The Impacts of Climate Change &
Outline of Topics: • Climate Change & Global Warming • Identify The IPCC (Intergovernmental Panel on Climate Change) • Data Presentation • The Current Impacts For Humans & Earth • Future Impacts for Humans & Earth
What’s the difference?
vClimate Change v Climate is categorized as
average weather, based on at
least three decades of data
v Significant climactic change
lasting an extended period of
time, several decades or
longer constitutes as climate
vGlobal Warming v “The recent and ongoing
global average increase in
temperature near the Earth’s
v Many human contributions
are related to this process,
which stems from elevated
production of greenhouse
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. o For example: Over the last 65 million years?
Note that the overall trend on the graph is decreasing!
Global Climate Change (continued)
• For example, over the last 800,000 years?
Side note: modern humans (Homo sapiens) are about 200,000 years old
Note that the overall trend on the graph is continuous fluctuations (i.e. steady ups and downs)!
Global Climate Change (continued)
• For example, over the last 130 years?
Side note: the Industrial Revolution began in England & Scotland in the late 1700’s
Note that the overall trend on the graph is increasing!
Determining Past Climates – How do we know what the past climate looked like?
Paleoclimatology - the study of past climates
• Scientists use a variety of methods to determine earth’s past climate (I’ve summarized a few here and on the subsequent slides, but there
are more): o Dendrochronology
o Oxygen Isotope Analysis of Ocean Sediments
o Pollen Analysis
o 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.
Tree Ring Diagram
Oldest Trees in the World? Ancient Bristlecone Pines!
• White Mountains, California • 1953, established a continuous tree-ring sequence of
8,253 years. • Go see them!
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
o The sediment can be dated through radiocarbon dating,
o 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.
o Also provide data on 18O /16O
o Gas bubbles trapped in ice cores
(see images on the next slide)
also allow for the direct
measurement of gasses such as
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?).
o 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.
o 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.
o 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.
Location of Dome C (image on the left) and a look at one of the ice core samples (image on the right)
Dome C Data (graphs to the left): comparing carbon dioxide and methane concentratio ns 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)
o Findings for the above – they are factors, but there hasn’t been significant enough changes to account for the most recent temperature
• Feedback Mechanisms • Role of the Ocean • Role of Vegetation
o 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 o 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
v Est. in 1988 by the United Nations Environmental Program & the World Meteorological Organization (link to website is available in Canvas)
v A group of thousands of independent scientific experts from around the globe contribute to this organization
v 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)
v The IPCC, “does not conduct any research nor does it monitor climate related data or parameters.” (ipcc.ch)
v 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 v Sea Level Rise
v Melting of Glaciers/Ice Sheets vAdding fresh water into oceans,
limiting resources and albedo (further warming)
vJakobshavn Glacier: Greenland (Fastest moving with 66ft per day)
v The Thermohaline vAs water become warmer– less
sinking, or mixing with cooler denser water.
vAs water evaporates- leaves behind salt, further affecting the circulation (perhaps a cooling– eg 12kya)
Source: Climate Institute & NASA
Current Impact on Oceanic Life
v Oceanic Change v Coral Bleaching
vTemperature changes of oceanic water forcing nutrient providing algae to leave– making the coral weak and white
v Ocean Acidification vAcid from increased amounts of
The Holocene Extinction: The 6th Greatest
v During the last 10,000 years: v 1500-2009: 875 species went extinct
2009-today: 17,291 species out of the 47,677 known species are considered threatened (36%)
v The causation? Humans impact on the environment, or Global Warming.
v The next 10,000 years: v Invasive species v Tree Line retreat v Human migrations?
Source: iucn.org (International Union for Conservation of Nature)
Projections of Future Climate
v 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.
v Temperature v Sea-Level v Polar Region v Weather Patterns v Plant and Animal
A great resource: