Global Change Chapter 19

Global Change Global change- any chemical, biological or physical property change of the planet. Examples include cold temperatures causing ice ages. Global climate change- changes in the climate of the Earth. Global warming- one aspect of climate change, the warming of the oceans, land masses and atmosphere of the Earth.

The Greenhouse Effect When radiation from the sun hits the atmosphere, 1/3 is reflected back. Some of the UV radiation is absorbed by the ozone layer and strikes the Earth where it is converted into low-energy infrared radiation. The infrared radiation then goes back toward the atmosphere where it is absorbed by greenhouse gasses that radiate most of it back to the Earth. http://earthguide.ucsd.edu/earthguide/diagrams/greenh ouse/

Greenhouse Gases Water vapor Carbon dioxide Methane Nitrous oxide Ozone

Greenhouse Gases Anthropogenic Greenhouse Gasses Natural Greenhouse Gasses Anthropogenic Greenhouse Gasses Volcanic eruptions- mainly carbon dioxide Methane – from decomposition Nitrous oxide- from denitrification Water vapor Burning of fossil fuels Agricultural practices Deforestation Landfills Industrial production- CFC’s are an example

Increasing CO2 Concentrations David Keeling began measuring CO 2 in 1958.

Emissions from the Developed and Developing World

Global Temperatures since 1880 Since 1880 temperatures have increased 0.85°C.

Temperatures and Greenhouse Gas Concentrations in Past 400,000 Years No one was around thousands of years ago to measure temperatures so we use other indirect measurements. Some of these are Changes in species compositions Chemical analyses of ice

How We Study Climate Instrumental Records Climate measurements began in 1860s Data from pre 19th century is Estimates Extrapolated Interpolated We have very accurate data since 1960 Improved instrumentation

How We Study Climate Historical Records Paleoproxy records Go back a few centuries Mostly qualitative Books, newspapers, journal articles, personal journals, ships’ logs, travelers’ diaries, and farmers’ logs Paleoproxy records Proxy data- not strictly climatic, but provides insight into climate Tree rings, sediments, ice cores, fossil pollen, corals, and carbon‑14 (14C)

Proxy Climate Records Tree Rings Many trees create one growth ring per year Width, density and ionic composition of the ring are indicative of climate

Proxy Climate Records Ice Cores Polar ice and mountain glaciers have ice records that go back 100s or 1000s of years Oldest is 800,000 years Ice cores have small bubbles of air Can measure carbon dioxide and methane levels from the time the ice was created

Proxy Climate Records Sediment Biological material (ex: pollen) is deposited on the land and stored for extended periods in lake, bog, and pond sediments Pollen is useful Quantity of pollen is an indicator of relative abundance of each plant species Pollen can be dated Can be used to construct a climate history

Proxy Climate Record Coral Coral exoskeleton made of calcium carbonate Carbonate contains isotopes of oxygen Used to determine temp of water in which the coral grew

Proxy Climate Record Carbon-14 and sun sunspots

Solar Cycles The Sun Goes Through Cycles Sometimes hotter, sometimes cooler Documented by differing amounts of isotopes trapped in glacial ice Variability of solar input of energy explains some of the climatic variability too

Putting It Together We know that an increase in CO2 in the atmosphere causes a greater capacity for warming through the greenhouse effect. When the Earth experiences higher temperatures, the oceans warm and cannot contain as much CO2 gas and, as a result, they release CO2 into the atmosphere.

Feedbacks

Consequences to the Environment Because of Global Warming Melting of polar ice caps, Greenland and Antarctica Melting of many glaciers around the world Melting of permafrost Rising of sea levels due to the melting of glaciers and ice sheets and as water warms it expands Heat waves Cold spells Change in precipitation patterns Increase in storm intensity Shift in ocean currents https://weather.com/science/environment/news/climate-trends- future-earth-day

Potential Effects of Global Warming

Consequences to Living Organisms Wild plants and animals can be affected. The growing season for plants has changed and animals have the potential to be harmed if they can’t move to better climates. Humans may have to relocate, some diseases like those carried by mosquitoes could increase and there could be economic consequences.

The Controversy of Climate Change The fundamental basis of climate change- that greenhouse gas concentrations are increasing and that this will lead to global warming is not in dispute among the vast majority of scientists. What is unclear is how much world temperatures will increase for a given change in greenhouse gases, because that depends on the different feedback loops.

The Kyoto Protocol In 1997, representatives of the nations of the world went to Kyoto, Japan to discuss how best to control the emissions contributing to global warming. The agreement was that emissions of greenhouse gases from all industrialized countries will be reduced to 5.2% below their 1990 levels by 2012. Developing nations did not have emission limits imposed by the protocol.

Carbon Sequestration An approach involving taking CO2 out of the atmosphere. Some methods include storing carbon in agricultural soils or retiring agricultural land and allowing it to become pasture or forest. Researchers are looking at cost-effective ways of capturing CO2 from the air, from coal-burning power stations, and from other emission sources. This captured CO2 would be compressed and pumped into abandoned oil wells or the deep ocean.

Paris Climate Conference 2015 At the Paris climate conference (COP21) in December 2015, 195 countries adopted the first-ever universal, legally binding global climate deal. The agreement sets out a global action plan to put the world on track to avoid dangerous climate change by limiting global warming to well below 2°C. The agreement is due to enter into force in 2020. Countries still have to sign it at the UN in April.

Current NASA data Carbon dioxide at 405 ppm Global temp. increased by 1.7 degrees F Global sea ice decreased by 13.3 percent Sea level is increasing by 3mm per year

Climate change headlines March 2017 was second-warmest March on record Climate change is hurting U.S. corn farmers -- and your wallet Bloomberg Adds Climate Change Site To Its Financial News Empire Analysis | The nation is immersed in its warmest period in recorded history The pristine Arctic has become a garbage trap for 300 billion pieces of plastic As sea levels rise, where will all the people go? Record number of billion-dollar weather disasters strikes US in early 2017

Climate Scientists are Confident in their Findings From rising sea levels to retreating glaciers to coral bleaching, human-induced global warming is affecting every corner of our planet. Scientists are confident in this statement because of the large amounts of data collected using satellites and other technological advances.  Ancient paleoclimate evidence collected from tree rings, ocean sediments, coral reefs and layers of sedimentary rocks indicate that current warming is occurring about 10 times faster than the average ice-age-recovery warming, notes NASA.

Worst Case Scenario That is actually hard to say, which is one reason scientists are urging that emissions be cut; they want to limit the possibility of any worst- case scenario coming to pass. Perhaps the greatest fear is a collapse of food production, accompanied by escalating prices and mass starvation. Even with runaway emissions growth, it is unclear how likely this would be, as farmers are able to adjust their crops and farming techniques, to a degree, to adapt to climatic changes. Another possibility would be a disintegration of the polar ice sheets, leading to fast-rising seas that would force people to abandon many of the world’s great cities and would lead to the loss of trillions of dollars worth of property and other assets. Scientists also worry about other wild- card scenarios like the predictable cycles of Asian monsoons’ becoming less reliable. Billions of people depend on monsoons to provide water for crops, so any disruptions could be catastrophic.