Chapter 10: Global Climate Change Climate Past, Present and Future.

Chapter 10: Global Climate Change

Climate Past, Present and Future

Foreword

The issue of global climate change may be one of the most important issues facing humanity in its history

This issue has the potential to affect the economies, safety and health of the entire world’s population

Hopefully you’ll understand after this brief review why the science of this topic is so difficult to understand and why it generates so much political controversy

The Earth’s climate system consists of complex interactions between many components!

The Earth Systems Science Approach recognizes five natural subsystems: atmosphere, hydrosphere, geosphere,biosphere and heliosphere. Most researchers now recognize a sixth, non-natural subsystem: the anthroposhere.

Sun

About 30% of incomingsolar energy reflected back to space

radi

ated

hea

t

Greenhouse gases absorb radiated heat andreradiate some of it to the lower atmosphere

Earth materials absorb about 70% of incoming light energy; some portion of this energy is emitted to the atmosphere asradiated heat

Greenhouse Effect – gradualwarming of the Earth’s loweratmosphere and surface whencertain gases (e.g., H2O, CO2 andCH4 ) absorb heat radiated from theEarth’s surface

Greenhouse Effect

Don’t use the terms “greenhouse effect”, “greenhouse warming” and “global warming” synonymously - they are related, but different topics

Would the average person view the greenhouse effect as beneficial or detrimental?

Most people erroneously think that the greenhouse effect is detrimental; the greenhouse effect is a natural phenomenon that helps modify the Earth’s climate and produce livable biological niches

Greenhouse Effect

Atmospheric scientists suggest the Earth’s average surface temperature would be about 60 - 70 degrees F colder without a greenhouse effect; under these conditions most of the Earth’s surface would host Arctic conditions - the flora and fauna of Earth would be drastically reduced in number and diversity

Greenhouse Effect

So: the greenhouse effect is a natural phenomenon; “global warming” indicates that average global temperatures are rising but implies no particular cause(s); “greenhouse warming” indicates that average temperatures are rising due to increased concentrations of atmospheric greenhouse gases

Global Warming Evidence There is firm evidence that the

greenhouse effect is being enhanced and that we are entering a global warming period

This evidence includes: 29 of the highest world average annual

temperatures ever recorded (since 1880) recorded from 1976-2013; with the exception of 1998, the nine hottest years have occurred since 2001 (2013 was the fourth hottest global year on record, 2005 and 2010 the hottest);

about a 50% reduction in European Alps glacier ice in the last 100 years;

Source: National Geographic, Sept. 2012

an average rise in world sea levels of about 1 foot during the last century; a decline of about 42% in Arctic sea ice volume in the last 30 years; and the quick melting of portions of the Greenland and Antarctic ice sheets and Antarctic ice shelves (1995, 2002 and 2008 – in March 2002 a portion of the Larsen ice shelf the size of Rhode Island (1250 mi2 ) collapsed into the Antarctic Ocean) (see slides)

Change in Arctic Sea Ice Minimum 1979-2007

Global Warming Evidence

Global Warming Evidence

Global Warming

The accumulating evidence suggests global warming is occurring but whether natural or human forces (or both) were causing climate change was vigorously debated

However, the debate in the scientific community has mostly ceased

Why? See slides

Global Climate Change

The 2013 IPCC (Intergovernmental Panel on Climate Change) report contends that human actions are significantly driving climate change (95% confidence level)

Global Climate Research

What can we say with 100% certainty?

Atmospheric concentrations of greenhouse gases (especially carbon dioxide) are increasing; the increase of atmospheric CO2 parallels the increased consumption of fossil fuels worldwide (CO2 is a byproduct of the combustion of any C-bearing fuel) (see figures)

Data from 1958 – present,measurements of atmosphere; prior to 1958, analysis of icecore air bubbles


In simple models, the more greenhouse gases in the atmosphere the more radiated heat from the surface gets trapped and the higher the atmospheric and surface temperatures

What are some natural sources of greenhouse gases?

Greenhouse Gas Sources What are some other

natural sources of greenhouse gases? Are these sources easy to accurately quantify on a worldwide basis?

Is this a simple or complex research topic?

Climate Reconstruction Research

Ice sheet core samples (see figure) and other materials are being ingeniously investigated for their ability to retain indications of prior atmospheric chemistry and temperature

Scientists are attempting to detail ancient atmosphere greenhouse gas levels to see if they’ve ever fluctuated as much naturally as they’ve done in the last 55 years

Climate Reconstruction Research

Particularly, scientists are interested in establishing how pre- and post-Industrial Revolution atmospheric greenhouse gases have fluctuated

Why is this research important? Why should you care?


Although evidence supports that circa 1840 air CO2 levels were about 270 ppm (parts per million) and that measured air CO2 levels from 1958 to present have risen from about 310 ppm to about 400 ppm, we still can’t discern what percentage factor human activities are to atmospheric chemistry and climate changes

Industrial Revolution

Possible Global Climate Change Outcomes If atmospheric greenhouse gas

concentrations continue to rise and enhance the greenhouse effect, what are some of the proposed consequences of global climate change?

Remember: although the topic is “global warming” the entire globe won’t be affected similarly, subsequently many researchers and politicians now employ the phrase, “global climate change”

Possible Global Climate Change Outcomes

Consequences could include: 1) significant rises in sea levels as increased glacial ice melting occurs; the rising waters could permanently displace millions of people (see figures);

National Geographic: August, 2007


Note the adjacent examples of the threat of rising seas

2) Reduction of tillable land as sea levels rise;


3) Changes in world weather patterns and a higher frequency of severe weather events (e.g., hurricanes, severe thunderstorms, extended heat waves,

more winter blizzards);

North Atlantic Tropical Storm Frequency

National Geographic: August, 2007


Source: National Geographic, Sept. 2012


Global climate change will have local impacts!

1980 - 1995: 46 US weather disasters with at least $1 billion in damages

1996 - 2011: 87 US weather disasters with at least $1 billion in damages

Source: US National ClimaticData Center


4) A greater percentage of land becomes arid and less productive; the glacial source of some major rivers (e.g., the Ganges) may be reduced or eliminated long term (a few hundred years)


5) The biodiversity of coastal ecosystems declines due to an inability to adapt quickly to rising, warming, and increasingly acidic seas (e.g., reefs);

CNN.com 3/31/06

Bleached coral


6) Diseases spread by flies, mosquitoes, ticks become more prevalent as the warmer climates produce longer and more intense infection periods (think about the rapid spread of West Nile Virus across the U.S.); and

1/26/2012

Warm, less salty surface current

Cold, salty deep current

Gulf Stream:50-90 miles wide;maximum discharge:540 billion tons/hour

7) The deep-water return flow of the Gulf Stream current is reduced/eliminated leading to much colder conditions in the North Atlantic (see figure)


Most climate scientists think there is enough evidence of these effects occurring to strongly support that global climate change is occurring at a rate that requires worldwide action

Complicating factors: How would climate change influence the Jet Stream or weather patterns generated during El Nino and La Nina events?

Possible Global Climate Change Outcomes Please remember that the seven categories

of global climate change outcomes we discussed are projections, not a guaranteed reality - the projections are based on incomplete data and an incomplete mathematical understanding of the Earth’s dynamic processes

The first global climate change computer models treated the Earth as a rocky ball devoid of life - simpler to model mathematically!


The most sophisticated computer models of climate today still lack the required data and knowledge of how Earth’s systems quantitatively interact to make long-term predictions with a high degree of certainty

Does that mean we should ignore this issue?

Global Climate Change Alternatives

There are alternatives that have been proposed to the worst case global warming model that suggest modest, but not catastrophic climate change, will occur

However, currently these hypotheses are currently shared by a low percentage of earth scientists and climatologists

Addendum

If you’re interested in the worldwide political and economic implications of this topic, conduct a Web search using the key words “Kyoto Protocol” or IPCC (Intergovernmental Panel on Climate Change)

Geoengineering

Pay attention to this topic!

Chapter 10: Global Climate Change Climate Past, Present and Future.

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Transcript of Chapter 10: Global Climate Change Climate Past, Present and Future.