Climate Change: Fitting the pieces together From 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’ – Tyndall –caused by a few trace gases in the atmosphere (water vapor and carbon dioxide) 1896 – Arrhenius – Doubling CO 2 will raise global temperature about 6C – present estimates are in the 3- 4C range. 8/25/2015 Old Dominion University - Climate Change and Sea Level Rise Initiative 7 Will Elder, NPS

Greenhouse gases Nitrous oxide Water Carbon dioxide Methane 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.

Arctic Sea Ice 2012

Effects on precipitation

Effects on ecosystems

How do we know?

Present day observations

Computer models

Aspen, CO Forecast: Partly cloudy today High : 28°F Low: 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 Rise What if they melted Area of Oceans 361x10 6 kilometers 2 Volume of Antarctic Ice Sheet 26.5 x10 6 km 3 73 m or over 200 feet

Volume of Greenland Ice Sheet 2.8 x10 6 km 3 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 21 st century that would extremely likely be larger than those observed during the 20 th 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 ( Other organizations: – NAS ( – US CCSP ( Look for contrasting opinions Evaluate the source

What next—what can we do?

Produce more fuel-efficient vehicles Reduce vehicle use Improve energy-efficiency in buildings Develop carbon capture and storage processes Triple nuclear power Increase solar power Decrease deforestation/plant forests Improve soil carbon management strategies

Individual actions Use mass transit, bike, walk, roller skate Tune up your furnace Unplug 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

IPCC Video on Recent Study

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.