Transcript 1091-Lec24(Climate1)

Introducing alien ecosystem engineers to
Round Island, Mauritius
Species lost – 2 giant tortoises
Role – dispersal of herbivore adapted seeds
Surrogate species
Aldabra Giant Tortoise Madagascar radiated tortoise
250 kg
16 kg
New topic
Climate change and
conservation
The main message
Humans
Climate
Biodiversity
Climate change is unequivocal
Natural and human systems have been impacted
Adaptation and mitigation are necessary
Biodiversity/conservation plays a role in
climate regulation
Biodiversity/conservation is central to
tackling climate change
Outline for Climate change and conservation
Overview
Recent changes to the climate
Physical feedback loops
Future Climate Change
Biological Impacts
Ecosystem feedback loops
Conservation Implications
Climate shifts are due to change in the retention
and distribution of solar energy
Carbon dioxide, methane and water vapour are important
in maintaining the current energy balance
Svante Arrhenius (1896) predicted
“the emission of CO2 due to the combustion of coal
will eventually warm the world”
Air bubbles in ice give
CO2 conc’n of atmosphere at
time of ice deposition
Ratio of 18O2 and 16O2 can
be used to calculate
temperature at time ice is
formed
 Record dating back
740,000 years
CO2 levels and global temperatures are correlated
Current levels (360ppm) are far higher than “natural” levels
CO2 levels and mean global temperature have increased faster since
the Industrial Revolution
Climate change scientists agree heating is largely due to human
induced increases in greenhouse gas concentrations
Changes in temperature over the last 30 years
Changes in precipitation over the last 100 years
Snow, ice and hydrological change
1979
2003
Snow, ice and hydrological change
Grinnell Glacier
1938
1981
1995
2005
Glacier National Park – glaciers decline by 70%
- gone by 2020
Mount Kenya and Kilimanjaro
- decline by 60%
Swiss Alps - decline by 40% since 1850
- gone by 2050?
Changes in sea level over the last 100 years
Feedback loops
The surface ocean has absorbed nearly half of
the increased CO2 levels due to the burning of
fossil fuels
The ocean is becoming more acidic
0.1 pH unit since 1750
Continued acidification will reduce the ability of
the ocean to take up CO2
Feedback loops
Permafrost soils act as a giant carbon sink
approx . 1000 billion tons of Carbon
Warming will thaw the tundra
Melting permafrost will release frozen methane
and allow decomposition of frozen plant material
The additional CH4 and CO2 will increase warming
Feedback loops
Warming will melt sea ice and promote growth of
shrubs in the arctic
Puddles and shrubs have different albedo
(reflectance) than ice and tundra
Puddles and shrubs will warm up rather than
reflect UV
Warm puddles and shrubs will increase ice melt
and further shrubification
C02 emissions will rise at least until 2040
All scenarios predict C02 levels will continue
to rise until the turn of the century
Predicted global temperature and sea levels
So
IPCC predicts
a rise in temp of 2 to 6.4 C by 2100
Bob Watson (Chair IPCC)
the world should “prepare for 4C of warming”
What happens if the world warms by 4C?
What happened the last time?
55 million years ago
Palaeocene-Eocene Thermal Event
5-6C increase
Tropical forests in ice free polar regions
Acidified oceans led to vast die-off
Sea levels rose 100m higher than todays
Desert from South Africa to Europe
What happens if the world warms by 4C?
India Bangladesh Pakistan
shorter fierce asian monsoon
drought
swUS, Central America, China, South America
dried rivers and exhasution of aquifers
deglaciation
lack of freshwater
Canada/Siberia - reliable precipitation
- shelter and food for the world?