Climate Change Evidence Across Scientific Disciplines
Connecting evidence from the atmosphere, oceans, ice, ecosystems, and geology
Climate Change Evidence Across Scientific Disciplines
Connecting evidence from the atmosphere, oceans, ice, ecosystems, and geology
Science - Grade 9-12
- 1
Scientists study climate change using evidence from many fields. Name four scientific disciplines that provide evidence for climate change, and give one type of evidence each discipline uses.
Think about air, water, ice, living things, and rocks.
Atmospheric science uses measurements of greenhouse gases and air temperature. Oceanography uses sea surface temperature, ocean heat content, and sea level data. Glaciology uses glacier retreat and ice sheet mass measurements. Biology uses shifts in species ranges, migration timing, and ecosystem changes. - 2
An ice core contains trapped air bubbles from thousands of years ago. Explain how ice cores provide evidence about past climate and why they are useful for studying climate change today.
Ice cores preserve air bubbles that show past carbon dioxide and methane levels. The ice also contains oxygen isotope ratios that help estimate past temperatures. They are useful because they allow scientists to compare modern greenhouse gas levels and warming trends with natural climate changes from the past. - 3
A graph shows atmospheric CO2 rising from about 315 ppm in 1958 to about 420 ppm in 2023. Calculate the total increase in CO2 and explain why this evidence matters.
Subtract the starting value from the ending value.
The total increase is 105 ppm because 420 ppm minus 315 ppm equals 105 ppm. This evidence matters because CO2 is a greenhouse gas, and a large increase in atmospheric CO2 strengthens the greenhouse effect and contributes to global warming. - 4
Tree rings can be used as climate evidence. Describe what tree rings can reveal about past climate conditions and name one limitation of using tree rings.
Tree rings can reveal information about past growing conditions, such as temperature, rainfall, drought, and length of growing season. A limitation is that tree growth can be affected by factors other than climate, such as disease, fire, soil nutrients, or competition with nearby trees. - 5
A glacier has retreated 1.8 kilometers over 60 years. What is its average retreat rate in meters per year?
First convert kilometers to meters, then divide by the number of years.
The average retreat rate is 30 meters per year. This is found by converting 1.8 kilometers to 1,800 meters and dividing 1,800 meters by 60 years. - 6
Explain how glacier retreat provides evidence for climate change. Include why scientists compare many glaciers instead of relying on only one glacier.
Glacier retreat provides evidence for climate change because glaciers lose mass when melting and sublimation exceed snowfall over time. Scientists compare many glaciers because one glacier can be affected by local conditions, but widespread retreat across regions is stronger evidence of a global warming trend. - 7
Sea level at a coastal station increased by 96 millimeters over 32 years. Calculate the average sea level rise per year at that station.
Average rate equals total change divided by time.
The average sea level rise is 3 millimeters per year because 96 millimeters divided by 32 years equals 3 millimeters per year. - 8
Identify two major processes that cause global sea level to rise as Earth warms, and explain each one briefly.
Thermal expansion causes sea level to rise because warmer seawater takes up more volume. Melting land ice, such as glaciers and ice sheets, adds water to the ocean and also raises sea level. - 9
Oceanographers report that ocean heat content has increased for several decades. Explain why ocean heat content is strong evidence for climate change.
The ocean stores much more heat than the atmosphere.
Ocean heat content is strong evidence because the oceans absorb most of the excess heat trapped by greenhouse gases. A long-term increase shows that the Earth system is gaining energy, even if year-to-year air temperatures vary. - 10
Biologists observe that some plant species now bloom earlier in spring than they did 50 years ago. Explain how this observation can be evidence of climate change.
Earlier blooming can be evidence of climate change because many plants respond to temperature and seasonal timing. If many species in many regions bloom earlier over decades, it suggests that warming is changing biological cycles. - 11
The ratio of carbon isotopes in atmospheric CO2 has changed in a way that shows more carbon from fossil fuels. Explain why fossil fuel carbon has a distinctive isotope signal.
Fossil fuels formed from once-living organisms.
Fossil fuels come from ancient plants, which contain relatively less carbon-13 compared with carbon-12. When fossil fuels are burned, they release CO2 with this isotope pattern, so changes in the atmosphere can show that added CO2 is largely from fossil fuel combustion. - 12
Satellite data show that the lower atmosphere has warmed while the stratosphere has cooled. Explain why this pattern supports greenhouse gas warming more than increased solar output.
Greenhouse gases trap more heat in the lower atmosphere while allowing the stratosphere to cool. If the Sun were the main cause, scientists would expect warming through more layers of the atmosphere, including the stratosphere, so the observed pattern supports greenhouse gas warming. - 13
Climate models are run twice: once with only natural factors such as volcanoes and solar changes, and once with natural factors plus human greenhouse gas emissions. The model with human emissions matches observed warming much better. What conclusion can scientists draw from this comparison?
Compare which model best matches the real observations.
Scientists can conclude that natural factors alone do not explain the observed warming well. The better match when human greenhouse gas emissions are included supports the conclusion that human activities are the main cause of recent global warming. - 14
Explain the difference between weather and climate, and describe why a single cold winter does not disprove global climate change.
Weather describes short-term conditions such as daily temperature, storms, or rainfall. Climate describes long-term patterns averaged over decades. A single cold winter does not disprove global climate change because climate change is identified from long-term global trends, not one season in one region. - 15
Write a short claim-evidence-reasoning response that explains how evidence from at least three scientific disciplines supports the conclusion that Earth is warming.
Use the structure: claim, evidence, reasoning.
A strong response states that Earth is warming and supports the claim with evidence from at least three disciplines. For example, atmospheric science shows rising greenhouse gases and air temperatures, oceanography shows increasing ocean heat content and sea level rise, and glaciology shows widespread glacier and ice sheet loss. The reasoning should explain that these independent lines of evidence all point to the same long-term warming trend, making the conclusion stronger than any single observation alone.