Another Look at Climate Change – Part 3 What Are Some Possible Effects of a Warmer Atmosphere?

As I mentioned in Part 1, I taught environmental science in the 1990s and the first decade of the 21st century.  Reviewing the textbook used for that course I provide information below that was taught at the time.  The purpose of this series on Another Look at Climate Change is to see whether the predictions made at that time are occurring now.  Part 3 – What Are Some Possible Effects…


One question expressed in the 1990s, as it is today, is why we should be concerned about a few degrees change in temperature.  Many at the time, and today, did not see the change of a few degrees any different than the change that occurred between the months of May and July.  What’s the big deal?  The response is that scientists were not looking at temperature changes over a short period of time, but over longer periods – and how rapidly they were changing.  In the ancient past, the warming of the planet was over thousands to hundreds of thousands of years.  It was now occurring over decades.


The greenhouse effect.
Image: NOAA



Climate models at the time were providing information on where food could be grown, how much could be grown, where droughts and flooding were going to increase, and where wildlife and people might have to live.  And, due to the rapid change in temperatures, that we were going to have to deal with it during the next century.


In 2003 a U.S. National Academy of Sciences report provided a “worst-case scenario” of climate and ecological changes that may occur.  It mentioned that we might reach an irreversible tipping-point and afterwards would not be able to reverse the effects for thousands of years.  It described ecosystems collapsing, low-lying cities would flood, vast wildfires in the forests, grasslands drying out from prolonged droughts.  As mountain glaciers melt, rivers that bring needed drinking water to many would dry up.  There would be pre-mature extinction of up to half of the planet’s species, prolonged heat waves, increased flooding, more destructive storms, and the spread of tropical diseases beyond their current range.


NOTE: Many of these predictions continue to be discussed today – some are occurring. 


The following lists were some of the predictions provided at the time.  Do you see any that have occurred?


Effects if CO2 levels reach 450 ppm NOTE: It was stated at that time that this was unavoidable. 

  1. Forest fires will worsen.
  2. Prolonged droughts will intensify.
  3. Deserts will spread.
  4. Major heat waves become more common.
  5. Conflicts over water supplies increase.
  6. Modest increases in crop production in temperate regions.
  7. Crop yields fall by 5-10% in tropical Africa.
  8. Coral reefs affected by bleaching.
  9. Many glaciers melt faster and threaten water supplies for millions of people.
  10. Sea levels rise enough to flood lo-lying coastal areas – such as Bangladesh.
  11. More people exposed to malaria.
  12. High risk of extinction for Arctic species – such as the polar bear.


  1. In 2024 the Western Fire Chiefs Association reported that though the number of annual wildfires has decreased since the 1990s, the area of land destroyed by wildfires has increased. In the 1990s there was an annual average of 3.3 million acres burned by over 78,000 wildfires in the U.S.  Since 2000 a little over 70,000 wildfires have burned over 7 million acres a year.  This is due to great fuel load due to drier/drought conditions largely caused by climate change.
  2. In 2023 two NASA scientists confirmed that droughts are becoming more frequent.
  3. In 2018 a study reported by the National Science Foundation confirmed that the Sahara Desert has expanded 10% since 1920.
  4. The U.S. EPA reported in 2023 that heat waves in major cities have increased from 2 a year in the 1960s to 6 a year during the 2010s and 2020s.
  5. The University of Southern California reported that conflicts between states over water supply from the Colorado River are occurring. Others indicate that, though nonviolent at this point, conflicts across the planet over water have begun.
  6. Climate change may negatively affect production of corn and wheat by 2030.
  7. Wheat grows well between 15° – 20°C. However, in sub-Sahara Africa temperatures already exceed this.  It is believed that by 2030 wheat production will decrease by 10-20% from 1998-2002 yields.
  8. NOAA reported in 2024 that the world is currently going through a fourth coral bleaching event.  Heat stressed bleaching has been a problem in both the northern and southern hemisphere.
  9. Recent evidence suggests that ancient glaciers are melting more than a quarter of a mile a day, which is faster than the models predicted.
  10. The annual frequency of high tide flooding in the U.S. has more than doubled since 2000 – and is predicted to triple by 2050.
  11. Although the risk of getting malaria in the U.S. is low, cases are increasing. Particularly in Florida and Texas.
  12. I could not find any reports of Arctic species that have gone extinct, but there are numerous reports of species endangered of it. One report stated that at the current rate of warming, polar bears could be extinct by the end of the century.





According to a 2005 study, between 1979 and 2002 the area of the earth’s land experiencing severe drought increased from 15% to 30%.  The 2007 IPCC report predicted this increase would continue.

The 2021 IPCC report stated the same, the frequency increase will continue.

This “browning” of the earth will enhance other ecological problems such as reduced soil moisture that will impact plant growth rates, impacting their ability to remove CO2, enhancing warming, and causing some bodies of water to dry up and rivers enable to reach the sea.


The light color of snow and ice in the polar regions reflects solar radiation helping to cool the planet.  The melting of this snow and ice – which is predicted / and is happening – will increase the absorption of solar radiation increasing warming.  A 2006 NOAA report predicted arctic summers with no floating ice by 2040.  Other studies suggest this will happen as early as 2013.


According to the 2007 IPPC report the average sea level is very likely (90-99% certainty) to rise 0.6-1.9 feet during this century.  In 2022, global average sea level set a record high – 4 inches above the 1993 level… and the 2021 IPPC report stated that we have passed the tipping for sea level rise – it will rise no matter what we do.  We are at a point that coastal communities need to begin planning for this.  Predictions from that time on the affects of sea level rise include:

  1. Degradation or destruction of at least one third of the world’s coastal estuaries, wetlands, and coral reefs.
  2. Disruption of many of the world’s coastal fisheries.
  3. Flooding of low-lying barrier islands and erosion of gently sloping coastlines.
  4. Flooding of agricultural lowlands and deltas where rice is grown.
  5. Contamination of coastal freshwater aquifers with salt water – salt intrusion.
  6. Submergence of low-lying islands in the Pacific, Caribbean, and Indian Oceans.
  7. Flooding of coastal cities.

It is known that the amount of methane (a major contributor to greenhouse gases) locked in the permafrost is 50-60 times great than the amount released by burning fossil fuels.  According to a 2004 study, 10-20% of the Arctic’s permafrost may thaw this century – enhancing warming.  A 2024 report stated that 7% of the current permafrost has melted.


Ocean currents move CO2, warm and cold water across the planet regulating the climate.  There was concern at the time that the melting of the poles (particularly Greenland) could introduce enough freshwater to alter these currents and impact the climates of northern Europe and northeastern North America.  At the time, scientists did not see this as a threat in the near future.


The increase in extreme weather…

Heat waves, droughts, desertification, flash floods from prolonged rain could all happen…

At the time there was disagreement as to whether warming would increase the frequency and intensity of tropical storms and hurricanes.  A 2008 study found that since 1950 for every 1°F increase in ocean temperature in the Atlantic, the number of hurricanes and tropical storms would increase by one third.  It also showed that the number of hurricanes with wind speeds of 110 mph or greater increased by 45%.  NASA stated since 1980 hurricane activity in the North Atlantic has increased but thus far much of this has been from natural climate variation.  However, they did point out one study that showed evidence that the rapid intensification of these storms cannot be explained by natural climate variations and could be connected to climate change.


As the planet warmed it was predicted that ecosystems would shift and change.  Some tropical species would disperse further north – tropicalization.  We have witnessed the expansion of mangroves into the northern Gulf of Mexico.  According to the 2007 IPCC report, about 30% of the land-based plants and animals could disappear.  A 2019 United Nations article stated that the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services reported that the rate of extinction has accelerated.  Warming was also predicted to disrupt biological clocks of migratory species and the Florida Museum of Natural History has already reported this is happening with migrating songbirds.  Warming was also predicted to increase the populations of some species of insects and fungi that damage trees.


There were also predictions to the health of humans…

One will be the increased deaths due to heat waves.  Others would be increased disease from insects and allergy issues from increased pollen.  A 2024 U.S. Environmental Protection Agency report showed that human deaths related to heat waves has increased since 1979.


This snapshot gives us an idea of how well the computer models predicted the impacts of climate change and whether we should pay closer attention to what the current models are saying for the future.  The 2021 IPPC report indicated that we have passed the tipping point for sea level rise and are approaching the tipping point for other possible impacts.


There has been talk about climate for a long time.  Though many things are beginning to happen there is more our world can do to help reduce the risk of these possible impacts.  In Part 4 of this series, we will look at what was suggested a decade ago and how we are doing with those.




Miller, G.T., Spoolman, S.E. 2011. Living in the Environment; Concepts, Connections, and Solutions. 16th Edition.  Brooks and Cole. Belmont CA. 674 pp.


Are Wildfires Increasing or Decreasing in the U.S.?  The Western Fire Chiefs Association.  2024.,due%20to%20approximately%2078%2C600%20fires.


Cawdrey, K. 2023. Warming Makes Droughts, Extreme Wet Events More Frequent, Intense. NASA Explore.


New Study Finds World’s Largest Desert, the Sahara, Has Grown By 10% Since 1920.  National Science Foundation News.


Climate Change Indicators: Heat Waves. 2023. U.S. Environmental Protection Agency.,the%202010s%20and%202020s%20(see%20Figure%201).


The Water Wars of the Future are Here Today. The University of Southern California Today.


Gray, E. 2021. Global Climate Change Impact on Crops Expected Within 10 Years, NASA Study Finds. NASA Global Climate Change News.


Munang, R., Andrews, J. 2014. Despite Climate Change, Africa can Feed Africa. Africa Renewal.


NOAA Confirms Fourth Coral Bleaching Event. 2024. NOAA News and Features.


Harvey, C. 2023. Glaciers May Melt Even Faster Than Expected, Study Finds.  Scientific American Newsletter.


Rising Seas, Flooding Coasts. 2023. Climate Central.


Malaria in the U.S. – Is Climate Change Affecting Disease Spread? 2023. Gavi. The Vaccine Alliance.,as%20dengue%20fever%20and%20malaria..


Climate Change 2021: A Summary for All. 2022. Intergovernmental Panel on Climate Change (IPCC).


A Force of Nature: Hurricanes in a Changing Climate. 2022. NASA Explore.


Van Hoose, N. 2017. Migratory Songbirds Bumped Off Schedule as Climate Change Shifts Spring. Florida Museum of Natural History Research News.


U.S. Environmental Protection Agency. 2024. Climate Change Indicators: Heat-Related Deaths.


Posted: July 3, 2024

Category: Coasts & Marine, Natural Resources
Tags: Climate Change

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