Global Climate Change: What the Future Holds, and What We Can Do About It Dr. David Karowe Professor, Department of Biological Sciences Schedule of Topics September 29: Recent climate change (Dave Karowe) 1
October 6: Future climate change (Dave Karowe) October 13: Effects of climate change on plants and animals (Dave Karowe) current future 2
October 20: Effects of climate change on aquatic ecosystems (Chuck Ide) October 27: Effects of climate change on human health (Dave Karowe) 3
November 3: Economics of climate change (Dave Karowe) Skeptics arguments (Dave Karowe) November 10: Biofuels, carbon capture and storage (Steve Bertman and Dave Barnes) 4
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 ( 2 o C) have taken hundreds of thousands or millions of years 5
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 18 O/ 16 O 6
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 7
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 ~ 5 o C cooler? 19,000 BC - Michigan was covered by almost a mile of ice 8
What s been happening over the last 1,500 years? modern warming Little Ice Age - tree ring and thermometer records indicate two anomalous periods since 500 AD Little Ice Age due to temporary reduction in solar output ~1 o C cooling of Northern Hemisphere 1550-1850 Maunder minimum 9
What s been happening over the last 130 years? modern warming Since 1880, Earth has warmed ~ 0.8 o C Temperature Change ( o C) 10 warmest years in history: 2010, 2005, 2007, 2009, 1998*, 2007, 2002, 2003, 2004, and 2008 10
Temperature difference relative to 1950-1980 http://data.giss.nasa.gov/gistemp/animations/ Rate of global warming has been increasing - global rate over land since 1979 is 5 times faster than since 1850 Global Land Ocean Northern Hemi. Land Ocean Southern Hemi. Land Ocean 1850-2005 0.054 0.039 0.063 0.040 0.036 0.038 1979-2005 0.244 0.134 0.317 0.188 0.127 0.091 - land is warming faster than the ocean - Northern Hemisphere is warming faster than Southern 11
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 12
Since 1979, Michigan has warmed by ~0.75 o C Antarctic peninsula Arctic Temperature relative the 1951-1980 mean - pronounced latitudinal pattern to recent warming Did 2010 feel like a particularly warm year? -Michigan was ~0.75 o C above the 1951-1980 mean Temperature relative the 1951-1980 mean 13
Last summer was Michigan s 6 th warmest on record This summer was Michigan s 18 th warmest on record 14
Since 1900, no consistent trend in total global precipitation But heavy precipitation events now account for a higher percent of total precipitation 15
Severe storms cause flooding, erosion, disease Flooding has increased globally in the last 50 years 16
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 2 nd wettest spring on record 17
As a result, Michigan experienced flooding this spring but Ohio had it worse 18
And there was extensive flooding along Mississippi Tunica, Mississippi Droughts have also increased, especially since 1950 - droughts are more widespread because of warming since 1950 19
Since 1950, global land surface area in severe or extreme drought increased from 13% to 30% Currently, 43% of U.S. is in drought 35% 18% 66% 85% Exceptional Drought: PDSI <- 5.0 or <5% of normal rainfall 20
Currently, 7% of Michigan is in drought - another 29% is abnormally dry September 20 As a result, the cryosphere has been melting - ice sheets, ice shelves, sea ice, glaciers, ice caps, frozen ground (permafrost) - any melting produces a positive feedback by reduced albedo (reflectivity) 21
Arctic summer sea ice extent (area) has been decreasing by up to 10% per decade http://nsidc.org/sotc/sea_ice_animation.html - record low in 2007 - thickness has decreased by >40% since 1960 Glaciers have been retreating worldwide 1978 2000 - ice loss from 30 reference glaciers from 1996-2005 was twice as fast as the previous decade, and four times as fast as the decade before that (1976-1985) 22
Recently, 97% of Earth s glaciers have been retreating Red = retreating Blue - advancing 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 23
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 24
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 Freeze dates ice cover has decreased by ~4 weeks for Grand Traverse Bay 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 since mid-1990s in many sites 25
Warming is detectable to ~40 meters in many places Can climate change be due to natural variation? Since 1900, energy increase from greenhouse gasses is about 20 times energy increase from the sun 26
Since 1900, energy increase from greenhouse gasses is about 20 times energy increase from the sun GHG added ~ 2.98 W/m 2 aerosols removed ~ -1.4 W/m 2 the sun added ~ 0.12 W/m 2 - aerosols have masked ~40% of the GHG warming During the current time of most rapid warming (the last 30 years), solar irradiance has been decreasing Solar Irradiance 27
Finally, models do a good job of replicating past climate change only if they use anthropogenic forcings natural variation would most likely have caused a slight cooling since 1900 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 necessary for life on Earth 28
The carbon cycle is out of balance Net: +4 bty +2 bty -3 bty +8 bty -3 bty Increased greenhouse gas (GHG) concentrations -CO 2 increased from 280 ppm < 1850 to >390 ppm today - CO 2 accounts for ~60% of GHG warming - methane, nitrous oxide, CFCs, ozone cause the rest 29
U.S. probably emits more carbon than any other major country Midwest would be 4 th highest emitting country Countries proportional to their 2000 emissions 30
U.S. also emits the most carbon per capita Residential and transportation sectors account for about half of US energy consumption (~80% heating and appliances) (~80% cars and trucks) 31
85% of US energy use comes from fossil fuels Hydropower Biomass Geothermal Wind Solar 2.4% 3.6% 0.3% 0.3% 0.08% Land use change (mostly deforestation) is also a major contributor to increased GHG levels - accounts for 20-25% of CO 2 added to the atmosphere 32
Best estimate: ~95% of current warming is due to human activities Greenhouse gas emissions Deforestation 33