of atmospheric loading of CO2.

Positive and negative feedback loops influence warming and cooling of the planet.

As surfaces with high albedo are replaced with low-albedo surfaces, warming occurs and positive feedback is triggered.


To model and make predictions about the future climate, scientists use a wide variety of clues from ice and sediment cores, tree rings, coral reefs, and fossils.Other natural forces include volcanic eruptions and sunspot cycles. Predictable long-term cycles of the Earth’s position relative to the Sun—Milanovitch cycles—also played an important part in earlier climate-change events.


To model and make predictions about the future climate, scientists use a wide variety of clues from ice and sediment cores, tree rings, coral reefs, and fossils.Other natural forces include volcanic eruptions and sunspot cycles. Predictable long-term cycles of the Earth’s position relative to the Sun—Milanovitch cycles—also played an important part in earlier climate-change events..


To model and make predictions about the future climate, scientists use a wide variety of clues from ice and sediment cores, tree rings, coral reefs, and fossils.Other natural forces include volcanic eruptions and sunspot cycles. Predictable long-term cycles of the Earth’s position relative to the Sun—Milanovitch cycles—also played an important part in earlier climate-change events.


Direct and indirect temperature measurements are used to measure change over time.

Readings from Mauna Loa laboratory go back to 1958, when Charles Keeling began taking precise CO2 readings.

CO2 gas bubbles from ice cores can also be used to estimate past levels.


Direct and indirect temperature measurements are used to measure change over time.

Readings from Mauna Loa laboratory go back to 1958 when Charles Keeling began taking precise CO2 readings.

CO2 gas bubbles from ice cores can also be used to estimate past levels.

A variety of factors affect climate26A comparison of

historic CO2 levels and temperatures as

determined from the Antarctic Vostok ice

core, show that the two parameters have been

closely aligned over the past 400,000 years.

The relationship between CO2 and temperature is one of both cause and effect. In the far past, natural events triggered warming, resulting in the release of more CO2, which then caused even more warming. Regardless of the reason for the release of extra greenhouse gases, temperatures change as CO2 increases and decreases.

Current climate change has both human and natural causes26

TERMS TO KNOW:AnthropogenicIntergovernmental Panel on Climate Change (IPCC)

A thin slice of ice from an ice core from Antarctica. The core contains trapped air bubbles that can reveal information about the atmosphere and temperatures of the past.

Computer models take factors known to have affected past climates to see what might be responsible for recent warming.

The Intergovernmental Panel on Climate Change (IPCC) is made up of thousands of scientists from

around the world who evaluate research in climate science. They agree that the Earth’s atmosphere

is changing dramatically and with alarming speed.


TERMS TO KNOWAnthropogenicIntergovernmental Panel on Climate Change (IPCC)

A thin slice of ice from an ice core from Antarctica. The core contains trapped air bubbles that can reveal information about the atmosphere and temperatures of the past.

Computer models take factors known to have affected past climates to see what might be responsible for recent warming.

The Intergovernmental Panel on Climate Change (IPCC) is made up of thousands of scientists from

around the world who evaluate research in climate science. They agree that the Earth’s atmosphere

is changing dramatically and with alarming speed.


NASA satellite reveals that 2011’s minimum sea ice extent in the Arctic Ocean, reached on September 9, 2011, as depicted here, was far smaller than the 30-year average (yellow) and opened up Northwest Passage shipping lanes (in red).

Some tree species are already migrating north; that doesn’t mean they will survive26


Species have evolved to live and thrive in a certain habitat. If the climate is changing enough to alter ecosystems, we expect to see species responding by changing where they live or the timing of important temperature-dependent biological events.



Species’ responses, such as shifting ranges or earlier blooming and hatching, may be the best evidence that climate is actually changing. It is unlikely that these temperature-dependent events would change in this way if the planet were not getting warmer.



The blue-gray gnatcatcher has moved more than 300 km north

since the 1970s.


TERMS TO KNOW:AnthropogenicIntergovernmental Panel on Climate Change (IPCC) Sugar maple trees are moving north.



Winter temperatures are no longer low enough to kill off bark beetles.

Climate change has environmental, health, and economic consequences26

As forests change to savanna or as losses due to fires outside of the normal cycle

continue to mount, the direct economic impact for the Boundary Waters area

around Ham Lake, Minnesota, alone can be expected to top $240 million in lost wages.

No longer will the area be able to support wildlife—moose, lynx, boreal owls—

invaluable on their own and integral to the ecosystem functioning of

northern forests.

Forests stabilize soil and clear water of pollutants.

Continued losses also play into a positive feedback

loop that will accelerate climate change.

Confronting climate change is challenging26TERMS TO KNOW:MitigationCarbon taxesPrecautionary principle

Resistance forestry is a new approach that uses techniques aimed at maintaining existing species in their current locations, despite the shifting climate.

Planned burning mimics natural cycles and planting seeds instead of saplings builds tougher populations. Field-grown seedlings are hardier and have a better chance of surviving changes.

Minimizing the damage is one strategy; limiting the amount of CO2 entering the atmosphere is another.

Researchers Pacala and Socolow from Princeton University have propose the “stabilization wedge,” whereby any eight of fifteen steps would stabilize in the atmosphere.


Minimizing the damage is one strategy; limiting the amount of CO2 entering the atmosphere is another.

The IPCC has several climate-change response scenarios that predict how much the climate will change based on

how the human population responds.

Confronting climate change is challenging26TERMS TO KNOW;MitigationCarbon taxesPrecautionary principle


Confronting climate change is challenging26TERMS TO KNOWMitigationCarbon taxesPrecautionary principle



Change is coming. Resistance buys some time, but ultimately, adaptation will be required.

How can we ensure an adequate water supply?

What do we need to plant as our ability to produce food becomes stressed?

Can or should we relocate trees in anticipation of where they might survive?

Mitigation might not be enough26

Impact: With a slight overall temperature increase, crop production can be expected to increase. With greater increases, crop yields will fall drastically.

Adaptation: Erosion-control techniques and choosing crops to fit the new conditions.

TERMS TO KNOW:Adaptation

Mitigation might not be enough26TERMS TO KNOW:Adaptation

Impact: The proportion of land area in severe drought is projected to increase from 1−3% today to 30% by 2090.

Adaptation: Focus on methods to capture and conserve water. Practice pollution prevention to increase and protect water supplies.


Impact: The proportion of land area in severe drought is projected to increase from 1−3% today to 30% by 2090.

Adaptation: Focus on methods to capture and conserve water. Practice pollution prevention to increase and protect water supplies.



Impact: The spread of waterborne pathogens should lead to increased incidence of infectious disease.

Adaptation: Improve disease surveillance, implement sanitation improvements in flood-prone areas, and establish emergency action plans.



Impact: Some species may benefit and expand their ranges. Many arctic species are likely to become extinct.

Adaptation: Wildlife and habitat management to provide mitigation corridors or relocation assistance; protect vulnerable habitats from further impact.



Impact: 30 to 300 million people will be affected at temperature increases of 2−4oC.

Adaptation: Relocation of some coastal communities may be necessary; construct protective barriers like seawalls and restore wetlands in coastal areas to protect inland areas.


PERSONAL CHOICES THAT HELP26

Offset CO2 productionTerrapass.com

Community awareness350.org

UNDERSTANDING THE ISSUE26

UNDERSTANDING THE ISSUE26

www.ipcc.ch

ANALYZING THE SCIENCE26

EVALUATING NEW INFORMATION26

MAKING CINNECTIONS26

chapter 26 climate change when the trees leave scientists grapple with a shifting climate

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