Human Climate Change

How much did temperature increase in 20th century?

+0.8 degrees

What caused climate change in the 20th century?

Milankovitch cycles and solar energy output, greenhouse gases

What are sunspots?

Dark areas on the surface of the sun with intense magnetic activity in 11 year cycle

What is the Maunder Minimum?

Solar radiation 0.25% weaker, making temperature 0.2-0.5 degrees cooler

What is a greenhouse gas?

A gas that absorbs and emits radiant energy within the infrared range causing an increase in atmospheric surface temperature

What are major greenhouse gases?

Water vapour, carbon dioxide, methane, nitrous oxide (N2O), ozone, human made chlorofluorocarbons (CFCs)

What is earth’s most abundant greenhouse gas?

Water vapour at 75%

How does water vapour affect climate?

Responds quickly to changes in air temperature and pressure by changing state which release latent heat, warmer air holds more water vapour

How do non condensing greenhouse gases contribute to atmosphere?

Can remain for centuries, stabilize temperature structures that sustain water vapour and clouds and keep Earth’s climate out of icy state

How do we know carbon emissions are rising?

Data collected from Mauna Loa away from industry influence shows sharply rising graphs

How is carbon dioxide added to atmosphere?

Burning wood and fossil fuels, cellular respiration

How much CO2 stays in atmosphere?

50% stays in atmosphere for 4-1000 years

How is methane released into atmosphere?

Released during decomposition of vegetation in oxygen poor environments: swamps, rice, cattle

How much methane release is natural?

40%, primarily from wetlands, termites and mud volcanoes

How much methane release is human emissions?

60% by fossil fuels, rice, livestock, landfills, wood burning

What is the life of methane in atmosphere?

9 years

How long does nitrous oxide last in atmosphere?

114 years

How much nitrous oxide is naturally produced?

70% from bacteria removing nitrogen from organic matter, especially in soil

How much nitrous oxide is produced by humans?

30% from chemical fertilizers, cropping practices, management of manure, burning, combustion of fuels, production of chemicals, wastewater treatment

What is causing greenhouse gas increase in 20th century?

By products of industrial and domestic energy production, rice and livestock agriculture, 20th century population growth, lifestyle of industrialized world

What is global warming/climate change?

A gradual increase in the overall temperature of the Eatyh’s atmosphere generally attributed to the greenhouse effect caused by increased levels of CO2, CFCs and other pollutants

What committee was created to address climate change?

International Panel on Climate Change (IPCC), Assessment Report 6 in March 2023

What was the result of the first climate model of the 1960s?

Warming of 2.3 degrees and doubling of atmospheric CO2

What do global climate models (GCMs) deal with?

Greenhouse gas and aerosol concentration, ocean temperature and circulation, wind strength and position, cloud cover

What do global climate models predict about temperature?

Increasing volumes of greenhouse gases and increasing surface temperatures

How do we expect temperature to change Northern Hemisphere?

Less areas with ice and snow, decreased sea ice, more thawing of frozen ground, disappearance of glaciers, increased evaporation from farmland

What are the results of raising temperatures?

Heat waves and droughts, longer and more frequent wildfires, precipitation amounts and locations may shift

How is precipitation expected to change?

Increase at high latitudes and decrease in tropics, patterns change, drought and famine risks in areas of decline

How will climate change cause drought and famine?

Low rain + high temperature, expected rains don’t arrive and vegetation dies, food sources shrink

How does famine affect a population?

Slow moving disaster that tends to drive people apart rather than bring them together as they battle for means to survive

What affect would melting glacial ice have?

Sea level rises by 65+ meters since glaciers hold 2.15% of water on earth

What is Arctic or Polar Amplification?

Changes in radiative forcing have largest effects near poles; arctic warming is twice that or mid latitudes

What is permafrost?

Perennially frozen ground where mean annual temperature is 0, 24% or exposed land in Northern Hemisphere

How is permafrost involved in climate change?

It stores 2700 billion tons of organic carbon and can release CO2 and methane

How much is sea level predicted to rise?

10cm in 15 years, 1.2m-2.4m by 2100

What causes sea level rise?

Melting glaciers, thermal expansion of warm water, isostatic adjustments where seawater floods coasts, shrinking them

What is the glacier like in Greenland?

3 million km3, could raise sea level by 7.4m if it all melted

Why are there stability concerns about the Greenland ice sheet?

Rate of melting increasing, more than 1000 meltwater lakes on top of ice sheet and water running under ice sheet, large ice masses falling off reduce support and could lead to collapse, melting faster than expected

What is the Antarctic Ice Sheet like?

29 million km3 ice, if melted sea would rise 60m

What is the stability of the Antarctic Ice Sheet?

Interior seems stable but could collapse, ice loss around coastlines, west ice sheet shrinking

Why is the West Antarctic Ice Sheet shrinking?

Rising air temperatures, warmer ocean currents melting it from the bottom, meltwater pouring down through cracks

What is acidification?

Decrease in ocean’s pH due to increased absorption of CO2

How much is the ocean increasing in acidity?

Decrease from 8.11 to 8.06, 12% more acidic, expected to increase by 170% by 2100

What does ocean circulation look like?

Warm tropical water flows north, cools and becomes dense so that it sinks and flows at intermediate depths towards Antarctica

How is climate change affecting global circulation?

Density contrasts lessening, slowing or stopping deep circulation, global heat transfer shutting down

How can we reduce CO2 emissions?

Improved energy use technology, cap and trade, air scrubbing, ocean fertilization, rock weathering

What is cap and trade?

Market based system setting a cap on emissions

What is air scrubbing?

Development of machines to remove CO2 from atmosphere

What is ocean fertilization?

Stimulate algae blooms that photosynthesize

What is rock weathering?

Crush rock, allow weathering to occur which increases cooling

How can we reduce solar radiation?

Release sulfates into stratosphere, cloud brightening

What is cloud brightening?

Spray sea salts into clouds to increase their albedo

What are the risks of managing solar radiation?

Unknown side effects, requires constant upkeep