Introduction

Global Environmental Change – Lecture 1 Spring 2015

Why Global Environmental Change?

• This course was designed as a climate change course, yet the name chosen was Global Environmental Change – WHY?

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Speculation• People have speculated that human activities

might influence the environment

• The Greeks, and later others, thought that forest cutting might influence rainfall, but there were disagreements about whether the influence would be positive (more rainfall) or negative

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Ice Ages• When it was discovered that the earth had once been covered

with ice, the obvious questions concerned the cause

• Possible causes: Variations in the heat of the Sun? Volcanoes erupting clouds of smoke? The raising and lowering of mountain ranges, which diverted wind

patterns and ocean currents? Changes in the composition of the air itself? Or?

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Man’s Effects• In 1827, Jean Baptiste Joseph Fourier, a French

mathematician, suggested that gases in the earth’s atmosphere might absorb infrared radiation and influence earth’s climate

• He made an analogy to a greenhouse, although the name greenhouse effect came much later

• In 1896, Swedish scientist Svante August Arrhenius published a paper in which he calculated the effect of carbon dioxide in heating the earth – more about this later

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Callendar Effect• By the 1930s, it was discovered that the United States

and North Atlantic region had warmed significantly during the previous half-century

• Guy Stewart Callendar (1898 - 1964), an English steam engineer and inventor, developed a theory that linked rising carbon dioxide concentrations in the atmosphere to global temperature

• Although previously discussed by Fourier, Arrhenius, and others, the effect is sometimes called the Callendar effect, because Callendar insisted that warming was on its way

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G.S. Callendar, 1934

Scientific Investigation• Callendar’s claims did provoke scientific investigation

• At the suggestion of Roger Revelle, Charles David Keeling began measuring carbon dioxide and, later, other greenhouse gas concentrations in the atmosphere, starting in 1957

• It was quickly discovered that CO2 levels were increasing

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Credit• Much of the remainder of this lecture is based on

Discovery of Global Warming site created by Spencer Weart, with initial support from the American Institute of Physics, the National Science Foundation and the Alfred P. Sloan Foundation

• http://www.aip.org/history/climate/impacts.htm#impacts

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Scientific Progress• Simple mathematical models of the climate were developed

Feedbacks that could make the system surprisingly variable were discovered

• Ingenious ways to retrieve past temperatures by studying ancient pollens and fossil shells were developed Apparently, grave climate change could happen, and in the past had

happened, within as little as a few centuries

Computer models of the general circulation of the atmosphere, the fruit of a long effort to learn how to predict (and perhaps even deliberately change) the weather, reinforced this finding

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1960’s• Calculations. made in the late 1960’s, suggested average

temperatures would rise a few degrees within the next century

• Groups of scientists that reviewed the calculations They were thought to be plausible No need for any policy action, aside from putting more effort into

research to find out for sure what was happening , was regarded as necessary, since the next century was a long way off

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1970’s• The rise of environmentalism raised public doubts about the

effects of human activity on the planet

• Curiosity about climate turned into anxious concern Greenhouse effect concerns Some scientists pointed out that human activity was putting dust and

smog particles into the atmosphere, where they could block sunlight and cool the world

Analysis of Northern Hemisphere weather statistics showed that a cooling trend had begun in the 1940s and was continuing

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Confusion• The mass media were confused

Sometimes predictions of a balmy globe, with coastal areas flooded as the ice caps melted, were given

Sometimes the media warned of the prospect of a catastrophic new ice age

• Study panels, first in the U.S. and then elsewhere, began to warn that one or another kind of future climate change might pose a severe threat Scientific agreement was limited to saying scientists scarcely understood

the climate system, and much more research was needed

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Increasing Research Activity• Research activity did accelerate, including huge data-gathering

schemes that mobilized international fleets of oceanographic ships and orbiting satellites

• Scientists were coming to understand that climate is an intricate system responding to a great many influences Volcanic eruptions and solar variations were still plausible causes of change,

with some arguments that these would swamp any effects of human activities Even subtle changes in the Earth's orbit could make a difference

To the surprise of many, studies of ancient climates showed that astronomical cycles had partly set the timing of the ice ages

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Chaos• The climate appeared to be so delicately balanced that almost

any small perturbation might set off a great shift According to the new "chaos" theories, in such a system a shift might

even come all by itself , and very suddenly Support for the idea came from ice cores arduously drilled from the

Greenland ice sheet, which showed large and disconcertingly abrupt temperature jumps in the past

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Late 1970’s• Global temperatures began to rise again

Many climate scientists had become convinced that the rise was likely to continue as greenhouse gases accumulated

One unexpected discovery was that the level of certain other gases was rising, which would add seriously to global warming

Some of these gases also degraded the atmosphere's protective ozone layer, and the news inflamed public worries about the fragility of the atmosphere

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1980’s• Greatly improved computer models began to suggest how dramatic climate

jumps could happen, for example, through a change in the circulation of ocean currents

• Experts predicted: Droughts Storms Rising sea levels Other disasters

Politicians began to suspect there might be a public issue here

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Beginnings of the Model Controversies• Modelers had to make many arbitrary assumptions about clouds and the

like, and reputable scientists disputed the reliability of the results

• Others pointed out how little was known about the way living ecosystems interact with climate and the atmosphere For example, what were the effects of agriculture and deforestation in adding

or subtracting carbon dioxide from the air

• One thing the scientists agreed on was the need for a more coherent research program

• By around 2000, some predicted, an unprecedented global warming would become apparent 

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1988• In the summer of 1988, climate scientist's worries first caught

wide public attention

• The summer of 1988 was the hottest on record till then

• An international meeting of scientists warned that the world should take active steps to cut greenhouse gas emissions

• James Hansen spoke out, becoming a powerful voice urging both climate research and efforts to reduce carbon dioxide emissions

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Beginnings of Climate Wars• Corporations and individuals who opposed all government

regulation began to spend many millions of dollars on lobbying, advertising, and "reports" that mimicked scientific publications, in an effort to convince people that there was no problem at all

• Environmental groups, less wealthy but more enthusiastic, helped politicize the issue with urgent cries of alarm

• Many scientific uncertainties, and the sheer complexity of climate, made room for limitless debate over what actions, if any, governments should take

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Early 1990’s• Was the global temperature rise due to an increase in the Sun’s activity?

Solar activity began to decline, but the temperature soared faster than ever

• Did computer models reproduce the present climate only because they were tweaked until they matched it, making them worthless for calculating a future climate change? Improved models successfully predicted the temporary cooling due to a huge

volcanic explosion in 1991 and passed many other tests In particular, the modelers could now reproduce in detail the pattern of warming,

changes in rainfall, etc. actually observed in different regions of the world over the past century (hindcasting)

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State of the Climate Models• Modeling teams that made different assumptions about the

physics of clouds and pollution got somewhat different results Most of them found a warming of around 3°C when the carbon

dioxide level doubled, late in the 21st century Some found a rise of 2°C or perhaps a bit less, costly but

probably manageable Others calculated a 5°C rise or even more, an unparalleled

catastrophe21

Antarctic Ice Cores• For hundreds of thousands of years, carbon dioxide and

temperature had been linked: anything that caused one of the pair to rise or fall had caused a rise or fall in the other

• It turned out that a doubling of carbon dioxide had always gone along with a 3°C temperature rise, give or take a degree or two This provided striking confirmation of the computer models, from

independent geologic evidence

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Response – Creation of IPCC• “It was established by the United Nations Environment

Programme (UNEP) and the World Meteorological Organization (WMO) in 1988 to provide the world with a clear scientific view on the current state of knowledge in climate change and its potential environmental and socio-economic impacts

• In the same year, the UN General Assembly endorsed the action by WMO and UNEP in jointly establishing the IPCC”

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What is IPCC?• “The IPCC is a scientific body under the auspices of the

United Nations (UN)

• It reviews and assesses the most recent scientific, technical and socio-economic information produced worldwide relevant to the understanding of climate change

• It does not conduct any research nor does it monitor climate related data or parameters”

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IPCC Reports• IPCC began to publish assessment reports:

First Assessment Report (FAR) 1990 Second Assessment Report (SAR) 1995 Third Assessment Report (TAR) 2001 Assessment Report 4 (AR4) 2007 Assessment Report 5 (AR5) 2013

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IPCC Progress• The world's governments had created a panel to give them the

most reliable possible advice, as negotiated among thousands of climate experts and officials. By 2001, the Intergovernmental Panel on Climate Change (IPCC)

managed to establish a consensus, phrased so cautiously that scarcely any expert or government representative dissented

The IPCC announced that, although the climate system was so complex that scientists would never reach complete certainty, it was much more likely than not that our civilization faced severe global warming

The discovery of global warming was essentially completed

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2000 – a New Millennium • Scientists knew the most important things about how

the climate could change during the 21st century

• How the climate would actually change now depended chiefly on what policies humanity would choose for its greenhouse gas emissions

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2000’s• Greatly improved computer models, together with an abundance of data of

many kinds, strengthened the conclusion that human emissions are very likely to cause serious climate change

• The IPCC's conclusions were reviewed and endorsed by the national science academies of every major nation from the United States to China, along with leading scientific societies and indeed virtually every organization that could speak for a scientific consensus

• Specialists meanwhile improved their understanding of some less probable but more severe possibilities

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James Lawrence Powell Pie-Charts

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New Finding’s• Dangerous change in ocean circulation seemed unlikely in the

next century or two

• There were signs that disintegrating ice sheets could raise sea levels faster than most scientists had expected

• Worse, new evidence suggested that the warming was itself starting to cause changes that would generate still more warming

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Beginning of the 2010’s• Scientists who had been predicting for decades that, by 2000,

the world would be significantly warmer were now obviously correct

• Science reporters, business leaders, government advisers and others increasingly believed them

• An ever larger number of individuals, corporate entities, and government agencies at every level decided that something had to be done

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Likely Consequences• Likely consequences of restrained warming, by two

or three °C What we may expect if humanity manages to begin

restraining its emissions soon, so that greenhouse gases do not rise beyond twice the pre-industrial level

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Anticipated Changes - 1• Most places will continue to get warmer

Especially at night and in winter

• Temperature change will benefit some regions while harming others Patterns of tourism will shift Warmer winters will improve health and agriculture in some areas Globally, mortality will rise and food supplies will be endangered due to

more frequent and extreme summer heat waves and other effects Regions not directly harmed will suffer indirectly from higher food prices and

a press of refugees from afflicted regions

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Anticipated Changes - 2• Sea levels will continue to rise for many centuries

The last time the planet was 3°C warmer than now, the sea level was at least 6 meters (20 feet) higher

That submerged coastlines where many millions of people now live, including cities from New York to Shanghai

The rise will probably be so gradual that later generations can simply abandon their parents' homes, but a ruinously swift rise cannot be entirely ruled out

Storm surges will cause emergencies34

Anticipated Changes - 3• Weather patterns will keep changing 

Toward an intensified water cycle with stronger floods and droughts Most regions now subject to droughts will probably get drier (because of

warmth as well as less precipitation), and most wet regions will get wetter Extreme weather events will become more frequent and worse

• In particular, storms with more intense rainfall are liable to bring worse floods

Some places will get more snowstorms, but most mountain glaciers and winter snowpack will shrink, jeopardizing important water supply systems

Each of these things has already begun to happen in some regions

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Anticipated Changes - 4• Ecosystems will be stressed 

Although some managed agricultural and forestry systems might benefit in the first decades of warming

Uncounted valuable species, especially in the Arctic, mountain areas, and tropical seas, must shift their ranges

Many that cannot will face extinction A variety of pests and tropical diseases are expected to spread to

warmed regions These problems have already been observed in numerous places

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Anticipated Changes - 5• Increased carbon dioxide levels will affect biological

systems, independent of climate change Some crops will be fertilized, as will some invasive weeds (the balance

of benefit vs. harm is uncertain) The oceans will continue to become markedly more acidic, gravely

endangering coral reefs, and probably harming fisheries and other marine life

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Anticipated Changes - 6• There will be significant unforeseen impacts

Most of these will probably be harmful, since human and natural systems are well adapted to the present climate

The climate system and ecosystems are complex and only partly understood, so there is a chance that the impacts will not be as bad as predicted

There is a similar chance of impacts grievously worse than predicted

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Climate Denial• Others insisted that the IPCC was wholly mistaken; there was

no need to worry

• A minority of scientists (scarcely any of them known for contributions to climate science) who held to the old conviction that human activity was too feeble to sway natural systems

• Distrust of the climate experts was encouraged by corporations and political interests that opposed any government interference in the economy

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Representative Concentration Pathways• Scenarios that include time series of emissions and concentrations

of the full suite of greenhouse gases (GHGs) and aerosols and chemically active gases, as well as land use / land cover

• The word representative signifies that each RCP provides only one of many possible scenarios that would lead to the specific radiative forcing characteristics

• The term pathway emphasizes that not only the long-term concentration levels are of interest, but also the trajectory taken over time to reach that outcome

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RCP 2.6• One pathway where radiative forcing peaks at

approximately 3 W m–2 before 2100 and then declines (the corresponding ECP assuming constant emissions after 2100)

• Corresponds to concentrations of 450 ppm CO2eq

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RCP 4.5• Intermediate stabilization pathways in which

radiative forcing is stabilized at approximately 4.5 W m–2 after 2100 (the corresponding ECPs assuming constant concentrations after 2150)

• Corresponds to concentrations of 650 ppm CO2eq

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RCP 6.0• Intermediate stabilization pathways in which

radiative forcing is stabilized at approximately 6.0 W m–2 after 2100 (the corresponding ECPs assuming constant concentrations after 2150)

• Corresponds to concentrations of 850 ppm CO2eq

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RCP 8.5• One high pathway for which radiative forcing reaches

greater than 8.5 W m–2 by 2100 and continues to rise for some amount of time (the corresponding ECP assuming constant emissions after 2100 and constant concentrations after 2250)

• Corresponds to concentrations of 1370 ppm CO2eq

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Scenario Constraints• Scenarios of how the future develops without

additional and explicit efforts to mitigate climate change (‘baseline scenarios’) and with the introduction of efforts to limit GHG emissions (‘mitigation scenarios’), respectively, generally include socio-economic projections in addition to emission, concentration, and climate change information

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AR5 Synthesis Report - 2014• The Synthesis Report discussed four areas:

SPM 1. Observed Changes and their Causes SPM 2. Future Climate Changes, Risks and Impacts SPM 3. Future Pathways for Adaptation, Mitigation and

Sustainable Development SPM 4. Adaptation and Mitigation

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Observed Changes and their Causes

• Human influence on the climate system is clear, and recent anthropogenic emissions of greenhouse gases are the highest in history

• Recent climate changes have had widespread impacts on human and natural systems

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SPM 1.1Observed changes in the climate system

• 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, and sea level has risen

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1880-2014 Temperature Anomalies

• 2014 was the hottest year during this period49

2014 Temperature Percentiles

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SPM 1.2 Causes of climate change• Anthropogenic greenhouse gas emissions have increased since the

pre-industrial era, driven largely by economic and population growth, and are now higher than ever

• This has led to atmospheric concentrations of carbon dioxide, methane and nitrous oxide that are unprecedented in at least the last 800,000 years

• Their effects, together with those of other anthropogenic drivers, have been detected throughout the climate system and are extremely likely to have been the dominant cause of the observed warming since the mid-20th century

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SPM 1.3 Impacts of climate change• In recent decades, changes in climate have caused

impacts on natural and human systems on all continents and across the oceans

• Impacts are due to observed climate change, irrespective of its cause, indicating the sensitivity of natural and human systems to changing climate

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SPM 1.4 Extreme events• Changes in many extreme weather and climate events have

been observed since about 1950

• Some of these changes have been linked to human influences, including a decrease in cold temperature extremes, an increase in warm temperature extremes, an increase in extreme high sea levels and an increase in the number of heavy precipitation events in a number of regions

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Future Climate Changes, Risks and Impacts

• Continued emission of greenhouse gases will cause further warming and long-lasting changes in all components of the climate system, increasing the likelihood of severe, pervasive and irreversible impacts for people and ecosystems

• Limiting climate change would require substantial and sustained reductions in greenhouse gas emissions which, together with adaptation, can limit climate change risks.

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SPM 2.1 Key drivers of future climate

• Cumulative emissions of CO2 largely determine global mean surface warming by the late 21st century and beyond

• Projections of greenhouse gas emissions vary over a wide range, depending on both socioeconomic development and climate policy

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SPM 2.2 Projected changes in the climate system

• Surface temperature is projected to rise over the 21st century under all assessed emission scenarios

• It is very likely that heat waves will occur more often and last longer, and that extreme precipitation events will become more intense and frequent in many regions

• The ocean will continue to warm and acidify, and global mean sea level to rise

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SPM 2.3 Future risks and impacts caused by a changing climate

• Climate change will amplify existing risks and create new risks for natural and human systems

• Risks are unevenly distributed and are generally greater for disadvantaged people and communities in countries at all levels of development

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SPM 2.4 Climate change beyond 2100, irreversibility and abrupt changes

• Many aspects of climate change and associated impacts will continue for centuries, even if anthropogenic emissions of greenhouse gases are stopped

• The risks of abrupt or irreversible changes increase as the magnitude of the warming increases

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Future Pathways for Adaptation, Mitigation and Sustainable Development

• Adaptation and mitigation are complementary strategies for reducing and managing the risks of climate change

• Substantial emissions reductions over the next few decades can reduce climate risks in the 21st century and beyond, increase prospects for effective adaptation, reduce the costs and challenges of mitigation in the longer term, and contribute to climate-resilient pathways for sustainable development.

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SPM 3.1 Foundations of decision-making about climate change

• Effective decision making to limit climate change and its effects can be informed by a wide range of analytical approaches for evaluating expected risks and benefits, recognizing the importance of governance, ethical dimensions, equity, value judgments, economic assessments and diverse perceptions and responses to risk and uncertainty

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SPM 3.2 Climate change risks reduced by mitigation and adaptation• Without additional mitigation efforts beyond those in place

today, and even with adaptation, warming by the end of the 21st century will lead to high to very high risk of severe, widespread, and irreversible impacts globally

• Mitigation involves some level of co-benefits and of risks due to adverse side-effects, but these risks do not involve the same possibility of severe, widespread, and irreversible impacts as risks from climate change, increasing the benefits from near-term mitigation efforts.

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SPM 3.3 Characteristics of adaptation pathways

• Adaptation can reduce the risks of climate change impacts, but there are limits to its effectiveness, especially with greater magnitudes and rates of climate change

• Taking a longer-term perspective, in the context of sustainable development, increases the likelihood that more immediate adaptation actions will also enhance future options and preparedness

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SPM 3.4 Characteristics of mitigation pathways

• There are multiple mitigation pathways that are likely to limit warming to below 2°C relative to preindustrial levels.

• These pathways would require substantial emissions reductions over the next few decades and near zero emissions of CO2 and other long-lived GHGs by the end of the century.

• Implementing such reductions poses substantial technological, economic, social, and institutional challenges, which increase with delays in additional mitigation and if key technologies are not available.

• Limiting warming to lower or higher levels involves similar challenges, but on different timescales

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SPM 4. Adaptation and Mitigation• Many adaptation and mitigation options can help address

climate change, but no single option is sufficient by itself

• Effective implementation depends on policies and cooperation at all scales, and can be enhanced through integrated responses that link adaptation and mitigation with other societal objectives

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SPM 4.1 Common enabling factors and constraints for adaptation

and mitigation responses

• Adaptation and mitigation responses are underpinned by common enabling factors

• These include effective institutions and governance, innovation and investments in environmentally sound technologies and infrastructure, sustainable livelihoods, and behavioral and lifestyle choices.

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SPM 4.2 Response options for adaptation

• Adaptation options exist in all sectors, but their context for implementation and potential to reduce climate-related risks differs across sectors and regions

• Some adaptation responses involve significant co-benefits, synergies and trade-offs

• Increasing climate change will increase challenges for many adaptation options

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SPM 4.3 Response options for mitigation

• Mitigation options are available in every major sector

• Mitigation can be more cost-effective if using an integrated approach that combines measures to reduce energy use and the GHG intensity of end-use sectors, decarbonize energy supply, reduce net emissions and enhance carbon sinks in land-based sectors

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SPM 4.4 Policy approaches for adaptation and mitigation, technology and finance

• Effective adaptation and mitigation responses will depend on policies and measures across multiple scales: international, regional, national and sub-national

• Policies across all scales supporting technology development, diffusion and transfer, as well as finance for responses to climate change, can complement and enhance the effectiveness of policies that directly promote adaptation and mitigation

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SPM 4.5 Trade-offs, synergies and interactions with sustainable development

• Climate change is a threat to sustainable development

• Nonetheless, there are many opportunities to link mitigation, adaptation and the pursuit of other societal objectives through

• integrated responses (high confidence)

• Successful implementation relies on relevant tools, suitable governance structures and enhanced capacity to respond (medium confidence)

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What If?• What if the CO2 level keeps rising to well beyond twice the pre-

industrial level along with a rise of other greenhouse gases, as must inevitably happen if we do not take strong action soon? The results will certainly be worse

• Under a "business as usual" scenario, recent calculations give even odds that global temperature will rise 5°C or more by the end of the century This will cause a radical reorganization and impoverishment of many of

the ecosystems that sustain our civilization

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What of the more distant future?• If emissions continue to rise for a century, whether because we fail to rein

them in, or because we set off an unstoppable feedback loop in which the warming itself causes ever more greenhouse gases to be evaporated into the air, then the gases will reach a level that the Earth has not seen since tens of millions of years ago The consequences will take several centuries to be fully realized, as the Earth

settles into its new state It is probable that, as in the distant geological eras with high CO2, sea levels

will be many tens of meters higher and the average global temperature will soar far above the present value: a planet grossly unlike the one to which the human species is adapted

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Answering the Original Question• The foregoing discussion is intended as the answer to the

question posed at the beginning

• We are not just changing the climate, but we are engaged in a planet-wide, severe, alteration of the environment

• For this reason, the title “Global Environmental Change” was deemed most appropriate

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Bizarro

73O8-08-0304-05-07

By Don Piraro