climate change: fitting the pieces together from the comet program presented by: larry atkinson
TRANSCRIPT
Climate Change:Fitting the pieces togetherFrom the Comet Program
Presented by:
Larry Atkinson
What is climate
Weather and Climate
• Will it be hot and humid this July?• Will it be raining a week from today? • Climate and Weather• We can predict climate and climate change
very well. • We can predict weather fairly good for a few
days to a few weeks depending on the season and location.
Outline
• What changes climate?• Is it real?• How do we know?• Why should we care?• How sure are scientists?• What next—what can we do?
What changes climate?
• Changes in:– Sun’s output– Earth’s orbit– Drifting continents– Volcanic eruptions– Greenhouse gases
Global Warming – almost 200 years of knowing about it
• 1827 – Fourier –The ‘greenhouse effect’.
• 1861 – Tyndall –caused by a few trace gases in the atmosphere (water vapor and carbon dioxide)
• 1896 – Arrhenius – Doubling CO2 will raise global temperature about 6C – present estimates are in the 3-4C range.
04/19/23 Old Dominion University - Climate Change and Sea Level Rise Initiative 7
Will Elder, NPS
Greenhouse gases
Nitrous oxide
Water
Carbon dioxideMethane
Sulfur hexafluoride
Could the warming be natural?
Is it real?
Effects: Snow and ice
Glacier Bay National Park and Reserve's White Thunder Ridge as seen on August 13, 1941 (left) and August 31, 2004 (right). Muir Glacier has retreated out of the field of view, Riggs Glacier has thinned and retreated significantly, and dense new vegetation has appeared. Muir Glacier was more than 2,000 feet thick in 1941 the Glacier Photograph Collection to access this and other photograph pairs.
Effects on precipitation
Effects on ecosystems
How do we know?
Present day observations
Computer models
Aspen, CO Forecast:
Partly cloudy todayHigh : 28°FLow: 13°F
Increasing clouds over night. Colder tomorrow.
Why should we care?
2003 European Heat Wave
Germany: Lowest river levels this century
Switzerland: Melting glaciers, avalanches
France: >14,000 deaths
Portugal: Forest fires
U.K.: Train rails buckle
Sea-level rise projections : a few inches to a few feet
•2 ft: U.S. would lose 10,000 square miles•3 ft: Would inundate Miami•Affects erosion, loss of wetlands, freshwater supplies•Half of the world’s population lives along coasts•Big question: Ice sheets
Ice Sheets and Sea Level RiseWhat if they melted
Area of Oceans 361x106 kilometers2
Volume of Antarctic Ice Sheet 26.5 x106 km3
73 m or over 200 feet
Volume of Greenland Ice Sheet 2.8 x106 km3
Rise 7 m or 21 feet
How sure are scientists?
What don’t we know?• Is there some critical piece of the about climate process we don’t understand?• How and when will our fossil fuel use change?• Will future , yet-to-be-discovered technologies mitigate the problem?• How will changing economics, global population, and political processes affect our ability to tackle the problem?
The IPCC
2014 Conclusions• Warming of the climate system is unequivocal• Medium confidence Warmest 30 years in past 1400• Ocean is warming high confidence and virtually certain• All ice masses are losing mass high confidence • Sea level is rising at fastest rate in 2000 years. High confidence. • Carbon dioxide, methane and nitrous oxide at highest levels in
800,000 years. 30% of emitted carbon dioxide in ocean causing acidification.
• Human influence on the climate system is clear. • Continued GHG emissions at or above current rates would cause
further warming and induce many changes in the global climate system during the 21st century that would extremely likely be larger than those observed during the 20th century.”
Consensus?• Do we know enough about the drivers of climate to know what causes change? • Are we underestimating the Earth system’s complexity ?• Can models accurately simulate the complex climate system? •Are there processes that will limit warming naturally?
On the other hand…
• Arctic sea ice melting faster than predicted.• Fossil fuel emissions exceeded most IPCC projections.• Are assumptions about global energy use are too optimistic?•How quickly can developing countries reduce GHG emissions?• Calculations don’t include unexpected melting in Greenland and Antarctica.
What do climate scientists really think?
Be an educated consumer
• IPCC AR5 Synthesis Report (http://www.ipcc.ch)
• Other organizations: – NAS (http://dels.nas.edu/climatechange/)– US CCSP (http://www.climatescience.gov/)
• Look for contrasting opinions• Evaluate the source
What next—what can we do?
What next—what can we do?
Produce more fuel-efficient vehiclesReduce vehicle useImprove energy-efficiency in buildingsDevelop carbon capture and storage processesTriple nuclear powerIncrease solar powerDecrease deforestation/plant forestsImprove soil carbon management strategies
Individual actions
Use mass transit, bike, walk, roller
skate
Tune up your
furnaceUnplug
appliances or plug into a
power strip and switch it off
Buy water-saving appliances and
toilets; installing low-flow shower
heads.
Caulk, weatherstrip, insulate, and replace old windows
Buy products with a U.S. EPA
Energy Star label
A calculation • Let’s calculate how much sea level will rise as the
ocean warms. • Depth of Ocean – average 4,300 meters (2.65
miles)• Coefficient of Expansion 250 x10-6 meters per
meters per degree• Expansion = Depth x Coefficient x temperature
change• 4300m x 250x10-6 m/m/C°x 1°C = how many feet?
Rough calculation of sea level rise and cities.
• Slope of land and rise rates• Norfolk say 30 feet (10 meters) highest point• Say 5 miles (10,000 m) from edge to center.• Slope = 10,000/10 = 1000 meters inland per
meter of rise. • So if sea level rises 1 meter (3 feet) it will
intrude 1000 meters (3000 feet) into the city.