It is well established that our world is warming because additional gases such as Carbon Dioxide trap more of the sun’s energy. It is also well known that this warming is changing the climate in a dangerous way.
On this page we examine the effects of warming and climate change on the earth, its ecosystems, animals and people.
The average global temperature has risen by more than 1 degree Celsius since the beginning of the 20th century. And, if climate change isn’t effectively addressed, it is predicted that the temperature will rise to somewhere between 2 and 4 degrees above the previous normal by the end of this century.
In Australia, if carbon emissions continue unabated, the annual number of days over 35 degrees C are expected to increase 4 times by the end of the century, and the number of days over 40 degrees C will likely increase about 7 times.
Heatwaves (defined as 3 or more extremely hot days in a row) kill more people in Australia than bushfires, cyclones, earthquakes, floods, and severe storms combined. And their duration, frequency and temperature are all increasing due to climate change.
Warmer water and storms have damaged almost half of Australia’s coastal habitat.
Around the world
Higher temperatures change land and (especially) sea habitat.
- High water temperature and greater ocean acidity (both the result of climate change) are destroying the Great Barrier Reef, which is important habitat for more than a thousand different species of birds, fish, mammals, reptiles and insects.
- Ice in both polar regions is melting. reducing habitat for animals such as polar bears. The maximum annual extent of Arctic sea ice has been almost halved in the last 40 years (see graph)
Higher temperatures around the world will make some cities uninhabitable and will increase the occurrence of infectious diseases.
- Australia’s biodiversity and climate change. Australian Government.
- Arctic Sea Ice. NASA.
- Heatwaves: Hotter, Longer, More Often. Climate Council of Australia, 2014.
- Heatwaves. NSW Government.
Rainfall is part of the water cycle. Water evaporates, mainly from the ocean, and air currents move it until it cools, condenses and falls as rain.
El Niño, La Niña, and other effects
Climate change leads to changes in air and water movement, and thus changes in rainfall patterns. For example, warmer sea temperatures in the central Pacific Ocean cause air movement that tends to move moist air away from Australia and towards South America. This weather pattern is known as El Niño, and causes warmer, drier weather and drought in eastern Australia.
If the central Pacific cools, the reverse occurs and Australia experiences cooler and wetter weather. Weather patterns in the Indian Ocean (the Indian Ocean Dipole) also have an effect on Australia. These and other weather patterns, of course, also affect climate in other countries.
Here’s the point. Climate change is intensifying El Niño. This means eastern Australia is getting warmer faster than many other places on earth. And it is getting drier, while more rain is falling in the Pacific and in South America.
Rainfall in Australia
Data confirms that Australian weather patterns are changing. It is clear that climate change is already causing lower rainfall and worsening drought in eastern Australia, where most of our food comes from (see graph).
This is slowly making some current forms of farming less viable and exacerbating bushfire conditions (see more below).
Changes in rainfall patterns are a significant problem in many other parts of the world, for example:
- Reduced rainfall is increasing drought and famine in North Africa.
- More concentrated rainfall is eroding soil on steep farming land in Nepal.
- What is El Niño and what might it mean for Australia? Australian Government, Bureau of Meteorology.
- Climate Change is Making El Niños More Intense, Study Finds. Yale Environment 360.
- Climate Change in Australia: Projections for Selected Australian Cities. CSIRO and Bureau of Meteorology.
Bushfires in Australia are becoming more ferocious and destructive. (Claims to the contrary are based on incomplete information and bias – see Fact check: Bjorn Lomborg and bushfires and Fact check: Craig Kelly and last summer’s bushfires.)
For example, the recent 2019/20 summer bushfires in eastern Australia were more destructive of valuable eucalyptus forest and the species which live there than any previous fires recorded.
The Emergency Leaders for Climate Action, a group of dozens of former fire and emergency services chiefs, held a Bushfire Summit in 2020, which concluded that climate change is driving worsening bushfire conditions in Australia, by creating:
- Hotter temperatures.
- A longer fire season.
- Drier vegetation & ‘fuel’.
- More lightning.
NASA reports on the global situation: “Since the 1980s, the wildfire season has lengthened across a quarter of the world’s vegetated surface, and in some places like California, fire has become nearly a year-round risk.”
Bushfires destroy native vegetation and species and property. They also cause deaths and ill health – over 400 people are estimated to have died in the 2019/20 eastern Australia fires because of smoke inhalation over and extended period.
- Unpacking the National Bushfire and Climate Summit, 2020. Emergency Leaders for Climate Action.
- The race to decipher how climate change influenced Australia’s record fires. Nature, January 2020.
- Satellite Data Record Shows Climate Change’s Impact on Fires. NASA.
As snow and glaciers melt, the volume of water in the oceans increases, and the sea level must rise.
In addition, most of the extra heat from global warming is stored in the oceans, so the average ocean temperature is rising. The warmer water expands, and this too raises the water levels around the world.
As shown in the graph, average sea levels have already risen almost a quarter of a metre in a little more than a century. If world temperatures are allowed to continue to rise, this rise could be several times this amount by the end of the century.
Rising sea levels will cause major problems for coastal communities, and is already beginning to cause flooding and storm damage.
- It is making some Pacific Islands less habitable, due to flooding, storm damage and sea water getting into water supply aquifers.
- Rising sea levels, more severe coastal storms and increased snow melt from the Himalayas are combining to increase destructive and deadly flooding in Bangladesh.
- Areas of valuable property in the densely populated New York city are facing increased flooding due to climate change.
- Rising sea levels and increasing coastal storms pose risks to Australia’s coastline, flooding and undermining properties and infrastructure and eroding the coastline.
- Studies predict that rising sea levels will see 40% of Australia’s beaches lost. Already valuable beaches in Sydney, the Gold Coast and elsewhere are being badly eroded.
- Planning for sea-level rise. CSIRO.
- Counting the costs: climate change and coastal flooding. Climate Council.
- Climate Change: Global Sea Level. NOAA.
- Sea Level 101, Part Two: All Sea Level is ‘Local’. NASA.
Storms & hurricanes
The effect of climate change on storms and hurricanes is less certain than other outcomes. But scientists are slowly gathering data that indicates that higher water temperatures are having an effect.
NASA says: “A warming ocean creates a perfect cauldron for brewing tempests.” Storms and hurricanes require relatively warm water temperatures, which is why hurricanes generally form in the tropics.
And while this may (or may not) produce more storms and hurricanes, the evidence suggests that hurricanes are becoming stronger and more destructive.
- There are now more Category 4 and 5 events in the Atlantic Ocean.
- The biggest and most damaging hurricanes are now three times more frequent than they were 100 years ago.
- Australia’s Climate Council has listed many record or near record storm events around the world in recent years.
Increasing storm damage has become a major issue around the world as climate change effects grow.
- Flood damage (from rainfall, storms and rising sea levels) cost $82bn worldwide in 2019, but only a sixth of that was covered by insurance.
- The World Bank says that climate change threatens major economic loss in many countries around the world. Without urgent action, climate impacts could push an additional 100 million people into poverty by 2030 and force over 143 million people in Latin America, South Asia and Sub-Saharan Africa to relocate within their country by 2050.
- In more economically developed countries such as the US and UK, insurance payouts for storm damage are increasing, and insurers are being forced to reconsider their storm policies.
The Climate Council says that “climate change is fuelling more intense and damaging storms”, and “without strong action on climate change, storms and other extreme weather events will continue to become more intense and more damaging”.
Insurers in Australia say premiums will need to rise to account for storm and water damage caused by increasing climate change.
- Climate change and disaster displacement. UNHCR.
- How Climate Change May Be Impacting Storms Over Earth’s Tropical Oceans. NASA.
- Super-charged storms in Australia: the Influence of Climate Change. Climate Council.
- New South Wales erosion: Huge swells leave homes at risk of collapse. BBC News.