Climate and Climate Change Notes

• hange ex Types of change experienced in climate perienced in climate (short term
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  Case Study: Tuvalu, South Pacific

  • Island nation in the South Pacific.

  • Nine small islands forming a 676 km chain over 757,000 km2.

  • Six are atolls.

  • Total population of 11,000.

  • Capital is Fonafuti on Fongafale Islet.

  • Settled 2000 years ago by Polynesian peoples.

  • Close to sea-level.

    • Highest elevation is 4.5 m.

    • Average elevation is 1.8 m.

  • Hazards of coastal erosion and flooding as well as reduced water quality.

    • High tides.

    • Storm surges.

    • Tsunami events.

    • All exacerbated by rising sea-levels.

Climate and Weather

• Weather: Atmospheric conditions of a given region over short periods of time (days and weeks).

• Climate: Characteristic atmospheric conditions of a given region over long periods of time (decades or hundreds to a thousand years).

• Climatology: Study of climate and its variability, including long-term weather patterns and spatial variations.

• Climatic regions: Areas with similar weather statistics that can be classified together.

• Short-term cyclical changes in Earth’s climate that appear to be natural (may be modified).

• Longer-term changes in climate linked to GHG-driven climate change that are projected to have measurable impacts on Earth’s future climate system.

Climate and Its Classification

• Determination of climate requires measuring annual average conditions over a long period of time, identifying significant patterns.

• Linking these conditions to patterns of vegetation and general atmospheric conditions/processes can also contribute to the classification employed.

• Principal Climate Components

  • Insolation

  • Temperature

  • Pressure

  • Air masses

  • Precipitation

• Classification of climatic regions typically rely on combining two types of principle climate components to reveal a general climate type called a climate regime.

Atmospheric Composition

• Heterosphere: Outer atmosphere (80 km altitude) with layers of gases sorted by gravity.

• Homosphere: Inner atmosphere (surface to 80 km) with a nearly uniform mixture of gases (notable exceptions).

  • Ozonosphere in the stratosphere and water vapor.

• Air is a simple mixture of gases that is naturally odorless, colorless, tasteless and formless, behaving as one gas.

Atmospheric Composition Continued

• Permanent gases: Those that form a measurable and consistent proportion of the atmosphere.

  • Nitrogen (N2), Oxygen (O2), Argon (Ar).

  • Helium (He), Krypton (Kr), Xenon (Xe), Hydrogen (H).

  • Very little to no impact on climate (some gas formations).

• Variable gases: Those that form a small and changing proportion of the atmosphere.

  • Water vapor (H2O), Carbon Dioxide (CO2), Methane (CH4), Nitrous Oxide (N2O), Ozone (O3), Halocarbons.

  • Very significant impact on climate (directly absorb energy).

• Aerosols: A suspension of microscopic liquid and solid particles in the atmosphere.

  • Dust, soot, H2SO4

Photochemical Smog and Climate Change

• Various permanent gases combine with other released gases/substances to form pollutions affecting atmospheric function.

• Many variable gases directly contribute to atmospheric function (CO2, O3, CH4, N2O, halocarbons).

• Despite the stability inferred in the definition of climate, changes to climate occur over time (regionally & globally).

• Modern focus on understanding natural and anthropogenic drivers, processes and implications.

• As the end product of all geo-processes on Earth, the study of climate entails researching the linkages among the atmosphere, lithosphere, hydrosphere, cryosphere and biosphere.

• Cryosphere: Refers to that part of the hydrosphere where water stays frozen year-round but also includes annual trends that part that varies throughout the year.

  • Permafrost, sea ice, ice caps, glaciers, and ice sheets.

• Glaciers refers to mainly terrestrial buildups of ice that flows under gravity and pressure in accordance with positive ice budgets.

Climate Change and Glaciation

• 3.2 million years of global climatic fluctuations between periods of cold climatic glacial intervals and relatively warmer interglacial intervals (where we are today).

  • Ice expansions covered much of North America, Europe and Northern Asia, as well as high altitude mountains at other latitudes by glaciers, causing sea-level fall.

• Current ice age is the Pliocene-Quaternary (AKA Pleistocene) began 2.58 million years ago with cyclical temperature shifts.

• Max extent 21,000 years ago and ending ~10,000 years ago.

  • Inter glacial periods experience warming, driving glacial retreat and sea-level rise.

• Last interglacial was 125,000 years ago with this one projected to last maybe up to 50,000 years.

Glaciation: Glacial Hazards

• Glaciers as moving masses of ice are inherently hazardous due to their mass and dynamism.

  • Glacial movement

    • Typically 1 m/day

  • Glacial surges

    • Increase speed (100x) up to tens of meters per day

  • Crevasses

  • Calving/collapse

  • Avalanches

  • Floodwaters (lahars, dams, pockets, lakes)

  • Iceberges

Case Study: Huascaran Avalanche Yungay, Peru

• Jan. 10, 1962 avalanche was triggered with the calving of ice.

  • Block of ice the size of two skyscrapers.

  • 6 million tons.

  • Traveled ~15 miles in 6 minutes and buried town in 12 meters of ice and debris.

  • 4,000 killed, 10,000 livestock killed and millions in damage.

• 1970 event was triggered by an earthquake.

  • ~20,000 people killed.

  • Burying entire village.

  • Town site is now a cemetery with reconstruction 1500 meters away at higher ground.

How We Study Past Climate Change and Make Predictions

• Data is gathered at various time frames and in reference to varying scales (local to global) focusing at both monitoring modern changes as well as understanding past changes.

  • Instrumental record

  • Historical record

  • Paleo-proxy record

• Instrumental record – 1880 and on with measures of land and ocean temperatures around the world increasing over time.

  • 1000 records from the late 19th century.

  • By 1957 there were measures from Antarctica.

  • 7000 records measured today (persistent spatial limits over the oceans and less inhabited areas).

  • Satellite record since 1979 providing global coverage.

Studying Climate Change: Instrumental Record

• CRUTEM3 (HadCRUT): Climatic Research Unit/Hadley center

  • 4349 stations

• NCDC: National Climatic Data Center (U.S.)

  • 7230 stations

• GISS: NASA’s Goddard Institute of Space Studies

  • >7200 stations

• Gaps still exist

  • Southern Hemisphere with few data points for Antarctica

  • Oceans

  • Less data collected during world wars

• RSS: Remote Sensing Systems

  • MSU/AMSU or microwave sounding units on polar orbiting NOAA satellites

• UAH: University of Alabama Huntsville

  • Satellite measures of radiance

Studying Climate Change: Historical Record

• Historical records are largely qualitative information about climate extending back several hundred years.

  • Written recollections (journal articles, books, newspapers, personal journals)

  • Travel diaries

  • Ship logs

  • Farmers’ crop records

• Medieval Warm Period – period of warm temperatures approximately as warm as they are today between the late 9th and early 14th centuries

  • Not uniformly warm, periods of interruptions

  • Debated whether it was a Northern Hemisphere phenomena or distinct global climatic period

• Little Ice Age – period of cold temperatures lasting between the 14th and 19th to early 20th centuries with cooling equivalent to the approximate present warming

• Natural variability can be powerful and should be of concern when mixed with human-caused warming

Studying Climate Change: Paleo-proxy Record

• Paleoclimatology – is the study of past climates

  • Extending our modern temperature records

  • Providing quantitative information for the analysis of modern climatic trends

• Proxy data – data that is not strictly climatic but can be correlated with climate (land and sea temperatures)

  • Tree rings

  • Ocean sediments

  • Ice cores

  • Fossil pollen

  • Corals

  • Carbon-14 (^{14}C)

• While not direct measures of climate, the correlations are scientific, and a range of confidence can be determined

  • Multi-method approach increases confidence that inferred trends are accurate and reflect true patterns of past climates

Studying Climate Change: Paleo-proxy Record and Tree Rings

• Dendroclimatology – the study of tree rings to better understand past climates

  • Growth is dependent generally on climatic conditions (temp/precip)

  • Most add one ring per year

  • Width, density and isotopic composition all studied

  • Radiometric dating or correlation of tree rings with others for dating

  • Stretches back ~5000 years

    • Temporally fine (annual)

    • Spatially local

  • Includes precipitation as an influence

Studying Climate Change: Paleo-proxy Record and Sediments

• Sediments on lake beds, ponds, bogs or even the ocean bottom accumulate from winds, rivers, volcanic eruptions and shells of dead organisms

  • Sediments accumulate gradually over time in a layered fashion, responding to changes in vegetation, ice coverage and atmospheric conditions

• Varves – lake sediment (~50,000 year record)

  • Pollens indicate vegetation and sediments are linked to seasons and drought

• Ocean sediments are studied through isotope analysis

  • Investigates changes in the concentrations of certain variations in the neutrons of particular atomic nuclei from its standard

• Oxygen (O) always has 8 protons but can have 8, 9, or 10 neutrons

• Oxygen-16 (^{16}O) or “light” O is the most common isotope in nature comprising 99.76% of all oxygen

• Oxygen-18 (^{18}O) or “heavy” O comprises only about 0.2% of all oxygen

Studying Climate Change: Paleo-proxy Record and Sediments 2

• ^{18}O/^{16}O ratio in water is diagnostic of global ice extent as glacial ice is enriched with ^{16}O, altering ocean ratio

  • Higher ratio with cooler climate (more ice)

  • Lower ratio with warmer climate (less ice)

• Planktonic organisms (shallow water) record sea surface temperatures

• Benthic organisms (deep water) record oxygen isotope composition of water

  • Varies only with glacial ice extent as temp. are fairly constant at depth

• Foraminifera shells (CaCO_3) provide record with deep sea cores drilled by ships

  • 70 million year record of global temperatures

Studying Climate Change: Paleo-proxy Record and Ice Cores

• Glaciers are comprised of yearly deposits of ice that are not ablated, resulting in layers of glacial ice that can accumulate over hundreds of thousands of years

  • Ice cores are drilled from long-lived glaciers

  • Small bubbles of atmosphere captured around the time of deposit can be studied as samples of past atmosphere

  • Other chemicals and materials are also captured including volcanic ash, dust and anthropogenic pollutions

  • Ice itself may be studied for the paleo-isotopic composition of water

Studying Climate Change: Paleo-proxy Record and Ice Cores 2

• Cold regions allow seasonal snow deposits to accumulate and eventually form glacial ice

  • Seasonal variations (chemistry and texture) allow recognition of yearly layer in upper sections

  • Bottom of cores require ID of dust/volcanic ash layers

• Ice cores are correlated to other ice cores and sediment cores to confirm dating and extend record

  • Greenland ice cores spanning 250,000 years

  • Antarctica Dome C core (3270.2m) ice core spanning 800,000 years

• Oxygen isotope ratios have the opposite relationship to climate in ice cores but serve as direct proxies for air temperature

  • Lower ^{18}O/^{16}O suggest colder climates

  • Higher ^{18}O/^{16}O suggest warmer climates

Studying Climate Change: Paleo-proxy Records from Other Sources

• Pollens

  • Accumulation in sediments will be in layers

  • Sufficient pollen may allow it to be dated and the layer chronology identified (localized)

  • Changes in pollen type indicate vegetative changes linked to ecosystem changes and maybe used to identify climatic changes due to known limiting factors

• Speleothems

  • CaCO_3 examined for depositional layers/rings and dated using uranium isotopes and O and C isotopes ratios

  • Indication of localized temperature and rainfall conditions

  • 350,000 years (localized)

• Corals

  • Polyp forms CaCO_3 exoskeletons that record water conditions

  • Use X-rays to ID growth bands and oxygen isotopes

Studying Climate Change: Paleo-proxy Records and Carbon-14

• Other proxy indicators are used to reconstruct temperatures on shorter time scales of hundreds and thousands of years

• Carbon Isotope Analysis

  • Stable isotopes is ^{12}C (98.90%), ^{13}C (1.10%)

  • Radioactive isotope is ^{14}C or carbon-14

    • Half-life of 5730 years

    • Formed by bombardment of nitrogen by cosmic radiation from the sun

• ^{13}C/^{12}C ratio is used in a similar manner to oxygen ratio as plants use different types of photosynthesis

• Carbon-14 can provide short-term climate reconstruction data regarding information on when life expired as well as solar activity

  • Dating of organisms that have expired as no new carbon-14 is being up taken from consumption of plant matter

  • Dendrochronology allows estimation of solar activity if climate is known (explains some of Medieval Warm Period and Little Ice Age but not recent warming trend)

Studying Climate Change: Paleo-proxy Records and Carbon Dioxide

• As one of the most important greenhouse gasses (apart from water vapor), climate has closely tracked CO2 levels over time

Studying Climate Change: Global Climate Models

• Model is comprised of a framework of three dimensional boxes with interactions calculated among all neighbors for each time step

  • Boundary conditions are set for overall model

• Models are tested by running them backward and checking fit with known climatic conditions

• Constant adjustments and increased spatial scales are applied and the general approach of referring to multiple runs and models is employed

Studying Climate Change: Global Climate Models 2

• Benefits of using models

  • Provide information based on a systems perspective for Earth focusing on interactions

  • Deficiencies in data and understanding become apparent, directing further research

  • Allows for scenario forecasting (range of possibilities)

• Limits

  • Models cannot anticipate human behavior as influenced by economic changes, technological innovations and social upheaval

  • Models do not produce actual data, only highlight interactions and assist in making improved forecasts

  • Incomplete understanding of climate

    • Water-cloud feedbacks and ice sheet dynamics, ect.

  • Parameterization of feedback mechanisms

  • Drift or the accumulation of errors on the centuries-scale

Global Warming

• The observed increase in the average temperature of the near-surface land and ocean environments during the past 60 years

• The consensus is that

  • Human activity (forced fluctuations) is the primary driver of global warming

  • Natural variations (unforced fluctuations) plays a lesser role

• Temperature of the Earth is determined by Earth’s the energy balance

  • Insolation from the Sun

  • Reflected energy due to Earth’s albedo

  • Thermal energy emitted from the top of the atmosphere based on its thermal balance

• Earth’s energy system will achieve a balance but the temperature at which that balance is reached will increase as the efficiency of the atmosphere at absorbing thermal energy is altered (book’s explanation is too simplistic)

Global Warming

• As temperature increases, radiated energy increases by a factor of 16

• Greenhouse Gasses

  • H2O, CO2, CH4, N2O, O3, CFCs

• Other Atmospheric Factors

  • Aerosols

  • Pollutants

Global Warming: Energy Budget

• Atmospheric window for thermal energy is 8-14 micrometers with peak emission at 10 micrometers

• CO2 is the most important anthropogenic GHG

  • Its absorption spectrum is in the thermal range 12-13 micrometers

  • Slightly closes the atmospheric window, absorbing additional energy that would otherwise escape

• Additional modified absorption of approximately 0.8 W/m2 (CO2 and other factors including land-use change)

• Temperature increases in response but only to achieve a new equilibrium

  • Increases in GHG concentrations keeps pushing the slow global temperature increases

Why Has and Does Climate Change?

• Climate forcing – an imposition of change of Earth’s energy balance

  • Unforced fluctuations (forcing) are those considered natural processes altering Earth’s climate (paleoclimatic change)

  • Forced fluctuations (forcing) are those considered to be anthropogenic in origin

• Climate sensitivity – response of climate to a specific climate forcing after a new equilibrium has been reached

  • Temperature gain at a specific CO2 concentration (doubling)

• Climate response time – time required for the response in forcing to occur in the climate

• Feedbacks – system interactions arising from the outputs of a system that influences its own operation

  • Negative feedbacks discourages change in the system

  • Positive feedback encourages change in the system

Mechanisms of Unforced Fluctuations

• Orbital variations – subtle cyclical changes in Earth’s orbit over long periods of time

  • First calculated by Milutin Milankovitch in the 1920s (from conceptual work of others)

• Milankovitch Cycles

  • Eccentricity or shape of Earth’s orbit around the sun

    • 100,000 year cycle

  • Obliquity or tilt of the Earth on its axis (23.5°)

    • Varies from 22° to 24.5°

    • 41,000 year cycle

  • Precession or wobble resulting from changes in the time of year when the Earth is closest to the sun

    • 19,000 and 23,000 year cycle

  • Simulations reproduce most of the long-term climatic cycles but not adequate to explain all the large-scale global climatic changes, particularly in the recent geologic past

Mechanisms of Unforced Fluctuations 2

• Orbital variations – subtle cyclical changes in Earth’s orbit over long periods of time

• Solar variability – changes in total solar irradiance

  • Increasing over billions of years

  • 11-year solar cycle connected to modest changes in solar output corresponding to changes in solar activity

    • More sunspots, more solar output

  • Maunder minimum was a 70-year period with very low solar activity that corresponded to cooler temperatures

  • No evidence of changes great enough to drive recent warming trend but a recognized influence

Mechanisms of Unforced Fluctuations 3

• Orbital variations – subtle cyclical changes in Earth’s orbit over long periods of time

• Solar variability – changes in total solar irradiance

• Continental Position and Topography

  • Changes in continental positions affect ocean currents, serve as locations for snow-ice accumulation, are connected to periods of increased volcanic eruptions and topographic uplift

Mechanisms of Unforced Fluctuations 4

• Orbital variations – subtle cyclical changes in Earth’s orbit over long periods of time

• Solar variability – changes in total solar irradiance

• Continental Position and Topography

• Atmospheric Gases and Aerosols

  • Volcanic emissions are primary natural source of CO2

  • Particulates including ash and sulfur dioxide increase Earth’s albedo, providing a 1-5 years of cooling (variable)

  • 1991 eruption of Mt. Pinatubo sent ash upward 30 km into the atmosphere resulting in 2.3°C cooling through 1992 (affects negligible by 1994)

Mechanisms of Forced Fluctuations: Radiatively Active Gases

• Anthropogenic Forcing

  • Human processes are responsible for slight cooling forcings

    • Land albedo changes (clearings)

    • Pollution particles (aerosols) have increased atmospheric albedo by as much as 10% (global dimming)

    • Total estimated negative forcing (-1.4 W/m2) may be offsetting up to 50% of the warming

  • Most significant forcing is the emission of GHGs (CO2 and CH4) and aerosols (CO and black carbon)

    • Overall anthropogenic forcing is believed to be ~2.25 W/m2 and cannot be explained by natural processes

    • Climate models suggest that natural processes cannot be responsible for the ~0.8°C rise in global temperatures from average since industrialization

Mechanisms of Forced Fluctuations AR 5 Climate Feedbacks

• Climate system is subject to a number of complex feedback systems that have varying degrees of influence on the environment, making predicting climate change and its affects particularly complex

• Positive feedbacks – amplifies system changes (destabilizes present conditions)

• Negative feedbacks – inhibits system changes (stabilizes present conditions)

• Ice-albedo feedback is an example of a positive feedback system

  • Warming reduces snow/ice cover, decreases polar albedo, and added insolation adsorption results in further warming

  • Cooling increases snow/ice cover, increases polar albedo, and reduced insolation absorbed results in further cooling

Climate Feedbacks, continued

• Water-Vapor Feedback

  • Most abundant natural GHG

  • Warming increases evaporation and the moisture capacity of the atmosphere, resulting in increased warming

  • Complicated by lack of clear tracking water vapor and the conflicted role of clouds (condensed water vapor)

• Permafrost-carbon Feedback

  • Warming melts permafrost, allowing further decomposition and releases of CO2 and CH4, further enhancing warming

• CO2-Weathering Feedback

  • Added CO2 increases warming resulting in increased precipitation, which in turn removes CO2 as it forms carbonic acids and these react with rocks to weather them. Weathered materials then recollect in the oceans or are deposited capturing CO2

  • Very slow feedback mechanism

Potential Effects of Global Climate Change

• Climate models suggest that even without any additional release of excess GHGs we would still experience a 0.5-1.0°C global temperature increase over the coming decades

• The same models suggest that a doubling of CO2 from preindustrial levels (as expected given current trends) will result in a 1.5-4.5°C rise in global average temperature

  • Global average temperature includes a much higher regional average temperature increase at the poles

  • Higher average temperatures also implies changes to temperature extremes

Potential Effects of Global Climate Change: Glaciers and Sea Ice

• Global warming drives the increase loss of ice mass for alpine glaciers, Greenland ice sheet and the sea ice pack

  • Most terrestrial glaciers are in retreat with added warming

  • Melting of Greenland ice sheet has doubled since 1998

    • 2005 saw about 200 km3 of glacial ice lost

  • Melt lubricates glacial ice, mobilizing its movement and risking more sudden losses (calving, water-induced melt)

  • Extent of Arctic sea ice remaining in September has declined an average of 10% per decade

  • Losses of high albedo ice, triggers the positive ice-albedo feedback cycle (warming)

• Gravity-based measures of ice loss between 1992 and 2011 from Greenland (2700 ± 930 Gt ice) and Antarctica (1350 ± 1010 Gt ice) together indicate an equivalent amount of water released to increase mean global sea-level 11.2 ±3.8 mm

  • Warming of the ocean contributes about equally to sea-level rise

Potential Effects of Global Climate Change: Climate Patterns

• Warming will feed additional energy into the Earth’s atmosphere leading to the potential for more severe storms and hazardous natural events

Potential Effects of Global Climate Change: Climate Patterns, continued

• Natural oscillations of the ocean, linked to the atmosphere can produce warmer and cooler periods for up to a decade or more

  • Effects of oscillations are temporary but may be 10 times as strong as long-term warming

• While still uncertain, the possibility remains that GW may influence the pattern and magnitude of climatic oscillations

  • Could greatly magnify the impacts of climate change

Climate Patterns: El Niño

• El Niño is a climatic oscillation occurring every few years (~7) involving unusually high sea-surface temperatures in the eastern equatorial Pacific Ocean

  • Likely random situation of weakened westward equatorial current allows reversal of in direction of warm water

Climate Patterns: El Niño, continued

• Impacts of El Niño events are variable

  • Increases in annual global temperatures

  • Increases in precipitation in the Southwest of the U.S. and Central and South America

  • Decreases in precipitation over Australia and South Asia

Climate Patterns: Decadal Oscillations

• Pacific Decadal Oscillation (PDO) – is a 20-30 year climatic oscillation defined by varying Northeast Pacific Ocean temperatures, affecting patterns of rainfall and drought as well as marine ecosystems

  • Positive phase occurs with the buildup of relatively warm surface waters adjacent to the far Northwest coast of North America

    • Wetter conditions for the Southwestern U.S.

  • Negative phase occurs with the cooling of surface waters adjacent to the far Northwest coast of North America

    • Drier conditions for the Southwestern U.S. but cooler and wetter conditions for the Northwest

Climate Patterns: Decadal Oscillations, continued

• North Atlantic Oscillation (NAO)

  • Positive phase (a): warm and wet winters to Northern Europe and Eastern North America, dry winters to the Mediterranean

  • Negative phase(b): cooler and drier winters to N Europe and Eastern North America, and wetter winters to the Mediterranean region

Climate Patterns: Arctic Oscillation (AO)

• Positive phase (a): lower-than-normal pressure over the polar region, steering ocean storms northward, wetter Scotland/Scandinavia and drier Western U.S./Mediterranean

• Negative phase (b): reversal of conditions (strong Arctic High)

• Melting of sea ice in Arctic may be forcing a more negative AO

Climate Patterns: Precipitation

• GW is anticipated to affect patterns of precipitation including both the overall average moisture and the patterns of storms

  • Sizable uncertainties for specific sub-region areas but anticipated that dry areas will become drier and wet areas will become wetter

  • More precipitation is anticipated to arrive in fewer, more intense storms (not helpful)

• Alterations in patters of precipitation will challenge agricultural production

  • Areas reliant on snowpack for summer irrigation are particularly vulnerable (arid)

  • MWP 1000 years ago suggests the possibility for prolonged severe droughts in the western U.S., Mexico and Central America as well as Africa, China, India and Southeast Asia

Sea-level Rise

• Global ocean temperatures to a depth of 3 km has increased since 1961, causing some sea-level rise

  • Estimated that oceans have absorbed 4/5 of GW heat in that time

  • Warming has caused thermal expansion, resulting in sea-level rise of 0.42 ± 0.2 mm per year 1961-2003

  • Increased rate of 1.6 ± 0.5 mm per year during 1995-2003, showing an accelerating rate

• Melting is also contributing to sea-level rise

  • Sea ice loss does not contribute to sea-level rise

  • Estimated to be 1.38 ± 0.4 mm per year 1961-2003

  • Increased rate of 1.5 ± 0.6 mm per year 1993-2003, showing an accelerated rate

Sea-level Rise, continued

• Summary points

  • Thermal expansion and melting have contributed to sea-level rise since 1961

  • Rates of both thermal expansion and melting of glaciers are accelerating

  • Contribution from Greenland ice sheet has increased about four times

• Expected sea-level rise over the next century varies 18-59 cm

  • Affecting coastal erosion

  • Imperiling additional inland areas to storm surges

  • Trigger reorganization of low-lying or island landscapes

Wildfires

• Complex relationship but increased temperature extremes and occurrence of drought facilitates additional wildfire dangers

• Models suggest that wildfires will be more frequent and severe, and the number of years between events in a given area will decrease

Changes in the Biosphere

• Impacts on ecosystems occurs as environmental conditions change

  • Shifting in habitat ranges

  • Increased extinction due to pressures and habitat limits

  • Altered disease ranges (human exposure)

• Ocean Acidification – decrease in pH due to adsorption of CO2 by the oceans

  • Forms carbonic acid (H2CO3) that dissociates to bicarbonate (HCO_3 -) and hydrogen ion H+

  • Acidity has increased 30% in past 15 years

  • Stressing of organisms results as they need to expend more energy to maintain pH and create shells

  • Bleaching with temperature increases beyond livable range also causes issues (corals)

Natural Adaptations

• During past 25 years, plants and animals have shifted their ranges 6 km per decade poleward

• Warmer temperatures have shifted bloom and breeding dates (2.3 days per decade)

• Lengthening of growing seasons as well indicate some of the shifts that have taken place

Strategies for Reducing Impacts of GW

• Recent collaborative movements between U.S. and China to reduce/stabilize CO2 emissions with India just announcing its first efforts

• U.S. has already greatly reduced its CO2 output due primarily to move from coal to natural gas and automotive efficiencies

• Strategies

  • Increased power plant efficiency

  • Move to less carbon intensive fossil fuels

  • Move to alternative energies

  • Nuclear power

  • Increased conservation methods

  • Carbon sequestration

  • Carbon storage in environ.