Delta

YVR

Richmond

Vancouver

Land-Based Ice Melt

Causes of Sea Level Rise Sea level rise is a consequence of global

warming. Warmer atmospheric temperatures cause land-based ice to melt, adding water to the oceans. Warmer ocean temperatures also

cause the oceans to expand. Both of these factors increase the volume of water in the

ocean, causing sea levels to rise.

Thermal Expansion

Lower mainland courtesy of Natural Recources Canada ‘Geoscape’ Project.

Hansen, J., et al, Global temperature change, PNAS, 2006, 103 (39), 14288-14293.

http://www.occupy.com/article/de-icing-myth-greenland

Sea Level Rise

Church et al. 2011, Geophys. Res. Lett. 38, L18601. :

Data from proxies, tide gauges, and satellites all show rising sea levels. The current average rate of sea level rise (~3mm/year) is projected to increase, leading to 0.5-1.2m of sea level rise by the year 2100.

http://www.realclimate.org

Observations: Purple - Proxy Data from Sediments Green – Tide Gauge Measurements Orange – Tide Gauge Measurements Blue – Satellite Measurements

IPCC projections

Contributions to sea level rise from thermal expansion and land-based ice melt (1960-2010). BC Lower Mainland

The Richmond and Delta areas of Vancouver, BC are part of the Fraser River delta. This area includes nearly 400,000 people, a large number of farms, and an international airport, but is only a metre above sea level.

Human Displacement

Areas of the world that are most susceptible to rising sea levels are shown in red on the map above. A large portion of the Earth’s population lives in these low-lying areas.

www.ucsusa.org/sealevelrise

sos.noaa.gov

Adapted from Allison et al (2009) The Copenhagen Diagnosis: Updating the World on the Latest Climate Science.

Many island nations are at risk from sea level rise. For example, 80% of the Maldives' 1,200 islands are less than one metre above sea level. The country (340,000 residents) could be submerged within 100 years. For the first time in modern history an entire country could be lost to climate change. They are looking to relocate their entire nation to Sri Lanka, India, or Australia.

Island Nations Lost

Malé, Maldives

Sea water expands as its

temperature rises.

Heat-trapping gases from human

activity have increased global

average temperatures by 0.85oC

since the 1880s. Shrinking glaciers and

ice sheets are adding

water to the world’s

oceans.

Historically the IPCC’s predictions have underestimated actual sea level rise.

Greenland and the West Antarctic Ice Sheet are two massive sources of land-based ice that are currently melting at a

significant rate. With projected warming these ice sheets could completely melt, leading to 7m (Greenland) and 4-6m (West Antarctic) of sea level rise. These changes would occur over hundreds of years.

The ocean surface absorbs a large amount of the Sun’s energy, increasing the sea surface temperature (SST). Thermal expansion will account for 30-55% of 21st century sea level rise. Present day temperatures will already lead to over 1m of sea level rise.

www.globalwarmingart.com

Bangladesh will suffer dramatic loss of arable land and displaced people with increased sea level. About 1.7 million people in Dhaka alone would be displaced.

Dhaka

Tide Gauge

What is the Albedo Effect?

Oceans typically have an albedo of 5-10%.

Vegetation absorbs incoming light for photosynthesis. Most forests have an albedo of 5-20%.

Deforestation usually increases albedo, which causes a local cooling effect. Urbanization, on the other hand, generally leads to a decrease in albedo and local warming.

New York City before and after urbanization.

Polar ice acts like a mirror, reflecting sunlight back into space. When temperature rises, sea ice melts and exposes darker ocean surfaces (lower albedo). This results in more sunlight being absorbed, which further increases temperature. This self-reinforcing cycle is called a positive feedback loop.

Dry, light colored soil has an albedo of 40%, while dark, wet soil has an albedo of 5%.

Land Use Change

Polar Ice Coverage

Earth’s Energy Budget Sunlight mainly passes directly through the atmosphere. On reaching the Earth’s surface, energy from the Sun that is not absorbed is reflected.

Changing the albedo of the landscape changes the relative amount of sunlight absorbed and reflected. Increasing albedo (fresh snow) leads to less energy being absorbed, and cooler temperatures.

The Arctic Ice Cap has an average albedo

value of 85%

Positive Feedback Loop

Decreasing polar ice cover due to global warming increases the amount of radiant heat absorbed by the Earth, which can amplify temperature increases.

Average Earth surface albedos range from 5-95%. Oceans absorb more light than land and ice.

Common Surface Albedo Values

Albedo is the percentage of light reflected from a surface. Black surfaces absorb all

light (albedo of 0%), white surfaces reflect all light (albedo of 100%). Any reduction in

Earth surface albedo leads to warming.

2012

1979

Ocean or land exposed

Temperature increases

Ice melts

More solar energy is absorbed

Arctic Sea Ice

Urban Heat Island

The lower albedo of urban areas can increase the temperature of cities by up to 8oC relative to the surrounding area. This is known as the Urban Heat Island Effect.

http://heatisland.lbl.gov/

http://ngm.nationalgeographic.com/2009/09/manhattan/miller-text

http://sandrolubis.wordpress.com/2012/04/29/mean-annual-of-global-outgoing-terrestrial-radiation-from-toa-clear-sky/

http://muchadoaboutclimate.wordpress.com/

http://www.u.arizona.edu/~korine/230/chap3_figs.htm

Albedo (%)

NASA Goddard's Scientific Visualization Studio

N2O

CH4

CO2

The figure above shows how atmospheric concentrations of CO2, CH4, and N2O have increased rapidly since the industrial revolution. The reconstruction of Northern Hemispheric temperatures over the last 1000 years (below) shows that temperature began to rise just after the industrial revolution.

Greenhouse gases absorb IR energy. Carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and water vapour (H2O) are the major greenhouse gases in Earth’s atmosphere. These gases do not absorb incoming solar energy (light) but do absorb outgoing IR energy (heat).

Temperature is a measure of molecular motion. When a greenhouse gas absorbs IR, it can pass the energy to neighbouring molecules by colliding into them. This increases the speed of the surrounding molecules, and therefore the temperature.

http://www.lcse.umn.edu/specs/labs/images/spectrum.gif

Infrared energy (IR) has slightly longer wavelengths than visible light. We can not see IR but we can feel it as heat.

IPCC 2001

http://www.wired.com/images_blogs/wiredscience/2009/12/earth_atmosphere-660x627.jpg

Infrared Energy

Temperature as Molecular Motion

Greenhouse Effect and Energy Balance

babble.com/CS/blogs/strollerderby/2009/02/car_exhaust.jpg

Fossil Fuels

Human activities, such as burning fossil fuels, have increased atmospheric concentrations of greenhouse gases since pre-industrial times.

The greenhouse effect traps heat that radiates from the surface of the Earth and prevents it from escaping into space.

The temperature of the Earth remains constant when the amount of solar energy absorbed by the Earth equals the amount of IR escaping into space. When more greenhouse gases are present in the atmosphere, less energy is able to escape into space, which results in increased global average temperatures.

The figure below shows the relative effect on climate of CO2, CH4, and N2O since 1750. The effect is measured as the amount of energy each gas it able to trap per second per square metre of Earth’s surface.

Greenhouse Gas Concentrations and Global Temperature Change

Global Warming Potential

Faster = Hotter Slower = Colder

Nitrous Oxide Carbon Dioxide

Methane Water

Warming by Greenhouse Gases

Fuel + O2 CO2 + H2O + Energy

Some greenhouse gases are more powerful than others. Each greenhouse gas has a global warming potential (GWP) that indicates how effective it is at warming the atmosphere compared to CO2. The GWP depends on how much heat a greenhouse gas absorbs, as well as its atmospheric lifetime.

Gas 20 year GWP 100 year GWP

CO2 1 1

CH4 86 34

N2O 268 298

Adapted from IPCC AR5 (2013)

csiro.au/en/Outcomes/Climate/Understanding/State-of-the-Climate-2012/Greenhouse-Gases.aspx

Adapted from IPCC

http://www.livescience.com/37743-greenhouse-effect.html

Greenhouse Gases

http://tea.armadaproject.org/activity/kolb/icecoresecrets_resources.html

What is ocean acidification? A large portion of the carbon dioxide (CO2)

released to the atmosphere dissolves into the ocean, forming carbonic acid. This causes the

oceans to become more acidic and increases the solubility of calcium carbonate.

Changes in pH between the 1700’s and 1990’s. Red indicates areas that have experienced the greatest increase in acidity.

http://i.treehugger.com/images/2007/10/24/diatoms-jj-001.jpg

www.babble.com/CS/blogs/strollerderby/2009/02/car_exhaust.jpg

Human activities, such as burning fossil fuels, have significantly increased atmospheric concentrations of CO2.

CO2 gas dissolves in water to form carbonic acid, increasing ocean acidity. This corresponds to a lower pH and lower carbonate ion concentration, which can lead to the extinction of important marine species.

For the past 400,000 years atmospheric CO2 concentrations have fluctuated between about 180 and 280 ppm. Since the industrial revolution, CO2 levels have risen sharply.

Conventional energy production releases large amounts of CO2.

http://www.babble.com/CS/blogs/strollerderby/archive/tags/pollution/default.aspx

www.ig.utexas.edu/jsg/css/images/carousel/oceans.jpg

en.wikipedia.org/wiki/File:WOA05_GLODAP_del_pH_AYool.png

ok4me2.net/wordpress/wp-content/uploads/image/ok8_31/image/9_34ok/slash-and-burn.jpg

Converting forest to farmland releases large amounts of CO2.

The Other CO2 Problem

Changes in Acidity Changes in Atmospheric CO2

Decades of observation show an increase in atmospheric and dissolved CO2, as well as a decrease in pH (increase in acidity).

An increase in acidity lowers the saturation state and availability of calcium carbonate minerals. Carbonate minerals are expected to become more soluble, especially in colder northern and southern oceans.

www.oceanacidification.org.uk

Some marine organisms including corals, shellfish and calcifying plankton use calcium carbonate for structure and exo-skeletons.

Marine phytoplankton make up the bottom of the food chain and produce roughly half of the worlds oxygen supply.

An increase in acidity has been shown to reduce the survivability of some calcifying marine organisms.

www.pmel.noaa.gov

www.ocean.si.edu

www.pmel.noaa.gov/co2/OA

R.A. Feely et al. 2009, Oceanography 22:36-47

www.eco2solar.co.uk/global-warming/

http://www.babble.com/CS/blogs/strollerderby/archive/tags/pollution/default.aspx

http://commons.wikimedia.org/wiki/File:Madoogali_reef.jpg