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Global Climate Change: What the Future Holds, and What We Can Do About It

Dr. David KaroweProfessor, Department of Biological Sciences

Schedule of Topics

September 29: Recent climate change (Dave Karowe)

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October 6: Future climate change (Dave Karowe)

October 13: Effects of climate change on plants and animals (Dave Karowe)

current

future

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October 20: Effects of climate change on aquatic ecosystems (Chuck Ide)

October 27: Effects of climate change on human health (Dave Karowe)

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November 3: Economics of climate change (Dave Karowe)Skeptics arguments (Dave Karowe)

November 10: Biofuels, carbon capture and storage (Steve Bertman and Dave Barnes)

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November 17: Wind, solar, and personal behaviors (John Patten and Dave Karowe)

Earth’s climate has always changed

Over the last billion years:

- but most or all large changes (≥2o C) have taken hundreds of thousands or millions of years

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Very good temperature data exist for the past 800,000 years:

~ 100,000 yr glacial/interglacial cycles

Data come from ice cores with annual rings

18O/16O

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What has caused climate to change over the last 800,000 years?

Long-term climate change due to cyclic changes in Earth's orbit, tilt, and precession of the equinoxes

(Milankovitch cycles)

Orbital eccentricity:~100,000 years

Axial tilt:~41,000 years

Precession:~26,000 years

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What’s happened over the last 21,000 years?

www.youtube.com/watch?v=C3Jwnp-Z3yE&hd=1

The future projection is based on the assumption of complete cessation of carbon dioxide emissions in 2100 (~IPCC A2). Because future world population is uncertain, it was frozen at 7 billion people.

What was North America like the last time Earth was ~ 5o C cooler?

- Michigan was covered by almost a mile of ice

19,000 BC

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Little Ice Age

modern warming

What’s been happening over the last 1,500 years?

- tree ring and thermometer records indicate two anomalous periods since 500 AD

Maunder minimum

Little Ice Age due to temporary reduction in solar output

~1o C cooling of Northern Hemisphere 1550-1850

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What’s been happening over the last 130 years?

modern warming

Tem

per

atu

re C

han

ge

(oC

) 10 warmest years in history: 2010, 2005, 2007, 2009, 1998*,

2007, 2002, 2003, 2004, and 2008

Since 1880, Earth has warmed ~ 0.8o C

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Temperature difference relative to 1950-1980

http://data.giss.nasa.gov/gistemp/animations/

0.244 0.134

0.317 0.188

0.127 0.091

0.054 0.039

0.063 0.040

0.036 0.038

GlobalLandOcean

Northern Hemi.LandOcean

Southern Hemi. LandOcean

1979-20051850-2005

Rate of global warming has been increasing

- global rate over land since 1979 is 5 times faster than since 1850

- land is warming faster than the ocean- Northern Hemisphere is warming faster than Southern

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Since 1900, greatest warming in northern North America, Asian interior, and southeastern Brazil

In Western Hemisphere, greatest warming in winter; in Eastern Hemisphere, greatest warming in spring

- but warming has occurred in all seasons

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Temperature relative the 1951-1980 mean

Since 1979, Michigan has warmed by ~0.75 oC

- pronounced latitudinal pattern to recent warming

Arctic Antarctic peninsula

Temperature relative the 1951-1980 mean

Did 2010 feel like a particularly warm year?

- Michigan was ~0.75o C above the 1951-1980 mean

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Last summer was Michigan’s 6th warmest on record

This summer was Michigan’s 18th warmest on record

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Since 1900, no consistent trend in total global precipitation

But heavy precipitation events now account for a higher percent of total precipitation

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Severe storms cause flooding, erosion, disease

Flooding has increased globally in the last 50 years

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In the U.S., severe rainstorms are now more common

- 20% increase in Michigan since 1948

- 50% increase in southwest Michigan

This year, Michigan had its 2nd wettest spring on record

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As a result, Michigan experienced flooding this spring

… but Ohio had it worse…

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And there was extensive flooding along Mississippi

Tunica, Mississippi

Droughts have also increased, especially since 1950

- droughts are more widespread because of warmingsince 1950

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Since 1950, global land surface area in “severe” or “extreme” drought increased from 13% to 30%

Currently, 43% of U.S. is in drought

Exceptional Drought: PDSI <- 5.0 or <5% of normal rainfall

35% 35%

18% 18% 66% 66%

85% 85%

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Currently, 7% of Michigan is in drought

- another 29% isabnormally dry

September 20

As a result, the cryosphere has been melting

- any melting produces a positive feedback by reduced albedo (reflectivity)

- ice sheets, ice shelves, sea ice, glaciers, ice caps, frozen ground (permafrost)

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Arctic summer sea ice extent (area) has been decreasing by up to 10% per decade

- record low in 2007

- thickness has decreased by >40% since 1960

http://nsidc.org/sotc/sea_ice_animation.html

Glaciers have been retreating worldwide

- ice loss from 30 ‘reference’ glaciers from 1996-2005 was twice as fast as the previous decade, and four times as fast as thedecade before that (1976-1985)

1978 2000

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Red = retreatingBlue - advancing

Recently, 97% of Earth’s glaciers have been retreating

Seasonal snowcover has also been decreasing

- mean winter maximum of 33% of Earth’s land surface, ~98% in the Northern Hemisphere

- so biggest albedo effect

- earlier spring snowmelt in western U.S. - effects on soil moisture

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Greenland ice sheet is melting at an accelerating rate

- meltwater also accelerates ice slippage into ocean

Antarctic ice shelves are shattering

- recent collapse of Wilkins Ice Shelf

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Lake and river ice are also decreasing

- since 1850, for NH lakes and rivers, spring ice breakup is ~9 days earlier, and autumn freeze-up is ~10 days later

ice cover has decreased by ~4 weeks for Grand Traverse Bay

Freeze dates

Breakup dates

Permafrost is warming and, to a small extent, melting

~25% of NH land mass is underlain by permafrost

- thickness of active layer has increased by ~10-30 cm sincemid-1990s in many sites

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Warming is detectable to ~40 meters in many places

Can climate change be due to “natural variation”?

Since 1900, energy increase from greenhouse gassesis about 20 times energy increase from the sun

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- aerosols have masked ~40% of the GHG warming

GHG added ~ 2.98 W/m2

aerosols removed ~ -1.4 W/m2

the sun added ~ 0.12 W/m2

Since 1900, energy increase from greenhouse gassesis about 20 times energy increase from the sun

During the current time of most rapid warming (the last 30 years), solar irradiance has been decreasing

So

lar

Irra

dia

nce

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“natural variation” would most likely have caused a slight cooling since 1900

Finally, models do a good job of replicating past climate change only if they use anthropogenic forcings

So what’s really causing current warming?Greenhouse gasses

GHGs let visible wavelengths pass, but absorb and re-radiate IR (heat)

Some greenhouse effect is necessaryfor life on Earth

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The carbon cycle is out of balance

Net: +4 bty

-3 bty

+8 bty

+2 bty

-3 bty

Increased greenhouse gas (GHG) concentrations

- CO2 increased from 280 ppm < 1850 to >390 ppm today

- CO2 accounts for ~60% of GHG warming

- methane, nitrous oxide, CFCs, ozone cause the rest

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U.S. probably emits more carbon than any other major country

Midwest would be 4th highest emitting country

Countries proportional to their 2000 emissions

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U.S. also emits the most carbon per capita

Residential and transportation sectors account for about half of US energy consumption

(~80% cars and trucks)

(~80% heating and appliances)

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85% of US energy use comes from fossil fuels

0.08%Solar

0.3%Wind

0.3%Geothermal

3.6%Biomass

2.4%Hydropower

Land use change (mostly deforestation) is also a major contributor to increased GHG levels

- accounts for 20-25% of CO2 added to the atmosphere

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Best estimate: ~95% of current warming is due to human activities

DeforestationGreenhouse gas emissions