Climate Change
Besides fossil fuels, what are two other ways in which humans are increasing the level of CO2 in the atmosphere?
- Burning of forests • Deforestation
What type of precipitation becomes less common as temperatures warm? Why does this concern us?
- snow • The Western U.S. relies on melting snow to supply the yearround flow of rivers, such as the Colorado and Columbia river
What are CFCs used for? What 2 chemicals have been substituted for CFCs? Why?
-Used as refrigerants, aerosol propellants, solvents, and fire retardants - HCFCs and PFCs, as they do not destroy ozone, but they are potent greenhouse gases (man-made)
What is the deadliest aspect of a hurricane? Explain how a storm surge occurs
-the storm surge it generates - Hurricanes have extremely low atmospheric pressures, allowing the ocean to rise to much higher than normal sea levels -The high sea level, combined with strong winds and high waves, causes the ocean to surge onto land
The Antarctic and Greenland ice sheets together contain about what percentage of Earth's freshwater?
75%
What do greenhouse gases do with the infrared radiation they absorb? What does this do to the Earth?
Much of this absorbed infrared radiation is directed back towards the Earth, warming the Earth and the troposphere, causing global warming
What is proxy data? Besides tree rings and ice cores, what are 3 other types of proxy data we can use to reconstruct past climates?
Other techniques for gathering proxy data (proxy data = preserved characteristics of the environment that can stand in for direct measurements): • Sediment cores of ocean or lake sediments • Calcium carbonate precipitated to formed stalagmites • Ancient coral reef deposition of calcium carbonate
How will the thawing of permafrost influence carbon dioxide and methane levels in the atmosphere? How is this another example of a positive feedback loop?
increase, will further accelerate projected warming
What is happening to houses, trees, roads, and telephone poles in Alaska? Why?
sinking because of thawing
How much did sea level rise between 1901 and 2010? What was the rate per year? What is happening to the rate of sea level rise?
• 0.19 m (19 cm or 7.5 inches) • 1.7 mm per year for the time period • The rate of sea level rise is accelerating
What was the rate of increase in CO2 in 1959? What is the rate of increase now?
• 1959 = 0.94 ppm/yr • 2015 = 3.17 ppm/yr
In 2012, Arctic sea ice dropped what percentage below the 1981-2010 average? What is happening to Arctic temperatures, compared to the rest of the world, over the past 50 years?
• 44% • Arctic temperatures have risen almost twice as fast as average temperatures over the rest of the world over the past 50 years
How will a 1 m rise in sea level affect wetlands and deltas? What is commonly grown in deltas? How will this sea level rise affect coastlines and barrier islands? Which U.S. states are especially vulnerable?
• A 1 meter rise by 2100 (very possible) would cause: • Degradation or destruction of at least 1/3 of estuaries, wetlands, coral reefs and deltas (where much of the world's rice is grown) • Flooding and erosion of low-lying coastlines and barrier islands • In the U.S., Florida, Louisiana, Texas, and the Carolinas are esp. vulnerable
What would a warmer climate prevent, and what would this shut down? What would this do to the climate of Europe?
• A warmer climate would prevent this sinking of cold water, shutting down the conveyor belt • A shutdown would cause the climate to Europe to cool, whereas the rest of the planet would warm
What are aerosols? What do aerosols do to solar radiation? What does this prevent? What do high aerosol levels do to temperature?
• Aerosols = liquid or solid particles that are small enough that they remain suspended in the atmosphere for days, weeks, or months • Aerosols scatter solar radiation, preventing some of the incoming solar radiation from reaching the surface of the Earth (they increase albedo) • High aerosols = cooler temperatures
What is albedo? Albedo varies between what 2 values? What do each of these values represent?
• Albedo = the fraction of incoming solar radiation reflected by a surface (like Earth's surface) • Albedo varies between 0 and 1 • 0 = perfect absorber of energy • 1 = perfect reflector of energy
As global temperatures rise, what happens to evaporation of water? What does this lead to? Why?
• As global temperatures rise, evaporation of water increases • Increased evaporation causes increased water vapor in the atmosphere, which leads to even more warming, because water vapor is a greenhouse gas • More warming = more evaporation = even more warming - a classic example of positive feedback
What happens to the water of the Gulf Stream after it transfers heat to the atmosphere of Northern Europe? What is driven by this sinking?
• As the warm Gulf Stream water transfers heat to the atmosphere of N. Europe, it cools, sinks, then travels southward along the floor of the Atlantic • This sinking drives the circulation of water around the Atlantic and Pacific
As water temperatures rise, the ocean's ability to do what decreases? What is this contributing to? What will happen as the ocean warms up?
• As water temperatures rise, the ability of the ocean surface to absorb CO2 decreases - this is contributing to the increased rate CO2 over time • As the ocean warms up, more and more of its dissolved CO2 will be released into the atmosphere, further increasing atmospheric levels of CO2
What are the oldest individual trees on Earth? How old are they?
• Bristlecone pines, in the White Mountains of California, are the oldest individual trees on Earth (5000 years old)
CO2 is what type of gas? What does this mean?
• CO2 is a greenhouse gas, meaning it enhances the greenhouse effect • Greenhouse gas = a gas that absorbs infrared radiation
A shutdown of the oceanic conveyor belt would prevent the transport of what substance to the deep ocean? What would this do to temperatures? What type of feedback is this?
• CO2, which would cause more warming and a further shutdown of the conveyor - the is an example of positive feedback
What is the name for thick, white, puffy, low-altitude clouds? What effect do these clouds have on temperature? Why?
• Cumulus clouds, probably cool temperatures by reflecting more sunlight back into space
What is dendroclimatology? What type of climate conditions are indicated by wide rings (larger cells)? What type of climate conditions are indicated by narrow rings (smaller cells)?
• Dendroclimatology = use of tree rings to infer past climates • Trees produce larger cells (wider rings) when conditions are better (warmer or wetter) - smaller cells (narrower rings) are produced in years when conditions are poor for growth (cold and dry)
Future increases in global temperature depend on future concentrations of what substance? What is the best-case scenario in terms of CO2 concentration and temperature increase?
• Depends on CO2 concentrations by the year 2100: • Best case scenario = 430 ppm CO2 concentration = 1.5°C increase (2.7°F)
What has happened to Earth's climate during the past hundreds of thousands of years? How are temperature and ice volume related?
• Earth's climate has gone through repeated warm and cold phases during the past hundreds of thousands of years • Note that as temperature goes up, ice volume on Earth goes down
What has caused global warming in the past? What do ice core data show us?
• Elevated CO2 levels • Ice core data show that every time CO2 levels increase, temperatures also increase
What is the greenhouse effect? How are humans enhancing the greenhouse effect?
• Greenhouse effect = the process by which infrared radiation (heat) from a planetary surface is absorbed by atmospheric greenhouse gases and re-radiated back towards the surface of the planet, causing it to warm -by adding greenhouse gases to the atmosphere
What measure is used to compare greenhouse gases? How is this measure defined?
• Greenhouse gases (GGs) are compared to one another using a measure called the global warming potential (GWP) • GWP = a relative measure of how much heat a greenhouse gas traps in the atmosphere
Greenhouse gases differ from one another in what two important ways that influence GWP?
• Greenhouse gases differ in their ability to absorb energy (called radiative efficiency) and how long they stay in the atmosphere (known as their lifetime)
What do greenhouse gases like CO2 do to infrared rays? What do these gases prevent?
• Greenhouse gases, like CO2, absorb these infrared rays, preventing the heat from escaping into space
Why will hurricanes become more severe as the globe warms? How will rainfall amounts during El Niño and La Niña be influenced by global warming?
• Higher ocean temperatures = more evaporation = more energy to drive hurricanes • El Niño and La Niña events will become more extreme • More rainfall in the eastern Pacific during El Niño, and less rainfall during La Niña
What is the equation for burning a hydrocarbon? How does deforestation increase levels of CO2?
• Hydrocarbon + O2 → CO2 + H2O • fewer trees means that less CO2 gets removed from the atmosphere
What does IPCC stand for? Why was it established? How much has average global temperature increased from 1880 to 2012?
• IPCC = Intergovernmental Panel on Climate Change • Established by a number of nations in 1988 to document past climate changes and project future ones • Average global temperature increased 0.85°C (1.5°F) from 1880 to 2012
What are some variables that are being affected by increased greenhouse gas levels and the accompanying global warming?
• Ice cover • Sea level • Precipitation patterns • Ranges of organisms • Behavior of organisms • Human health • Agriculture • Ocean pH
How does the albedo of ice/snow compare to that of the ocean? What is global warming doing to ice? What does this do to albedo?
• Ice covered with snow reflects 85% of the incoming energy and absorbs 15% • Ocean 6% and absorbs 96% of incoming solar radiation • This melting lowers the albedo (by converting ice to ocean/land)
What can scientists do to ice in glaciers and ice sheets that helps determine past climate? How old is the deep ice at the bottom of a glacier?
• Ice deposited in Antarctic or Greenland ice sheets is drilled, and a core of ice is removed and studied • Deep ice, at the bottom of the ice sheet, is hundreds of thousands of years old
What is projected to happen if temperatures go up 2-4°C? How much will sea level rise if this happens?
• If temperature goes up 2-4°C (a possibility by 2100), the Greenland Ice Sheet will completely melt, causing sea level to rise 7 m (23 ft)
How much would sea level rise if the Greenland Ice Sheet melted completely? How much would sea level rise if the Antarctic Ice Sheet melted completely?
• If the Greenland Ice Sheet were to melt completely, sea level would rise 7 m (23 feet) • If the Antarctic Ice Sheet were to melt completely, sea level would rise 60 meter (200 feet)
In August 2015, the surface temperature was how much warmer than the 20th century average?
• In August 2015, the average sea surface temperature was 0.78°C (1.40°F) warmer than the 20th century average
In past global warming episodes, how long did it take to warm 5°C? How much faster is this level of warming occurring today?
• In past global warming episodes, it took 5,000 years to warm 5°C • The predicted rate of warming today is 20 times faster!
What is currently driving the increase in CO2? What does anthropogenic mean?
• Increased burning of fossil fuels by humans! • humangenerated
Have CO2 levels fluctuated in the past? What are the 3 possible causes of past increases in CO2? Are these things occurring now?
• Increased volcanic activity • Increased release from the deep ocean • Increased weathering of certain rocks • None of these natural things are occurring now
What are 4 ways in which methane is produced?
• Industry emissions • Some bacteria that carry out anaerobic respiration in wetlands/swamps • Given off by domestic livestock as part of their digestive process • Given off by landfills as waste decomposes • Rice farming in flooded rice paddies releases methane
What are some large cities that will be flooded by rising sea levels? Rising sea levels make us more vulnerable to what phenomena? What are the world's 2 most vulnerable cities to rising sea levels?
• Kolkata and Mumbai (India), Dhaka (Bangladesh), Guangzhou and Shanghai (China), Bangkok (Thailand), and Miami and New York City • Increased vulnerability to hurricanes and their associated storm surges - Shangai (China) and Dhaka (Bangladesh)
Explain how the loss of sea ice is a positive feedback system.
• Less sea ice = low albedo = more global warming = even less ice • This is a positive feedback system - the rate of loss of sea ice is accelerating!
Explain how the melting of ice is an example of positive feedback
• Lowered albedo = more absorption = more warming = more melting = lower albedo
Why doesn't melting of sea ice directly raise sea level? How does it indirectly raise sea level?
• Melting of sea ice does not directly raise sea level, as this ice is already floating in the ocean and displacing its mass of water - • It does lower albedo, though, indirectly causing sea level rise by causing more land ice to melt
Is CO2 the only greenhouse gas? What is CO2 the biggest contributor to? What are 7 other greenhouse gases?
• No! - it is the biggest contributor to global warming, though Other greenhouse gases include: • Methane (CH4) • Nitrous oxide (N2O) • Chlorofluorocarbons (CFCs) • Hydrochlorofluorocarbons (HCFCs) • Hydrofluorocarbons (HFCs) • Same as HCFCs (man-made) • Perfluorocarbons (PFCs) • Tropospheric ozone
Is climate change something new? What is weather? What is climate, and how is it different from weather?
• No, climate change has happened many times during Earth's history • Weather = short-term changes in atmospheric variables, such as temperature, precipitation, wind, and barometric pressure, over a period of hours or days • Climate = average weather conditions of the Earth or a particular area, especially temperature and precipitation, over periods of at least 3 decades to thousands of years
Loss of sea ice caused what fabled sea route to open up in 2007? This route links what 2 bodies of water by traveling north of Canada? This allows quicker shipping between what 2 areas?
• Northwest Passage • linking the North Atlantic Ocean with the North Pacific Ocean • northern Europe and northern Asia
What would be the average surface temperature of the Earth without the natural greenhouse effect? What is the average surface temperature with the greenhouse effect?
• Our average surface temperature would be a frigid -18 degrees Celsius without the natural greenhouse effect, instead of 15 degrees Celsius
What is permafrost? What percentage of the exposed land in the Northern Hemisphere is underlain by permafrost? How much is Arctic permafrost is expected to thaw?
• Permafrost = frozen soil • Permafrost underlies 24% of then exposed land in the Northern Hemisphere • Global warming is expected to thaw out 10-20% of the Arctic permafrost
What is the phenological spring? How much earlier is it now than in 1959? What type of events have increased? Who is especially vulnerable to these events?
• Phenological spring = the date the buds of specific plants open • Occurring 6 days earlier now than it did in 1959 •Increased frequency of extreme heat-stress events -the elderly
What happens to CO2 levels in winter and in summer? What causes this difference?
• Plants conduct much more photosynthesis during spring and summer, removing CO2 from the atmosphere • In winter, photosynthesis slows down, causing CO2 levels to go up
What is positive feedback? What is the most abundant non-anthropogenic greenhouse gas? what is the lifetime of water vapor in our atmosphere? What is the lifetime of CO2?
• Positive feedback = a situation in which a change in some condition triggers a response that intensifies or amplifies the changed condition • Water vapor is the most abundant nonanthropogenic greenhouse gas • The lifetime of water vapor is only 1-3 weeks • Lifetime of CO2 is 5-200 years (100 years is typical)
What was the pre-industrial level of CO2? How much has the CO2 concentration gone up relative to the pre-industrial level?
• Pre-industrial level was 280 ppm, so since industrialization CO2 has increased by 44%
What is radiative forcing? How much of the radiative forcing caused by greenhouse gases is due to CO2?
• Radiative forcing = the capacity of a gas to affect the balance of energy that enters and leaves Earth's atmosphere • CO2 accounts for 60% of the increased radiative forcing caused by GGs
How will rising sea levels affect our coastal aquifers? How will low-lying islands be affected? What island nation is especially vulnerable?
• Saltwater intrusion into coastal aquifers (groundwater contaminated) • Submersion of low-lying islands - The Maldives
Studies show that higher CO2 and the corresponding warmer temperatures will have what effect on cumulus clouds? What will this allow, and how will it influence temperatures?
• Some studies show that higher CO2 levels, and the corresponding warmer temperatures, will shrink the size of low cumulus clouds, allowing more solar radiation to reach Earth's surface • This will accelerate atmospheric warming
What have human activities done to the Greenland Ice Sheet? How does this influence melting and albedo?
• Soot and dust from human activities has darkened the ice as well, lowering its albedo and speeding up the rate of melting
What are 3 uses of perfluorocarbons? How is tropospheric ozone produced?
• Substitute for CFCs (same as HCFCs) • used to manufacture semiconductors • Emitted during aluminum production • Tropospheric ozone Forms from reactions involving nitrogen oxides produced by burning fossil fuels, light, and volatile organic compounds
What are 3 examples of aerosols? What can soot composed of black carbon particles do to temperature of the atmosphere?
• Sulfate particles from burning fossil fuels • Soot (black carbon particles) from burning fossil fuels can actually warm the atmosphere • Ash and sulfur dioxide particles from volcanic eruptions
How many of Earth's warmest years have occurred since 1990? What does this show?
• The 16 warmest years since the mid-1800s have occurred since 1990, and are probably the warmest years in the past 1000 years • This shows that global warming is a real phenomenon
What is the largest ice sheet? How thick is it?
• The Antarctic Ice Sheet is about 14 million km2 in size and up to 4700 meters thick
What are the GWPs of CO2, methane, nitrous oxide, CFC-12, and sulfur hexafluoride? What does a larger GWP mean?
• The GWPs of some GGs: • CO2 = 1 • Methane = 25 • Nitrous oxide (N2O) = 298 • CFC-12 = 10,890 • Sulfur hexafluoride (SF6) = 22,800 • The larger the GWP, the more that a given gas warms the Earth compared to CO2 over that time period
How does the annual rate of ice loss from the Greenland Ice Sheet compare to the average annual rate of loss in the 20th century?
• The annual rate of loss in the period from 2003 to 2010 was double compared to average annual rate of loss in the 20th century
The Sun emits what 3 forms of electromagnetic radiation? What is another name for infrared radiation?
• The electromagnetic radiation emitted from the Sun is mostly in the ultraviolet (UV), visible, and infrared (also called heat) wavelengths
What happens to the energy output of the Sun over time? Is this causing global warming? Why not?
• The energy output of the Sun The Sun varies over time - could this be the cause of the current warming we are experiencing? • No! Studies show that the energy output from the Sun has actually dropped slightly in the past few decades
How does the warming time of the ocean compare to that of the atmosphere?
• The ocean is warming, but not as fast as the air
What large oceanic circulation pattern has a profound influence on climate? The oceanic conveyor belt redistributes heat from where to where? How does this influence the climate of Northern Europe?
• The oceanic conveyor belt has a profound influence on climate • The conveyor belt delivers heat from the tropics to the N. Atlantic • The Gulf Stream current, a portion of the oceanic conveyor belt, moderates the climate of northern Europe, keeping it from getting too cold
It is important that oceans absorb what substance from the atmosphere? About what fraction of the CO2 pumped into the lower atmosphere by humans is absorbed by the oceans? What does this absorption do to Earth's average temperature and climate?
• The oceans absorb CO2 from the atmosphere • The oceans remove about 1/3 of the CO2 pumped into the lower atmosphere by humans • This helps to moderate Earth's average surface temp and climate
What is happening to the rate of global warming over time? What was the average increase in temperature per decade over the last 100 years? Last 50 years? Last 37 years?
• The rate of global warming is increasing • Over the last 100 years, the average increase was 0.07°C per decade • Over the last 50 years, the average increase was 0.13°C per decade • Over the last 37 years, temp has been increasing at an average of 0.28°C (0.50°F) per decade
What was the rate of sea level rise between 1993 and 2010? What is the rate now? How much is sea level projected to rise by 2100? Why is the range so big?
• The rate was 3.2 mm per year between 1993 and 2010 • The rate of sea level rise is currently 3.4 mm per year • Sea level is projected to rise by 0.26 to 0.82 m by 2100 (depending on carbon dioxide concentrations)
Bubbles of what are present in ice cores? What do they allow us to measure?
• This ice has bubbles of gases that were present in the atmosphere at the time the ice was formed • We can measure levels of gases, such as CO2, O2, etc.
What are the two different isotopes of oxygen? How can we tell if the ice was deposited during a cold period? What about a warm period? How far back does our current ice core data go?
• Two isotopes of oxygen exist, O-16 and O-18 • Ice formed during cold periods has less O-18 • The oldest ice core to date gives us 800,000 years of climate data
The amount of sea ice lost is equivalent to the area of what? What is the approximate rate of sea ice loss in the Arctic? What is the current volume of Arctic sea ice, compared to what it was in 1979?
• U.S. • Arctic sea ice has been decreasing at a rate of approximately 4% per decade - the volume of Arctic sea ice is ¼ of what it was in 1979
What are 2 ways in which nitrous oxide (N2O) is being produced?
• Use of synthetic fertilizers on crops • Burning transportation fuels
How do warmer temperatures cause drought? What will happen to droughts in the future?
• Warmer temperatures = more evaporation = less available freshwater = drought • Droughts will become more frequent and severe
What type of heat capacity does water have? What does this mean?
• Water has a high heat capacity, meaning that it can absorb and store much of the atmospheric heat
What gas is responsible for the majority of Earth's natural greenhouse effect? This gas accounts for what percentage of Earth's greenhouse effect?
• Water vapor • Water vapor is the most abundant greenhouse gas in the atmosphere, and accounts for 66% of the Earth's greenhouse effect
Water vapor exerts what type of feedback on our climate? What does this do to global warming?
• Water vapor exerts a positive feedback on the climate that amplifies warming
What happens to the energy of UV radiation when it strikes the Earth? The energy gets radiated back towards space in what form?
• When the UV strikes the Earth, it loses some of its energy, and is radiated back towards space in the form of infrared radiation
What will happen to hurricanes, in terms of wind speed and rainfall amounts, as global warming continues? From where do hurricanes derive their energy? How will this be influenced by higher water temperatures? What type of events will become more common?
• Wind speeds and rainfall amounts will increase • Hurricanes derive their energy from the evaporation of warm water -more energy • Extreme heat waves and rainfall events will become more common
What is the worst-case scenario for future increases in global temperature? What is the most probable scenario?
• Worst case scenario = 1000 ppm CO2 concentration = 5°C increase (9°F) • Most probable scenario = 550-600 ppm CO2 conc. = 2.5°C increase (4.5°F) • The worst-case scenario would be disastrous for the planet, but even the most probable scenario will cause major problems on Earth
What is happening to zooplankton in the California Current? Why? What is this affecting?
• Zooplankton have declined in the California Current, affecting the entire ecosystem • Zooplankton do best in cold water
What is global warming doing to biodiversity? How? Which organisms are especially affected by loss of sea ice? What are 2 reasons why we are losing wetland species?
• loss of biodiversity through extinction -polar bears and walruses • Wetland species will be lost as wetlands disappear, or saltwater intrusion occurs
What has happened to the number of glaciers in Glacier National Park since 1850? The IPCC estimates that glacier volume will decrease how much by the year 2100?
• lowered by 125 • The IPCC estimates that glacier volume will decrease anywhere from 15-85% by the year 2100
What are 2 examples of how global warming is affecting migration patterns?
• migrating birds will return to their summer homes earlier • whales migrate during the summer to cold waters to feed, they eat krill, krill live in cold waters, as cold waters disappear so will krill
Icefields supply ice to what other things? The Greenland and Antarctic ice sheets contain what percentage of the world's freshwater ice?
• several glaciers • 99% of the freshwater ice on Earth
What is the role of mountain glaciers in the water cycle? Due to loss of glacier ice and snowpack, the flow of the Columbia, Sacramento, and Colorado rivers is expected to decrease how much by 2050?
• storewater as ice during cold seasons and releasing it slowly to streams during warm seasons • 70%
A hotter, more energetic Sun would heat which layer of the atmosphere the most? How is the atmosphere actually being heated (which direction)? What does this indicate?
• stratosphere • from the bottom up, indicating inputs at the surface of the Earth are more important
What is happening to glaciers around the world? What is happening to sea level? What about extreme weather events?
•Glaciers around the world are melting at an unprecedented rate • Sea levels are rising at an unprecedented rate • Extreme weather events, such as severe rainstorms, are occurring at an increasing rate
We are not only losing sea ice, but also what other kind of ice? What is a climate change tipping point? What are 3 types of persistent land ice?
•land ice, at an alarming rate • natural systems could change for 100s to 1000s of years, with possibly catastrophic effects • Glacier • Icefield • Ice sheet
What is locked up in the permafrost, in amounts 50-60 times the amount emitted by burning fossil fuels each year?
carbon
What is the name for thin, wispy, high-altitude clouds? What effect do these clouds have on temperature? Why?
Cirrus, probably warm temperature by preventing some heat from escaping back into space
What volcano erupted in 1991 in the Philippines? What did this do to worldwide temperatures? What are 2 reasons why aerosols are not as potent as greenhouse gases in terms of climate change?
Eruption of Mt. Pinatubo in the Philippines in 1991 caused a worldwide drop in temperature of 1 degree F (0.6 degrees C) • Aerosols don't stay in atmosphere as long as GGs, and only cool during the daytime
What is a glacier? How is an icefield different from a glacier? What is an ice sheet? Where are the 2 major ice sheets located?
Glacier = a large, long-lasting mass of ice formed by the recrystallization of snow, which moves because of its own weight • Icefield = similar to a glacier, but unlike a glacier, which flows in one direction, an ice field flows outward in all directions from its center • Ice sheet = icefield that covers more that 50,000 km2 • The Earth has 2 major ice sheets, one in Greenland and one in Antarctica
What was the CO2 concentration of the atmosphere at the Mauna Loa Observatory in 1958? What is it now? By what percentage has it increased? What is the name given to the curve that shows the increase in atmospheric CO2 levels over time?
Recent CO2 levels at the Mauna Loa Observatory: • 1958 = 316 parts per million (ppm) • January 1, 2016 = 402 ppm • So in the last 57 years, CO2 has increased by 27% • The curve shown to the right is called the Keeling Curve
What are the 2 main causes of sea level rise? Explain how each of these raises sea level. Which one is more important?
Thermal expansion of the ocean • A liquid expands as it warms - the principal behind a thermometer • Melting of land ice (glaciers, ice sheets, and ice shelves) • This increases the amount of water in the ocean, raising sea level
