Climate Change & Global Warming
Identify The IPCC:
Intergovernmental Panel on Climate Change
The Current Impacts For Humans & Earth
Future Impacts for Humans & Earth
What’s the difference?
Climate is categorized as average weather, based on at least three decades of data
Significant climactic change lasting an extended period of time, several decades or longer constitutes as climate change
“The recent and ongoing global average increase in temperature near the Earth’s surface”
Many human contributions are related to this ideal– elevated production of greenhouse gasses
Global Climate Change
There are always fluctuations in weather from year to year.
Timescale is extremely important when looking at climate data. The overall trend will change depending the timescale.
For example: Over the last 65 million years?
Global Climate Change
For example, over the last 800,000 years?
Side note: modern humans (Homo sapiens) are about 200,000 years old
Global Climate Change
For example, over the last 130 years?
Side note: the Industrial Revolution began in England & Scotland in the late 1700’s
Determining Past Climates
Paleoclimatology – the study of past climates
Scientists use a variety of methods to determine earth’s past climate (I’ve summarized a few here, but there are more):
Oxygen Isotope Analysis of Ocean Sediments
Ice Cores/Dome C in Antarctica
The analysis of tree rings to provide information on past climates.
Certain species of trees grow a new ring each year. This happens in trees that exist in areas where the climate halts their growth at some point during the year (such as cold temperatures or lack of water). So, this happens to trees in high altitude and high altitude areas (such as conifers and deciduous trees). Tropical tree do not grow rings each year.
Oldest Trees in the World? Ancient Bristlecone Pines!
White Mountains, California
1953, established a continuous tree-ring sequence of 8,253 years.
Oxygen Isotope Analysis of Oceanic Sediments
Provides information on climate through the ratio of 16O and 18O
“Lighter” 16O evaporates more readily than 18O when temperatures are warmer.
This ratio can also be examined in ocean floor sediment.
Learn more here – https://earthobservatory.nasa.gov/Features/Paleoclimatology_OxygenBalance /
Palynology – studies pollen trapped in sediment layers at the bottom of lakes and bogs
The sediment can be dated through radiocarbon dating,
Certain plants are better adapted to different climates, so the type of pollen in each layer can provide an indication of climate conditions when the layers were formed.
Also provide data on 18O /16O ratio
Gas bubbles trapped in ice cores (see images on the next slide) also allow for the direct measurement of gasses such as carbon dioxide.
Dome C is located 1750 kilometers from the South Pole, where the Antarctica ice cap is thickest (this is where we’ve extracted the longest ice core sample on Earth).
Ice coring under the European Project for Ice Coring in Antarctica (EPICA) has extracted core dating back 800,000 years (remember that timescale graph earlier?).
The Dome C climate record shows that the present concentration of CO2 in the atmosphere is higher than anytime during the past 800,000 years.
Also shows that increases and decreases in global temperature are closely correlated with changes in concentration—with temperatures high when concentrations are high, and vice versa.
Further, the findings at Dome C closely match the proxy climate record derived from the oxygen isotope analysis of the calcium carbonate in foraminifera (tiny marine creatures) found in oceanic sediments, adding to the scientists’ confidence in the soundness of the Dome C data.
Dome C Data – comparing carbon dioxide and methane concentrations to the overall temperature trend during the last 800,000 years. Do you see a correlation?
Now, let’s take a look at carbon dioxide a little more closely. Carbon dioxide (CO2) is one of the two most important greenhouse gases (the other is water vapor). These act like invisible blankets in our atmosphere. They allow short-wave radiation from the Sun to enter into the atmosphere and reach the surface of earth. The surface then heats up and emits long-wave radiation back out to space. BUT CO2 and water vapor do not allow long-wave radiation to escape as easily (hence the term ”blanket”) and trap that heat in the lower portion of the atmosphere. Most of the time this is a great process, known as the Greenhouse Effect. It keeps the surface of earth at a livable temperature for us. The problem though is when we increase the amount of CO2 in the atmosphere (i.e. add more and more blankets) and heat up the Earth’s surface temperature too much, too quickly. This is the case we are seeing now, and the reason why any solutions to climate change focus on reducing CO2 emissions. The graph above summarizes the concentrations of CO2 (measures in PPM or parts per million) As of April 2018, we are at 407 PPM.
Causes of Long-Term Climate Change
Plate Tectonics & Volcanic Activity
Variations in Earth-Sun relations (Milankovitch Cycles)
Fluctuations in Solar Output (Solar Flares)
Findings for the above – they are factors, but there hasn’t been significant enough changes to account for the most recent temperature trend
Role of the Ocean
Role of Vegetation
Findings for the above – they are factors, but alone they do not account alter climate without other factors (such as carbon dioxide)
Greenhouse Gas Concentrations
Findings for the above – most scientific research/data supports that increases in greenhouse gases (such as carbon dioxide, nitrous oxide, methane, etc.) is the cause of the current climate change trend we are seeing. Over the last century, the burning of fossil fuels, like coal and oil, has increased these concentrations – particularly carbon dioxide. According to the IPCC in it’s Fifth assessment Report, “There’s a more than 95% probability that human activities over the past 50 years have warmed our planet”.
You may be familiar with the phrase, “causation does not equal correlation”. Which means that just because two variables are related, doesn’t mean that one causes the other. In order to establish that CO2 concentrations are the cause of climate change, scientists need to examine all other variables that could change our climate long term. Here is a summary of those other variables:
The IPCC: Intergovernmental on Climate Change
Est. in 1988 by the United Nations Environmental Program & the World Meteorological Organization (link to website is available in Moodle)
A group of thousands of independent scientific experts from around the globe contribute to this organization
Provides an annual assessment report that covers, “the scientific, technical and socio-economical information relevant to understanding the scientific basics of risk of human-induced climate change, its potential impacts and options for adaptation and mitigation” (ipcc.ch)
The IPCC, “does not conduct any research nor does it monitor climate related data or parameters.” (ipcc.ch)
Read the most recent report here: https:// www.ipcc.ch/pdf/assessment-report/ar5/syr/AR5_SYR_FINAL_SPM.pdf
Current Impacts on Humans & Earth
Sea Level Rise
Melting of Glaciers/Ice Sheets
Adding fresh water into oceans, limiting resources and albedo (further warming)
Jakobshavn Glacier: Greenland (Fastest moving with 66ft per day)
As water become warmer– less sinking, or mixing with cooler denser water.
As water evaporates- leaves behind salt, further affecting the circulation (perhaps a cooling– eg 12kya)
Source: Climate Institute & NASA
Current Impact on Oceanic Life
Temperature changes of oceanic water forcing nutrient providing algae to leave– making the coral weak and white
Acid from increased amounts of Caron Dioxide
The Holocene Extinction: The 6th Greatest
During the last 10,000 years:
1500-2009: 875 species went extinct 2009-today: 17,291 species out of the 47,677 known species are considered threatened (36%)
The causation? Humans impact on the environment, or Global Warming.
The next 10,000 years:
Source: iucn.org (International Union for Conservation of Nature)
Projections of Future Climate
A 66 percent change of a doubling of preindustrial CO2 levels with a corresponding temperature increase of 2.0°C to 4.5°C with a best estimate of 3.0°C.
Plant and Animal